Guyot Science 2005

GuyotGuyot Science 2005

Department of Geosciences, Princeton University

1 2 Guyot Science 2005

A Summary of the Research Progress and Accomplishments Made by the Faculty Members of the Department of Geosciences During the Year 2005

Last year, January–December 2005, was a transitional year for a number of faculty members of the Princeton Department of Geosciences. In June Bob Phinney transferred to emeritus status, following a distinguished career as a professor and former department chair. We are pleased that Bob has agreed to remain at Princeton, and plans to continue to teach his popular freshman seminar, Active Geological Processes, which has long been an attraction for prospective departmental majors. In July Satish Myneni was promoted to the rank of associate professor with continuing tenure. Two professors were named to endowed chairs: George Philander is now the Knox Taylor Professor of Geosciences and Bess Ward is now the William J. Sinclair Professor of Geosciences. In April, George was inducted into the National Academy of Sciences, raising the departmental membership to four. Nadine McQuarrie, a structural geologist who studies mountain building and other active tectonic processes, completed her ﬁ rst highly successful year as our newest assistant professor. Next year, we will be joined by two new assistant professors, Adam Maloof, a geologist who applies paleomagnetism and other tools to the study of the ancient earth, and Frederik Simons, a geophysicist who is developing a variety of innovative new tools to study the structure and evolution of planetary lithospheres as well as pioneering in the development of a freely drifting submersible vehicle to increase teleseismic coverage in the world’s oceans. In December, François Morel was awarded the Maurice Ewing Medal of the American Geophysical Union and the U.S. Navy, “for his leadership in the revolution in low-temperature aqueous geochemistry that has resulted in a new ﬁ eld of studies at the interface between marine chemistry and biology.” Finally, Allan Rubin was inducted as a Fellow of the American Geophysical Union; this is a prestigious honor restricted to no more than 0.1 percent of the membership each year. More than half of the faculty members in the Department of Geosciences are now Fellows of the AGU. The recent research accomplishments of each member of the geosciences faculty are described in the individual reports that follow. A list of faculty publications during the past two years, 2004-2005, is appended to each narrative report.

Back Row: Rob Hargraves (deceased), Satish Myneni, Greg van der Vink, Guust Nolet, Tony Dahlen, Jorge Sarmiento, John Suppe. Middle Row: Bob Phinney (emeritus), Lincoln Hollister, Peter Bunge, Ken Deffeyes (emeritus), François Morel, Michael Bender, Nadine McQuarrie, Bess Ward, Tullis Onstott. Front Row: Jason Morgan (emeritus), Tom Duffy, Franklyn van Houten (emeritus), Gerta Keller, George Philander, Bill Bonini (emeritus), Allan Rubin. Photo by Pryde Brown, with additions by Laurie Wanat.

3 Michael Bender gases in ice cores, and of dissolved gases in seawater. We also Professor made a modest beginning on 2 new programs of ice core Ph.D., 1970, Columbia University research. Here are some specﬁ c accomplishments. email: [email protected] 1. We prepared for publication papers on the meridional

gradient of O2 in air and its implications for the ocean carbon cycle, on the concentration and isotopic composition of

O2 in Southern Ocean surface waters and their implications for the fertility of these waters, and on technical aspects of deriving a timescale climate records in slowly accumulating ice in East Antarctica. These papers are now either accepted or in revision. We also worked on several other manuscripts that are now in review. 2. Jan Kaiser participated in 2 cruises of the “Atlantic The activities of my laboratory focus on studies of the Meridional Transect” program and made measurements that strongly contradict the hypothesis that shallow, nutrient-poor geochemistry of O2, with applications to understanding the global carbon cycle and glacial-interglacial climate change. ocean waters are chronically net heterotrophic (i. e., that The geochemical properties we study are the concentration respiration exceeds photosynthesis). of O2 in air (which we measure to very high precision), and 3. We began measurements in a collaboration with David 16 the relative abundance of the three stable O isotopes ( O, Marchant, Boston University, to study ice of apparently great 17 18 O, and O) in O2. There are two subjects for the isotopic antiquity in the Dry Valleys, Antarctica. This ice underlies studies: O2 in fossil air extracted from ice cores, and dis- volcanic ash deposits dated as old as 10,000,000 years. The solved O2 in seawater. evidence suggests that the ice is older than the overlying The results inform us about a range of topics. Studies of ash, but this conclusion is highly controversial. If proved, it the O2 concentration (or ratio of O2/N2) in air constrain the would allow us to measure the concentrations of greenhouse fate of fossil fuel CO2 that does not remain in the atmo- gases in bubbles of air trapped in the ice, and determine the sphere. These measurements allow us to partition the “miss- carbon dioxide concentration of the atmosphere at times ing” CO2 between the oceans and the land biosphere. They when Earth was much warmer than at present. We showed also constrain rates of seasonal biological production by the that the gases in the bubbles are original samples of trapped oceans. Finally, they provide a test of models describing the air, and we are currently developing isotopic methods for dat- global interaction of ocean circulation and biogeochemistry. ing the ice. The isotopic measurements of O2 in ice core trapped gases refl ect the relative fertility of Earth’s biosphere, averaged 4. We began a collaboration with Lonnie Thompson, Ohio State University, to date climate records of ice cores he over about 1,000 years. The triple isotope composition of O2 in seawater refl ects the fraction of dissolved O from photo- has collected from tropical and temperate regions. To date 2 our results confi rmed the relatively recent age of the deep synthesis. O2 supersaturation refl ects net production (photosynthesis in excess of respiration); by combining measure- part of one core (ruling out the possibility that the bottom of this core might date back to the last ice age). ments of O2 concentrations and isotopes, we can determine rates of photosynthesis, respiration, and net production in Two-Year Bibliography aquatic ecosystems. Of course rate determinations of these Refereed articles: processes in seawater have been made for many years; what Hendricks, Melissa B., Michael L. Bender and Bruce A. Barnett Net and gross O production in the southern ocean from makes our work new is that our approach does not require 2 measurements of biological O2 saturation and its triple labor-intensive bottle incubations at sea, and our measure- isotope composition, Deep-Sea Research Part I, 51, 1541- ments can be made on large numbers of samples collected by 1561, 2004. colleagues on cruises of opportunity, and returned to the lab. Brook, E. J., J. W. C. White, Annie S. M. Schilla, Michael L. Supplementing the O studies are studies of Ar. In seawa- Bender, Bruce Barnett, Jeffery P. Severinghaus, Kedrick C. 2 Taylor, Richard B. Alley, Eric J. Steig Timing of millennial- ter samples, Ar gives a measure of physical supersaturation scale change at Siple Dome, West Antarctica, during the last due to warming of waters and bubble entrainment. In air glacial period, Quaternary Science Reviews, 24, 1333-1343, samples, the Ar/N2 ratio refl ects seasonal outgassing and 2005. ingassing due to temperature-driven solubility changes, and Bender, M. L., D. T. Ho, M. B. Hendricks, R Mika, M. O. Battle, P. also to atmospheric mixing. P. Tans, T. J. Conway, B. Sturtevant, and N. Cassar Atmo- spheric O2/N2 changes, 1993–2002: Implications for the

Highlights of our research during the past year: partitioning of fossil fuel CO2 sequestration, Global Biogeo- Our primary focus was on preparing papers for publication chemical Cycles, 19, GB4017, doi:10.1029/2004GB002410, and writing proposals for research funding. We continued 2005. our measurements of the O /N /Ar ratio of air, of trapped Hendricks, Melissa B., Michael L. Bender, Bruce A. Barnett, 2 2 Peter Strutton, and Francisco Chavez The triple oxygen

isotope composition of dissolved O2 in the equatorial Paciﬁ c: a tracer of mixing and biological production, Journal of

4 Geophysical Research - Oceans, 110, C12021, doi:10.1029/ Suwa, Makoto, Josepth C. von Fischer, Michael L. Bender, 2004JC002735, 2005. Amaelle Landais, and Edward J. Brook Chronology recon- Kaiser, Jan, Matthew K. Reuer, Bruce Barnett, and Michael L. struction for the disturbed bottom section of the GISP2 and Bender, Marine productivity estimates from continuous the GRIP ice cores: implications for Termination II in Green- oxygen/argon ratio measurements by shipboard membrane land, Journal of Geophysical Research - Atmospheres, in inlet mass spectrometry, Geophysical Research Letters,32, press. 2005. L19605, doi:10.1029/2005GL023459, 2005. Bender, M. L., G. Floch, J. Chappellaz, M. Suwa, J._M. Barnola, T. Blunier, G. Dreyfus, J. Jouzel, and F. Parrenin Gas age-ice Articles in press or submitted: age differences and the chronology of the Vostok ice core, Battle, Mark, Sara Mikaloff Fletcher, Michael L. Bender, Ralph F. 0-100 ka, Journal of Geophysical Research – Atmospheres Keeling, Andrew C. Manning, Nicolas Gruber, Pieter P. Tans, (in review), 2005. Melissa B. Hendricks, David T. Ho, Caroline Simons, Robert Reuer, Matthew K., Bruce A. Barnett, Michael L. Bender, Paul Mika, and Bill Paplawsky Atmospheric potential oxygen: New G. Falkowski, and Melissa B. Hendricks New estimates of Observations and their implications for some atmospheric Southern Ocean biological production rates from O /Ar ratios and oceanic models of the global oxygen and carbon dioxide 2 and the triple isotope composition of O , Deep Sea Re- cycles, Global Biogeochemical Cycles, in press, 2005. 2 search, in review, 2005.

F. Anthony Dahlen boundary beneath Cape Verde, Cook Island and Cape Verde. Department Chair This strong confi rmation of the deep-mantle plumes seen in Professor Raffa’s earlier P-wave-wave resultsresults is signifi cant not only because Ph.D., 1969, University of Cali- the raypath coverage differs, but also because the off-path fornia, San Diego sensitivity of fi nite-frequency S waveswaves differs fromfrom that of email: [email protected] P waves.waves. Raffa left PrincetonPrinceton in SeptemberSeptember to begin a newnew career as a research geophysicist for ExxonMobil in Houston. Fourth-year graduate student Tarje Nissen-Meyer made substantial progress during 2005 on his dissertation project, to compute exact waveform and traveltime sensitivity kernels in a background spherical earth model, using an axially sym- metric spectral element method. Once the method is fully developed, it will be capable of computing the response of a spherical earth to a moment tensor or point force source up In 2005 I continued my longstanding collaboration with to 1-Hz frequency, substantially better than can be achieved Guust Nolet and postdoctoral fellow Raffaella Montelli, with normal-mode summation codes. Individual 2-D codes to account for fi nite-frequency wavefront healing effects are required for the monopole, dipole and quadrupole com- in global seismic traveltime tomography. Raffa and I spent ponents of the source. At the present time, these three source much of the summer repairing a minor error in our ray-theo- types have been successfully implemented in the simple case retical crustal traveltime corrections. As expected, the repairs of an earth model lacking a fl uid outer core. Preliminary led to only minor changes in her P-wave-wave velocityvelocity images results have been submitted for publication as two back-to- (Science 2004), and do not alter the importantimportant conclusion back papers Geophysical Journal International. The next steps that there least six well-resolved plumes—Ascension, Azores, are to account for the core using a displacement potential Canary, Easter, Samoa and Tahiti—that originate in the representation, to optimize the mesh for a realistic spherical vicinity of the core-mantle boundary, as originally proposed earth model such as PREM, and to parallelize the code for by Jason Morgan more than thirty years ago. All of the implementation on a small cluster. This work is being con- observed plumes have a diameter of several hundred kilome- ducted in collaboration with Alex Fournier, who defended ters, indicating that plumes convey a substantial fraction of his Princeton Ph.D. dissertation in December 2003, and who the internal heat escaping from the earth. In a recent paper is now a member of the faculty at the University of Toulouse. submitted to the AGU electronic journal G3, Raffa has gone During the summer of 2005, I collaborated with Ying on to invert S-wave-wave traveltimestraveltimes using fi nite-frequencynite-frequency sensi- Zhou, who is now a postdoctoral fellow working with Jeroen tivity kernels, in order to provide an independent check on Tromp at the Caltech Seismological Laboratory, to develop her very exciting P-wave-wave results.results. InIn fact, her recentlyrecently obtained fi nite-frequency Fréchet sensitivity kernels for surface-wave S-wave-wave images confi rm the presencepresence of the six well-resolvedwell-resolved group-delay and attenuation measurements. Quite unexpect- deep-mantle plumes listed above, as well as the existence edly, we found that a fi nite-frequency group delay exhibits of starting plumes that have not yet risen all the way to the strong sensitivity to the local phase velocity perturbation earth’s surface beneath the Coral Sea, east of Solomon and δc/c as well as to the local group-velocity perturbation δC/C. south of Java, and plume conduits that are poorly resolved in This dual dependence makes the inversion of measured the P-wave-wave tomography extending downdown to the corcore-mantlee-mantle surface-wave group delays for 2-D maps of δC/C a dubious 5 procedure, unless the lateral variations in group velocity are Ampuero, J.-P. & Dahlen, F. A., Ambiguity of the moment tensor, extremely smooth. Bull. Seismol. Soc. Amer., 95, 390-400, 2005. Dahlen, F. A., Finite-frequency sensitivity kernels for boundary Guust Nolet and I are both very excited about a recently topography perturbations, Geophys. J. Int., 162, 525-540, launched collaboration with Ingrid Daubechies in the Princ- 2005. eton mathematic department, to use wavelets and possibly Nolet, G., Dahlen, F. A. & Montelli, R., Travel times of seismic curvelets as a basis for fi nite-frequency tomographic inver- waves: a reassessment, in Seismic Earth: Array Analysis sions. We will be joined in this project by Huub Douma, of Broadband Seismograms, edited by Levander, A. & Nolet, G., Geophysical Monograph 157, American Geophysical a new postdoctoral fellow, who recently received his Ph.D. Union, Washington, D.C., pages 37-47, 2005. from the Colorado School of Mines. Dahlen, F. A. & Nolet, G., Comment on ‘Onsensitivity kernels for Finally, in 2005, I was pleased to be able to continue my ‘wave-equation’ transmission tomography’ by de Hoop and collaboration with Frederik Simons, who is now a member of van der Hilst, Geophys. J. Int., 163, 949-951, 2005. the faculty at University College London, but who will join Zhou, Y., Dahlen, F. A., Nolet, G. & Laske, G., Finite-frequency the geosciences department as our newest assistant professor effects in global surface-wave tomography, Geophys. J. Int., 163, 1087-1111, 2005. in September 2006. We extended our spherical generalization of the one-di- Articles in press or submitted: Simons, F. J., Dahlen, F. A. & Weiczorek, M., Spatiospectral con- mensional time-frequency multitapers of Slepian and Thom- centration on a sphere, SIAM Review, in press, 2005. son to the case of a double polar cap, for application to the Zhou, Y., Nolet, G., Dahlen, F. A. & Laske, G., Global upper-man- so-called “polar gap” problem in satellite geodesy. tle structure from fi nite-frequency surface-wave tomography, J. Geophys. Res., in press, 2005. Two-Year Bibliography Dahlen, F. A. & Zhou, Y., Surface-wave group-delay and attenua- Refereed Articles: tion kernels, Geophys. J. Int., in press, 2005. Montelli, R., Nolet, G., Dahlen, F. A., Masters, G., Engdahl, E. R. Nissen-Meyer, T., Dahlen, F. A. & Fournier, A., Spherical-earth & Hung, S.-H., Finite-frequency tomography reveals a variety Fréchet sensitivity kernels, Geophys. J. Int., submitted, 2005. of plumes in the mantle, Science, 303, 338-343, 2004. Nissen-Meyer, T., Fournier, A. & Dahlen, F. A., A 2-D spectral- Dahlen, F. A., Resolution limit of traveltime tomography, Geo- element method for computing 3-D spherical-earth seismo- phys. J. Int., 157, 315-331, 2004. grams, Geophys. J. Int., submitted, 2005. Zhou, Y., Dahlen, F. A. & Nolet, G., 3-D sensitivity kernels for Montelli, R., Nolet, G., Dahlen, F. A. & Masters, G., A catalogue surface-wave observables, Geophys. J. Int., 158, 142-168, of deep-mantle plumes: new results from fi nite-frequency 2004. tomography, Geoshem., Geophys, Geosystems, submitted, Baig, A. M. & Dahlen, F. A., Statistics of traveltimes and ampli- 2005. tudes of waves in random 3-D media, Geophys. J. Int., 158, Montelli, R., Nolet, G. & Dahlen, F. A., 2005. Comment on ‘Ba- 187-210, 2004. nana-doughnut kernels and mantle tomography’ by van der Montelli, R., Nolet, G., Master, G., Dahlen, F. A. & Hung, S-H., Hilst and de Hoop, Geophys. J. Int., submitted, 2005. Global P and PP traveltime tomography: rays versus waves, Simons, F. J. & Dahlen, F. A., Spherical Slepian functions and the Geophys. J. Int., 158, 637-654, 2004. polar gap in geodesy, Geophys. J. Int., submitted, 2005. Baig, A. M. & Dahlen, F. A., Traveltime biases in random media and the S-wave discrepancy, Geophys. J. Int., 158, 922-938, 2004.

Thomas S. Duffy temperature of the deep mantle. We are exploring crystal Associate Professor structures, phase relations, elasticity, and other fundamental Ph.D., 1992, California Institute properties at these ultra-high pressure conditions. of Technology Experimental capabilities for studying materials at email: [email protected] planetary interior conditions are progressing rapidly. For example, advances in synchrotron diffraction methods have expanded the P-T range accessible to direct measurements all the way up to 200 GPa and 3000 K, while at the same time leading to improved resolution that has resulted in dramatically better ability to recover crystallographic details. In combination with new geophysical observations of the Earth, we can now better address such fundamental questions as the origin of seismic discontinuities, chemical heterogeneity in the mantle, and the nature of the core-mantle boundary My research program focuses on understanding the large- region. scale physical and chemical behavior of Earth and other Phase transitions and crystal structures of deep Earth planets through experimental study of geological materials minerals directly under extreme pressure and temperature conditions. Phase transformation in CaSiO3 perovskite We are using the diamond anvil cell together with laser Experimental studies have shown that the main rock types of heating and optical spectroscopy techniques at pressures and the Earth’s mantle (e.g. peridotite, basalt) transform under

6 lower mantle conditions to assemblages dominated by miner- sistent with theoretical predictions. Upon decompression als in the perovskite crystal structure. CaSiO3 perovskite is without further heating, it was found that the post-perovskite an important phase because it is thought to be the repository phase could still be observed at pressures as low at 12 GPa for many high-charge trace elements (including radioactive and evidence for at least partial persistence to ambient condi- elements). This phase was long thought to possess cubic tions was also obtained. symmetry on the basis of many low-resolution x-ray diffrac- We have recently carried out experiments using glass tion experiments reported over ~20 years. We conducted starting materials with compositions along the MgSiO3- the fi rst high-resolution diffraction study of this material at Al2O3 join to investigate the effects of Al content on the 20-50 GPa [Shim et al., 2002] and showed that the sym- equation of state, transformation pressure, and stability metry of CaSiO3 perovskite at room temperature after laser limits of the new phase (Kubo et al., in preparation). The heating is not cubic, but of lower symmetry, most likely post-perovskite phase was synthesized for compositions with tetragonal. Our result is consistent with theoretical calcula- 0, 5, 15, and 20 mol. % corundum at maximum pressures tions using density functional theory (DFT) and more recent between 145-164 GPa. For the En85Co15 composition, experiments which suggest that the transformation from the the perovskite to post-perovskite phase transformation was low-symmetry to cubic form may occur under certain mantle found to occur at 130 GPa and 1800 K, which is higher by conditions. Such a transition could be accompanied by ~10 GPa than the transition pressure in Al-free samples. In signifi cant anomalies in elastic properties and may therefore contract to earlier studies on pyrope compositions, our work have relevance for interpretation of seismic profi les of the suggests the two-phase (perovskite + post-perovskite) stability mantle. fi eld is narrow, although analysis is complicated by the slug- Post-perovskite phase transition in silicates and germanates gish reaction kinetics. We also fi nd that incorporation of Al The Earth’s core-mantle boundary region, 2900 km below has only a negligibly small effect on the unit cell volume of the surface, is highly complex and potentially holds the key the post-perovskite phase in the 80-160 GPa pressure range. to a host of questions about the planet’s interior and evolu- Due to the extreme high pressures of the transition and tion. Thus, the recent discovery of a post-perovskite phase sluggish transformation rates, studies of the post-perovskite phase of MgSiO3 are challenging. Germanates are known to in MgSiO3 at 125 GPa, close to conditions expected for the D” region has major potential implications for understand- be excellent analogs for silicates as similar phase transitions ing geophysics of the deep mantle. We have been pursuing occur but at signifi cantly lower pressures in germanates. We a number of lines of research related to the post-perovskite have carried out a detailed set of synchrotron x-ray diffraction experiments on the post-perovskite phase of MgGeO in phase. We had previously demonstrated the stability of Mg- 3 which we have synthesized the phase, measured its equation SiO3 perovskite to 108 GPa [Shim et al., 2001] and reported evidence for a potential modifi cation within the perovskite of state and refi ned the crystal structure (Rietveld method) structure. The existence of the post-perovskite phase was over broad pressure intervals. Our equation of state measurements span a range from 7-201 GPa and place new later confi rmed in MgSiO3 on the basis of angle-dispersive diffraction at 144 GPa [Shim et al., 2004]. constraints on the compressibility and structural anisotropy Besides the crystal structure, the equation of state (EOS) of the new phase (Kubo et al., 2005). WeWe could successfully is the most fundamental parameter obtained from high-pres- conduct Rietveld refi nements at very high pressures using sure experiments. Using the laser-heated diamond anvil cell, data obtained between 80 and 110 GPa with both Ar and we have recently investigated the equation of state of coex- NaCl pressure media, including high temperature (1400- 1700 K) data at ~90 GPa. Our structure refi nements provide isting perovskite and post-perovskite (CaIrO3-type) phases synthesized from a natural pyroxene composition with Fe the fi rst experimental constraints on the evolution of bond content close to that expected for the lower mantle (Shieh et distances and angles with compression, thereby providing al., 2005). OurOur measuredmeasured pressure-volumepressure-volume data for the post- insight into the mechanisms by which the structure responds perovskite phase from 12-106 GPa yield a bulk modulus of to compression (Kubo et al., in preparation). The structural 219(5) GPa and a zero-pressure volume of 164.9(6) Å3 when response appears to be generally smooth over the pressure range investigated. Average Mg-O and Ge-O bond lengths at K0’=4. The bulk modulus of post-perovskite is 575(15) GPa at a pressure of 100 GPa. These results are broadly consis- room temperature are consistent with those determined for tent with theoretical calculations and put limits on the effect other germanates and silicates. It is also notable that trends of Fe content on the bulk modulus. Our x-ray diffraction in structure parameters obtained by Rietveld refi nement are data indicate the post-perovskite phase can be formed in this qualitatively consistent with results of our theoretical (DFT) composition at P-T conditions corresponding to ~400-550 calculations. The temperature effect on average Mg-O bond km above the core-mantle boundary. Direct comparison of length is strong while average Ge-O bond length is less sensitive to temperature. volumes of coexisting perovskite and CaIrO3-type phases at 80-106 GPa demonstrates that the post-perovskite phase has One of the most interesting properties of the D” region a smaller volume than perovskite by 1.1(2)%. Using mea- is that it possesses strong (and variable) seismic anisotropy. sured volumes together with the bulk modulus calculated Interpretation of this anisotropy has been limited due to poor from EOS fi ts, we fi nd that the bulk sound velocity decreases constraints on the lattice preferred orientation of D” con- by 2.3(2.1)% across this transition at 120 GPa, again constituents such as the post-perovskite phase. In collaboration

7 with R. Wenk’s group at Berkeley, we have carried out the diamond anvil cell using fi nite element calculations (Kiefer fi rst experimental deformation study of the post-perovskite and Duffy, 2005). WeWe carried out simulations using a phase (of MgGeO 3 composition) in the diamond anvil cell at realistic experimental geometry (including insulation layers 104-130 GPa and ambient temperature (Merkel et al., 2005). between the diamonds and sample) to investigate the factors Previous phenomenological considerations had suggested controlling development of axial and radial thermal gradi- that (010) or (001) may be the dominant slip planes, based ents for optically thin samples. The two key parameters for on either the nature of layering in the structure or compari- controlling the axial thermal gradient are the ratio of sample son of theoretical elastic constants with seismic constraints. to insulator thermal conductivity and the ratio of the sample However, our results showed that slip on (100) or (110) thickness to total gap between the diamonds. We also sys- planes dominated plastic deformation, in good agreement tematically quantifi ed the magnitude of the axial temperature with a recent independent theoretical study which found that gradients as these parameters are varied. On-going work (110) slip could produce a series of polytype structures inter- is focused on simulating more closely the actual complex mediate between perovskite and post-perovskite. With the sample geometries that are used in practice for both CO2 assumption that silicate post-perovskite behaves similarly at and Nd:YLF laser heating. For example, we have simulated lower mantle conditions, a quantitative model of this phase’s single- and double-sided hot plate geometries, single- and contribution to seismic anisotropy in D” was constructed. double-sided heating of metallic samples and the micro-fur- Studies of the post-perovskite phase remain challenging and nance geometry. We have also systematically investigated there are many unanswered questions that will be a focus the effects of different laser modes. The results in some cases for future research. Our equation of state studies will be confi rm preconceptions, but in several cases rather surpris- extended to more complex compositions and new analytical ing results are obtained. These calculations promise to yield techniques for examining the quenched samples are being insights that will lead to improved experimental designs to adopted. Plastic deformation studies will soon be extended yield more homogeneous pressure-temperature conditions in to silicate compositions. the sample.

Phase transitions in SnO2 to megabar pressurespressures Elastic properties of minerals and structure of the mantle There are many other systems with potentially interesting The elastic tenor is fundamental to a range of solid-state phase relations in the Mbar regime to be explored. As one phenomena including elastic wave propagation, mechanical example, the metal dioxides exhibit extensive polymorphism stability, interatomic interactions, material strength, equation at high pressures, and a variety of transformation pathways of state, and phase transition mechanisms. The single-crystal leading to highly coordinated structures have been uncov- elastic properties of minerals are essential for interpretation ered. Some high-pressure polymorphs in these systems have of the seismic velocity structure of the Earth’s mantle. De- very high bulk moduli and may qualify as strong or even spite this importance, the elastic properties of many mantle superhard solids. Many of these phases have been investi- minerals are poorly constrained, particularly for low-sym- gated as analogs for SiO2 as they exhibit similar sequences of metry species at elevated pressures. Brillouin scattering is a transitions but at lower pressures compared with silica. Our method whereby one can measure the complete elastic tensor high-pressure and high-temperature x-ray diffraction study by recording the frequency shift induced in scattered laser of SnO2 demonstrates the existence of four phase transitions light by thermally generated sound waves. We are using this during compression to 117 GPa. The observed sequence of technique in the diamond anvil cell to investigate the single- high-pressure phases for SnO2 is rutile-typerutile-type (P42/mnm) → crystal elastic properties of a variety of minerals at pressures CaCl2-type (Pnnm) → pyrite-type ( ) → ZrO2 ortho- corresponding to depths as great 1000 km. rhombic phase I (Pbca) → cotunnite-type (Pnam). The Elasticity of olivines and garnets latter two phases were observed here for the fi rst time in this The single-crystal elasticity of fayalite (Fe2SiO4) was mea- system. The bulk moduli for the Pbca (259 GPa)GPa) and Pnam sured to 12 GPa by Brillouin scattering at ambient tempera- (417 GPa) phases of SnO determined by fi tting pressure- 2 ture (Speziale et al., 2004), more than an order of magnitude volume data to the second-order Birch-Murnaghan equa- higher pressure than previous investigations. Fayalite is tion of state indicate these high-pressure phases are highly challenging because it is Fe-rich, of low symmetry (ortho- incompressible – although the potential role of deviatoric rhombic), and good crystals are rare. Nevertheless, we could stress still needs better characterization. Rietveld refi nements recover the 9 elastic stiffness moduli as well as crystal orien- of powder diffraction patterns for both phases have been tation information by an extensive measurement program successfully carried out. Our static high-pressure results also using several natural crystals. Our results demonstrate enable us to provide an interpretation for previous shock unequivocally that the bulk modulus of olivine increases with compression data that show evidence for two discontinuities iron content, and this effect is enhanced by the application of along the Hugoniot curve. Our results indicate that the fi rst pressure. The shear constants C44 and C55 show non-linear transformation may be associated with the formation of the pressure dependence at P>5 GPa, and this leads to non-linear Pbca phase whereaswhereas the second transformation is consistent behavior in the aggregate shear modulus as well. The soften- with the cotunnite-type phase. ing of C44 is comparable to the behavior observed in Mg-rich Finite element simulations of the laser-heated diamond cell olivines, but softening of C55 is much stronger in the Fe-rich We have examined the thermal structure of the laser-heated composition. This shear softening of high-pressure meta- 8 stable fayalite is likely connected to the previously observed longitudinal moduli, C11/C33, decreases from 3.3 at ambient pressure-induced amorphization above 35 GPa. pressure to 1.2 at 15 GPa. We have also carried out single-crystal elasticity studies The epidote family is a group of hydrous Ca-Al silicates of three natural garnets (grossular, almandine-pyrope, and that may be important water carriers in cold subducting andradite) to above 11 GPa (JiangJiang et al., 2004a; JiangJiang et al., slabs. In general, little is known about the elastic properties 2004b). Garnets are major constituents of the Earth’s upper of Ca-Al silicates. Our measurements of the elastic tensor mantle. They have high symmetry and exhibit a great deal of the epidote-member zoisite at ambient pressure (Mao et of compositional variability, making them an ideal testing al., in preparation) place the fi rst experimental constraint on ground for our understanding of elasticity variations in min- zoisite’s shear modulus and resolve discrepancies in the bulk eral systems. In combination with other Brillouin scattering modulus from static compression experiments. data for pyrope, our results allow us to constrain the effect In addition to continued characterization of single-crys- of Fe-Mg substitution on the dodecahedral site in pyrope- tal elastic properties of important mantle phases and their almandine and Fe-Al substitution on the octahedral site in variation with chemistry and structure, we are also focusing andradite-grossular at high pressures. This was not possible future efforts on examining elastic anomalies associated with previously due to systematic differences between results at high-pressure phase transitions. Over the longer term, we high pressures from different experimental techniques. Bril- plan to develop equipment for carrying out Brillouin scat- louin scattering measurements (at ambient or high pressures) tering at simultaneous high pressures and temperatures, and and pressure-volume equation of state data were shown to to extend measurements to higher pressures, particularly for be a powerful combination for evaluating the reliability and polycrystalline samples. potential pitfalls of static compression measurements (e.g. Yield strength at high pressures deviatoric stress effects, parameter tradeoffs). The yield strength of materials at high pressure is a funda- Global seismological and geodynamic models require an mental property that has not yet been well characterized. assessment of not only thermal effects on seismic velocities Static strength determination is a preliminary step toward but also compositional effects. Our new elasticity measure- eventual characterization of the complete fl ow laws that ments together with selected values from the literature have govern rheological properties at high pressure or deep Earth allowed us to comprehensively evaluate the sensitivity of conditions. Among the basic questions are how pressure af- seismic velocity to composition, pressure, and temperature fects yield strength, how relative strengths of different classes for major upper mantle minerals (Speziale et al., 2005). of materials compare at ~1 Mbar, and whether theoretically Logarithmic compressional and shear velocity variations with predicted strength inversions (e.g. strengths of rare gas solids respect to iron content are most strongly sensitive to crystal exceeding those of metals) can occur at ultrahigh pressures. structure but pressure and temperature effects may also be Knowledge of strength properties is also important for opti- important at upper mantle conditions. As one example of mizing the design and performance of high-pressure appara- the fi ndings from this study, the very different responses of tus. Quantitative evaluation of differential stresses developed olivines and garnets to iron substitution gives rise to signifi - under various pressure-transmitting media is one example in cant variations in the sensitivity of different rock types to this regard. Elasticity and strength are interconnected prop- iron concentration in accordance with their garnet content. erties that play a mutual role in several basic areas of high- Velocities in mid-ocean ridge basalts are thus much less af- pressure science such as development of accurate pressure fected by variations in iron content than other rock types calibration. Interest in strength properties is also driven by such as harzburgite. These differences need to be accounted several themes in current materials research including theo- for in evaluating the effects of Fe variability on seismic veloc- retical determinations of ideal shear strength, the connection ity heterogeneity. between strength and particle size in the nano-crystalline Elasticity of hydrous minerals realm, and the search for new super hard solids. The elastic properties of subduction zone minerals are In the radial x-ray diffraction technique, a sample is necessary for understanding basic features of the subduction compressed in a diamond cell under intentionally non-hy- factory including the existence and distribution of hydrous drostatic conditions and the lattice strain is measured as a phases and the effect on seismic wavespeeds of thermal and function of angle from the loading axis using synchrotron metamorphic processes. Modeling of seismic velocities in x-rays. Such studies can constrain yield strength and provide subduction zones is greatly limited by lack of constraints on insights into other properties including elastic moduli, equa- the elastic properties of the metamorphic phases expected to tion of state, and texture development to very high pressures. exist there. We have begun to address this problem by mea- In ongoing research over the last seven years, we have used suring the elastic tensors (at ambient and high pressures) of a this method to characterize the strength of a suite of met- suite of hydrous minerals including brucite, diaspore, alunite, als, oxides, silicates, and nitrides. Our recent studies have and zoisite. The elasticity of brucite has been measured to 14 included: tungsten (He and Duffy, 2005), platinum (Kavner

GPa (JiangJiang et al., 2005). BruciteBrucite shoshowsws highly anomalous and Duffy, 2003); MgGeO 3 post-perovskite (Merkel et al., elastic properties including the largest shear modulus pres- 2005), SiOSiO2 (Shieh et al., 2002), CaSiOCaSiO3 (perovskite) (Shieh sure derivative (Gʹ=3.6) yet measured. The elastic anisotropy et al., 2004), CaO (Speziale et al., 2005), B6O (He and Duffy, of brucite changes strongly with pressure. The ratio of the 2004), and cubic-Si3N4 (Kiefer et al., 2005). In general, 9 strength increases with compression at a rate greater than He, D. W. and T. S. Duffy, Equation of state and strength of the shear modulus, implying signifi cant strain hardening boron suboxide from radial x-ray diffraction in a diamond cell under nonhydrostatic compression, Physical Review B, 70, under diamond cell loading conditions. At pressures of 20-80 184121, 2004. GPa, metals typically exhibit strengths of 1-3% of the shear Jiang, F., S. Speziale, and T. S. Duffy, Single-crystal elasticity of modulus, G. For silicates, six-coordinated silicates exhibit grossular- and almandine-rich garnets to 11 GPa, Journal of lower strengths relative to their shear modulus (2-4% G) Geophysical Research, 109, B10201, 2004. compared with four-coordinated silicates (4-7% G). StrongStrong Shieh, S. R., T. S. Duffy, and G. Shen, Elasticity and strength of calcium silicate perovskite at lower mantle pressures, Phys- covalent oxides, silicates, and nitrides such as ringwoodite, ics of the Earth and Planetary Interiors, 143 144, 93-106, boron suboxide, and spinel-structured silicon nitride possess 2004. yield strengths that can approach 10% of the shear modulus. Shim, S.-H., T. S. Duffy, R. Jeanloz and G. Shen, Stability and The maximum strength value we have measured is 28 GPa crystal structure of MgSiO3 perovskite to the core-mantle boundary, Geophysical Research Letters, L10603, 2004. for B6O at 65 GPa confi ning pressure. The general increase in strength with pressure for all material classes implies that Yin, H. Z., K. D. Hobart, F. J. Kub, S. R. Shieh, T. S. Duffy, J. C. Sturm, High-Ge content SiGe islands formed on compliant most materials are “strong” at megabar pressures if one recog- oxide by SiGe oxidation, Applied Physics Letters, 84, 3624- nizes that the strength of high-grade steel at ambient pressure 3626, 2004. is ~2 GPa. Furthermore, the consistency of general strength Shim, S.-H., T. S. Duffy, R. Jeanloz, C.-S. Yoo, and V. Iota, Ra- trends across material classes suggests that reasonable em- man spectroscopy and x-ray diffraction of phase transitions pirical predictions of strength in the multimegabar pressure in Cr2O3 to 61 GPa, Physical Review B, 69,144107, 2004. Jiang, F., S. Speziale, S. R. Shieh, and T. S. Duffy, Single-crystal regime can now be made, and this is borne out by our recent elasticity of andradite garnet to 11 GPa, Journal of Physics: data on tungsten metal. Condensed Matter, 16, S1041-S1052, 2004. Combination of radial x-ray diffraction and Brillouin Speziale, S., F. Jiang, and T. S. Duffy, Compositional depen- scattering at high pressures is a potentially powerful tech- dence of the elastic wave velocities of mantle minerals: nique for constraining mechanical properties at high pres- Implications for seismic properties of mantle rocks, Structure, Composition, and Evolution of Earth’s Mantle, edited by R. sures. We carried out a study of calcium oxide, CaO, by both van der Hilst, J. D. Bass, J. Matas, and J. Trampert, AGU, Brillouin scattering (to 23 GPa) and by radial nonhydrostatic Washington, DC, 303-323, 2005. x-ray diffraction (to 65 GPa) (Speziale et al., 2005). Cal- Duffy, T. S., Synchrotron facilities and the study of deep plane- cium oxide supports a low differential stress of ~1% of the tary interiors, Reports of Progress in Physics, 68, 1811-1859, shear modulus (<2 GPa at high pressures). The Brillouin 2005. results show a softening of C and consequent increase in the Yin, H., K. D. Hoburt, R. L. Peterson, S. R. Shieh, T. S. Duffy, J. 44 C. Sturm, Tunable uniaxial vs biaxial in-plain strain in inte- elastic anisotropy in qualitative agreement with theoretical grated silicon and silicon-germanium thin fi lms using compli- predictions. Over the common pressure range, Brillouin and ant substrates, Applied Physics Letters, 87, 061922, 2005. radial diffraction data yield results in very good agreement Kiefer, B., S. R. Shieh, T. S. Duffy, and T. Sekine, Strength, elas- for the elastic tensor. However, the radial diffraction data ticity, and equation of state of nanocrystalline cubic silicon diverge from the extrapolation of Brillouin results at higher nitride (c-Si3N4) to 68 GPa, Physical Review B, 014102, 2005. pressures, perhaps related to the onset of plasticity or modifi - Shieh, S. R., T. S. Duffy, and G. Shen, X-ray diffraction study cation to stress/strain continuity relationships. of phase stability in SiO2 at deep lower mantle conditions, There are a number of directions for future develop- Earth and Planetary Science Letters, 235, 273-282, 2005. ments in this area. Additional measurements are needed for Kiefer, B. and T. S. Duffy, Finite element simulations of the laser- both the softest and hardest materials; the former to better heated diamond anvil cell, Journal of Applied Physics, 97, 114902, 2005. quantify stress states actually achieved in experiments, and the latter to better characterize the properties of ultrahard Other miscellaneous publication: Duffy, T. S., Deeper understanding, Nature, 430, 409-410, 2004. solids. On the technical side, advances in diamond cell Rubie, D. C., T. S. Duffy, and E. Ohtani, New developments in technology will be pursued to improve the capabilities of the high-pressure mineral physics and applications to the Earth’s diamond cell as a deformation device with the goal toward interior, introduction to special issue, Physics of the Earth eventual direct examination of rheological properties at very and Planetary Interiors, 143-144, 1-3, 2004. high P-T conditions. Yin, H., K. D. Hobart, S. R. Shieh, R. L. Peterson, T. S. Duffy, and J. C. Sturm, Interference-enhanced Raman Scattering Two-Year Bibliography in Strain Characterization of Ultra-thin Strained SiGe and Si Books: Films on Insulator, in High-Mobility Group-IV Materials and Rubie, D. C., T. S. Duffy, and E. Ohtani, editors, New Develop- Devices, edited by M. Caymax, E. Kasper, S. Zaima, K. Rim, ments in High-Pressure Mineral Physics and Applications to and P. F. P. Fichtner, Materials Research Society, Warren- the Earth’s Interior, Elsevier, Amsterdam, pp. 625, 2004. dale, Pa, vol. 809, pp. B3.6.1-B.3.6.3, 2004. Chen, J., Y. Wang, T. S. Duffy, G. Shen, and L. Dobrzhinetskaya, Advances in High Pressure Technology for Geophysical Ap- Articles in press or submitted: plications, Elsevier, Amsterdam, pp. 512, 2005. Jiang, F., S. Speziale, and T. S. Duffy, Single-crystal elasticity of brucite, Mg(OH)2, to 14 GPa by Brillouin scattering, Physical Refereed articles: Review B, submitted, 2005. Speziale, S., T. S. Duffy, and R. J. Angel, Single-crystal elasticity 7He, D. W., and T. S. Duffy, Static strength of tungsten to 69 of fayalite to 12 GPa, Journal of Geophysical Research, 109, GPa, Physical Review B, submitted, 2005. B10201, 2004.

10 Merkel, S., A. Kubo, L. Miyagi, S. Speziale, H.-k. Mao, T. S. Speziale, S., S. R. Shieh, and T. S. Duffy, High-pressure elastic- Duffy, and H.-R. Wenk, Plastic deformation of MgGeO¬3 ity of calcium oxide: A comparison between Brillouin scat- post-perovskite at lower mantle pressures, Science, in press, tering and radial x-ray diffraction, Journal of Geophysical 2005. Research, in press, 2005. Shieh, S. R., A. Kubo, T. S. Duffy, V. B. Prakapenka, and G. Kubo, A., B. Kiefer, G. Shen, V. Prakapenka, R. J. Cava, and T. Shen, High-pressure phases in SnO2 to 117 GPa, Physical S. Duffy, Stability and equation of state of MgGeO¬3 post- Review B, in press, 2005. perovskite phase to 2 Mbar, Geophysical Research Letters, Shieh, S. R., T. S. Duffy, A. Kubo, G. Shen, V. B. Prakapenka, N. submitted, 2006. Sata, K. Hirose, and Y. Ohishi, Equation of state of the post- perovskite phase synthesized from a natural (Mg,Fe)SiO3 orthopyroxene, Proceedings of the National Academy of Sciences, in press, 2005.

Lincoln S. Hollister Bhutan. With my colleague Djordje Grujic at Dalhausie Professor University, we have defi ned a process in mountain building, Ph.D., 1966, California Institute based on our studies in Bhutan. This process involves the of Technology rapid extrusion of a low viscosity, partially melted orogenic email: [email protected] channel from lower crustal depths. It was published in 2002. In 2005 we completed an article on pulsed channel fl ow in Bhutan. This rationalizes seemingly contradictory fi eld data to the theoretically based channel fl ow model of Beaumont and others. I have helped recruit Bhutanese students to study geology in USA. Two recently received MS degrees at UTEP, and one of these, Tobgay Tobgay, is expected to come to Princ- eton for a Ph.D. Lamellar magnetism. Following up on our hypothesis How are mountains and continental crust made? These (Hollister, et al, 2004) that reheating of ilmenohematite are the major questions driving my research and teaching. may explain anomalous remanent magnetization in rocks I interpret the pressure-temperature-time-strain history of along the west coast of North America, I am collaborating rocks in the context of the tectonic processes operating on on a NSF proposal funded through UC Berkeley to test the the continental crust. My contributions are based on direct hypothesis. The graduate student working on the project observation of the products of mountain building. I have is one of our former undergraduate students. We may be forged collaborations with people in other disciplines and headed for a solution to the Baja British Columbia contro- work in an interdisciplinary mode where the objective is to versy, which holds that parts of western Canada traveled from achieve results unattainable by individual investigators. I latitudes corresponding to Baja California during the latest also help students learn how to use fi eld observations in the Cretaceous. construction of hypotheses, and for eliminating alternatives. Two-Year Bibliography My research is on three fronts: the origin of the Coast Refereed articles: Mountains of British Columbia, the origin of the Himalayas Hollister, L. S., R. B. Hargraves, T. S. James, and P. R. Renne, in Bhutan, and the application of lamellar magnetism for The paleomagnetic effects of reheating the Ecstall pluton, resolving the Baja British Columbia controversy. British Columbia. Earth and Planetary Science Letters v.v. 221, 397 407, 2004. Batholiths. My biggest research commitment for the next Other miscellaneous publications: few years is the new multidisciplinary collaboration, called Clowes, R.M., L.S. Hollister, G.Woodsworth, BATHOLITHS: BATHOLITHS, which proposes to resolve the continental How the Coast Mountains of British Columbia Formed. Infor- crust composition paradox: although continental crust begins mational Brochure for EA and Outreach. 16pp. http://www. as accreted island arcs the average composition of continental eos.ubc.ca/research/batholiths/, 2005. crusts is more silicic than that of island arcs. Before becom- Clowes, R.M., L.S. Hollister, G. Woodsworth, Batholiths: learning how the Coast mountains of British Columbia formed. ing stable continental crust, the original island arc composi- Informational sheet; 2 pp. http://www.eos.ubc.ca/research/ tion is modifi ed by processes that are not understood. This batholiths/, 2005. is a fundamental problem in the earth sciences. The disci- Articles in press or submitted: plines of BATHOLITHS include active and passive source Hollister, L.S. & D. Grujic,, in press, Pulsed Channel Flow in seismology, geochemistry, structural geology, and petrology. Bhutan. Geological Society of London Special Publica- Most of these endeavors are underway, but the active source tion on Channel Flow, Ductile Extrusion and Exhumation of seismology experiment has been delayed due to ship sched- Lower-mid Crust in Continental Collision Zones. uling problems and to complexities in obtaining Canadian Hollister, L.S., J. Diebold, T. Das, in revision, Whole crustal response to Late Tertiary extension near Prince Rupert, British environmental permits. For information on the permitting Columbia. Canadian J. Earth Sciences. process, see http://www.eos.ubc.ca/research/batholiths/ 11 Two-Year Bibliography Gerta Keller Refereed articles: Professor Keller, G., Paleoecology of Late Maastrichtian-early Danian Ph.D., 1978, Stanford Univer- planktic foraminifera in the eastern Tethys (Israel and Egypt). sity J. Foram. Res., 34(1): 49-73, 2004. email: [email protected] Keller, G. and Pardo, A., Paleoecology of the Cenomanian- Turonian Stratotype Section (GSSP) at Pueblo, Colorado. Marine Micropleontology, 51: 95-128, 2004. Keller, G., Stueben, D., Berner, Z. and Adatte, T., Cenomanian- Turonian δ13C, δ18O, sea-level and salinity variations at Pueblo, Colorado. Paleoclimatol. Paleoecol. Paleogeogr., 211, 19-43, 2004. Keller, G., Adatte, T., Stinnesbeck, W., Rebolledo-Vieyra, M., Urrutia Fucugauchi, J., Kramar, U. and Stueben, D., Chicxu- lub crater predates K-T boundary mass extinction.PNAS, 101(11): 3721-3992, 2004. Keller, G., Adatte, T., Stinnesbeck, W., More Evidence that During the past two years the 15 year long research proj- Chicxulub predates KTboundary. Meteoritics and Planetary ect on the Cretaceous-Tertiary boundary impact and mass Science (MAPS), 39,(6/7), 1127-1144, 2004. extinction has culminated in spectacular success with the Wolfgang Stinnesbeck, Gerta Keller, Thierry Adatte, coming together of empirical evidence from sedimentol- Markus Harting, Doris Stüben, Georg Istrate and Utz Kra- mar: Yaxcopoil-1 and the Chicxulub impact. International ogy, stratigraphy, paleontology, mineralogy, geochemistry Journal of Earth Sciences, Volume 93, Number 6, pp. 1042 and paleomagnetic stratigraphy. The environmental history - 1065, 2004. revealed by all of these disciplines indicates that the current Keller, G. and Pardo, A., Disaster Opportunists Guembelitrinidae impact mass extinction scenario can no longer be supported. – Index for Environmental Catastrophes. Marine Micropale- The Chicxulub impact, commonly believed to be the cause ontology, 53, 83-116, 2004. for the KT mass extinction, predates this mass extinction by Adatte, T. Keller, G., Stueben, D., Harting, M., Kramar, U., Stinnesbeck, W., Abramovich, S. and Benjamini, C., Late 300,000 years. A second impact together with major Deccan Maastrichtian and K/T paleoenvironment of the eastern Te- volcanism is the likely cause for the mass extinction. thys (Israel): mineralogy, trace element and platinum group Our new theory and its supporting evidence has been elements, biostratigraphy and faunal turnovers. Bulletin carried by news outlets all over the world and more than Société Géologique de France, 176, 1, 35-53, 2005. 100 news articles have appeared in international magazines, Keller, G., Biotic effects of late Maastrichtian mantle plume volcanism: implications for impacts and mass extinctions. including top journals like Nature, The Economist, La Lithos, 79, 317-341, 2005. Recherche, Der Spiegel, Focus, Facts etc. and the Geological Keller, G. Impacts, volcanism and mass extinctions: random Society of London has sponsored a debate on my team’s work coincidence or cause & effect? Australian Journal of Earth (Geoscientist, November, 2003). Sciences, 52, 725-757, 2005. Six documentary fi lms have been made over the past Stueben, D., Harting, M., Kramar, U., Stinnesbeck, W., Keller, G., and Adatte, T., High resolution geochemical record in year, including BBC Horizon (released in October 2004 in Mexico during the Cretaceous-Tertiary transition. Geochmica the UK), ABC, the History Channel, Swiss TV (released et Cosmochimica Acta, 69, (10), 2559-2579, 2005. Nov. 24), The New York Museum of Natural History, (re- Stinnesbeck, W., Ifrim, C., Schmidt, H., Rindfl eisch, A., Buchy, leased May 2005) and TV interview with Alexander Kluge M-C., Frey, E., González-González, A.H., Vega, H.J., Cavin, for German Film, TV and Media released October 2005. L., Keller, G. and Smith, K.T., 2005. A new lithographic lime- stone deposit in the Upper Cretaceous Austin Group at El Accomplishments during 2005 include the successful Rosario, County of Muzquiz, Coahuila, Northeastern Mexico. drilling of the K-T boundary sequences along the Brazos Revista Mexicana Ciencias Geologicas, v. 22 (3), 401-418. River in Texas funded by NSF. These cores form a critical Other miscellaneous publications: part in testing the new impact theory and preliminary results Keller, Suche nach der Ursache des Massensterbens vor 65 Mil- confi rm previous studies. New drilling of K-T sequences near lionen Jahren. Werdenberger Jahrbuch, p. 189-200, 2004. Recife in Brazil, also funded by NSF, commenced in Septem- Keller, La Météorite innocentée. La Recherche, 379, 30-36, 2004. ber and fi nished at the end of December 2005 with nearly Articles in press or submitted: 100% core recovery. The three core localities recovered K-T Keller, G. and Pardo, A., Guembelitria and Heterohelix Blooms sequences with the purpose of assessing the environmental ef- – Planktonic proxies for Environmental Catastrophes. Creta- fects of the Chicxulub impact at 8000km from its crater. The ceous Research, in press. cores will be shipped to Princeton in early 2006. Harting, M., Keller, G., Stinnesbeck, W., Volker, Z. and Fotouh, M., Geochemical characterisation of Chicxulub-Impact A 2000 word summary of our results is published in the ejecta: New constraints from the Gulf of Mexico and the Geoscientist and can be downloaded at Caribbean. EPSL, in prep. http://www.geolsoc.org.uk/template.cfm?name=NSG23498 57238495

12 Nadine McQuarrie in the December issue of Geospheres, 2005. The power of Assistant Professor these sequential reconstructions come from 1) highlighting Ph.D., 2001, Arizona University areas that are not strain compatible and require additional email: [email protected] research on the timing, magnitude and style of deformation. Richard Lease for his Sr. Thesis conducted fi eld research to constrain the amount and timing of fault offset in the Mo- jave portion of the Eastern California Shear Zone (ECSZ). The palinspastic reconstructions modeled through the Arc GIS script required large fault displacements through the eastern Mojave, but the geologic data to support model off- sets were unavailable. Richard found a unique marker offset along the fault, which suggests 22± 5 km of offset (15-25 km more than previous estimates), and provided a positive fi eld test for kinematic compatibility models. 2) The palinspastic My research focuses on the kinematic evolution of moun- reconstructions allow us to restore other data sets of inter- tain belts. My interests range from evaluating the sequential est, such as the volcanic eruptive centers through the Basin accumulation of strain in folds and faults that form a wide and Range. For her Sr. Thesis, Margee Prat started integrat- (350-350 km), high elevation plateau to the kinematics and ing the ARC GIS database of extension in the central Basin dynamics of diffuse continental extension. Research projects and Range with the NAVDAT (North American Volcanic) start with structurally based fi eld studies, typically through Database. Together these data sets have the potential to show the creation of new geologic maps at previously unpublished how mantle lithospheric thickness has evolved with time in scales or resolutions. Projects also typically involve the cre- conjunction with crustal thinning, as well as provide insight ation and sequential restoration of cross sections to evaluate into geodynamical links between extension and volcanism in viable kinematic deformation histories. Current projects I this region. am working on in conjunction with colleagues and students Interaction between erosion and deformation in fold- are: 1) tectonic reconstructions of the North America-Pacifi c thrust belts: Quantifying the interactions of lithology, plate boundary over the last 36 Myr, 2) the interaction be- tectonics and climate on multi-scale morphologies of moun- tween erosion and deformation in fold-thrust belts in Bolivia tain ranges is at the forefront of current geological research. 3) the fundamental controls on the width of mountain belts, One of the central facets to this research is the magnitude of specifi cally looking at the northern edge of the Andean Pla- control climate and the associated erosion has on the forma- teau in Peru and 4) how has deformation evolved in time and tion and development of orogens. Active research in Bolivia space during arc-continent collision in Timor. (collaborative research with Dr. Todd Ehlers and graduate Tectonic reconstructions of the North America-Pacifi c student Jason Barnes at University of Michigan) use low- plate boundary: Precise displacement fi elds of continental temperature thermochronometry, fi eld-constrained structural deformation are becoming increasingly more common and analysis, and numerical models to delineate the kinematic exact through the advent and expansion of global positioning evolution of the fold-thrust belts, and the impact of erosional systems (GPS). However, displacement histories over much variations on their formation. In Bolivia we have obtained longer scales (105-107) are required for addressing questions cooling ages and structural data that has been combined in of how the lithosphere responds to major changes in plate a preliminary kinematic model of how the fold thrust belt geometry and kinematics. For many regions on earth the has developed through time. We have used new mapping detailed geologic history necessary for long-term displace- to construct a balanced cross section across the Andean ment fi elds is just not available. However, in western North plateau from the volcanic arc to the undeformed foreland. America more is known about timing, amount, and spatial The restored cross section was imported into 2-D MOVE variations of deformation than any other comparable region. (a cross section restoration program) and the displacement By using an Arc GIS (global information systems) database along folds and faults was forward modeled providing a of timing, magnitude and direction of deformation, we can quantitative description of the kinematics (displacement, sequentially restore deformation through western North velocity, velocity change) of fold-thrust belt deformation. America with time creating a series of palinspastic maps from The simulated velocity fi eld will be the input into 2D and 36 million years ago to present. The data from these maps 3D thermo-mechanical models that link uplift and erosion can be displayed in a variety of ways that highlight not only to an evolving thermal fi eld. This thermal history is used to the areas where the reconstructions are accurate, but more calculate and predict apatite fi ssion track and apatite and importantly where the reconstructions are inaccurate (im- zircon (U-Th)/He sample ages. plying where more fi eld-based data are needed). The maps Controls on orogen width: The Andes mountains extend can also be displayed as a movie that illustrates how exten- over 8000 km along the western side of the South American sion varies with time and as velocity fi elds over 2-5-10 m.y. continent. Signifi cant along strike changes in morphology, increments that can be compared to the modern GPS strain structure and zonal climate regimes make the South Ameri- fi eld. The fi rst version of these reconstructions was published can Andes an ideal location to look at the factors that control 13 orogen width. Interesting, the widest portion of the Andes, deformation history and 4) Rocks which can provide cool- between 12° and 27° S, is also the driest suggesting the lack ing ages of apatite grains which indicate the window of time of erosion is an important factor in broad (350-550 km) these rocks were cooled through uplift and erosion. These high (4-5 km) plateaus. One of the most abrupt along strike factors allowallow is to quantify botbothh rratesates of crcrustalustal shshorteningortening changes in morphology of the Andes is along the northern as well as rates of surface uplift in East Timor. Th e colli- edge of the Andean plateau in Peru. Here a wide zone (~350 sion history of the Banda arc is also signifi cant because the km) of high topography with minimal vertical relief transi- obliquity of the collision provides a unique insight into the tions abruptly into a signifi cantly narrower (150 km) moun- temporal evolution of the orogen through trading space for tain range with a narrow drainage divide. This west stepping, time along strike. Th e westward propagation of the orogen right angle bend in topography is mimicked in the structural (110 km/m.y.) provides a way to simultaneously observe this elevation (i.e. stratigraphic erosion level) of lower Paleozoic active arc-continent collision at various stages of develop- rocks. This signifi cant change in topographic and structural ment. Th is last summer Sarah Johnston (graduate student) width provides a unique opportunity to evaluate the factors and I undertook a six-week fi eld season in East Timor to that govern the width of orogens. collect structural data along a roughly N-S transect across This last summer, Nicole Gotberg (graduate student) the island of Timor in the country of East Timor. Sarah is and I mapped 2 transects through the Peruvian Andes. The in the process of compiling her preliminary mapping with northern transect was through the narrow portion of the pre-existing published and unpublished data of collaborators mountain range and the southern transect was across wide, into a comprehensive GIS database. This database alone will northern border of the Andean plateau. One of the sur- be an important contribution to the current understanding prising things that we found was although the stratigraphy of East Timor geology. As the map is being compiled, Sarah varies signifi cantly across the Northern Plateau boundary, will construct an orogen-scale balanced cross section along the cumulative stratigraphic thickness if each region (north the transect line. When fi nished, She will be able to use the and south) is essentially the same. This fall Nicole has been section to estimate the amount of shortening and thicken- digitally combining her mapping with Peruvian geologic ing for this location, thus producing an estimate of thicken- maps to create new geologic maps that can be used as the ing-induced uplift. The construction of the section will also bases for balanced cross sections across each region. A map pinpoint geographic areas in need of more research and data of the northern edge of the Andean Plateau and an accom- collection for future work. panying geologic cross section will be products of Nicole’s Two-Year Bibliography fi rst year project. Refereed articles: 4-D Evolution of arc-continent collision in East Timor: McQuarrie, N., Crustal-scale geometry of Zagros fold-thrust belt, Iran. Journal of Structural Geology, v.26, p. 519-535, 2004. The island of Timor in southeast Asia formed and is actively McQuarrie, N., Horton, B.K., Zandt, G., Beck, S., and DeCelles, growing by the processes of island arc collision with a conti- P.G., The lithospheric evolution of the central Andean Pla- nental margin. Collision of the Indonesian volcanic islands teau: Tectonophysics, v. 399, p. 15-37, 2005. (the Banda arc) with the Australian continental margin McQuarrie, N. and Wernicke, B.P., An Animated Tectonic Recon- caused the growth and emergence of Timor, Rote, Savu and struction of Southwestern North America since 36 MA: Geo- sphere, v. 1, p 147-172. doi: 10.1130/GES00016.1, 2005. Sumba islands in the Banda forearc. In the mountainous region of East Timor, maximum elevations reach ~ 3000 m. Articles in press or submitted: Lease, R.O., McQuarrie, N., Oskin, M., (in review), Dextral Shear Preserved in these mountains are: 1) Flights of coral terraces on the Bristol-Granite Mountains Fault Zone: Successful that record the emergence of the islands by marking an eleva- Geologic Prediction from Kinematic Compatibility of the East- tion that once was at sea level, 2, Young, marine sedimen- ern California shear zone: Journal of Geology. tary rocks record the progressive shoaling of ocean water Barnes, J., Ehlers, T.A., McQuarrie, N., O’ Sullivan, P.B., (in re- depths. 3) Deformed rocks suffi ciently exposed to reveal their view), Erosion, Climate and plateau growth in the central An- des, northern Bolivia: Earth and Planetary Science Letters.

14 François M. M. concentrations of this metal. The biochemical utilization of cadmium by diatoms and coccolithophores is, we believe, the Morel key to the ocean biogeochemistry of Cd and also, perhaps, to Albert G. Blanke, Jr., Professor of the ecology of these dominant phytoplankton taxa. Geosciences In collaboration with John Reinfelder (at Rutgers Uni- Director, Princeton Environmental versity) we have continued our work on the mechanism of Institute Director, Center in Envi- inorganic carbon uptake and fi xation in diatoms. By follow- ronmental BioInorganic Chemistry ing the rates of CO uptake and O evolution in the presence Ph.D., 1971, California Institute of 2 2 Technology of various inhibitors, we have obtained convincing data sup- email: [email protected] porting our earlier (and controversial) report of unicellular C4 photosynthesis --a pathway that involves accumulation of carbon as a C4 compound prior to fi xation-- in these organisms. This project, in concert with our work on Cd-carbonic anhydrase and on the physiological role of the silica frustule Marine phytoplankton are responsible for about half of the indicate that a particularly effective carbon acquisition sys- global primary production and for a major fraction of reverse tem may be in part responsible for the ecological success of weathering on the Earth. Some of the carbon dioxide they diatoms in the oceans. fi x is exported to the deep sea; some of the SiO precipitated After a hiatus of several years (during which iron became 2 the fashionable element in oceanography), we have reactivat- by diatoms and of the CaCO3 precipitated by coccolithophores is accumulated in sediments and eventually subjected ed our research on the iron physiology of marine phytoplank- to diagenesis. What physical and chemical factors control ton. Our present foci are the mechanism of uptake of iron the growth and activity of phytoplankton is the overarching complexed in organic chelates or precipitated as colloidal question addressed in my research group. Our focus is on oxides (the major form of iron in the oceans), and intracel- trace metals, some of which are essential for phytoplankton lular Fe storage. 1) Fe uptake. A considerable amount of growth (e.g., Fe), some are toxic (e.g., Hg), some are both laboratory data show that the uptake of Fe by phytoplankton (e.g., Cd). is modulated by the free Fe(III) concentration in seawater. An outstanding question of oceanography is why phy- But some laboratory and fi eld data also show that Fe uptake toplankton precipitate hard parts: what physiological and depends on the reduction of Fe(III)complexes by surface ecological benefi ts diatoms obtain from their silica frustule? enzymes. We have posited a new model of Fe uptake that and coccolithophores from their calcite liths? We’ve been reconciles these results by making the uptake dependent on working on the hypothesis that the hard parts of phytoplank- the Fe(II) concentration at the surface and obtained new ton are important in key extracellular enzymatic processes. data supporting the validity of this “Fe(II)s” model. 2) Fe We have shown that the silica frustule of diatoms is an excel- storage. We have identifi ed in the recently published genome lent buffer for hydrogen ion that enables the rapid conver- of the marine cyanobacterium Trichodesmium two sequences - with high homology to genes known to code for ferritin, the sion of HCO3 to CO2 through the activity of an extracellular carbonic anhydrase enzyme, a key step in the acquisition major iron storage protein in living organisms. This is the of inorganic carbon by diatoms. We have now obtained fi rst evidence of ferritin in marine microorganisms and we evidence that the calcium carbonate liths of coccolitho- are in the process of isolating and characterizing this protein phores likewise enhance the activity of extracellular alkaline to study its role in the ecology of Trichodesmium, the organ- phosphatase –an enzyme that liberates orthophosphate from ism thought to be responsible for the bulk of N2 fi xation in organic compounds. the ocean. The biogeochemistry of cadmium continues to be a re- Our continuing work on the biogeochemistry of mer- search focus in our group. Because of its excellent correlation cury is presently focused on mercury methylation. Since with phosphate, cadmium is used as a paleotracer of nutri- methyl mercury is the species accumulated in fi sh via the ents in the sea. We have obtained mounting evidence from food chain, this is a key transformation, but it has received laboratory and fi eld work that cadmium is an important surprisingly little attention over the past 20 years. The two micronutrient for marine phytoplankton. From our previ- questions we are trying to answer are: 1) where is methyla- ous work, we know that Cd promotes the growth of diatoms tion occurring in the ocean and by what mechanism? and under low zinc conditions as the result of the synthesis of a 2) what controls the rate of methylation by sulfate reducing Cd-carbonic anhydrase. Cadmium thus catalyses the acquisi- bacteria in freshwater systems? New data on the concentration of inorganic carbon for photosynthesis. Having now tion of mercury in tuna caught off Hawaii show that this obtained the full DNA sequence for this enzyme (the fi rst Cd concentration has not changed in thirty years. Mercury in enzyme discovered) and over-expressed it in a bacterial host, tuna thus does not respond to the increase in mercury in we are in the process of characterizing it in collaboration the atmosphere and in the surface of the oceans caused by with protein chemists at Pen. Our next goal is to elucidate anthropogenic inputs. We thus propose that methyl mercury the biochemical/physiological role of Cd in coccolitho- in the open ocean may originate from the deep sea, perhaps phores which we have found to accumulate unusually high from hydrothermal vents. Our biochemical work with sulfate

15 reducing bacteria has shown that, contrary to what is com- Amyot, M., F.M.M. Morel and P. A. Ariya, Dark oxidation of monly believed, the acetylCoA pathway is not necessary for dissolved and liquid elemental mercury in aquatic environments, Environ. Sci. Technol., 39(1) p. 110, 2005. Hg methylation in these organisms. We are now trying to Sternberg, E., D. Tang, T.-Y. Ho, C. Jeandel and F.M.M. Morel, elucidate what enzymes are actually involved in methylation Barium Uptake and Adsorption in Diatoms, Geochemica and what control their activity in these organisms. Acta, Vol. 69(11) 2745-2752, 2005. Kustka, A. B., Y. Shaked, A.J. Milligan, D. W. King, F.M.M. Morel, Two-Year Bibliography Extracellular production of superoxide by marine diatoms: Refereed articles: Contrasting effects on iron redox chemistry and bioavail- Shaked, Y., A.B. Kustka, F.M.M. Morel and Y. Erel, Simultaneous abilty. Limnol. and Oceanogr., 50(4) 1172-1180, 2005. determination of iron reduction and uptake by phytoplank- Shaked, Y., A.B. Kustka and F.M.M. Morel, A general kinetic ton, Limnol. and Oceanography: Methods, http://www.aslo. model for iron acquisition by eukaryotic phytoplankton. Lim- org/lomethods/free/2004/0137.pdf, Vol 2, 137-145, 2004. nol. And Oceanogr., 50(3) 872-882, 2005. Reinfelder, J.R., A.J. Milligan, F.M.M. Morel, The role of the C4 pathway in carbon accumulation and ﬁ xation in a marine Articles in press or submitted: diatom. Plant Physiolog, Vol. 135, 2106-2111, 2004. Castruita, M., M. Saito, P.C. Schottel, L.A.Elmegreen, S. Myneni, Lalonde, J.D., M. Amyot, J. Orvoine, F.M.M. Morel, J-C. Auclair, E.I. Stiefel, and F.M.M. Morel, Overexpression and charac- P.A. Ariya, Photoinduced Oxidation of Hg0(aq) in the Waters terization of an iron storage and DNA-binding Dpsprotein from the St. Lawrence Estuary Environ. Sci. Technol., 38 (2) from Trichodesmium erythraeum. , Applied Env. Microbiol- 508-514, 2004. ogy, in press. Kraepiel, A.M.L., K. Keller, H.B. Chin, E.G. Malcolm, F.M.M. Mo- Shaked, Y., Y. Xu, K. Leblanc and F. M. M. Morel, Zinc availability rel, Response to Comment on “Sources and Variations of and alkaline phosphatase activity in Emiliania huxleyi: Im- Mercury in Tuna” Environ. Sci. Technol., 38(14) 4048, 2004. plications for Zn-P co-limitation in the ocean Limnology and Milligan, A. J. and F.M.M. Morel. Dynamics of silicon metabolism Oceanography, in press. and silicon isotopic discrimination in a marine diatom as a Tang, D. and F.M.M. Morel, Distinguishing between cellular and Fe-oxide associated trace elements in phytoplankton Marine function of pCO2 Limnol. Oceanogr., 49 (2), 322-329, 2004. Morel, F.M.M. and E.G. Malcolm, “The biogeochemistry of Chemistry, in press, 2005 Cadmium” in Biogeochemical Cycles of Elements, Vol. 43 Xu, Y., T.M. Wahlund, L. Feng, Y.Shaked, and F. M.M. Morel, A of Metal Ions Biological Systems; ( A. Sigel, H. sigel, and novel alkaline phosphatase in the coccolithophore Emiliania R.K.O. Sigel, eds), M. Dekker, New York, pp. 301, 2005. huxleyi (Prymnesiophyceae) and its regulation by phospho- Sunda, W., N.M. Price, F.M.M. Morel “Trace Metal ion buffers rus, J. of Phycology, submitted, 2005. and their use in culture studies” in Algal Culturing Tech- Park, H., B.Song, and F.M.M. Morel, Diversity of the Cadmium niques, R. Anderson Editor, Academic Press p. 35-63, 2005. Containing Carbonic Anhydrase (CDCA) in Marine Diatoms Lane, T.W, M.A. Saito, G.N. George, I.J. Pickering, R.C. Prince, and Seawater, Env. Microbiology, submitted, 2005. F.M.M. Morel, A cadmium enzyme from a marine diatom, Nature, Vol. 435 p. 42, 2005.

Satish Myneni fate and transport of contaminants in the environment. This Associate Professor area of research is gaining importance, and researchers from Ph.D., 1995, Ohio State different disciplines began conducting studies to explore University these interactions in greater detail. I am interested in explor- email: [email protected] ing one of these fundamental interactions, which include the evaluation of the chemical state of water in different geologic media and how this modifi es the biogeochemical behavior of different inorganic and organic moieties in the natural systems. I am also interested in evaluating the chemical state(s) of important geochemical species to develop predictive patterns for explaining their macroscale behavior. A summary of my current research projects, and accomplishments in the last one year are provided below. Speciation of Aluminum and Iron in Aqueous Solutions Water is essential for the origin and survival of life on our and in Solid phases planet and perhaps plays an important role on the existence Aluminum and iron are one of the most abundant elements of life on other planetary bodies as well. In several different in the Earth’s crust and form common minerals of all soils forms, water mediates the physical and chemical interactions and sediments. The oxides (Fe only) and oxyhydroxides between various components of the Earth’s surface environ- of these elements are highly reactive towards aqueous con- ment, which includes mineral oxides, biota and their byprod- taminants and nutrients and play an important role in the ucts, and the atmosphere. One of the challenges in environ- geochemical cycling of several elements. However, several mental sciences is to gain a better understanding of interac- oxides and oxyhydroxides of Al3+ and Fe3+ exist in the form of tions between these different components in nature, and to amorphous and poorly crystalline precipitates and aqueous use it to predict a variety of biogeochemical processes such as polymers, whose genesis, structure, composition and reactiv- elemental cycling, biological chemistry of elements, and the 16 ity are poorly understood. These metastable phases occur polymers in aquatic and biological systems (e.g. ferritins), as nanosize particulates, and convert to crystalline phases if and their precipitates. given enough time. The rates of transformation depend on Chemistry of Natural Organic Molecules several physico-chemical variables in the environment, and Organic molecules are found everywhere on the surface of vary from a few hours to several months. My research focuses the Earth, and their composition, molecular structure and on the structural chemistry of these metastable phases, and concentration modifi es the biogeochemical processes in the on the infl uence of different environmental variables that environment. One of the bottlenecks in our understanding of modify their transformation. My group members, Laura the elemental cycles is related to the speciation of C, N, and Harrington and Michael Hay are participating in this inves- S associated with the organic molecules, and their variation tigation. in the environment. For the past several years, my research We use different X-ray scattering and spectroscopy group has been using and developing X-ray spectroscopy and techniques to evaluate the coordination environment of Al3+ 3+ spectromicroscopy methods for studying the chemistry of and Fe in the stable and metastable phases, and vibrational natural organic molecules in their pristine state (Rev. Min- spectroscopy to understand the coordination environment of eral., 2002). Using these methods I am investigating the: bridging and terminal hydroxyls. We also use X-ray spectromicroscopy to evaluate the heterogeneity in size and compo- • Functional group composition and macromolecular sition of these phases. In collaboration with Dr. Ann Chaka structure of natural organic molecules in soils and at the National Institute of Standards and Technology, we are sediments, conducting quantum chemical calculations to complement • Role of minerals in the retention and fractionation of the experimental investigations. organic molecules in the environment, The formation of different oxyhydroxides of Al3+ and • Chemistry of natural organohalogens in the environ- Fe3+ in the environment is infl uenced by the speciation of ment: coordination chemistry, rates of formation in these ions in aqueous solutions. It is well understood that the environment and their role in various biogeo 3+ chemical reactions, and these ions exist as hexaqua complexes (e.g. Al(H2O)6 ) in highly acidic solutions and hydroxylated species (e.g. • Reactions at the microorganism-water interfaces. l+/- Al(OH)m(H2O)n ) at all other pH values, and exhibit least To investigate the biogeochemical processes involved in solubility at near neutral pH. The chemical behavior of these organic molecule halogenation in terrestrial systems and their two ions in aqueous solutions and their species is primarily rates in detail, we built a fi eld station in Princeton University determined by the hydroxylation of these ions, which in turn campus. In addition, we are monitoring the speciation of is dictated by different aqueous chemical conditions. We C, N, and S in organic molecules to evaluate the association built a new synchrotron experimental chamber to evaluate of these elemental cycles with the halogen-cycle. We found the electronic states of the hydroxylated species of these ions several interesting results on these systems, and some of the in aqueous solutions. Although Al-speciation in aqueous highlights are as follows. solutions and precipitates is well studied using NMR spectroscopy, variations in the structural environment of Al in Chemistry of natural organohalogens. While manmade organo- these systems are not well understood. Our preliminary X-ray halogens are widely distributed throughout the biosphere studies on aluminum indicate that Al3+ forms octahedral and are characterized by varying degrees of persistence and toxicity, natural production of organohalogen compounds complex with H2O in highly acidic solutions, and converts to a tetrahedral complex with 4OH- in alkaline solutions, which is gaining recognition as a signifi cant contributor to the are in agreement with previous NMR spectroscopy studies. organohalogen burden in the environment. With the help However, Al3+ converts to a pentacoordinate species when it of my research group members, I made signifi cant progress reacts with an OH- in moderately acidic solutions. Although in understanding the chemistry of natural organohalogens recent theoretical studies lend support to this observation, in the past 3-4 years. Using X-ray spectroscopy, I directly experimental evidence is missing. Changes in the coordina- showed that the formation of organochlorines and their spe- tion of Al3+ modify its electronic state and thus its reactivity. ciation variations in soils are directly related to the weather- The behavior of Fe3+ follows the chemistry of Al3+ closely. ing of plant material. Dr. Deshmukh (post-doctoral scholar) Since Fe3+ exhibits stronger interactions with sulfate among conducted a detailed speciation of organochlorines in the all inorganic ligands, and both of them occur together in sev- O-horizons of soils, and his studies indicated that a majority eral natural systems, our initial studies focused on Fe3+-sulfate of chlorinated organic molecules in weathering plant material interactions. Our infrared and X-ray spectroscopy studies of are associated with the soluble polyphenol fraction, but not these systems provided unequivocal evidence for the occur- with stable lignins, as thought by several previous investiga- rence of H-bonding complexes of sulfate with Fe-oxyhy- tors. Specifi c molecules identifi ed in our investigation are droxide polymers (Myneni et al. submitted). These studies chlorinated xanthones (probably associated with lichens), unravel the mystery of solution and solid phase speciation of and several other aliphatic and aromatic chlorinated mol- Fe3+ in acidic environments (Majlan and Myneni, Environ. ecules (sources uncertain at this stage). The X-ray microscopy Sci. Technol., 2005). The current emphasis is also on the studies conducted by Ms. Leri (graduate student) indicated a understanding of the structural environments of soluble Fe3+- heterogeneous distribution of organochlorines in weathering leaves, which we are attributing to the differences in organic 17 molecule halogenation processes. Maria S., Russell L. M., Gilles M. K., Myneni S. C. B. Organic Researches conducted by Ms. Hakala (senior) and Leri aerosol growth mechanisms and their climate forcing implications. Science, 306: 1921-1924 2004. have shown that organobromines, like organochlorines, are Wei J. Saxena A., Song B., Ward B. B., Beveridge T.J ., Myneni common in terrestrial and marine environments. Since they SCB. Elucidation of functional groups on Gram-positive and are present at high concentrations in marine systems, we are Gram-negative bacterial surfaces using infrared spectros- planning detailed studies on their formation in the photic copy. Langmui,r 20: 11433-1144211433-11442 2004. zone of ocean water, and their accumulation and dehalogena- Edwards, D. C., Nielsen S. B., Jarzecki A. A., Spiro T. G., Myneni S. C. B. Experimental and theoretical vibrational spectros- tion in sediments. Although iodine is present at trace concen- copy studies of acetohydroxamic acid and desferrioxamine trations, we are fi nding that iodide and iodate present in soils B in aqueous solutions: Effects of pH and iron complexation. react with naturally occurring organic molecules and form Geochim. Cosmochim. Acta, 69: 3237-3248 2005. organoiodines in short time. The presence of Ca is signifi - Edwards D. C., Myneni S. C. B. Hard and soft X-ray absorption cantly affecting the sensitivity of X-ray spectroscopy methods spectroscopic investigation of aqueous Fe(III)-hydroxamate in detecting organoiodines in all natural samples. However, siderophore complexes J. Phys. Chem., A 109: 10249- 10256. 2005 we found that the reactions of inorganic iodine with organic Strathmann T. J., Myneni S. C. B. Effect if soil fulvic acid on molecules are slow, and take about a week to reach equilib- nickel (II) sorption and bonding at the aqueous-boehmite rium in laboratory microcosms. Rachel Zwillinger, a senior in (γ-AlOOH) interface. Environ. Sci. Technol., 39: 4027-4034 my research group, conducted these investigations. 2005. Majzlan J., Myneni S. C. B. Speciation of iron and sulfate in acid Reactive Carboxylic Acids in Natural Organic Molecules. waters: Aqueous clusters to mineral precipitates. Environ. Carboxylic acid groups are one of the most important reac- Sci. Technol., 39: 188-194 2005. tive groups in naturally occurring organic molecules. It has Naslund L., Edwards D. C., Wernet P., Bergmann U., Ogasawara been widely assumed that a majority of these carboxylic acids H., Pettersson L. G. M., Myneni S. C. B., Nilsson A. X-ray are present as aromatic carboxylic acids (such as in salicylic absorption spectroscopy study of the hydrogen bond network in the bulk water of aqueous solutions. J. Phys. Chem., A acid). However, a combination of multidimensional NMR 109: 5995-6002 2005. and infrared spectroscopy studies indicated that a majority Li W., Seal S., Rivero C., Lopez C., Richardson K., Pope A., of carboxylic groups in natural organics are associated with Schulte A., Myneni S. C. B., Jain H., Antoine K., Miller A. C. the aliphatic fraction, and have an electron withdrawing Role of S/Se ratio in chemical bnding of As-S-Se glasses group on the adjacent C-atom (in the α- and β-positions). investigated by Raman, X-ray photoelectron, and extended X-ray absorption fi ne structure spectroscopies. J. App. Phys- The presence of such groups makes the carboxyl group much ics ,98: 053503 2005. more reactive and promotes the formation of strong com- Bluhm H., Andersson K., Araki T., Benzerara K., Brown G. plexes (chelation) with aqueous metals and mineral surfaces. E., Dynes J. J., Ghosal S., Gilles M. K., Hansed H. –Ch, This information is important in understanding the reactiv- Heminger J. C., Hitchcock A. P., Ketteler G., Kilcoyne A. L. ity of common stable biomacromolecules and their origin in D., Kneedler E., Lawrence J. R., Leppard G. G., Majzlan J., Mun B. S., Myneni S. C. B., Nilsson A., Ogasawara H., aquatic systems. Ogletree D. F., Pecher K., Salmeron M., Shuh D. K., Tonner In summary, my research group is developing into a diverse B., Tyliszczak T., Warwick T., Yoon T. H. (2005) Soft X-ray and interdisciplinary research group to address the funda- microscopy and spectroscopy at the molecular environmental science beamline at the Advanced Light Source. J. mental biogeochemical processes in the environment. Electron Spectosc. Relat. Phenom., 150: 86-104 2005. Two-Year Bibliography Articles in press or submitted: Refereed articles: Myneni S. C. B. Applications of X-ray and infrared spectroscopy Strathmann T., Myneni S. C. B., Speciation of aqueous Ni(II)- methods in studying microbe-mineral interfaces, in press. Carboxylate and Ni(II)-Fulvic Acid Solutions: Combined Myneni S. C. B., Waychunas G. A., Traina S. J., Brown Jr. G. E. ATR-FTIR and XAFS Analysis. Geochim. Cosmochim. Acta, Understanding the speciation of oxoanions in aquatic sys- 68: 3441-1458, 2004. tems, Proc. Natl. Acad. Sci., in review. Xue S., Leri A., Myneni S. C. B., Jaffe P. Uptake of bromide by Bellenger J., Arnaud-Neu F., Asfari Z., Myneni S. C. B., Stiefel two wetland plants (Typha latifolia and Phragmites australis E. I., Kraepiel A. Complexation of oxoanions and cationic (Cav.) Trin. Ex Steud). Environ. Sci. Technol.,38: 5642-5648 metals by the bis(catecholate) siderophore azotochelin, 2004. Inorganic Chemistry, in review. Reina R., Leri A., Myneni S. C. B. Cl K-edge X-ray spectroscopic investigation of enzymatic formation of organochlorines in weathering plant material. Env. Sci. Technol., 38: 783-789 2004.

18 Guust Nolet With Stephanie Gautier and Jean Virieux, both at George J. Magee Professor of Geosciences Azur in France, I have developed a new method Geophysics and Geological to compute the fi nite-frequency sensitivity of arrival times Engineering and amplitudes of local seismic waves in complicated, three- Ph.D., 1976, University of Utre- dimensional media. A fi rst application, to image the seis- cht (The Netherlands) mogenic zone in the area of the Gulf of Corinth (Greece) is email: [email protected] under way. Two-Year Bibliography Books Levander, A. and G. Nolet (eds.), Seismic Earth: Analysis of broadband seismograms, AGU Monograph Series, 2005. Refereed articles: Montelli, R., G. Nolet, F.A. Dahlen, G. Masters, E.R. Engdahl, S.-H. Hung, Finite-frequency tomography reveals variety of plumes in the mantle, Science, 303, 338-343, 2004. With Raffaella Montelli and Tony Dahlen, we continued the Montelli, R., G. Nolet, F.A. Dahlen, G. Masters, E.R. Engdahl, S.- exploration of the effects of fi nite frequency – introduced by H. Hung, Global P and PP travel time tomography: rays vs. us fi ve years ago – into the imaging of the Earth’s interior. waves, Geophys. J. Int., 158, 637-654, 2004. An investigation of long period S, ScS and SS waves led to Zhou, Y., F.A. Dahlen and G. Nolet, Three-dimensional sensitivity kernels for surface wave observables, Geophys. J. Int., 158, a spectacular confi rmation of the earlier results that showed 142-168, 2004. a number of mantle plumes reach deep down into the lower Nolet, G. and R. Montelli, Optimum parameterization of tomo- mantle. This fi nding has important implications for the geographic models, Geophys. J. Int., 161, 365-372, 2005. dynamics of the Earth. This is probably the last time we in- Nolet, G., F.A. Dahlen and R. Montelli, Traveltimes and ampli- vert data sets that exist in the pubic domain or that we obtain tudes of seismic waves: a re-assessment, in A. Levander and G. Nolet (eds.), Seismic Earth: Analysis of broadband by collaboration with others. Since 2002, Karin Sigloch has seismograms, AGU Monograph Series, 37-48, 2005. been developing a new method based on matched fi lters that Levander, A. and G. Nolet, Perspectives on array seismology will allow us for the fi rst time to measure arrival times and and US Array, in A. Levander and G. Nolet (eds.), Seismic amplitudes of body waves from shallow earthquakes – the Earth: Analysis of broadband seismograms, AGU Mono- complicating interacting of the ghost refl ections from the graph Series, 1-6, 2005. Earth’s surface are fully taken into account in the fi lter. The Dahlen, F.A. and G. Nolet, Comment on the paper “On sensitivity kernels for wave-equation transmission tomography” by measurements can be done in different frequency windows, de Hoop and van der Hilst, Geophys. J. Int., 163, 949-951, thus fully exploiting the power of fi nite frequency tomogra- 2005. phy, the new method of interpretation pioneered at Princ- Zhou, Y., F.A. Dahlen, G. Nolet and G. Laske, Finite-frequency eton in the past decade. Using the matched fi ltering method, effects in global surface-wave tomography, Geophys. J. Int., Karin has recently been able to show that fi nite frequency 163, 1087-1111, 2005. effects are clearly visible in the arrival times and amplitudes Articles in press or submitted: of teleseismic P waves recorded by the RISTRA array in the Sigloch, K. and G. Nolet, Measuring fi nite-frequency body wave amplitudes and travel times, subm. to Geophys. J. Int., 2005. western United States. She, and new graduate student Yue Montelli, R., G. Nolet, F.A. Dahlen and G. Masters, A catalogue Tiang, have embarked upon an ambitious project to develop of deep mantle plumes: new results from fi nite-frequency to- our own data base of amplitudes and arrival times, which will mography, subm. to Geochemistry, geophysics, geosystems include complete dispersion information. (G3), 2006. Raffaella Montelli has left for Exxon, and we are at pres- Montelli, R., G. Nolet and F.A. Dahlen, Comment on `Banana- ent cleaning up the fi nite-frequency tomography software doughnut kernels and mantle tomography’ by van der Hilst and de Hoop, subm. to Geophys. J. Int., 2006. that she developed, making it more general and user friendly. Zhou, Y., G. Nolet, F.A. Dahlen and G. Laske, Global Upper- I have started writing a book that summarizes not only the Mantle Structure from Finite-Frequency Surface-Wave theory of classical as well as fi nite-frequency tomography, but Tomography, J. Geophys. Res., in press, 2006. also the various methods of data analysis, model parameterization and inversion. No such book exists at present.

19 Tullis C. Onstott abiogenic or biotic origin. No instruments are currently Professor fl ight ready that are capable of performing C and H isotopic Ph.D., 1980, Princeton University analyses of methane. In a paper that has been accepted for email: [email protected] publication by Astrobiology Journal, I outlined the possible origins of the Martian methane and what type of analyses would be required to distinguish between the different origins. The bad news is that the shuttle back to fl ight program is bleeding NASA’s science programs dry and the funding prospects for Mar’s related initiatives over the next several years is bleak. It’s time to seek a well endowed benefactor! The South African Deep Microbiology Project The environments sampled over the past 5 years in the deep mines of South Africa have revealed new microbial phyla that have never been reported elsewhere, unusual biogeochemical Deep Permafrost Environments and the Mars Deep Drill- phenomena that are diffi cult to understand and microscopic ing Mission features that a frankly so bizarre that their origin is a mystery. The past year’s IPTAI astrobiology effort has experienced some For these reasons we’ve had great diffi culty in publishing the signifi cant setbacks. Lupin Mine, a Au mine in the Canadian fi ndings of this project, but this past year has seen a confl u- Arctic that was our sole access to brine situated beneath 500 ence of efforts by the co-investigators participating in this meters of permafrost and rock, was closed. We were able to project, which at long last had led to the acceptance for pub- obtain some high quality planktonic samples prior to the lication of numerous manuscripts describing the microbial closure in March and Daniel McGown has been successful diversity and geochemistry of the deep subsurface of South in amplifying 16SrDNA from these samples. This was not a Africa. A great deal more research remains to be performed trivial undertaking given that the biodensity in these brines including the following: appears to be 100 to 1000 times less than we’ve experienced 1. The Joint Genomics Institute completed sequencing of in South Africa. Despite his success, the low biodensity the complete genome of the DNA of the microorganism doesn’t bode well for obtaining complete genomic analyses of which appears to dominate the microbial ecosystem at depths these environments using large fragment DNA cloning and greater than 1.5 km. in South Africa. This organism repre- sequencing. The investigators involved in research at Lupin sents a new genus of Firmicutes with genetic capabilities that will be gathering in January ’06 to share their results and are surprising when compared to what we thought were the plan publications based on the data in hand. The lead IPTAI characteristics of deep subsurface organisms. Now we have investigator, Prof. Pratt of Indiana University, and I prepared to agree upon a name for this organism, utilize the genomic a proposal to the NAI to support drilling into the permafrost information to try to isolate the microbe from more envi- at another Au mine further north called Ulu. This proposal ronmental samples, discover the function of specifi c genes by went through two reviews and now it appears to be funded performing cloning experiments and complete annotation pending quotation from the drilling contractor and develop- of the sequence. A manuscript to be submitted to Science is ments at Ulu for this coming summer. This campaign will be being prepared for the release of the genome. the fi rst of several designed to develop the technology required for 1) locating subsurface brines beneath deep permafrost on 2. Over the past year we have been installing and instrument- Mars, 2) retrieving samples of permafrost and brine with little ing boreholes at 3.7 km depth at Tau Tona mine as part of organic or microbial contamination, 3) performing life detec- an NSF funded project to monitor earthquake seismicity and tion experiments on these same samples in the fi eld or in the relate that activity to geochemical and microbial properties. borehole and 4) determining how sensitive the organic and Progress, however, has been much slower than anticipated inorganic constituents are to the thermal histories that Martian primarily because of safety issues regarding the site. Nev- samples will be subjected to upon their return from Mars be ertheless, the borehole for in situ monitoring of microbial robotic craft. It is anticipated that such a mission would take and geochemical transients will be completed in January ’06 place in the 2018-2020 time frame and none of the technol- and if all goes well this will represent the deepest site in the ogy required has reached fl ight capability as of yet. world for long term observation of subsurface phenomena. In this context we have resubmitted a proposal to This is truly an international effort as the ICDP has paid for NASA’s ASTID, Astrobiology Science and Technology In- the acquisition of pristine cores from the site, the German strument Development, program for perfecting the means of government is supporting a group from Univ. of Potsdam to contaminant removal on the surface of Mars by Mars rovers investigate changes in gas chemistry and the South African with Honeybee Robotics Ltd. and development of a laser NRF is supporting out colleagues from the Univ. of Free spectrometer of methane isotope analyses. Our group has State to run the site. Having the capability for long term in focused upon methane as a biomarker of Martian life since situ studies will hopefully lead to an understanding of some the discovery of methane in the Martian in 2004 by several of the mysterious relationships we’ve been observing with investigators led to a plethora of papers speculating on its spot samples.

20 3. A new weirdophile? In a Pt mine in South Africa we’ve Articles in press or submitted: discovered a star-shaped microbe that probably represents a Sherwood Lollar, B., Lacrampe-Couloume, G., Slater, G.F., Ward, J., Moser, D.P., Lin, L.-H. and Onstott, T.C. Abiogenic new phylum of Archaea. Although we returned to this mine gases support H2-based autotrophy and methanogenesis in to collect additional samples and attempted to isolate the the deep subsurface. Chem. Geol., in press, 2006. organism in culture, we failed to fi nd it in the new collection. Onstott, T. C., Lin, L.-H., Davidson, M., Mislowack, B., Borc- This is probably because the original seep had been sealed sik, M., Hall, J., Slater, G., Ward, J., Sherwood Lollar, B., with cement. In January ’06 we’ll try to return to see if we Lippmann-Pipke, J., Boice, E., Pratt, L. M., Pfi ffner, S. M., Moser, D. P., Gihring, T. M., Kieft, T., Phelps, T. J., van can obtain a sample of this organism for further study. Heerden, E., Litthaur, D., DeFlaun, M., Rothmel, R., Wanger, Deep Underground Science and Engineering Laboratory G. and Southam, G. The origin and age of biogeochemical (DUSEL) trends in deep fracture water of the Witwatersrand Basin, South Africa. Geomicrobiol. Jour, in press The NSF has selected two candidates to compete in the fi nal Pfi ffner, S. M., Cantu, J.M., Smithgall, A., Peacock, A., White, stages of the DUSEL. These two sites will submit proposals D.C., Moser, D. P., Onstott, T. C. and van Heerden, E. to NSF in July ’06. The fi nal winner will be selected in early Phospholipid Fatty Acid Profi les and Biodensity Estimates for ’07 for funding to be used to develop an MRI proposal that Water, Rock and Air Samples Recovered from Witwatersrand would go to Congress in ’09. As an S1 Investigator I will be Basin Mines. Geomicrobiol. Jour., in press, 2006. Slater, G. F., Lippmann-Pipke, J., Reddy, C. M., Lacrampe-Cou- coauthor of the “glossy” report on DUSEL that will be used loume, G., Onstott, T.C., Sherwood Lollar, B. 14C distribution by NSF for justifi cation of the facility. We will be complet- in methane and DIC in South African gold mines: Implica- ing this document early in ’06. Given the funding trends at tions to timing of methanogenesis. Geomicrobiol. Jour., in NSF, DOE and NASA, the DUSEL may actually represent press, 2006. the best candidate for supporting long term investment in Wanger, G., Onstott, T. C. and Southam, G. Structural and the fi eld of terrestrial subsurface microbiology. Chemical Characterization of a Natural Fracture Surface from 2.8 Kilometers Below Land Surface: Biofi lms in the Two-Year Bibliography Deep Subsurface. Geomicrobiol. Jour., 2006. Refereed articles: Gihring, T. M., Moser, D. P., Lin, L.-H., Davidson, M., Onstott, T. Hall, J.A., Mailloux, B.J., Onstott, T.C., Scheibe, T.D., Fuller, C., Morgan, L., Milleson, M., Kieft, T., Trimarco, E., Balkwill, M.E., Dong, H. and DeFlaun, M.F., Physical versus chemical D.L. and Dollhopf, M. The distribution of microbial taxa in effects on bacterial transport as determined during in situ the subsurface water of the Kalahari Shield, South Africa. sediment core pulse experiments, Jour. Cont. Hydrology, 76: Geomicrobiol. Jour., in press, 2006. 295-314, 2004. Lihung, L.-H., Gihring, T. M., Sherwood Lollar, B., Boice, E., Pratt, Lin, L-H, Slater, G. F., Sherwood Lollar, B., Lacrampe-Couloume, L. M., Lippmann-Pipke, J., Bellamy, R.E.S., Hall, J. and On- G. and Onsott, T. C., Yields and hydrogen isotopic composi- stott, T. C. Heterogeneous microbial communities associated with a 0.7 to 1.4 kmbls section of the continental crust. tions of radiolytic H2 and the implications for deep biosphere in continental crust. Geochim. Cosmochim. Acta, 69, 893- Geomicrobiol. Jour., in press, 2006. 903, 2004. Moser, D. P., Gihring, T. M., Brockman, F. J., Fredrickson, J. K., Fuller M. E., Mailloux B. J., Streger S., Hall J. A., Zhang P., Balkwill, D. L., Dollhopf, M. E., Sherwood-Lollar, B., Pratt, L. Vainberg S., Johnson W. P., Onstott T. C., and DeFlaun M., Boice, E., Southam, G., Wanger, G., Baker, B. J., Pfi ffner, M. F. Application of a vital fl uorescent staining method for S. M., Lin, L.-H. and Onstott, T. C. (2005) Desulfotomacu- simultaneous, near-real-time concentration monitoring of two lum spp. and Methanobacterium spp. Dominate 4-5 km Deep bacterial strains in an Atlantic Coastal Plain aquifer in Oyster, Fault. Appl. Environ. Microbiol., in press, 2006. Virginia. Applied and Environmental Microbiology, 70: 1680- Onstott, T. C., McGown, D., Kessler, J., Sherwood Lollar, B.,

1687, 2004. Lehmann, K. K. and Clifford, S. Martian CH4: sources, fl ux Ward, J.A., Slater, G.F., Lacrampe-Couloume, G., Lin, L.-H., Hall, and detection. Astrobiology Journal, in press, 2006. J.A., Moser, D.P., Bonin , A., Bellamy, R.E.S., Onstott, T.C. DeFlaun, M. F., Fredrickson, J. K,., Dong, H., Pfi ffner, S. M., and Sherwood Lollar, B., Microbial Hydrocarbon Gases in Onstott, T. C., Balkwill, D .L., Streger, S. H., Stackebrandt, the Witwatersrand Basin, South Africa: Implications for Deep E., Knoessen, S. and van Heerden, E. Isolation and char- Biosphere, Geochim. Cosmochim. Acta, 68; 3239-3250, acterization of a novel Geobacillus thermoleovorans species 2004. from an ultra-deep South African gold mine. Systematic and Applied Microbiology, in press, 2006. Onstott, T.C. Impact of CO2 Injections on Deep Subsurface Microbial Ecosystems and Potential Ramifi cations for the Lihung, L.-H., Wang, P-L, Rumble, D., Lippmann-Pipke, J., Boice, E., Pratt, L. M., Sherwood Lollar, B., Brodie, Eoin, Hazen, T., Surface Biosphere. In The CO2 Capture and Storage Project, Vol. II, D.C. Thomas and S.M. Benson, eds., 1207-1239, Andersen, G., DeSantis, T., Moser, D. P., Kershaw, D. and 2004. Onstott, T. C. Long term biosustainability in a high energy, Lin, L-H, Hall, J.A., Lippmann, J., Ward, J.A., Sherwood-Lollar, low diversity crustal biotome. Science, submitted, 2006. Mac Lean, L.C.W., Pray, T.J., Onstott, T.C. and Southam, G. B. and Onstott, T.C., Radiolytic H2 in the continental crust: Nuclear power for deep subsurface microbial communities, High-resolution structural and chemical studies of framboidal Geochem. Geophys. Geosys., 6: 10.1029/2004GC000907, pyrite formed within a bacterial biofi lm. Geology, submitted, 2005. 2006. Kieft, T.L., McCuddy, S.M, Onstott, T. C., Davidson, M., Lin, L-H, Mailloux, B. J., Devlin, S., Fuller, M. E., Onstott, T. C., DeFlaun, M. Mislowack, B., Pratt, L.M., Boice, E., Sherwood Lollar, B., F., Choi, K-H, Green, M., Swift, D. J.P. and McCarthy, J. The Lippmann-Pipke, J., Pfi ffner, S. M., Phelps, T. J., Gihring, T., Role of Aquifer Heterogeneity on Metal Reduction in an Atlan- Moser, D., and van Heerden, A. Geochemically Generated, tic Coastal Plain Aquifer. App. Geochem., submitted, 2006. Energy-Rich Substrates and Indigenous Microorganisms Mailloux B. J., Devlin S., Fuller M. E., Onstott T. C., Sigman D. in Deep, Ancient Groundwater, Geomicrobiology Journal, M., Williams K. H., and Hubbard S. S. The fate of nitrate 22:325-355, 2005. during stimulation of coastal plain sediments. Environmental

21 Michael Oppenheimer of risk assessment. The “dangerous warming” project and (Woodrow Wilson School and De- the “negative learning” project will be the focus of my main partment of Geosciences) efforts in the near future. I will also continue to supervise Albert G. Millbank Professor of postdoctoral students and graduate students in efforts to Geosciences and International include the nitrogen cycle and ice-ocean interactions in the Affairs aforementioned Earth System Model. Ph.D., 1970, University of Chicago Two-Year Bibliography email: [email protected] Refereed Articles: The West Antarctic Ice Sheet and Long Term Climate Policy (with R.B. Alley). Climatic Change, 64, 1-10, 2004. Climate Change Impacts Sensitive to Path to Stabilization (with B.C. O’Neill).Proc. Nat. Acad. Sci. 101, 16411–16416, doi_10.1073_pnas.0405522101, 2004. Book Review: The Discovery of Global Warming. J. Environmen- tal Hist., 9, 327-8, 2004. The broadest frame for my research is the question of what The infl uence of climate on in-stream removal of nitrogen (with S.D. Donner and C.J. Kucharik). Geophys. Res. Letters, 31, constitutes a dangerous level of climate change. Within that L20509, doi:10.1029/2004GL020477, 2004. framework, I have explored particular outcomes or impacts Ice Sheets, Global Warming, and Article 2 of the UNFCCC (with of climate change that might have important consequences R.B. Alley). Climatic Change, 68, 257-267, 2005. for people and societies, and therefore could produce useful Global Assessment of Coral Bleaching and Required Rates benchmarks for policy makers on an appropriate approach of Adaptation under Climate Change (with S.D. Don- ner, W.J.Skirving, C.M. Little, and O. Hoegh-Guldberg). for limiting the greenhouse gas emissions that are caus- Global Change Biology, 11, 1–15, doi: 10.1111/j.1365- ing warming. Specifi c studies have focused on the effect 2486.2005.01073.x, 2005. of warming on 1)the Antarctic and Greenland ice sheets 2) Article 2 of the UNFCCC: Historical Origins, Recent Interpreta- coral reef ecosystems and 3)the nitrogen biogeochemical cy- tions (with A. Petsonk). Climatic Change, 73, 195-226, 2005. cle. In each case, attempts are being made to use modeling, Attribution of Regional Radiative Forcing due to Tropospheric Ozone: A Step Toward Climate Credit for Reductions in observations, and paleo-climatic data to provides bounds on Emissions of Ozone Precursors (with V. Naik, D. Mauzerall, the probability of various outcomes for given levels of warm- L. Horowitz, D. Schwarzkopf, V. Ramaswamy). J. Geophys. ing. The most important outcome has been recognition that Res.,in press, 2005. a warming in excess of two degrees Celsius is likely to lead to Avoiding Dangerous Anthropogenic Interference with the Climate outcomes that would be widely recognized as dangerous. System (with K. Keller, M. Hall, S.-R. Kim, and D. F. Brad- ford). Climatic Change, 73, 227-238, 2005. Most recent research and future research plans Defi ning Dangerous Anthropogenic Interference: The Role of My recent research has focused on the stability of the West Science,The Limits of Science. Risk Analysis, 25, 1-9, 2005. Antarctic and Greenland ice sheets, a global assessment of The Potential Impacts of Sea Level Rise on the Coastal Region of New Jersey, USA (with M.P. Cooper and M.D. Beevers). coral reef ecosystems, construction of a nitrogen sub model Submitted to Climatic Change, 2005. within the Geophysical Fluid Dynamics Laboratory’s Earth System Model and the construction of new decision making Published (or submitted or in press) chapters in books: What is the Economic Value of Information about Climate Thresh- models appropriate to the global warming problem,including olds? (with K. Keller, S-R Kim, J. Baehr, and D. F. Bradford), the recognition of a new phenomenon, “negative learning”. Integrated Assessment of Human-Induced Climate Change, As a lead author of the Fourth Assessment Report of the M. Schlesinger, ed., submitted October 14, 2004. Intergovernmental Panel on Climate Change, I am spending Emissions Pathways to Avoid Dangerous Climate Change: A considerable time this year on developing a comprehensive Transatlantic View (with C. Jaeger) in Options for Future Climate Policy: Transatlantic Perspectives, German Institute framework for evaluating the question of what constitutes for International and Security Affairs, Berlin, 2005. dangerous levels of warming, within a context that recognizes uncertainty, learning, and the group and individual aspects

22 S. George H. nents (which affects the frequency of volcanic eruptions and hence the composition of the atmosphere), is mainly respon- Philander sible for the long-term global cooling. The other associated Knox Taylor Professor of with the Milankovitch cycles, the periodic variations in Geosciences sunlight. The global cooling affected the response to relative- Ph.D., 1970, Harvard University ly constant Milankovitch forcing by introducing feedbacks email: [email protected] at certain times. For example, the global cooling led to the appearance of northern glaciers around 3 Ma, bringing into play the ice-albedo feedback. (White glaciers refl ect sunlight, thus promoting the growth of glaciers by depriving the Earth of heat.) This mechanism has been studied extensively in connection with the ice-ages, but many puzzles remain. One is the amplifi cation of obliquity but not precession cycles in global ice volume. Another concerns fl uctuations in equatorial sea surface temperatures, very similar to those in the bottom panel, which lead fl uctuations in ice volume by several thousand years. This, and other evidence, clearly indicate that the ice-ages involve more than ice, that the tropics played a role. Equatorial sea surface temperature patterns depend on the winds and in turn infl uence the winds. This implies that interactions between the ocean and atmosphere amount to positive feedbacks. Their impact on the global climate is evident during El Niño episodes when the atmospheric concentration of the powerful greenhouse gas water vapor increases signifi cantly. Sea surface temperature patterns depend critically on the subsurface thermal structure of the ocean, especially the depth of the thermocline, the interface between the shallow layer of warm surface waters and the much colder water at depth. El Niño corresponds to changes in the slope

These geological records show that the present is an unusual moment in the recent history of our planet. Super-imposed on the global cooling that started some 50 million years (Ma) ago when polar temperatures were close to100C, are periodic oscillations that were modest in amplitude up to ~3 million years but then started to amplify, culminating in dra- matic fl uctuations between prolonged ice-ages that persisted for some 100,000 years, and brief, temperate interglacials. (Variations in O18 in seafl oor cores, the top panel, are a measure of polar temperatures.) Our species took advantage of the current interglacial -- it started 10,000 years ago -- to advance rapidly, from the invention of farming to industrial activities that are causing a rapid rise in the atmospheric concentration of greenhouse gases. This rise, the vertical red bar in the lower panel which shows measurements from Antarctic glaciers, is occurring at a time when those concentrations are at a natural maximum. That it is also occurring in an era, the past 1 Ma, of great climate sensitivity, follows from the cause of the recurrent ice-ages: very modest, periodic variations in the distribution of sunlight because of periodic variations of the equatorial thermocline as in the sketch on the left. in orbital parameters such as the tilt of the Earth’s axis. To Changes in the spatially averaged depth of the thermocline, anticipate what will happen next it will be helpful to under- as in the sketch on the right, also alter sea surface tempera- stand what had happened in the past. tures, by means of entirely different (diabatic) processes that Two sets of processes determine the climate variations involve changes in the heat budget of the ocean. described above. One, associated with the drifting of conti- Whereas the oceanic heat gain, in low latitudes where cold 23 water rises to the surface, depends on oceanic factors, specifi - Two-Year Bibliography cally the depth of the thermocline, the oceanic heat loss Refereed articles: in high latitudes depends on atmospheric factors, the air Boccaletti G., R. Pacanowski, S.G. Philander and A. Fedorov The Thermal Structure of the Ocean, J. Phys. Oceanogr., temperature for example. In a state of equilibrium, heat gain 34, 888-902, 2004. balances heat loss so that a warm world, with a small loss of Fedorov A.V., R.C. Pacanowski, S. G. Philander and G. Boc- heat from the oceans, must have a small gain and hence a caletti: The effect of salinity on the wind-driven circulation deep tropical thermocline. Atmospheric conditions in high and the thermal structure of the upper ocean, J. Phys. latitudes can therefore determine the depth of the tropical Oceanogr., 31, 1949-1966, 2004. Boccaletti G., R. Pacanowski, and S.G. Philander: A diabatic thermocline, and the intensity of air-sea interactions. These mechanism for decadal variability in the tropics, Dynamics connections between low and high latitudes depend on the of Atmospheres and Oceans, 39, 3-19, 2005. oceanic circulation which has two main components: the Barreiro M., S.G. Philander, R. Pacanowski, A. Fedorov: Simula- deep, slow thermohaline circulation, and the shallow, rapid tions of warm tropical conditions with application to middle wind-driven circulation. Both effect a poleward transport Pliocene atmospheres. Climate Dynamics, doi:10.1007/ s00382-005-0086-4, 2005. of heat by means of meridional overturning; surface waters sink in the extra-tropics and rise back to the surface in lower Other miscellaneous publications: latitudes. The sinking depends on the buoyancy of the water Philander S.G. El Niño and the Uncertain Science of Global Warming. Daedalus, Journal of the American Academy of and hence on its temperature and salinity. The heat trans- Arts and Sciences pp 105-108, Spring 2004. port, and consequently the depth of the tropical thermocline, Philander S.G. Science in an Uncertain World,World, News from can therefore be affected by several high latitude factors that ICTP, Trieste, Italy, Autumn, 2004. include temperature, rainfall, and the melting of snow. Philander S.G. State of Fear The Day After TTomorrow,omorrow, P-ROK, The global cooling that started 50 Ma ago was accompa- Vol. 1 No. 2, 2005. (P-ROK = Princeton Report on Knowledge) nied by a gradual elevation of the oceanic thermocline which, around 3 Ma, was so shallow that tropical air-sea interac- Articles in press or submitted: Philander S.G. Sextant to Satellite; the Education of a Land- tions started infl uencing the global climate. Such insights, based Oceanographer from studies of oceanic connections between low and high Chapter in History of Physical Oceanography - Developments latitudes, are shedding light on phenomena that range from since 1960. Editors M. Jochum and R. Martugudde. Pub- the decadal modulation of El Niño, to the perennial (rather lisher Springer/New York, 2006. than intermittent) El Niño conditions of the early Pliocene, Fedorov A., C. Ravelo, P. Dekens, M. Barreiro, R. Pacanowski, to the recurrent ice-ages of the past million years. The S.G. Philander: The Pliocene Paradox, Science, submitted. Fedorov A, G. Boccaletti, R. Pacanowski and S. G. Philander: theories help explain the geological record of past climates, The Freshening of Surface Waters in High Latitudes; Effects which in turn provide valuable checks for computer models on the Thermohaline and Wind-driven Circulations, J. Physi- of future global warming. cal Oceanography, submitted.

Allan Rubin datasets has been that location errors are typically ~1 km, Professor a value that exceeds both the earthquake dimensions (tens Ph.D., 1988, Stanford University of meters for magnitude 1 events) and the length scales of email: [email protected] signiﬁ cant structures within fault zones. By cross-correlating the seismograms of “similar” earthquakes (those with similar locations and focal mechanisms), it is possible to determine relative arrival times with errors that are less than one-tenth the sampling rate. From such measurements I and students and post-docs working with me have relocated many thousands of microearthquakes recorded by seismic networks in California and Hawaii. In most of our study regions we have reduced errors in relative location to meters to tens of meters for events separated by tens to hundreds of meters. This increased resolution allows us to image fault-zone structures For the past few years I have been studying earthquake that previously were invisible, and to obtain catalogs of many physics both observationally and theoretically. The primary thousands of events in which relative location errors are impetus for this work has been the advent of waveform cross- much smaller than the earthquakes themselves. For studies correlation as a tool for obtaining precise relative locations of earthquake interaction, which can be conducted sensibly of microearthquakes. Because the number of earthquakes in- only in a statistical sense, such large numbers are essential creases exponentially with decreasing magnitude, earthquakes and cannot be obtained using standard catalogs. near the detection threshold of a given seismic network rep- For the past year most of my research has been devoted resent a potential wealth of data for both structural geologists to developing a theoretical understanding of earthquake nu- and seismologists. A major impediment to exploiting these cleation, a spin-off of one of our ongoing projects designed

24 to study the very asymmetric distribution of earthquake haps more signifi cantly, we showed that the aspect of this law aftershocks in our central San Andreas fault catalog. The that leads to such large nucleation zones (possibly hundreds modern view of fault friction is that it depends upon both of meters across) is clearly contradicted by existing laboratory the fault sliding velocity and the evolving physical or chemi- experiments. A second popular state evolution law leads to cal state of the fault surface, which together comprise the much smaller “pulses” of slip that travel in one direction only. “rate” and “state” aspects of “rate-and-state” friction. Despite Because all variants of these laws are strictly empirical and the fact that the standard rate-and-state equations have been are certainly inadequate at some level, it seems much more around for over 20 years, their implications for earthquake important to obtain a generic understanding of, for example, nucleation on elastically-deformable faults (meaning any the conditions under which the nucleation zone expands or fault in the Earth, as opposed to small laboratory versions) contracts, rather than to just run computer simulations using have remained elusive. The interest in this topic stems from the currently favored friction law. Only then can one be in a the fact that if nucleation occurred on large enough tempo- position to predict the outcome when other physics (in- ral and spatial scales, precursory signals could be detected elastic dilation and pore pressure reduction within the fault and interpreted prior to damaging earthquakes. While the zone; frictional heating of pore fl uids, etc.) comes into play. observational record in this regard has not been promising, This is where my efforts are now focused. In addition, our there have been numerous suggestions of “nucleation events”, theoretical work has pointed to non-traditional rock friction occurring on timescales of fractions of a second to hours, that experiments that might better distinguish between compet- scale with the ultimate size of the earthquake. ing state evolution laws; I am currently working with Chris For the fi rst time, we have succeeded in obtaining ana- Marone at Penn State and Nick Beeler at the USGS to design lytic approximations for the size and timescale of earthquake and implement these. nucleation that are consistent with full numerical simula- Two-Year Bibliography tions. These approximations are based on well-established Refereed articles: principles of fracture mechanics, allowing much greater in- Rubin, A. M., and J.-P. Ampuero, Earthquake nucleation on (ag- sight into the complex behaviors that result when the nonlin- ing) rate and state faults, J. Geophys. Res., 110, B11312, ear friction equations operate in an elastic system. We found, doi:10.1029/2005JB003686, 2005. Peng, Z., J.E. Vidale, C. Marone, and A. Rubin, Systematic for example, that under the most popular of the laws for the variations in recurrence interval and moment of repeating evolution of the fault “state”, nucleation near the base of the aftershocks, Geophys. Res. Lett., 32 (15): Art. No. L15301 seismogenic zone takes the form of an expanding crack that AUG 2 2005. might often be detectable using surface seismometers. Per-

Jorge L. Sarmiento reasons it took so long to complete (10 years) is because there Professor was a great deal of new research we needed to do in areas Ph.D., 1978, Columbia University that were just not adequately understood. I estimate that I email: [email protected] published more than two-dozen papers over the past decade that grew primarily out my attempts to fi ll in the gaps in our understanding. The gathering of several major new data sets as part of the WOCE and JGOFS programs in the decade of the 1990’s provided a basis for a new look at the fi eld, but much of the analysis of these data had not been done when I started writing during an earlier sabbatical. In addition, while some areas had a great deal of exciting new research that we could base our book on, no one had successfully attempted to pull all of this together into a new synthesis since Broecker and Peng’s magnum opus of 1982, TracersTracers in The primary focus of my research over the past year was the the Sea. Our ambition was to provide a modern analogue to completion of my textbook cum research monograph on that wonderful textbook that has served as an introduction ocean biogeochemistry (Ocean Biogeochemical Dynamics, for a whole generation of ocean biogeochemists. We will be now in press with Princeton University Press) together with delighted if we succeed even partially in accomplishing that my old post doc and now UCLA faculty member (soon to be goal. ETH faculty member), Nicolas Gruber. We have reviewed As a result of the exceptional efforts required to fi nish up the galley proofs, and the book is scheduled to come out the book over the last year, my journal publications dropped in May. It is of course diffi cult to anticipate how it will be from a high of nine achieved in 2004 to one in 2005. received, but there are already quite a few colleagues who However, I have eight journal articles in press or submitted have been happily using earlier versions of the book in their that refl ect the culmination of several ongoing projects that courses for some years. carried over from previous years, as well as refl ecting my ever- The book represents much more than just a synthesis deepening interest in understanding the critical role of the of our present knowledge and understanding. One of the Southern Ocean in controlling ocean biogeochemistry and its 25 carbon cycle. These new journal articles can be categorized ferences have major consequences for the rate of CO2 uptake into three broad areas: (1) ocean biogeochemical processes estimated by these models. We are developing a new ocean and modeling, (2) modeling and observational constraints on model in collaboration with colleagues at GFDL that we ocean and land carbon sinks for anthropogenic carbon, and hope will provide us with an improved simulation of pro- (3) Southern Ocean biogeochemistry and circulation. Each cesses in this region. of these areas is discussed briefl y below, with reference to the Two-Year Bibliography in press and submitted papers. Books: Ocean Biogeochemical Processes and Modeling: The Orr Sarmiento, J. L., and N. Gruber, Ocean Biogeochemical Dynam- ics, Princeton University Press, in press. et al. (2005) Science paper, my only 2005 journal publication, discusses the impact of ocean acidifi cation by anthropo- Refereed articles: Doney, S. C., K. Lindsay, K. Caldeira, J.-M. Campin, H. Drange, genic carbon on the depth of the saturation horizon of arago- J.-C. Dutay, M. Follows, Y. Gao, A. Gnanadesikan, N. nite, and its likely outcropping at the surface of the Southern Gruber, A. Ishida, F. Joos, G. Madec, E. Maier-Reimer, J.C. Ocean during the middle of this century. The possible Marshall, R.J. Matear, P. Monfray, A. Mouchet, R. Najjar, consequences of this are very disturbing. The in press and J.C. Orr, G.-K. Plattner, J. Sarmiento, R. Schlitzer, R. Slater, submitted articles (1) and (2) by Dunne et al. and Jin et al. I.J. Totterdell, M.-F. Weirig, Y. Yamanaka, and A. Yool, 2004. Evaluating global ocean carbon models: The importance of present results from our latest efforts to develop new ocean realistic physics, Global Biogeochem. Cycles, 18, GB3017, biogeochemistry models. This is ongoing research aimed at doi:10.1029/2003GB002150. model development with the goal of providing new analyses Edmonds, J., F. Joos, N. Nakicenovic, R. G. Richels, and J. L. of the impact of global warming on ocean biology and the Sarmiento, Scenarios, targets, gaps, and costs. In: The ocean carbon cycle. Article (3) (Behrenfeld et al., submitted) Global Carbon Cycle, ed. C. B. Field and M. R. Raupach, is a byproduct of a parallel effort to develop empirically based Island Press, Washington, D.C., pp. 77-102. 2004. Gnanadesikan, A., J. P. Dunne, R. M. Key, K. Matsumoto, J. L. ocean ecosystem models based on a new analysis of satellite Sarmiento, R. D. Slater, and P, S. Swathi, Oceanic ventila- color observations. tion and biogeochemical cycling: Understanding the physical mechanisms that produce realistic distributions of tracers Modeling and Observational Constraints on Carbon and productivity. Global Biogeochem. Cycles, 18, GB4010, Sinks: A major research directions that my group has taken doi:10.1029/2003GB002097, 2004. in the past years is estimation of the magnitude, spatial Greenblatt, J. B., and J. L. Sarmiento, Variability and climate distribution, and temporal variability of carbon sources and feedback mechanisms in ocean uptake of CO2. In: The Global Carbon Cycle, ed. C. B. Field and M. R. Raupach, sinks by inverse modeling of atmospheric and oceanic CO2 observations and by evaluation of models with the major Island Press, Washington, D.C., pp. 257-275, 2004. Marinov, I., and J. L. Sarmiento, The role of the oceans in the new data sets that were gathered by the global surveys of the global carbon cycle: An overview. In: The Ocean Carbon past decade. This work culminated during previous years in Cycle and Climate, ed. M. Follows and T. Oguz, NATO ASI, several papers that converged on an estimate for the oceanic Ankara, Turkey, Kluwer Academic Publishers, pp. 251-295, carbon sink of 2.0 ± 0.3 Pg C yr—1 for the 1990’s. In a series 2004. of new papers (references (4) to (6) by Fletcher et al., and Matsumoto, K., J.L. Sarmiento, R.M. Key, O. Aumont, J.L. Bullis- ter, K. Caldeira, J.-M. Campin, S.C. Doney, H. Drange, J.-C. Jacobson et al, a and b) my group has explored the implica- Dutay, M. Follows, Y. Gao, A. Gnanadesikan, N. Gruber, tions of this oceanic constraint for our estimates of land A. Ishida, F. Joos, K. Lindsay, E. Maier-Reimer, J.C. Mar- carbon sources and sinks. The submitted papers by Jacobson shall, R.J. Matear, P. Monfray, A. Mouchet, R. Najjar, G.-K. et al., a and b suggest that the large anthropogenic carbon Plattner, R. Schlitzer, R. Slater, P.S. Swathi, I.J. Totterdell, sink postulated to exist in tropical rain forests is probably M.-F. Weirig, Y. Yamanaka, A. Yool, J.C. Orr, Evaluation of ocean carbon cycle models with data-based metrics. Geo- a chimera. The absence of this CO2 fertilization sink has phys. Res. Lett., 31, L07303, doi:10.1029/2003GL018970, major negative implications for the future growth rate of 2004. atmospheric CO2 – mitigation will be much more diffi cult Mignone, B. K., J. L. Sarmiento, R. D. Slater, and A. Gnanadesi- than had been previously been thought. kan, Sensitivity of sequestration effi ciency to mixing processes in the global ocean. Energy, 29: 1467-1478, 2004. Southern Ocean Circulation and Biogeochemistry: Refer- Sarmiento, J. L., N. Gruber, M. A. Brzezinski, and J. P. Dunne, ence (7) (Marinov et al., submitted) demonstrates that there High latitude controls of the global nutricline and low latitude is a clear separation in the Southern Ocean between regions biological productivity. Nature, 427: 56-60, 2004a. that control the air-sea balance of CO (confi ned primarily to Sarmiento, J. L., R. Slater, R. Barber, L. Bopp, S. C. Doney, A. 2 C. Hirst, J. Kleypas, R. Matear, U. Mikolajewicz, P. Monfray, high latitude regions of deep-water formation), and regions V. Soldatov, S. A. Spall, and R. Stouffer, Response of ocean that control the return of nutrients from the deep ocean to ecosystems to climate warming. Global Biogeochem . the surface (lower latitude areas where Subantarctic Mode Cycles, 18, GB3003, doi:1029/2003GB002134, 2004b. Water forms; see Sarmiento et al.,, 2004a). In Mignone et Orr, J. C., V. J. Fabry, O. Aumont, L. Bopp, S. C. Doney, R. al., in press (reference (9)), we show that major differences in M. Feely, A. Gnanadesikan, N. Gruber, A. Ishida, F. Joos, R. M. Key, K. Lindsay, E. Maier-Reimer, R. Matear, P. Mon- the representation of Southern Ocean circulation previously fray, A. Mouchet, R. G. Najjar, G.-K.Plattner, K. B. Rodgers, identifi ed and analyzed by Matsumoto et al. (2004) can be C. L. Sabine, J. L. Sarmiento, R. Schlitzer, R. D. Slater, explained as resulting from differences in the representation I. J. Totterdell, M.-F. Weirig, Y. Yamanaka, and A. Yool, of wind forcing and mixing in the ocean models. These dif- Anthropogenic ocean acidifi cation over the 21st century and

26 its impact on marine calcifying organisms. Nature, 437: 681- Jacobson, A. R., S. E. Mikaloff-Fletcher, N. Gruber, J. L. 686, 2005. Sarmiento, M. Gloor, and TransCom Modelers, A joint atmosphere-ocean inversion for surface fl uxes of carbon dioxide: Articles in press or submitted: I. Methods and global-scale fl uxes, Global Biogeochem Dunne, J. P., R. A. Armstrong, A. Gnanadesikan, and J. L. Sarmiento, Empirical and mechanistic models for the par- Cycles, submitted. ticle export, Global Biogeochem. Cycles, in press. Jacobson, A. R., S. E. Mikaloff-Fletcher, N. Gruber, J. L. Jin, X., N. Gruber, J. P. Dunne, J. L. Sarmiento, and R. A. Sarmiento, M. Gloor, and TransCom Modelers, A joint atmosphere-ocean inversion for surface fl uxes of carbon dioxide: Armstrong, Diagnosing CaCO3 and opal export and phytoplankton functional groups from global nutrient and alkalinity II. Regional results, Global Biogeochem Cycles, submitted. distributions, Global Biogeochem. Cycles, in press. Marinov, I. A. Gnanadesikan, J. R. Toggweiler, and J. L. Behrenfeld, M., R. O’Malley, D. A. Siegel, C. McClain, J. Sarmiento, The Southern Ocean biogeochemical divide, Sarmiento, G. Feldman, P. Falkowski, E. Boss, and A. Mil- Nature, submitted. ligan, Climate-driven trends in contemporary ocean produc- Mignone, B. K., A. Gnanadesikan, J. L. Sarmiento, R. D. Slater, tivity, Science, submitted. Central role of southern hemisphere winds and eddies in Fletcher, S. E., N. Gruber, A. R. Jacobson, S. C. Doney, S. modulating the oceanic uptake of anthropogenic carbon, Dutkiewicz, M. Follows, K. Lindsay, D. Menemenlis, A. Geophys. Res. Lett., in press. Mouchet, and J. Sarmiento, Inverse estimates of anthropogenic carbon uptake, transport, and storage by the ocean, Global Biogeochem. Cycles, in press.

Daniel Sigman • What terms and rates compose the budgets of “fi xed” (biologically available) N in the modern ocean, on Assistant Professor Ph.D., 1997, MIT and Woods Hole land, and in the atmosphere? What are the sensitivities Oceanographic Institution of the different inputs and outputs? How have the N email: [email protected] budgets in these systems changed over climate cycles, and how have these changes affected the fertility of ocean and land? What has been the role of such changes in the global carbon cycle? My research activities over the past year are summarized below under the following headings: (1) isotope method development, (2) laboratory studies of isotope discrimination, (3) studies in the modern ocean, (4) studies in the terrestrial biosphere, the atmosphere, and ice cores, (5) paleoceanographic studies, and (6) model studies of past ocean changes. My group members and I are focused on two distinct but My group’s entire body of work in these areas represents our complementary research goals. First, we use of the isotopic effort to progress from the introduction of new measure- composition of dissolved nitrogen species (such as nitrate ments, to the development of the background information - (NO3 ) and dissolved organic nitrogen) to provide integrative needed to make those measurements useful, to their appli- constraints on nitrogen cycle processes in modern environ- cation to important questions, and fi nally to a quantitative ments, mostly in the ocean but also in terrestrial systems consideration of the fi ndings in a broader environmental and the atmosphere. Second, we treat the past, as recorded context. The citations below refer to manuscripts listed in the in marine sediments and glacial ice, as an archive of natural publications section of the annual review form. experiments from which the underlying controls on the phys- Isotope method development ical and biogeochemical fl uxes of the environment can be In 2005, building on my group’s previously developed meth- determined; we study the past N cycle both in its own right ods for isotopic analysis of nitrate, graduate student Angela and as an indicator of broader environmental change. Knapp published the fi rst method for the 15N/14N analysis of A unifying goal of all of this work is to understand the bulk dissolved organic matter in seawater, a major N pool in role of plant nutrients in the interaction between life and the the ocean that had not previously been characterized isotopi- environment. Two sets of questions, focused on the ocean, cally [Knapp et al., 2005]. In turn, on the basis of this work, have most centrally motivated our studies: a collaboration among Moritz Lehmann, Ben Houlton, and • The polar oceans are special domains in the ocean Masha Prokopenko has resulted in the development of a high- where the “major nutrients” nitrogen (N) and sensitivity method for measuring the 15N/14N of dissolved + phosphorus (P) are not completely consumed by algal ammonium (NH4 ), as described in Houlton’s 2005 Ph.D. growth. What factors control the physical conditions dissertation. Also building upon Knapp’s dissolved organic N and nutrient status of the polar surface ocean? Over method, Becky Robinson and Brigitte Brunelle have estab- the ice age/interglacial cycles of the last 3 million lished, improved, and tested a new technique for the 15N/14N years, how have the characteristics of the polar ocean of diatom microfossil-bound N, for paleoclimate studies affected other regions of the ocean, atmospheric [Robinson et al., 2005, Brunelle et al., in review]. Finally, Julie carbon dioxide, and climate? Granger has developed a versatile method for the removal of 27 - nitrite (NO2 ) from aqueous samples to prevent this species budget for the surface ocean at the Bermuda Atlantic Time- from contaminating the isotopic analysis of nitrate [Granger series Station (BATS), indicating that N2 fi xation accounts et al., in review]. This method is particularly relevant to for <10% of the N supply at this site and reopening the ques- Granger’s culture studies of denitrifying bacteria (see below), tion of the N source for the large summertime drawdown in in which there were large accumulations of nitrite. CO2 at BATS. Laboratory studies of isotope discrimination Nitrate N and O isotope data are also contributing to The utility of isotopic distributions in the environment is our understanding of fi xed N loss from the ocean. In 2005, premised on knowledge of the magnitudes of isotope dis- Moritz Lehmann published a study of the Bering Sea in crimination by individual biogeochemical reactions, which which we fi nd that the down-slope transport of organic is most often gained through lab studies of cultured organ- matter from the productive Bering shelf drives denitrifi ca- isms. Julie Granger’s focus is on the isotope effects of nitrate- tion in the deep sea sediments, leading to the development consuming processes, in particular, nitrate assimilation by of a previously observed nitrate defi cit in the deep basin of photosynthetic organisms (central to studies of nutrient sup- the Bering Sea [Lehmann et al., 2005]. These fi ndings sug- ply and uptake in the surface ocean) and denitrifi cation by gest that sedimentary denitrifi cation is likely at the heart of heterotrophic bacteria (central to studies of the global ocean’s unexplained variations in the nitrate-to-phosphate ratio of input/output budget of fi xed N). In previous years, we have deep waters, with implications for globally integrated rates of studied the relationship between N and O isotope fraction- nitrate loss from the ocean. ation during nitrate assimilation. In 2005, our investigations Finally, the isotopes of nitrate also represent a potentially were extended to denitrifi ers. Because we believe that nitrate powerful constraint on the internal cycling of fi xed N in the reductase is the driver of isotope fractionation during both ocean, with implications for ocean circulation and the carbon nitrate assimilation and denitrifi cation, we had predicted cycle. My strongest interest in this regard is in the supply, that the N-to-O isotope coupling would be the same for transport, and consumption of nitrate in regions of the polar both processes. This prediction has been borne out by Julie’s ocean, the Southern Ocean in particular. Combined concen- culture experiments, but one exotic denitrifi er demonstrated tration and isotope data, interpreted with a numerical model, different and unexpected behavior, which we believe relates allowed Peter DiFiore to quantify the different physical to the several forms of nitrate reductase found in certain mechanisms of nitrate supply, the rate of biological export denitrifi ers (manuscript in preparation). production, and the isotope effect of nitrate assimilation in the Subantarctic Zone of the Southern Ocean [DiFiore et al., Studies in the modern ocean in review]. These studies of the modern polar ocean comple- In projects carried out in various regions of the open ocean ment our lab studies of algal physiology and our paleoceano- and in previously well-studied isolated basins, we are devel- graphic studies. oping and applying the N and O isotope ratios of nitrate and dissolved organic N as integrative signals of spatially and Studies in the terrestrial biosphere, the atmosphere, and temporally variable processes. Important results have begun ice cores to arise. Recent Ecology and Evolutionary Biology graduate stu- In regions where the input of newly fi xed N has been dent Ben Houlton has measured the isotopic composition proposed to augment the subsurface nitrate pool, the 15N/14N of nitrate, dissolved organic N, and ammonium in cloud of this nitrate converges toward the 15N/14N of newly fi xed N water, rainfall, soil extracts, soil water, and streams across a and thus appears consistent with this process [Knapp et al., well-constrained rainfall gradient on the island of Maui, as 2005]. Ongoing work described in Knapp’s Ph.D. disserta- described in his 2005 Ph.D. dissertation. The resulting N tion seeks to combine the isotope data with constraints on isotope budgets for these forests indicate an important and rainfall-dependent role for denitrifi cation in tropical sys- circulation to quantify the rate of N2 fi xation in the overlying surface ocean. Perhaps more surprising is the tentative tems [Houlton et al., in review]. Associated with changes in evidence from our coupled nitrate 15N/14N and 18O/16O the forest N budget across the rainfall gradient, we found a measurements for a previously unrecognized input of (low- remarkably abrupt transition in the form of N fueling plant 15N/14N) newly fi xed N in a region of intense nitrate loss by growth, from nitrate to ammonium with increasing rainfall. denitrifi cation [Sigman et al., 2005]. In contrast to a widely held view that plants control forest With our new ability to measure the 15N/14N of dissolved N fl uxes, the Maui gradient suggests that the plants in these organic N (DON), we have begun to study this enigmatic forests are not so much driving the N fl uxes as fi nding a solu- N pool, which has been hypothesized to be an important tion for their N demand that is consistent with the condi- N source and sink for algae growing in the surface ocean as tions of microbial growth. well as a form in which N can be exported from the surface With recent Princeton Ph.D. Meredith Hastings, I have ocean [Knapp et al., 2005]. In general, we have found the worked on the nitrate N and O isotopes in rain, snow, and bulk DON pool of the tropical and subtropical surface ocean ice as tracers of reactive nitrogen sources and processing to be remarkably stable in isotopic composition, implying in the modern and ancient atmosphere. Hastings’s down- core study in the GISP2 ice core from Greenland indicates that this pool is not a direct participant in the rapid N cy- 15 14 cling that is known to take place in the surface ocean. Angie a dramatically (~20‰) higher nitrate N/ N in ice from Knapp’s measurements of DON completes the N isotope the last ice age than in the Holocene [Hastings et al., 2005]. 28 Although post-depositional artifacts cannot be ruled out cycles in CO2 and climate. 15 14 for glacial-age ice, the N/ N data suggest a major cli- Two-Year Bibliography mate-driven change in the relative contributions of different Refereed articles: sources of atmospheric reactive N, such as may result from a Hastings, M. G., E. J. Steig, and D. M. Sigman, Seasonal varia- reorganization of the terrestrial biosphere. While the isotopic tions in N and O isotopes of nitrate in snow at Summit, signatures of reactive N sources and processing require better Greenland: Implications for the study of nitrate in snow and ice cores, Journal of Geophysical Research – Atmospheres, description to realize the true potential of the isotope tracers 109, D20306, 10.1029/2004JD004991, 2004. of atmospheric reactive N, our new methods are expediting Deutsch, C., D. M. Sigman, R. C. Thunell, N. Meckler, and G. H. progress in this fi eld. Haug, Isotopic constraints on glacial/interglacial changes in the oceanic nitrogen budget, Global Biogeochemical Cycles, Paleoceanographic studies 18, GB4012, 10.1029/2003GB002189, 2004. Former postdoctoral researcher Rebecca Robinson and Granger, J., D. M. Sigman, J. A. Needoba, and P. J. Harrison, current graduate student Brigitte Brunelle have used their Coupled nitrogen and oxygen isotope fractionation of nitrate recently developed method for diatom microfossil-bound N during assimilation by cultures of marine phytoplankton, Lim- isotope analysis to generate down-core records from polar nology and Oceanography, 49, 5 , 1763-1773, 2004. Robinson, R. S., B. G. Brunelle and D. M. Sigman, Revisiting nu- ocean regions, where the nutrient status and physics of the trient utilization in the glacial Antarctic: Evidence from a new surface layer can strongly affect atmospheric CO2. New method for diatom-bound N isotopic analysis, Paleoceanog- down-core records from the Subantarctic Zone of the South- raphy, 19, 3, PA3001, 10.1029/2003PA000996, 2004. ern Ocean provide evidence for more complete nutrient Thunell, R. C., D. M. Sigman, F. Muller-Karger, Y. Astor and R. drawdown in the region during the last ice age [Robinson et Varela, The nitrogen isotope dynamics of the Cariaco Basin, Venezuela, Global Biogeochemical Cycles, 18, 3, GB3001, al., 2005]. This represents some of the fi rst evidence for natu- 10.1029/2003GB002185, 2004. rally driven, long term iron fertilization of the ocean, in this Lehmann, M. F., D. M. Sigman, and W. M. Berelson, Coupling case due to greater dust inputs to the region during the last the 15N/14N and 18O/16O of nitrate as a constraint on benthic ice age, much as had been predicted by the late John Martin. nitrogen cycling, Marine Chemistry, 88, 1-20, 2004. Ice age enhancement of nitrate consumption in the Subant- Needoba, J. A., D. M. Sigman, P. J. Harrison, The mechanism of arctic Zone may also explain observations of lower nutrient isotope fractionation by algal nitrate assimilation as illumi- nated by the 15N/14N of intracellular nitrate, Journal of Phycol- content, higher dissolved O2 content, and less denitrifi cation ogy, 40, 517–522, 2004. in the tropical thermocline during the last ice age, with im- Sigman, D. M., S. L. Jaccard, and G. H. Haug, Polar ocean plications for climate-related changes in global ocean fertility stratifi cation in a cold climate, Nature, 428, 59-63, 2004. and the N budget. In 2005, my collaborators (in particular, Hastings, M. G., D. M. Sigman, and E. J. Steig, Glacial/intergla- Gerald Haug) and I have published several papers demon- cial changes in the isotopes of nitrate from the Greenland Ice Sheet Project 2 (GISP2) ice core, Global Biogeochemical strating that the Subarctic North Pacifi c and the most polar Cycles, 19, GB4024, doi:10.1029/2005GB002502, 2005. Southern Ocean respond similarly to climate change, includ- Sigman, D. M., J. Granger, P. DiFiore, M. F. Lehmann, A. v. ing glacial/interglacial cycles [Haug et al., 2005; Jaccard et al., Geen, R. Ho, and G. Cane, Coupled nitrogen and oxygen 2005]. These studies and a manuscript in review by graduate isotope measurements of nitrate along the eastern North student Brigitte Brunelle on the ice age Bering Sea greatly Pacifi c margin, Global Biogeochemical Cycles, 19, GB4022, doi:10.1029/2005GB002458, 2005. strengthen the case for a pervasive and general tendency for Lehmann, M. F., D. M. Sigman, D. C. McCorkle, B. G. Brunelle, these polar ocean regions to undergo vertical stratifi cation S. Hoffmann, M. Kienast, G. Cane, and J. Clement, The ori- during cold climates. The reconstructed polar ocean changes gin of the deep Bering Sea nitrate defi cit -- Constraints from the nitrogen and oxygen isotopic composition of water col- have the capacity to affect atmospheric CO2 in the observed sense of its glacial/interglacial change. umn nitrate and benthic nitrate fl uxes, Global Biogeochemi- cal Cycles, 19, GB4005, 10.1029/2005GB002508, 2005. Model studies of past ocean changes Jaccard, S. L., Haug, G. H., Sigman, D. M., Pedersen, T. F., I have recently begun to consider a physical mechanism for Thierstein, H. R., Röhl. U., Glacial/interglacial changes in the apparent climate/polar stratifi cation link mentioned Subarctic North Pacifi c stratifi cation, Science, 308,1003- above that involves the reduced sensitivity of seawater density 1006, 2005. Robinson, R. S., D. M. Sigman, P. J. DiFiore, M. M. Rohde, to temperature at low temperatures: in the case of a globally T. A. Mashiotta, and D. W. Lea, Diatom-bound 15N/14N: colder ocean, temperature gradients become less important New support for enhanced nutrient consumption in the in polar ocean density structure, reducing their opposition ice age Subantarctic, Paleoceanography, 20, PA3003, to the stratifying effect of the net atmospheric deposition of 10.1029/2004PA001114, 2005. fresh water on polar ocean regions. Postdoctoral researcher Haug, G. H., A. Ganopolski, D. M. Sigman, A. Rosell-Mele, G. E. A. Swann, R. Tiedemann, S. L. Jaccard, J. Bollmann, M. A. Agatha de Boer has used a general ocean circulation model Maslin, M. J. Leng, and G. Eglinton, North Pacifi c seasonal- to investigate this effect [de Boer et al., in review]. The results ity and the glaciation of North America 2.7 million years ago, provide proof of concept for a signifi cant role for whole Nature, 433, 821-825, 2005. ocean temperature change in polar ocean overturning. They Knapp, A. N., D. M. Sigman, and F. Lipschultz, N isotopic compo- also point to interactions among the polar regions of the sition of dissolved organic nitrogen and nitrate at the Ber- different ocean basins that, along with the inclusion of other muda Atlantic time-series study site, Global Biogeochemical Cycles, 19, GB1018, 10.1029/2004GB002320, 2005. feedbacks, are leading us toward a more complete hypothesis for the role of polar ocean stratifi cation in the Pleistocene 29 Articles in press or submitted: Granger, J., D. M. Sigman, M. Prokopenko, and P. D. Tortell, A de Boer, A. M., D. M. Sigman, and J. R. Toggweiler, The effect of method for nitrite removal in nitrate N and O isotope analy- global ocean temperature change on deep ocean ventilation, sis, Limnology and Oceanography: Methods, in review. Paleoceanography, in review. Galbraith, E. D., D. M. Sigman, R. S. Robinson, T. F. Pedersen, DiFiore, P. J., D. M. Sigman, T. W. Trull, A. J. Lourey, and K. L. “Nitrogen in Past Marine Environments”, in Nitrogen in the Karsh, Nitrogen isotope constraints on Subantarctic biogeo- Marine Environment (2nd edition), edited by D. A. Bronk, M. chemistry, Journal of Geophysical Research – Oceans, in R. Mulholland, and D. G. Capone, in review. review. Houlton, B. Z., D. M. Sigman, and L. O. Hedin, Isotopic evidence Brunelle, B. G., D. M. Sigman, M. S. Cook, L. D. Keigwin, G. H. for large gaseous nitrogen losses from tropical rainforests, Haug, B. Mingram, and G. Schettler, Evidence from diatom- Proceedings of the National Academy of Sciences, in review. bound nitrogen isotopes for Subarctic Pacifi c stratifi cation during the last ice age and a link to North Pacifi c denitrifi cation changes, Paleoceanography, in review.

John Suppe ary faults. Results using this new theory indicate very weak Blair Professor of Geology faults in Taiwan, Japan and Niger delta. Furthermore this Ph.D., 1969, Yale University work shows that the upper crust is relatively strong, which email: [email protected] raises the fundamental question of how a crust containing weak faults is able to be strong. Two-Year Bibliography Books (with J. Shaw, C. Connors, editors) Seismic Interpretation of Contractional Fault-Related Folds: an AAPG Seismic Atlas. American Association of Petroleum Geologists, 156pp, 2005. Refereed articles: San Andreas fault in southern California: Three-dimensional fault models and earthquake scenarios. Journal of Geophysical Research, v. 109, B04313, 17 pp, 2004. Essay Review of John Rodgers “The Company I Kept.” Ameri- Since I am in the midst a one-year sabbatical I should can Journal of Science, v. 304, p. 285-286, 2004. be brief. I am currently Visiting Professor of Tectonics at (with Erickson, S. G., and Strayer, L. M.) Numerical modeling of Caltech and in the second half of the sabbatical will be at hinge-zone migration in fault-bend folds. . In McClay, K. ed., the Ludwig Maximillians University in Munich. The stay “Thrust Tectonics and Hydrocarbon Systems” American Asso- ciation of Petroleum Geologists Memoir, 82, p. 438-452, 2004. in Germany is the fi rst part of a total of one-year of sojourns (with L. M. Strayer and S. G. Erickson) Infl uence of growth strata supported by an honorifi c award from the Alexander von on the evolution of fault-related folds: Distinct-element mod- Humboldt Foundation. els. . In McClay, K. ed., “Thrust Tectonics and Hydrocarbon I spent much effort in the spring as the scientifi c orga- Systems” American Association of Petroleum Geologists nizer of an “International Conference on Theory and Ap- Memoir, 82, p. 413-437, 2004. plication of Fault-Related Folding in Foreland Basins” which (and Chris Connors and Yikun Zhang) Shear fault-bend folding. In McClay, K. ed., “Thrust Tectonics and Hydrocarbon was attended by a stellar cast of ~70 international experts Systems” American Association of Petroleum Geologists and ~140 Chinese, held in Beijing 25-27 June, followed by Memoir, 82, p. 303-323, 2004. a logistically ambitious one-week fi eld trip for 110 people to (with A. Ferrari, X. Wang and C. Jia) The Yakeng detachment fold, remote areas of far western China to observe many examples China. In J. Shaw, C. Connors, J. Suppe, editors, Seismic of actively growing anticlines, which was the phenomenon of Interpretation of Contractional Fault-Related Folds. American Association of Petroleum Geologists, p. 110-113, 2005. interest to this conference. The conference was enormously (with J. H. Shaw and S. C. Hook) Pitas Point anticline, California, successful and is being followed by two major collections USA. In J. Shaw, C. Connors, J. Suppe, editors, Seismic of papers; one is a Memoir of the American Association of Interpretation of Contractional Fault-Related Folds. American Petroleum Geologists and the other a special section of the Association of Petroleum Geologists, p. 60-62, 2005. Journal of Geophysical Research. I am involved in many (with J. H. Shaw and C. D. Connors) Part 1: Structural Interpretation Methods. In J. Shaw, C. Connors, J. Suppe, editors, Seismic papers and with the editing. So many of my former students Interpretation of Contractional Fault-Related Folds. American and friends were involved in the conference that it could be Association of Petroleum Geologists, p. 1-58, 2005. considered a Festschrift. (with F. Corredor and J. H. Shaw) Shear fault-bend fold, deep water However my main current focus is completing a major Niger Delta. In J. Shaw, C. Connors, J. Suppe, editors, Seismic monograph on fault-related fold theory to be published by Interpretation of Contractional Fault-Related Folds. American Association of Petroleum Geologists, p. 87-92, 2005. Princeton University Press. In addition I have obtained a (with A. Hubert-Ferrari and Jerome Van Der Woerd) Irregular surprising result in critical-taper wedge theory which allows earthquake cycle along the southern Tianshan, China (Aksu one to determine absolute fault strength from wedge taper area). Journal of Geophysical Research, v. 110, B06402, data, independent of signifi cant assumptions about material doi:10.1029/2003JB002603, 2005. properties. This is an important contribution to the longstanding controversy over the strength of major plate-bound- 30 (with Li-Fan Yue and Jih-Hao Hung) Structural geology of a (with A. Hubert-Ferrari, Ramon Gonzalez-Mieres, X. Wang) classic thrust belt earthquake: the 1999 Chi-Chi earthquake Active folding of the landscape in the southern Tianshan,

Taiwan (Mw7.6). Journal of Structural Geology v,v, 27, 2058- China. Journal of Geophysical Research, submitted, 2005. 2083, 2005. (with Ramon Gonzalez-Mieres) Relief and shortening in detachment folds. Journal of Structural Geology, submitted, 2005. Other miscellaneous publications: Mass balance and thrusting in detachment folds. (In K. McClay, (with Dengfa He) Guidebook for ﬁ eldtrip in souh and north Tian- J. H. Shaw and J. Suppe, editors) Thrust-Related Folding, shan foreland basin, Xinjiang Uygur Autonimous Region, American Association of Petroleum Geologists Memoir, China: International Conference on Theory and Application submitted, 2005. of Fault-Related Folding in Foreland Basins, 78 pp, 2005. (with K. McClay and J. H. Shaw), editors, Thrust-Related Fold- Articles in press or submitted: ing, American Association of Petroleum Geologists Memoir, (with Kauan-Yin Lai,Yue-Gau Chen, Jih-Hao Hung and Ya-Wen (chapter manuscripts in review), 2005. Chen) Fault geometry related surface deformation of an active fault: evidence from geomorphic features and coseismic slip. Quaternary International, in press, 2005.

Bess B. Ward to planktonic communities and in determining the net nitro- William J. Sinclair Professor of gen budget of ecosystems. A new project on phytoplankton Geosciences nitrogen dynamics now makes the link between the carbon Ph.D., 1982 University of and nitrogen cycles explicit, by investigating the potential for Washington N assimilation to control the composition of photosynthetic planktonic assemblages. Ward lab has a web page where all of this is described. http://geoweb.princeton.edu/research/ecomicrobio/ecomicrobio.html 1. “Biocomplexity of Aquatic Microbial systems: Relat- ing diversity of Microorganisms to Ecosystem Function” (O’Mullan, Adhitya) (http://geoweb.princeton.edu/research/ biocomplexity/index.html) 2005 was the last offi cial year of this collaborative project, in- My research concerns the marine and global nitrogen cycle, volving several other institutions, all working in Chesapeake using molecular and immunological probes for marine Bay and coordinated through Princeton as the lead institu- bacteria and bacterial processes (especially nitrifi cation and tion. Microbial biogeochemical cycling of the elements regu- denitrifi cation), and measuring the rates of N transforma- lates a dynamic environment in which the cycles of different tion processes. We have ongoing research on denitrifi cation elements are linked through the physiology of microorgan- in several suboxic zones of the world ocean (Arabian Sea, isms. Our present understanding of ecosystem function has Eastern Tropical North and South Pacifi c) and in Antarctica, been gained through physical/chemical approaches to mea- the genes involved in nitrogen assimilation by phytoplank- surement and modeling of the net transformations. These ton, diversity of functional guilds of bacteria involved in the approaches necessarily rely on gross simplifi cations about the nitrogen cycle of aquatic systems, and the role of metals in role and regulation of the various functional groups (guilds) nitrogen redox biogeochemistry. Some of the main projects involved. Recent advances in molecular microbial ecology are summarized explicitly below. have shown the microbial world to contain immense diversi- Microbes control many of the important biogeochemical ty and complexity at every level: redundancy and duplication processes that occur in the oceans as well as on land. They of functional genes within a single organism; molecular di- contribute to the trace gas cycles that infl uence climate; they versity among functional genes that encode the same process utilize and produce nutrients that are involved in eutrophica- in different organisms; large genetic diversity among different tion; and they are even capable of cleansing the environment organisms apparently engaged in the same biogeochemical by degrading a vast variety of chemical compounds, both function within single communities; great variability in the naturally occurring and anthropogenically produced. My species composition of different communities that apparently research focuses on the nitrogen cycle and the microorgan- perform equally well. isms involved in transformations of inorganic and organic The goal of this project is to investigate the functional nitrogen in the ocean and in sediment environments. This relationship between complexity in microbial communi- research makes use of technical approaches that range from ties and the physical/chemical environment at a range of molecular biology to stable isotope biogeochemistry. The two biological and ecological scales. Previously, such analysis was main bacterial groups we study are the nitrifi ers, autotrophs technologically limited by the inability to assay large num- that oxidize ammonium to nitrite and nitrate, and the deniti- bers of samples simultaneously for a large number of genes fi ers, heterotrophs that can respire nitrate in the absence of and phylotypes. Using gene array technology, we will be able oxygen. The linked activities of these two groups can be cru- to detect the distribution and differential expression of func- cial in determining the chemical form and supply of nitrogen tional genes in natural systems. The gene arrays, along with 31 a full suite of ecosystem process measurements, are deployed 4. “Draft Level Sequencing of a Selection of Nitrifying along a transect that spans the eutrophic -oligotrophic gradi- Bacteria” (O’Mullan) and “Microbial genome sequencing; ent from the inland waters of the Chesapeake Bay out to the The complete genome sequence of a mini consortium of Sargasso Sea. Experiments and functional gene studies focus marine ammonia oxidizers” on key transformations in the carbon and nitrogen cycles Sequencing is nearly complete for the entire genome of fi ve (C fi xation, N fi xation, nitrifi cation, denitrifi cation, urea ammonia-and nitrite-oxidizing bacteria. Nitrobacter hambur- assimilation). The goal of these experiments is to determine gensis 14X was grown in our lab and I extracted the DNA how microbial species diversity affects the major energy and that was used for sequencing. Ward lab is the lead on the N. nutrient fl ows within ecosystems, and to assess the degree of hamburgensensis genome and annotation is currently under- stability or instability associated with changes in redundancy way. In the NSF project, we are sequencing two additional within guilds of microorganisms responsible for major nitro- ammonia oxidizers, including Nitrosococcus oceanus. The gen and carbon pathways. Moore foundation microbial genome project has agreed to The fi eld work for this project has been completed (~20 sequence another N. oceanus genome, and that project is now fi eld trips/research cruises have been completed in Chesa- underway. peake Bay, the Choptank River and the Sargasso Sea). Both 5. “Diversity and distribution of denitrifying bacteria in microarrays (using 70-bp oligomer probes) and macroarrays relation to chemical distributions in theoxygen minimum (using ~350 bp PCR products) derived from functional genes zone of the Arabian Sea” (Jayakumar, Tuit, Rich) for ammonia monooxygenase, nitrite reductase and nitroge- The Arabian Sea is one of three regions in the open ocean nase, have been developed and applied in this system. The where signifi cant denitrifi cation occurs in the water column. array technology is robust and “works” for most genes. Genes Nitrous oxide is an intermediate in the denitrifi cation path- encoding the essential enzymes RuBisCO (rbcL) and nitrate way, and is also produced during aerobic nitrifi cation at low reductase (NR) in eukaryotic phytoplankton were used in oxygen tensions. It is very effective as a greenhouse gas, and the fi rst successful second generation array to analyze phy- what controls its production and release from marine systems toplankton communities in the English Channel. This array is not well understood. Nitrous oxide accumulates in a char- detected both community composition (DNA) and gene acteristic pattern in oxygen minimum zones (OMZs), such expression (mRNA) in natural assemblages and demonstrated as that found in the Arabian Sea. In previous work (Granger the power of the approach. and Ward, 2003), we showed that denitrifi cation by cultured 2. “What limits denitrifi cation and bacterial production bacteria in the lab could be limited by copper availability, in Lake Bonney, Antarctica?” (Tuit) leading to the accumulation of denitrifi cation intermediates During the two recent fi eld seasons, we developed and tested in the medium. We hypothesized that copper availability in a series of fl ow cytometric assays for bacterial abundance OMZs might be quite low, low enough in fact to limit de- and physiological state in samples from Lake Bonney, where nitrifi cation at the nitrous oxide reduction step, thus leading denitrifi cation appears to proceed normally in one lobe of the to accumulation of nitrous oxide. Copper limitation might lake but not the other. Hypotheses about the ability of trace also lead to accumulation of nitrite in denitrifying bacteria metals to limit denitrifi cation in natural environments were that possess the copper type nitrite reductasae, rather than tested on laboratory cultures and on incubation experiments the iron enzyme. Thus, if copper limitation were a fact of life in the lake. It appears that copper availability can indeed in the OMZ, we might expect that the iron NiR should be regulate denitrifi cation but this is probably not the funda- more common than the copper NiR. mental reason for the dysfunctional N cycle in Lake Bonney. We have now completed three major cruises in the last 3. “Center for Environmental Bioinorganic Chemistry” three years, one each to the three major oxygen minimum (Jayakumar, Tuit) zones of the world ocean. Using chelators and various carbon The two forms of dissimilatory (respiratory) nitrite reductase, and nutrient additions to manipulate the natural communi- the cd-NiR (nirS gene) and Cu-NiR (nirK gene), are distrib- ties in trace metal clean incubations, we have shows that uted across the Bacterial and Archaeal domains in a great Carbon is probably the most important limitation in these diversity of microorganisms. Because trace metal availability systems, that denitrifi cation is very Anammox (anaerobic can limit denitrifi cation in the lab, we hypothesized that ammonium oxidation) is a recently discovered step in thee N metal distributions might infl uence the type of nir found in cycle, that performs essentially thee same role as denitrifi ca- natural marine assemblages. The fi rst step in addressing this tion. We have made some of the fi rst measurements of this hypothesis is to describe the distribution and diversity of nir process in Chesapeake Bay, and in the OMZ regions of thee genes in marine systems. One paper (Jayakumar, Francis and ocean (Jeremy Rich). Contrary to the fi rst reports by Danish Ward, 2004) describes the diversity and distribution of nirS and German investigators, we fi nd the anammox occurs in genes in the low oxygen coastal waters of the Arabian Sea in both sediments and the water column, but is not the domi- the continental shelf region of India. The sequences found nant process. We hypothesize that our methods, which were here are the fi rst reported for a water column environment, designed to minimize artifacts we perceived in the original and are quite different from those previously reported from methods, may be responsible for the different conclusions. sediment environments. This is a very controversial area in which we are keenly involved and plan to continue working (pending proposals).

32 6. “Functional diversity of phytoplankton N assimila- Ward, B. B. Temporal variability in nitrifi cation rates and related tion” (Adhitya, Allen) biogeochemical factors in Monterey Bay. Marine Ecology- Progress Series, 292: 97-109, 2005. Diatoms are an important component of marine photo- Allen, A. E., B. B. Ward and B. K. Song. Characterization of synthetic assemblages, and tend to be especially important diatom (Bacillariophyceae) nitrate reductase genes and their in coastal and upwelling systems. We hypothesize that detection in marine phytoplankton communities. Journal of their ability to utilize variable and high nitrate concentra- Phycology, 41:95-104, 2005. tions and to grow more rapidly on nitrate than many other O’Mullan, G. D. and B. B. Ward. Comparison of temporal and spatial variability of ammonia-oxidizing baceria to nitrifi ca- phytoplankton, is partly responsible for their success. We tion rates in Monterey Bay, CA. Applied and Environmental will investigate the response of important diatom groups Microbiology, 71: 697-705, 2005. to changing N and light regimes in an upwelling scenario Casciotti, K. L. and B. B. Ward. Nitric oxide reductase (norB) to test this hypothesis. Initial work on the key gene, nitrate genes identifi ed in ammonia-oxidizing bacteria. FEMS Micro- reductase, was done by Andy Allen (a post doc) who found bial Ecology, 52: 197-205, 2005. the fi rst diatom NR gene, and by Anita Adyhitya (student), Song, B., and B. B. Ward. Genetic diversity of benzoyl coen- zyme A reductase genes detected in denitfi ying isolates and who investigated the NR gene diversity in diatoms associated estuarine sediment communities. Applied and Environmental with seagrass beds. This work lays the foundation for quanti- Microbiology, 71:2036-2045, 2005. tative assays of diatom gene expression, which we will use to Articles In Press study differential success of various phytoplankton groups in Taroncher-Oldenburg, G. and B. B. Ward. Oligonucletoide micro- response to N availability. arrays for the study of microbial communities. In: DNA Analy- sis by Nonradioactive Probes (Ed.) Hilario, E. and Mackay, Two-Year Bibliography J.F., Humana Press, Totowa, NY, USA. Refereed articles: Bronk, D. A. and B. B. Ward. Inorganic and organic nitrogen cy- Jiang, W., A. Saxena, B. Song, B. B. Ward, T. J. Beveridge, S. C. cling in the Southern California Bight, Deep-Sea Research. B. Myneni. Elucidation of functional groups on Gram-positive Ward, B. B. and G. D. O’Mullan. Community level analysis: Ge- and Gram-negative bacterial surfacesusing infrared spec- netic andbiogeochemcial approaches to investigate commu- troscopy. Langmuir, 20:11433-11442,20:11433-11442, 2004. nity composition and function inaerobic ammonia oxidation. Song, B., and B. B. Ward. Molecular characterization of the as- In: Method in Enzymology. Ed: J. Leadbetter. similatory nitratereductase gene and its expression in the Glatz, R. E., P. W. Lepp, B. B. Ward and C. A. Francis. Microbial marine green alga Dunaliella tertiolecta. Journal of Phycol- diversity in the watercolumn of permanently ice-covered ogy, 40: 721-731, 2004. Lake Bonney, Antarctic, Geobiology. Jenkins, B. D., G. F. Steward, S. M. Short, B. B. Ward and J. P. Zehr. Fingerprinting diazotroph communities in the Chesa- Submitted peake Bay by using a DNA macroarray. Applied and Environ- Jackson, G. A., B. B. Ward, G. D. O’Mullan, C. A. Francis, M. A. mental Microbiology, 70: 1767-1776, 2004. Voytek, D. Eveillard.Estimating total numbers of microbial Steward, G. F., B. D. Jenkins, B. B. Ward and J. P. Zehr. Devel- operational taxonomic units (OTUs) using DNA sequence opment and testing of a DNA macroarray to assess nitro- data, Applied and Environmental Microbiology. genase (nifH) gene diversity. Applied and Environmental Ward, B. B., Nitrogen Cycling in Aquatic Environments. In: Microbiology, 70: 1455-1465, 2004. Manual ofEnvironmental Microbiology. Jayakumar, D. A., C. A. Francis, S. W. A. Naqvi and B. B. Ward. Ward, B. B. Nitrifi cation in marine systems. In: Nitrogen in the Diversity of nitrite reductase genes in the denitrifying water Marine Environment, Eds. D. G. Capone, D. A. Bronk and M. column of the coastal Arabian Sea. Aquatic Microbial Ecol- Mulholland. ogy, 34: 69-78, 2004. Adhitya, A., F. I. M. Thomas and B. B. Ward. Diversity of nitrate Ward, B. B., J. Granger, M. T. Maldonado, K. L. Casciotti, S. reductase genes from planktonic and epiphytic environments Harris and M. L. Wells. Denitrifi cation in the hypolimnion of in seagrass communities, Microbial Ecology. permanently ice-covered Lake Boney, Antarctica. Aquatic Microbial Ecology, 38: 295-307, 2005. Ward, B. B. Molecular approaches to marine microbial ecology and the marine nitrogen cycle. In: Annual Review of Earth and Planetary Science, 33:301-333, 2005.

33 34 Princeton Geosciences 2006 35 Guyot Hall, front entrance.

Princeton University Department of Geosciences Guyot Hall Princeton, NJ 08544-1003