GuyotGuyot Science 2004

Department of Geosciences, Princeton University

1 2 Guyot Science 2004

A Summary of the Research Progress and Accomplishments Made by the Faculty Members of the Department of Geosciences During the Year 2004

Last year, January-December 2004, was a year of transition for the Princeton Department of Geosciences. In June Jason Morgan retired from active service as a faculty member, after a distinguished 44-year career as a geoscientist at Princeton, and in July we were delighted to welcome the newest member of the geosciences faculty, Nadine McQuarrie. A second new faculty member, Adam Maloof, will join us approximately one year from now, following the completion of his postdoctoral fellowship at MIT. Nadine is a structural geologist who studies mountain building and other active tectonic processes, whereas Adam applies paleomagnetism and other tools to the study of the ancient earth. As usual, a number of geosciences faculty members received outside honors and awards in recognition of the excellence of their research. George Philander was elected a Member of the National Academy of Sciences, raising the departmental membership to four, and Bess Ward was elected a Fellow of the American Academy of Arts and Sciences, raising the departmental membership to three. Jorge Sarmiento was elected a Fellow of the American Association for the Advancement of Science; he is the fi rst Princeton geoscientist to be so honored. Danny Sigman received the 2004 Macelwane Medal of the American Geophysi- cal Union, which recognizes signifi cant contributions to the geophysical sciences by an outstanding young scientist. Danny is the fi rst member of the geosciences department to receive this coveted award; he also received a prestigious Friedrich Wilhelm Bessel Research Award of the Humboldt Foundation. François Morel will be the next recipient of 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 chem- istry and biology.” Finally, Allan Rubin was elected 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, 2003−2004, 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, Lincoln Hollister, Peter Bunge, Ken Deffeyes (emeritus), François Morel, Michael Bender, Bess Ward, Tullis Onstott. Front Row: Jason Morgan, 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 Highlights of our research of last year include: Professor 1. Completing data interpretation and preparing papers Ph.D., 1970, Columbia University summarizing the following studies: email: [email protected] (a) Measurements of atmospheric O2/N2 variations since 1991, and their implications for land and ocean CO2 sequestration (and its interannual variability). We show that

the oceans take up twice as much CO2 as the land biosphere between 1993-2002, and confi rm previous conclusions that

the land biosphere is a major CO2 source during El Nino events. (paper in review)

(b) The meridional gradient in the annually averaged O2/ N2 ratio of air. This work, led by my former postdoc Mark Battle (Bowdoin College), fi nds that the gradient is similar to recent model predictions, with a large equatorial maximum The activities of my laboratory focus on studies of the due to ocean outgassing in the tropics. (paper still in prepa- geochemistry of O2, with applications to understanding the ration) global carbon cycle and glacial-interglacial climate change. (c) Studies of the isotope geochemistry of O2 in the The geochemical properties we study are the concentration tropical Pacifi c. This paper, led by former postdoc Melissa of O in air (which we measure to very high precision), and 2 Hendricks, shows that the triple isotope composition of O2 the relative abundance of the three stable O isotopes (16O, in the tropical Pacifi c refl ects rates of all the metabolic and 17 18 O, and O) in O2. There are two subjects for the isotopic water mass mixing processes relevant to regional carbon studies: O2 in fossil air extracted from ice cores, and dis- fl uxes and the nutrient supply, which can therefore be quan- solved O2 in seawater. tifi ed from the data. (paper in review) They inform us about a range of topics. Studies of the (d) Studies of the triple isotope composition of O2 in O2 concentration (or ratio of O2/N2) in air constrain the fate surface waters of the Southern Ocean. This work, led by of fossil fuel CO2 that does not remain in the atmosphere: Matt Reuer, gives far more data than heretofore available on these measurements allow us to partition the “missing” CO2 rates of net and gross production in the upper water column between the oceans and the land biosphere. They also con- of the Southern Ocean, and show that rates of net and gross strain rates of seasonal biological production by the oceans. production increase to the north, contrary to our general Finally, they provide a test of models describing the global understanding of controlling factors. (paper still in prepara- interaction of ocean circulation and biogeochemistry: these tion) models predict that there should be a relatively large maxi- 2. Other signifi cant developments: mum in the atmospheric O /N ratio in air over the tropical 2 2 (a) Jan Kaiser’s instrument for continuously measuring Pacifi c. the O2/Ar ratio along cruise tracks was deployed on two The isotopic measurements of O in ice core trapped 2 additional equatorial Pacifi c cruises. His extensive data set gases refl ect the relative fertility of Earth’s biosphere, averaged allows continuous estimates of net oceanic production and over about 1,000 years. gives a great deal of new information about the regional The triple isotope composition of O in seawater refl ects 2 variations in this rate, and factors controlling them. the fraction of dissolved O from photosynthesis. O super- 2 2 (b) Bruce Barnett has completed the 400 ka record of the saturation refl ects net production (photosynthesis in excess triple isotope composition of O based on analyzing trapped of respiration); by combining measurements of O concen- 2 2 gases in the Vostok ice core. The preliminary interpreta- trations and isotopes, we can determine rates of photosyn- tion is that photosynthesis rates of the global biosphere were thesis, respiration, and net production in aquatic ecosystems. about 15% lower during glacial times and vary strongly with Of course rate determinations of these processes in seawater ice volume and the atmospheric CO concentration. have been made for many years; what makes our work new 2 (c) Makoto Suwa participated in an Antarctic expedition is that our approach does not require labor-intensive bottle led by Jeff Severinghaus (Scripps) that advanced our under- incubations at sea, and our measurements can be made on standing of the processes by which gases are trapped in glacial large numbers of samples collected by colleagues on cruises ice. of opportunity, and returned to the lab. (d) We have installed automated air samplers at nearly all Supplementing the O studies are studies of Ar. In 2 of our air sampling sites; the last one will go in this coming seawater samples, Ar gives a measure of physical supersatura- March. We hope for a signifi cant improvement in the qual- tion due to warming of waters and bubble entrainment. In ity of our atmospheric Ar/N ratio measurements, in particu- air samples, the Ar/N ratio refl ects seasonal outgassing and 2 2 lar. ingassing due to temperature-driven solubility changes, and (e) John Dunne has put the isotopes of O into his GFDL also to atmospheric mixing. model of ocean biogeochemistry, a key step in quantitively interpreting our data on this property. (f) Experiments with a postdoctoral fellow of Chuck

4 Dismukes, Department of Chemistry, showed that less than Bender, M. L., Climate-biosphere interactions on glacial-inter- glacial timescales, Global Biogeochemical Cycles, in press, 1 part in 105 of photosynthetic O2 production is from bicar- bonate; water is the main source. 2003. Battle, M., M. Bender, M. Hendricks, D. T. Ho, R. Mika, G. (g) We have constructed a vacuum line for doing He/U McKinley, S. Fan, T. Blaine, and R. Keeling, Measurements dating of speleothems. Speleothems are emerging as the and models of the atmospheric Ar/N2 ratio, Geophysical Re- most exciting new climate archive, and He/U dating would search Letters, 30 (15), 1786, doi:10.1029/2003GL017411, allow us to study samples that are too old to be dated by cur- 2003. rent methods (> 400,000 years). Articles in press or submitted: (h) We have established a collaboration with Dave Hendricks, Melissa, Michael L. Bender, and Bruce Barnett, The

Marchant, Boston University, to study samples of glacial ice triple isotope composition of dissolved O2 in the equatorial from the Dry Valleys, Antarctica, that are believed to be as Pacifi c: a tracer of mixing and biological production, submit- ted to Deep-Sea Research. old as Miocene. These samples could represent a major new Bender, Michael L., David T. Ho, Melissa B. Hendricks and Rob- climate archive but it remains to be demonstrated that their ert Mika, Mark O. Battle, Pieter P. Tans, Thomas J. Conway, gas records are properly preserved. Blake Sturtevant, and Nicolas Cassar, Atmospheric O2/N2 changes, 1993-2002: implications for the partitioning of Two-Year Bibliography fossil fuel CO2 sequestration, submitted to Global Biogeo- Refereed articles: chemical Cycles. Hendricks, Melissa B., Michael L. Bender and Bruce A. Barnett, E. Brook, E., J.W.C. White, A.S.M Schilla, M.L. Bender, B. Bar- Net and gross O production in the southern ocean from 2 nett, J.P. Severinghaus, K. C. Taylor, R. B. Alley, E. J. Steig, measurements of biological O saturation and its triple 2 Timing of millennial-scale climate change at Siple Dome, isotope composition, Deep-Sea Research Part I, 51, 1541- West Antarctica, during the last glacial period, submitted to 1561, 2004. Quaternary Science Reviews.

F. Anthony Dahlen surface beneath the Coral Sea, east of Solomon and south of Department Chair Java. This strong confi rmation of her earlier P-wave results Professor is signifi cant not only because the raypath coverage differs, Ph.D., 1969, University of Cali- but also because the off-path sensitivity of fi nite-frequency S fornia, San Diego waves is different from that of P waves. email: [email protected] Research on fi nite-frequency seismic tomography also proceeded on a number of other fronts in 2004. Graduate student Ying Zhou completed her Ph.D. dissertation project, in which she developed and 3-D sensitivity kernels for the measured phases, arrival angles, and amplitudes of waves that travel along the earth’s surface rather than through its inte- rior. The off-great-circle sensitivity that is accounted for by Ying’s surface-wave kernels enables a signifi cant improvement in the imaging and resolution of small-scale structural fea- Last year in this report, I described the fi rst success of my tures in the upper mantle. Her upper-mantle S-wave velocity longstanding collaboration with Guust Nolet, to account for model, obtained by inversion of a relatively small global fi nite-frequency wavefront healing effects in global seismic phase-delay dataset collected by Gabi Laske at the Scripps In- traveltime tomography: the successful imaging of deep- stitution of Oceanography, is comparable in quality to recent mantle thermal convection plumes by then graduate student ray-theoretical inversions of much larger datasets, with denser Raffaella Montelli. Raffa’s P-wave velocity images (Science crossing-path coverage. Ying has moved on to a postdoctoral 2004) show at least six well-resolved plumes — Ascension, position, working with Jeroen Tromp, at Caltech. Azores, Canary, Easter, Samoa and Tahiti — that originate in Third-year graduate student Tarje Nissen-Meyer has the vicinity of the core-mantle boundary, as originally pro- made substantial progress on his dissertation project, to posed by Jason Morgan more than thirty years ago. All of the compute exact waveform and traveltime sensitivity kernels in observed plumes have a diameter of several hundred kilome- a background spherical earth model, using an axially sym- ters, indicating that plumes convey a substantial fraction of metric spectral element method. The method should also be the internal heat escaping from the earth. Raffa successfully capable of computing the response of a spherical earth to a defended her Ph.D. dissertation in September 2003, and has moment tensor or point force source up to 1-Hz frequency, been working since that time as a postdoctoral fellow in the substantially better than can be achieved with normal-mode Department of Geosciences. In 2004 she has gone to invert summation codes. Individual 2-D codes are required for the S-wave traveltimes using fi nite-frequency sensitivity kernels, monopole, dipole and quadrupole components of the source. in order to provide an independent check on her very excit- At the present time, these three source types have been suc- ing P-wave results. In fact, Raffa’s recently obtained S-wave cessfully implemented in the simple case of an earth model images confi rm the presence of the six well-resolved deep- lacking a fl uid outer core. The next steps are to account for mantle plumes listed above, as well as the existence of start- the core using a displacement potential representation, and ing plumes that have not yet risen all the way to the earth’s to parallelize the code, for implementation on a small cluster. 5 This work is being conducted in collaboration with Alex Dahlen, F.A., Resolution limit of traveltime tomography, Geophys. Fournier, who defended his Princeton Ph.D. dissertation in J. Int., 157, 315–331, 2004. December 2003, and who is now a member of the faculty at Zhou, Y., Dahlen, F.A. & Nolet, G., 3-D sensitivity kernels for surface-wave observables, Geophys. J. Int., 158, 142–168, the University of Toulouse. 2004. Second-year graduate student Paul McGee has nearly Baig, A.M. & Dahlen, F.A., Statistics of traveltimes and ampli- completed his pre-generals research project, to investigate the tudes of waves in random 3-D media, Geophys. J. Int., 158, infl uence of near-fi eld terms on sub-receiver waveform and 187–210, 2004. traveltime sensitivity kernels in a uniform halfspace, using Montelli, R., Nolet, G., Masters, G. Dahlen, F.A. & Hung, S.-H., Global P and PP traveltime tomography: rays versus waves, the Cagniard-de Hoop method. Following the completion of Geophys. J. Int., 158, 637–654, 2004. his general examination, Paul will begin to work on the mea- Baig, A.M. & Dahlen, F.A., Traveltime biases in random media surement and inversion of S-wave traveltimes and amplitudes and the S-wave discrepancy, Geophys. J. Int., 158, 922– in the western U.S. 938, 2004. Finally, in 2004, I was able to shirk my administrative Ampuero, J.-P. & Dahlen, F.A., Ambiguity of the moment tensor, duties as department chair for long enough to (1) fully char- Bull. Seismol. Soc. Amer., 95, 390–400, 2005. Nolet, G. Dahlen, F.A. & Montelli, R., Travel times of seismic acterize the ambiguity of the moment-density tensor on a waves: a reassessment, in Data Analysis and Imaging with fault juxtaposing two dissimilar media, in collaboration with Global and Local Arrays, edited by Levander, A. & Nolet, G., postdoctoral fellow Pablo Ampuero (2) develop a spherical American Geophysical Union, Washington, D.C., in press, generalization of the one-dimensional time-frequency multi- 2005. tapers of Slepian and Thomson, for application to planetary Simons, F.J., Dahlen, F.A. & Wieczorek, M., Spatiospectral con- centration on a sphere, SIAM Review, in press, 2005. and cosmological data, in collaboration with postdoctoral Dahlen, F.A., Finite-frequency sensitivity kernels for boundary fellow Frederik Simons and (3) extend our recently developed topography perturbations, Geophys. J. Int., in press, 2005. fi nite-frequency (banana-doughnut) traveltime sensitivity Zhou, Y., Dahlen, F.A., Nolet, G. & Laske, G., Finite-frequency kernels, to allow for perturbations in the topography of ve- effects in global surface-wave tomography, Geophys. J. Int., locity discontinuities, such as those at 410 and 660 kilome- submitted, 2005. Zhou, Y., Nolet, G., Dahlen, F.A. & Laske, G., Global upper-man- ters depth within the earth. tle structure from fi nite-frequency surface-wave tomogra- Two-Year Bibliography phy, J. Geophys. Res., submitted, 2005. Baig, A.M., Dahlen, F.A. & Hung, S.-H., Traveltimes of waves in Dahlen, F.A. & Nolet, G. Comment on the paper “On sensitivity random 3-D media, Geophys. J. Int., 153, 1–16, 2003. kernels for ‘wave-equation’ transmission tomography” by de Zhou, Y., Nolet, G. & Dahlen, F.A., Surface sediment effects on Hoop and van der Hilst, Geophys. J. Int., submitted, 2005. teleseismic P wave amplitudes, J. Geophys. Res., 108 (B9), Montelli, R., Nolet, G., Dahlen, F.A. & Masters, G., Deep-mantle 2417, doi:10.1029/2002JB002331, 2003. plumes imaged with fi nite-frequency S-wave tomography, Montelli, R., Nolet, G. Dahlen, F.A., Masters, G., Engdahl, E.R. & G3 submitted, 2005. Hung, S.-H, Finite-frequency tomography reveals a variety of plumes in the mantle, Science, 303, 338–343, 2004.

Thomas S. Duffy edge of the physical and chemical properties of the materials Associate Professor composing the region. We are using the diamond anvil cell Ph.D., 1992, California Institute together with laser-heating techniques to produce pressures of Technology and temperature comparable to the deep mantle. Using email: [email protected] these tools, we are exploring crystal structures, phase rela- tions, elasticity, and other fundamental properties at ultra- high pressure conditions. Some examples of current research projects are listed below. Elastic properties of minerals. The elastic properties of minerals serve as a link between the observed seismic velocity structure of the Earth and its physical constituents at high pressures and temperatures. Elastic properties also provide insights into structure, bonding, and phase transitions. My research program focuses on understanding the large- Brillouin scattering is a method whereby one can measure scale behavior of Earth and other planets through experi- the complete elastic tensor by recording the frequency shift mental study of geological materials directly under extreme induced in scattered laser light by thermally generated sound pressure and temperature conditions. The study of planetary waves. We have recently used this technique to investigate interiors is currently progressing rapidly as a result of obser- the elastic properties of a variety of upper mantle minerals vational advances including new three-dimensional images of to pressures corresponding to ~300-400 km depth. Global the deep Earth. These new observations have the potential seismological and geodynamic models require an assessment to answer fundamental questions about the Earth’s origin, of not only thermal effects on seismic velocities but also evolution, and structure. Progress in this area is dependent compositional effects. We have used this new data together on coupling the new observations with a detailed knowl- with selected values from the literature to comprehensively 6 evaluate the sensitivity of seismic velocity to composition, Yin, H. Z., K. D. Hoburt, F. J. Kub, S. R. Shieh, T. S. Duffy, J. C. pressure, and temperature for major upper mantle miner- Sturm, High-Ge content SiGe islands formed on compliant als. As an example of the conclusions drawn from this type oxide by SiGe oxidation, Applied Physics Letters, 84, 3624- 3626, 2004. of study, we fi nd that the very different responses of olivines Shim, S.-H., T. S. Duffy, R. Jeanloz, C.-S. Yoo, and V. Iota, Ra- and garnets to iron substitution gives rise to signifi cant varia- man spectroscopy and x-ray diffraction of phase transitions tions in the sensitivity of different rock types to iron concen- in Cr2O3 to 61 GPa, Physical Review B, 69,144107, 2004. tration in accordance with their garnet content. Velocities in Jiang, F., S. Speziale, S. R. Shieh, and T. S. Duffy, Single-crystal mid-ocean ridge basalts are thus much affected by variations elasticity of andradite garnet to 11 GPa, Journal of Physics: Condensed Matter, 16, S1041-S1052, 2004. in iron content than other rock types such as harzburgite. Yin, H. Z., R. Huang, K. D. Hobart, J. Liang, Z. Suo, S. R. Shieh, Crystal structures at ultrahigh pressures. The recent T. S. Duffy, F. J. Kub, and J. C. Sturm, Buckling suppresion discovery of a post-perovskite phase in MgSiO may have of SiGe islands on compliant substrates, Journal of Applied 3 Physics, 94, 6875-6882, 2003. profound implications for understanding the Earth’s deep Speziale, S., F. Jiang, C. L. Caylor, S. Kriminski, C.-S. Zha, R. mantle and, in particular, the D” region near its base. Us- E. Thorne, and T. S. Duffy, Sound velocity and elasticity ing the laser-heated diamond anvil cell, we investigate the of tetragonal lysozyme crystals by Brillouin spectroscopy, Biophysical Journal, 85, 3202-3213, 2003. physical properties of the post-perovskite (CaIrO3-type) phase synthesized from a natural pyroxene composition with Kavner, A., and T. S. Duffy, Elasticity and rheology of platinum under high pressure and non-hydrostatic stress, Physical Fe content (9 mol.%) close to that expected for the lower Review B, 68, 144101, 2003. mantle. Our measured equation of sate is consistent with Yin, H., K. D. Hobart, F. J. Kub, S. R. Shieh, T. S. Duffy, and J. C. theoretical calculations for the Fe-free endmember, suggest- Sturm, Strain partition of Si/SiGe and SiO2/SiGe on compli- ing compressibility is not strongly sensitive to iron content. ant substrates, Applied Physics Letters, 82, 3853-3855, The transition pressure, on the other hand, is greatly lowered 2003. by the presence of 9 mol.% Fe. Our x-ray diffraction pat- Other miscellaneous publications terns indicate the formation of the post perovskite phase at Duffy, T. S., Deeper understanding, Nature, 430, 409-410, 2004. conditions corresponding to ~400-550 km above the core- Rubie, D. C., T. S. Duffy, and E. Ohtani, New developments in high-pressure mineral physics and applications to the mantle boundary. Comparison of volumes of coexisting Earth’s interior, introduction to special issue, Physics of the perovskite and CaIrO3-type phases at 80-106 GPa allow for Earth and Planetary Interiors, 143-144, 1-3, 2004. direct determinations of the volume change associated with Yin, H., K. D. Hobart, S. R. Shieh, R. L. Peterson, T. S. Duffy, the transformation. Using measured volumes together with and J. C. Sturm, Interference-enhanced Raman Scattering the bulk modulus calculated from equation of sate fi ts, we in Strain Characterization of Ultra-thin Strained SiGe and Si Films on Insulator, in High-Mobility Group-IV Materials and predict that the bulk sound velocity will decrease strongly Devices, edited by M. Caymax, E. Kasper, S. Zaima, K. Rim, across this transition. We also fi nd that the post-perovskite and P. F. P. Fichtner, Materials Research Society, Warren- phase can be at least partially quenched to ambient condi- dale, Pa, vol. 809, pp. B3.6.1-B.3.6.3, 2004. Yin H. Z., K. D. Hobart, R. L. Peterson , F. J. Kub, S. R. Shieh, T. tions. Companion studies on the analog material MgGeO3 have documented the existence of a post-perovskite phase in S. Duffy, and J. C. Sturm, Fully-depleted strained-Si on in- this material as well. sulator NMOSFETs without relaxed SiGe buffers, 2003 IEEE International Electron Devices Meeting, Technical Digest, Two-Year Bibliography pp. 3.2.1-3.2.4, 2003. Books Yin, H., R. L. Peterson, K. D. Hobart, S. R. Shieh, T. S. Duffy, and Rubie, D. C., T. S. Duffy, and E. Ohtani, editors, New Develop- J. C. Sturm, High Ge content (~0.6) relaxed SiGe layers by ments in High Pressure Mineral Physics and Applications to compliant substrates approaches, in Integration of Heter- the Earth’s Interior, Elsevier, Amsterdam, 625 pp., 2004. ogenous Thin-Film Materials and Devices, edited by: H. A. Atwater, M. I. Current, M. Levy, and T. Sands, Mat. Res. Soc. Refereed articles: Symp. Proc., 768, 15-19, 2003. Speziale, S., T. S. Duffy, and R. J. Angel, Single-crystal elastic- Yin, H., R. L. Peterson, K. D. Hobart, S. R. Shieh, T. S. Duffy, ity of fayalite to 12 GPa, Journal of Geophysical Research, and J. C. Sturm, Relaxed SiGe layers with high Ge content 109, B10201, doi:10.1029/2004JB003162, 2004. by compliant substrates, in COMOS Front-End Materials He, D. W. and T. S. Duffy, Equation of state and strength of and Process Technology, edited by T. J. King, B. Yu, R. J. boron suboxide from radial x-ray diffraction in a diamond P. Lander, and S. Saito, Materials Research Society Sympo- cell under nonhydrostatic compression, Physical Review B, sium Proceedings, 765, 147-151, 2003. 184121, 2004. Shieh, S. R., Duffy, T. S., and Li, B., Superhard Materials Under Jiang, F., S. Speziale, and T. S. Duffy, Single-crystal elasticity of Pressure: Strength and Elasticity of Stishovite, National grossular- and almandine-rich garnets to 11 GPa, Jour- Synchrotron Light Source Science Highlights, July, 23, 2003, nal of Geophysical Research, 109, B10201, doi:10.1029/ http://nslsweb.nsls.bnl.gov/nsls/sci&tech/science/2003/07- 2004JB003081, 2004. Shieh.htm. Shieh, S. R., T. S. Duffy, and G. Shen, Elasticity and strength of calcium silicate perovskite at lower mantle pressures, Phys- Articles in press or submitted ics of the Earth and Planetary Interiors, 143 144, 93-106, Kiefer, B. and T. S. Duffy, Finite element simulations of the 2004. laser-heated diamond anvil cell, Journal of Applied Physics, Shim, S.-H., T. S. Duffy, R. Jeanloz and G. Shen, Stability and submitted, 2004. Shieh, S. R., T. S. Duffy, and G. Shen, In situ x-ray diffraction crystal structure of MgSiO3 perovskite to the core-mantle boundary, Geophysical Research Letters, L10603, doi: study of SiO2 at deep lower mantle conditions, Earth and 10.1029/2004GL019639, 2004. Planetary Science Letters, submitted, 2004.

7 Speziale, S., F. Jiang, and T. S. Duffy, Compositional depen- dence of the elastic wave velocities of garnets, olivines, and other mantle minerals at high pressures, Structure, Compo- sition, and Evolution of Earth’s Mantle, edited by J. D. Bass, R. van der Hilst, J. Matas, and J. Trampert, AGU Monograph Series, submitted, 2004.

Lincoln S. Hollister we have defi ned a process in mountain building, based on Professor our studies in Bhutan. This process involves the rapid extru- Ph.D., 1966, California Institute sion of a low viscosity, partially melted orogenic channel of Technology from lower crustal depths. It was published in 2002. email: [email protected] With my colleagues at the University of Texas, El Paso, I helped establish a temporary seismic network in Bhutan in order to determine the whole crustal structure under the Himalayas and in order to assess earthquake hazard potential. The network operated for a year and we are now interpreting the results. This includes rationalizing fault plane solutions with convergence of India against Asia and with geologic features exposed at the surface. Lamellar magnetism With the late Robert Hargraves, I worked on using prop- How are mountains and continental crust made? These erties of lamellar magnetism for interpreting discordant are the major questions driving my research and teaching. paleomagnetic inclinations of plutons in western British I interpret the pressure-temperature-time-strain history of Columbia. We submitted a paper prior to Robert’s death; it rocks in the context of the tectonic processes operating on was published in 2004. In the paper, we propose a solution the continental crust. My contributions are based on direct to the origin of enigmatic paleomagnetic data pertaining to observation of the products of mountain building. I have the on-going Baja British Columbia controversy. forged collaborations with people in other disciplines and work in an interdisciplinary mode where the objective is to Two-Year Bibliography achieve results unattainable by individual investigators. I also Refereed articles: Hollister, L. S., R. B. Hargraves, T. S. James, and P. R. Renne, continue to work on ways to help students use the power of The paleomagnetic effects of reheating the Ecstall pluton, making observations in the fi eld. British Columbia, Earth and Planetary Science Letters v. Currently, my research is on three fronts: the origin of 221, 397-407, 2004. the Coast Mountains of British Columbia, the origin of the Morozov, I.B., N. L. Christensen, S. B. Smithson, and L. S. Hol- Himalayas in Bhutan, and the application of lamellar magne- lister, Seismic and laboratory constraints on crustal forma- tion in a former continental arc (ACCRETE, southeastern tism for resolving the Baja British Columbia controversy. Alaska and western British Columbia), Journal Geophysical Batholiths Research, 108(B1), 2, doi:10.1029/2001JB001740. 9pp, My biggest research commitment for the next fi ve years is 2003. Andronicos, C. L., D. H. Chardon, L. S. Hollister, G. E. Gehrels, a new multidisciplinary collaboration which proposes to and G. J. Woodsworth, Strain partitioning in an obliquely resolve the continental crust composition paradox: although convergent orogen, plutonism, and synorogenic collapse: continental crust begins as accreted island arcs the average The Coast Mountains batholith, British Columbia, Canada, composition of continental crusts is more silicic than that Tectonics, 22(2), 1012, doi:10.1029/2001TC00312, 24pp, of island arcs. Before becoming stable continental crust, the 2003. Daniel, C. G., L. S. Hollister, R. R. Parrish, and D. Grujic, Extru- original island arc composition is modifi ed by processes that sion of the Main Central Thrust zone from lower crustal are not understood. This is a fundamental problem in the depths, eastern Bhutan Himalaya, Journal Metamorphic earth sciences. Geology, v. 21, 317-334, 2003. The new project is located in the Coast Mountains of Articles in press or submitted British Columbia. It is called BATHOLITHS. The name Hollister & Grujic, Channel fl ow in Bhutan; submitted to Quarterly comes from the hypothesis that the formation of batholiths is Journal of Geological Society of London. a major factor in making typical continental crust. Our tool- Hollister, Diebold, Das, Whole crustal response to Late Tertiary box of techniques includes active and passive source seismol- east-west extension near Prince Rupert, British Columbia. Canadian J. Earth Sciences. ogy, geochemistry, structural geology, and petrology. Velasco and others. High seismicity rate in the Bhutan Himalaya Bhutan determined from a temporary seismic network. GRL. With my colleague Djordje Grujic at Dalhausie University,

8 Gerta Keller Keller, G., Stueben, D., Berner, Z. and Adatte, T. Cenomanian- Turonian d13C, d18O, sea-level and salinity variations at Professor Pueblo, Colorado, Paleoclimatol. Paleoecol. Paleogeogr., Ph.D., 1978, Stanford University 211, 19-43, 2004. email: [email protected] 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 Chicxulub predates KT Boundary, Meteoritics and Planetary Science (MAPS), 39,(6/7), 1127-1144, 2004. Wolfgang Stinnesbeck, Gerta Keller, Thierry Adatte, Markus Hart- ing, Doris Stüben, Georg Istrate and Utz Kramar: Yaxcopoil- 1 and the Chicxulub impact, International Journal of Earth Sciences, Volume 93, Number 6, pp. 1042 – 1065, 2004. Keller, G. and Pardo, A.. Disaster Opportunists Guembelitrinidae – Index for Environmental Catastrophes, Marine Micropale- During the past year the 10-year-long research project on ontology, 53, 83-116, 2004. the Cretaceous-Tertiary boundary impact and mass extinc- Abramovich S., and Keller, G.. Planktic foraminiferal response to tion has culminated in spectacular success with the coming latest Maastrichtian abrupt warm event a case study from midlatitude DSDP Site 525, Marine Micropaleontology, 48, together of empirical evidence from sedimentology, stratigra- 225-249, 2003. phy, paleontology, mineralogy, geochemistry and paleomag- Schulte, P., Stinnesbeck, W., Stueben, D., Kramar, U., Berner, Z., netic stratigraphy. The environmental history revealed by all Keller, G., and Adatte, T.. Fe-rich an K-rich mafi c spherules of these disciplines indicates that the current impact mass ex- from slumped and channelized Chicxulub ejecta deposits in tinction scenario can no longer be supported. The Chicxulub the northern La Sierrita area, NE Mexico, Int. J.Earth Sci. 92, 114-142, 2003. impact, commonly believed to be the cause for the KT mass Stueben, D., Kramar, U., Berner, Z.A., Meudt, M., Keller, G., extinction, predates this mass extinction by 300,000 years. A Abramovich, S., Adatte, T., Hambach, U., and Stinnesbeck, second impact together with major Deccan volcanism is the W.. Late Maastrichtian paleoclimatic and paleoceanograph- likely cause for the mass extinction. ic changes inferred from Sr/Ca ratio and stable isotopes, Our new theory and its supporting evidence has been Paleoclimatol. Paleoecol. Paleogeogr., 199, 107-127, 2003. carried by news outlets all over the world and more than Keller, G., Stinnesbeck, W., Adatte, T. and Stueben, D.. Multiple Impacts across the Cretaceous-Tertiary boundary, Earth Sci- 100 news articles have appeared in international magazines, ence Reviews, 62, 327-363, 2003. including top journals like Nature, The Economist, La Keller, G., Stinnesbeck, W., Adatte, T., Holland, B., Stueben, D., Recherche, Der Spiegel, Focus, Facts etc. and the Geological Harting, M., C. de Leon and J. de la Cruz. Spherule deposits Society of London has sponsored a debate on my team’s work in Cretaceous-Tertiary boundary sediments in Belize and (Geoscientist, November,November, 2003). Guatemala, J. Geol., London, 160, 1-13, 2003. Keller G. Biotic effects of impacts and volcanism, Earth and Six documentary fi lms have been made over the past Planetary Science Letters, 215, 249-264, 2003. year, including BBC Horizon (released in October 2004 in Gerta Keller, Thierry Adatte and Wolfgang Stinnesbeck. The non- the UK), ABC, the History Channel, Swiss TV (released smoking gun, Geoscientist, 13 (11), 8-11, 2003. Nov. 24), The New York Museum of Natural History, (to be Abramovich, S., Keller, G., Stueben, D. and Berner, Z. Char- released May 2005) and TV interview with Alexander Kluge acterization of late Campanian and Maastrichtian planktic foraminiferal depth habitats and vital activities based on for German Film, TV and Media to be released in January 6 stable isotopes, Paleoclimatol. Paleoecol. Paleogeogr., 202, and February (2005), 1-29, 2003. A 2000 word summary of our results is published in the Other miscellaneous publications Geoscientist and can be downloadeddownloaded at Keller. Suche nach der Ursache des Massensterbens vor 65 Mil- http://www.geolsoc.org.uk/template.cfm?name=NSG23498 lionen Jahren. Werdenberger Jahrbuch, p. 189-200, 2004. 57238495 Keller. La Météorite innocentée. La Recherche, 379, 30-36, 2004. Two-Year Bibliography Articles in press or submitted Refereed articles: In press. Keller, G. and Pardo, A., in press. Guembelitria Blooms Keller, G.. Paleoecology of Late Maastrichtian-early Danian – Environmental Catastrophes Index. planktic foraminifera in the eastern Tethys (Israel and In press, Stueben, D., Harting, M., Kramar, U., Stinnesbeck, W., Egypt), J. Foram. Res., 34(1): 49-73, 2004. Keller, G., and Adatte, T., in prep. High resolution geo- Keller, G. and Pardo, A.. Paleoecology of the Cenomanian- chemical record in Mexico during the Cretaceous-Tertiary Turonian Stratotype Section (GSSP) at Pueblo, Colorado, transition. Geochmica et Cosmochimica Acta. Marine Micropleontology, 51: 95-128, 2004.

9 Nadine McQuarrie data from these maps can be displayed in a variety of ways Assistant Professor that highlight not only the areas where the reconstructions Ph.D., 2001, Arizona University are accurate, but more importantly where the reconstructions email: [email protected] are inaccurate (implying where more fi eld-based data are needed). The maps can also be displayed as a movie that il- lustrates how extension varies with time and as velocity fi elds over 2-5-10 m.y. increments that can be compared to the modern GPS strain fi eld. This work has provided the background for two senior theses. Margee Prat is integrating the ARC GIS database of extension in the central Basin and Range with the NAVDAT (North American Volcanic) Database. The geochemistry of volcanic rocks in the NAVDAT data set is related to the lithospheric thickness at the time the rocks were formed. The palinspastic maps allow us to know where the rocks were located as they were erupting. Together these data sets My principal research interests include the structural and have the potential to show how mantle lithospheric thickness geodynamic evolution of mountain belts and orogenic pla- has evolved with time in conjunction with crustal thinning. teaus. I use structurally based fi eld studies, in conjunction Richard Lease is conducting fi eld research to constrain the with a variety geophysical and geochemical data sets to un- amount and timing of fault offset in the Mojave portion of derstand and quantify tectonic processes such as the growth the Eastern California Shear Zone (ECSZ). The ECSZ is and collapse of orogenic plateaus, development of fold-thrust a region east of the San Andreas fault that accommodates belts, kinematics of continental collision, fl ow of the lower a signifi cant portion of the Pacifi c/North American plate crust and the kinematics and dynamics of diffuse continental boundary and has been the site of several large (M 6-7), extension. Current projects I have been working on include: recent earthquakes. The model suggests large fault displace- 1) how extension varies is space and time within the western ments are needed in this region, but the geologic data to sup- United States over the last 36 m.y., 2) what controls the lat- port model offsets are unavailable. Richard found a unique eral extent of the Andean Plateau in Peru and 3) the interac- marker offset along the fault, which suggests 25 km of offset tion between erosion and deformation in fold-thrust belts (15-25 km more than previous estimates). both in Bolivia and Ecuador. Controls on orogen width. The formation of high eleva- Basin and Range, Western U.S. The Basin and Range tion plateaus has been linked to a wide variety of processes province of western North America is the classic example of including; shortening magnitudes, pre-existing sedimentary large magnitude diffuse deformation. More is known about or structural architecture, plate convergence rates and direc- timing, amount, and spatial variations of extension within tions, subducting plate geometry and climate. Although the the Basin and Range Province of than any other comparable Andes mountains extend over 8000 km along the western region. Thus, the western United States is the best natural side of the South American continent, only the segment laboratory available to look at the driving forces behind large between 12° and 27° S houses a high elevation plateau. magnitude diffuse deformation such as the interplay between The signifi cant along strike changes in morphology, struc- body and plate boundary forces. The critical body of data ture and zonal climate regimes make the South American required to evaluate the dynamics of continental extension Andes an ideal location to look at the factors that control is the detailed kinematic history of the region of interest. orogen width. One of the most abrupt along strike changes Reconstructing the strain history of the province as a whole in morphology of the Andes is along the northern edge of requires knowing both the extension rate and width of ex- the Andean plateau in Peru. Here a wide zone (~350 km) tending regions as a function of time. Although in some areas of high topography with minimal vertical relief transitions of the Basin and Range this information is very well known, abruptly into a signifi cantly narrower (150 km) mountain the kinematics of the province as a whole is not. To recon- range with a narrow drainage divide. This west stepping, struct the strain history of the Basin and Range, I have cre- right angle bend in topography is mimicked in the structural ated a GIS (global information systems) database of timing, elevation (i.e. stratigraphic erosion level) of lower Paleozoic magnitude and direction of extension for areas within the rocks. This signifi cant change in topographic and structural Basin and Range of North America in which the kinematics width provides a unique opportunity to evaluate the factors are well documented. This database is accessed by an ARC that govern the width of orogens. GIS script that sequentially restores the extension and allows This last summer I conducted a pilot fi eld study along me to determine possible extensional histories for areas that the northern border of the Andean plateau in central Peru. are not as well documented. The end results of this work are The goals of the study were to (1) evaluate road access and a series of palinspastic maps that show a sequentially restored safety, (2) understand the level of rock exposure (quality of Basin and Range from 36 million years ago to present. The outcrops) especially on the wet, eastern side of the orogen, (3) decipher the Paleozoic stratigraphy, (4) make a pre-

10 liminary strip map across one of the proposed transects, (5) input into 2D and 3D thermo-mechanical models that link collect and evaluate quality of samples for thermochronology, uplift and erosion to an evolving thermal fi eld. This thermal and (6) establish collaborations with Peruvian Scientists. history is used to calculate and predict apatite fi ssion track The preliminary data was incorporated into a collaborative and apatite and zircon (U-Th)/He sample ages. Numerical NSF grant that was submitted to the Tectonics panel. My modeling allows a physically based evaluation of the plausible colleague and I proposed to evaluate the fi rst order controls range of structural and erosion histories that could produce on plateau formation through mapping lithological, structur- an observed suite of ages. Thus, our approach to interpret- al and erosional changes along four structural transects that ing thermochronometer ages is not to determine the solution cross the entire orogen, constructing modern, crustal-scale that satisfi es a set of observations, but rather the range of balanced cross sections, and quantifying the timing and rates solutions. of exhumation and erosion with low-temperature thermo- In Ecuador our approach will be similar. Preliminary chronometry. Documenting the 3D kinematic history of fi eld work this summer in Ecuador allowed us to sample the northeastern Andean plateau enables an evaluation of rocks suitable for low temperature thermochronology across the relative importance of several features (climate, erosion, a thrust sheet composed entirely of granite rocks. Although pre-existing stratigraphy, pre-existing structure and regional the thrust sheet contains no traditional markers to determine tectonics) that are commonly cited as exerting a major con- the amount of fault offset, we propose that a robust set of trol on orogen width. cooling ages can help limit permissible amounts of fault Interaction between erosion and deformation in fold- offset and provide insight to erosion magnitudes. If this is thrust belts. Quantifying the interactions of lithology, tec- possible we will be able to use a suit of thermochronometers tonics and climate on multi-scale morphologies of mountain to describe the relative contributions of uplift, translation ranges is at the forefront of current geological research. One and erosion to the exhumation history of the Ecuadorian of the central facets to this research is the magnitude of con- fold-thrust belt. trol climate and the associated erosion has on the formation Two-Year Bibliography development of orogens. Projects in both Bolivia (collab- Refereed articles: orative research with Dr. Todd Ehlers and graduate student McQuarrie, N., Crustal-scale geometry of Zagros fold-thrust belt, Iran, Journal of Structural Geology, v.26, p. 519-535, 2004. Jason Barnes at University of Michigan) and Ecuador will McQuarrie, N., Stock, J.M., Verdel, C., and Wernicke, B.P. use low-temperature thermochronometry, fi eld-constrained Cenozoic evolution of the Neotethys and implications for structural analysis, and numerical models to delineate the ki- the causes of plate motions, Geophys. Res. Let., 30, 2036, nematic evolution of the fold-thrust belts, and the impact of doi:10.1029/2003GL017992, 2003. erosional variations on their formation. In Bolivia we have Articles in press or submitted obtained preliminary cooling ages and structural data for McQuarrie, N., Horton, B.K., Zandt, G., Beck, S., and DeCelles, balanced cross sections. During the following year we will P.G., in press, The lithospheric evolution of the central An- integrate the cross sections in to 2-D MOVE (a cross section dean Plateau, Tectonophysics. restoration program) that allows deformation to be forward modeled providing a quantitative description of the kinemat- ics (displacement, velocity, velocity change) of fold-thrust belt deformation. The simulated velocity fi eld will be the

François M. M. plankton in the sea is the overarching question addressed in my research group. Our ongoing projects (all more or less Morel related to trace metals) include: the acquisition of carbon and Blanke Professor of Geosciences iron by diatoms, the storage of iron by nitrogen fi xing cyano- Director, Princeton Environmental bacteria, the acquisition of phosphorus from organic com- Institute Director, Center in Envi- pounds by coccolithophores, the biological role of cadmium ronmental BioInorganic Chemistry in the sea, and the biogeochemistry of mercury. Ph.D., 1971, California Institute of Technology Iron Uptake by diatoms. Iron is now known to limit the email: [email protected] growth of phytoplankton, particularly diatoms, in large re- gions of the oceans. Old laboratory data from our group have shown that diatoms take up the free iron (i.e., the iron that is not bound to strong chelating agents) from solution. But, according to fi eld data, the free iron in surface seawater is too low to support the growth of these dominant primary pro- Marine phytoplankton are responsible for about half of the ducers. Both new and old laboratory data show that diatoms global primary production and, by exporting organic matter can obtain their iron by reducing Fe(III) in some chelates. to the deep sea, they maintain a low concentration of CO2 We have now established that Fe(III) reduction at the diatom in surface waters and in the atmosphere. What physical and surface is an essential step in the uptake of iron in all cases chemical factors control the growth and activity of phyto- 11 and developed a model for uptake kinetics that reconciles all the activity of the zinc enzyme alkaline phosphatase which available data (Shaked et al. submitted). This model provides cleaves phosphate from various organic substrates. We have a chemical framework to quantify the bioavailability of Fe in now studied the activity of this enzyme in the ubiquitous seawater. In the course of this study, we have also shown that species Emiliana huxleyi and demonstrated that very small diatoms produce an abundant quantity of superoxide (O2-), enzyme (and thus zinc) concentrations are necessary to by extracellular reduction of oxygen (Kustka et al. in press). provide the phosphate necessary for growth (Shaked et al. in Superoxide is an extremely active radical (able to reduce and prep). We have also shown that the activity of this extracellu- oxidize many solutes including Fe) but we have, so far, not lar enzyme is enhanced by association with the calcite liths of been able to establish a physiological role for its production the organism. We are in the process of purifying and charac- by diatoms. terizing the enzyme. Iron Storage in Cyanobacteria. In addition to directly The biological Role of Cadmium. Cadmium, an ele- limiting primary production in some oceanic regions, iron ment which has been thought to be only toxic to organisms, is thought to limit it indirectly in many other regions by behaves exactly like a nutrient in the sea. In fact because of controlling the input of fi xed nitrogen. This is because the its excellent correlation with phosphate, cadmium is used as a nitrogenase enzyme, which is responsible for dinitrogen (N2) paleotracer for nutrients. Over the past several years, we have fi xation, requires a lot of Fe. The most important nitrogen demonstrated that cadmium is an important micronutrient fi xer in the sea is the cyanobacterium Trichodesmium which for marine phytoplankton. In particular, we have discovered thrives in tropical and subtropical regions where iron inputs that diatoms possess a Cd-carbonic anhydrase, which is from atmospheric dust are highly episodic. We have thus involved in the acquisition of inorganic carbon for photo- been studying the mechanism of Fe storage in Trichodes- synthesis. We have now obtained the full DNA sequence for mium. As a fi rst step, we have identifi ed, isolated, over- this enzyme (the fi rst Cd enzyme discovered), over-expressed expressed and partially characterized a Dps protein (DNA- it in a bacterial host, characterized its active center by X-ray binding protein from starved cells) from this organism spectroscopy and shown its induction upon Cd addition (Castruita et al. submitted). This protein, the fi rst Fe storage (Lane et al. submitted). We have also now shown that many protein isolated from a marine microbe, is able to store vast diatom species possess closely homologous versions of this quantities of Fe; it is also able to bind to DNA and protect Cd enzyme and that it is induced under CO2 and Zn limita- it from degradation. This second attribute may be impor- tion (Park et al. in prep.). These results make it now pos- tant to protect the genetic material of the organism during sible for us to design experiments that will test the presence periods of dormancy when nutrient concentrations are low or and induction of this Cd –carbonic anhydrase in the fi eld. other environmental conditions are unfavorable. Mercury Methylation. Our continuing work on the bio- Inorganic Carbon Acquisition by Diatoms. A few years geochemistry of mercury is presently focused on mercury ago, we reported that diatoms growing under present day methylation. Since methyl-mercury is the species accumu- atmospheric conditions function as unicellular C4 plants, i.e., lated in fi sh via the food chain, this is a key transformation in that they concentrate carbon by accumulating an intermedi- determining human exposure to mercury. Yet it has received ate C4 organic compound before CO2 fi xation in their chlo- surprisingly little attention over the past 20 years. The two roplast. This work, which implies that CO2, may limit the questions we are trying to answer are: 1) where is methyla- productivity of diatoms, has been controversial. In a recent tion occurring in the ocean and by what mechanism? and paper (Reinfelder et al. 2004) we have now provided strong 2) what controls the rate of methylation by sulfate reducing supporting evidence for the C4 pathway: i) specifi c inhibi- bacteria in freshwater systems? New data on the concentra- tors of the enzymes involved in the C4 pathway effectively tion of mercury in tuna caught off Hawaii show that this stop oxygen evolution under low (i.e., atmospheric) pCO2; concentration has not changed in thirty years. Mercury in ii) addition of the C4 intermediates drastically lowers inor- tuna thus does not respond to the increase in mercury in the ganic carbon uptake but not photosynthesis; iii) the carbon atmosphere and in the surface of the oceans caused by an- accumulated in the cells in very short duration experiments is thropogenic inputs (Kraepiel et al. 2003). We thus propose an organic rather than an inorganic compound as previously that methyl mercury in the open ocean may originate from thought. This project, in concert with our work on cadmi- the deep sea, perhaps from hydrothermal vents. An ongoing um-carbonic anhydrase, indicates that a particularly effective Bachelor thesis (April Brown ’05) indicates that methylation carbon acquisition system may be in part responsible for the might be effected chemically by methane at high pressure ecological success of diatoms in the oceans. and temperature. In terrestrial systems, we know that mercu- Use of Organic Phosphorus Sources by Coccolithophores. ry methylation is effected by sulfate reducing bacteria. Our Coccolithophores are calcite precipitating phytoplankton biochemical work with these organisms has shown that, con- that are dominant in many oligotrophic gyres of the oceans trary to what is commonly believed, the acetylCoA pathway and they can form massive blooms visible from space. They is not necessary for Hg methylation (Ekstrom et al. 2003). owe part of their ecological success to their ability to obtain We are now trying to elucidate what enzymes are actually phosphorus from organic compounds when inorganic P involved in methylation and what control their activity. concentrations are vanishingly low. This is achieved through

12 Two-Year Bibliography Saito, M. A., D.M. Sigman and F.M.M. Morel. The bioinorganic Refereed articles: chemistry of the ancient ocean: the co-evolution of cyano- Shaked, Y., A.B. Kustka, F.M.M. Morel and Y. Erel, Simultaneous bacterial metal requirements and biogeochemical cycles at determination of iron reduction and uptake by phytoplank- the Archean – Proterozoic boundary? Inorganica Chimica ton, Limnol. and Oceanography: Methods http://www.aslo. Acta 356C, 308-318, 2003. org/lomethods/free/2004/0137.pdf, Vol 2, 137-145, 2004. Morel, F.M.M. and N.M. Price. The Biogeochemical Cycles of

Reinfelder, J.R., A.J. Milligan, F.M.M. Morel, The role of the C4 Trace Metals in the Oceans, Science, 300: 944-947, 2003. pathway in carbon accumulation and fi xation in a marine Articles in press or submitted: diatom, Plant Physiology Vol.Vol. 135, 2106 2111, 2004. Amyot, M., F.M.M. Morel and P. A. Dark, Oxidation of dissolved Lalonde, J.D., M. Amyot, J. Orvoine, F.M.M. Morel, J-C. Auclair, and liquid elemental mercury in aquatic environments, Envi- P.A. Ariya, Photoinduced Oxidation of Hg0(aq) in the Waters ron., Sci. Technol., 2004, in press. from the St. Lawrence Estuary Environ., Sci. Technol., 38 (2) Sternberg, E., D. Tang, T.-Y. Ho, C. Jeandel and F.M.M. Morel, 508-514, 2004. Barium Uptake and Adsorption in Diatoms, Geochimica Kraepiel, A.M.L., K. Keller, H.B. Chin, E.G. Malcolm, F.M.M. Mo- Acta , 2004, in press. rel, Response to Comment on “Sources and Variations of Kustka, A. B., Y. Shaked, A.J. Milligan, D. W. King, F.M.M. Morel, Mercury in Tuna,” Environ. Sci. Technol., 38(14) 4048, 2004. Extracellular production of superoxide by marine diatoms: Milligan, A. J. and F.M.M. Morel, Dynamics of silicon metabolism implications for iron redox chemistry and bioavailabilty, and silicon isotopic discrimination in a marine diatom as a Limnol. and Oceanogr., 2004, in press. function of pCO Limnol. Oceanogr., 49 (2), 322 329, 2004. 2 Shaked, Y., A.B. Kustka and F.M.M. Morel, A general kinetic Ekstrom, E.B., F.M.M. Morel, J.M. Benoit, Mercury Methylation model for iron acquisition by eukaryotic phytoplankton, Independent of Acetyl CoA Pathway in SRB, Appl. and Envi- Limnol. and Oceanogr., 2004, submitted. ron. Microbiol., 69 (9) 5414 – 5422, 2003. Tang, D. and F.M.M. Morel, Distinguishing between intracellular Kraepiel, A.M.L., K. Keller, H.B. Chin, E.G. Malcolm, F.M.M. Mo- and extracellular trace metals in phytoplankton. Marine rel, Sources and Variations of Mercury in Tuna, Environ. Sci. Chemistry., 2004, submitted. Technol., 37 (24) 5551-5558, 2003. Lane, T., M.A. Saito, H. Park, G.N. George, I.J. Pickering, R.C. Quigg, A., Z.V. Finkel, A.J. Irwin, Y. Rosenthal, T.-Y.Ho, J.R. Prince, F.M.M. Morel, Isolation and Characterization of a Reinfelder, O. Schofi eld, F.M.M. Morel, P.G. Falkowski, The Cadmium Carbonic anhydrase from a Marine Diatom, Na- evolutionary inheritance of elemental stoichiometry in ma- ture, 2004, submitted. rine phytoplankton, Nature, 425: 291-294, 2003. Castruita, M. , M. Saito, L. Elmegreen, E. Stiefel, F.M.M. Morel, Ho, T.-Y., A. Quigg, Z.V. Finkel, A.J. Milligan, K. Wyman, P.G. Over-expression and characterization of an iron storage and Falkowski, F.M.M. Morel, The Elemental Composition of DNA-binding Protein from Trichodesmium erythraeum. Ap- Some Marine Phytoplankton, J. Phycol., 39, 1145-1159l plied and Environmental Microbiology, 2004, submitted. 2003.

Satish Myneni ing one of these fundamental interactions, which include the Assistant Professor evaluation of the chemical state of water in different geologic Ph.D., 1995, Ohio State media and how this modifi es the biogeochemical behavior of University different inorganic and organic moieties in the natural sys- email: [email protected] tems. I am also interested in evaluating the chemical state(s) of important geochemical species to develop predictive pat- terns for explaining their macroscale behavior. A summary of my research projects and accomplish- ments in the last one year are provided below. Molecular Studies on Water and Aqueous Systems The goals of this research project are to evaluate H-bond- ing environment in liquid water, and how this modifi es ion solvation and complex formation in aqueous solutions and Water is essential for the origin and survival of life on our at natural interfaces. Results from our previous studies and planet and perhaps plays a pivotal role on the existence of collaborations have been published or to be submitted for a life on other planetary bodies as well. In several different publication, and these are, forms, water mediates the physical and chemical interactions • H-bonding interactions in liquid water (J. Phys.Phys. between various components of the Earth’s surface environ- 2002), ment, which includes mineral oxides, biota and their byprod- • Chemical state of ion-solvated water (J. Phys.Phys. Chem. ucts, and the atmosphere. One of the challenges in environ- 2003), and mental sciences is to gain a better understanding of interac- • Dissolved ion infl uence on the H-bonding networks in tions between these different components in nature, and to bulk water (to be submitted shortly) use it to predict a variety of biogeochemical processes such as Experimental studies on the nature of solvated hydro- elemental cycling, biological chemistry of elements, and the nium and hydroxyl ions have been conducted and we are fate and transport of contaminants in the environment. This waiting for contributions from the ab initio calculations in area of research is gaining importance, and researchers from interpreting the structural environments of these ions. My different disciplines began conducting studies to explore studies on water will continue, and the future emphasis will these interactions in greater detail. I am interested in explor- 13 be on the nature of water at the mineral-water interfaces as a eral., 2002). Using these methods I am investigating the: function of water-fi lm thickness and pH, and the nature of • Functional group chemistry and macromolecular surface hydroxyls. We built a new synchrotron experimental structure of natural organic molecules in soils and chamber to conduct these studies both in vacuum and under sedi ments, ambient conditions. Using this new facility, we hope to • Role of minerals in the retention and fractionation of understand hydration of mineral surface functional groups, organic molecules in the environment, and how surface hydration changes with variations in the • Chemistry of natural organohalogens in the environ- composition of water fi lms, and how this further modifi es ment: coordination chemistry, rates of formation in ion interactions at mineral-water interfaces. Michael Hay and the environment and their role in various biogeo- Laura Harrington, graduate students in my group, will focus chemical reactions, and on these studies. • Reactions at the microorganism-water interfaces. Our recent studies on solvation focused on the structure and speciation of Al3+ in aqueous solutions. Aluminum is an We found several interesting results on these systems, important element that forms a majority of stable minerals in and the highlights are as follows. weathering environments. A majority of them are amorphous Chemistry of Natural Organohalogens. While manmade and nanocrystalline, whose chemistry is poorly understood. organohalogens are widely distributed throughout the Although Al-speciation in aqueous solutions and precipitates biosphere and are characterized by varying degrees of per- is well studied using the NMR spectroscopy, variations in sistence and toxicity, natural production of organohalogen the structural environment of Al in these systems are not compounds is gaining recognition as a signifi cant contribu- well understood. Using a combination of X-ray spectroscopy tor to the organohalogen burden in the environment. With and NMR spectroscopy we are evaluating the variations in the help of my research group members, I made signifi cant the chemical state of Al3+ associated with these structural progress in understanding the chemistry of natural organo- variations. This information is important in predicting the halogens in the past three years, and a summary is as follows- behavior of aqueous and solid phase Al in the weathering environments. Michael Hay, a graduate student in my group, • Using X-ray spectroscopy, I directly showed that the and Juraj Majzlan, a former post-doctoral scholar in my formation of organochlorines and their speciation group, are working on this project. variations in soils are directly related to the weathering Iron (especially in ferric state), which is also an im- of plant material (Science, 2002) portant rock forming element in terrestrial systems and an • Using haloperoxidase enzymes common to all soils important nutrient to living organisms, follows the chemistry and sediments, we have successfully halogenated plant of Al closely. We are investigating the structure and chemistry materials. The products of these reactions are similar of Fe3+ in aqueous solutions and in precipitates. Since Fe3+ to those found in naturally weathered plant material, exhibits stronger interactions with sulfate, and both of them which implicates their role in extensive organohaloge- occur together in several natural systems, our initial studies nation in the nature (Rachel Reina, M. Eng Thesis; focused on Fe3+-sulfate interactions. Our studies (a combina- Environ. Sci. Technol, 2004). tion of infrared, Raman and X-ray spectroscopy) on these • Detailed speciation of organochlorines, conducted un- systems provided unequivocal evidence for the occurrence of til recently, indicated that a majority of chlorinated H-bonding complexes of sulfate with Fe-oxyhydroxide poly- organic molecules in weathering plant material are mers. These studies unravel the mystery of solution and solid associated with the soluble polyphenol fraction, but phase speciation of Fe3+ in acidic environments (Environ. Sci. not with stable lignins, as thought by several previous Technol. In press). My former post-doctoral scholar (Dr. Juraj investigators. Specifi c molecules identifi ed are fl avones Majzlan) and one of the current graduate students (Laura (derived from weathering plant material), and xantho Harrington) are continuing these studies, and the future nes (probably from the lichens). (Dr. Ashish emphasis will be on the understanding of the structural envi- Deshmukh, a post-doctoral scholar in my group, is ronments of soluble Fe3+-polymers in aquatic and biological conducting this investigation). systems (e.g. ferritins). • We also found that organobromines, like organochlo- rines, are common in terrestrial and marine environ- Chemistry of Natural Organic Molecules ments. Since they are present at high concentrations in Organic molecules are found everywhere on the surface of marine systems, we are planning detailed studies on the Earth, and their composition, molecular structure and their formation in the photic zone of ocean water, concentration modifi es the biogeochemical processes in the and their accumulation and dehalogenation in sedi environment. One of the bottlenecks in our understanding of ments. (Jacqueline Hakala, a senior in my group, the elemental cycles is related to the speciation of C, N, and began this work. Alessandra Leri, a graduate student in S associated with the organic molecules, and their variation my group, is currently working on this system). in the environment. For the past several years, my research • Although iodine is present at trace concentrations, we group has been using and developing X-ray spectroscopy and are fi nding that iodide and iodate present in soils react spectromicroscopy methods for studying the chemistry of with naturally occurring organic molecules and form natural organic molecules in their pristine state (Rev. Min- organoiodines in short time. The presence of Ca 14 is signifi cantly affecting the sensitivity of X-ray spec- organic molecules in modern aerosols (in collaboration with troscopy methods in detecting the organoiodines in Dr. Lynn Russell, Scripps; Science, 2004). This molecular all natural samples. However, we fi nd that the reac- information is useful to predict the light scattering and water tions of inorganic iodine with organics are slow, and absorption characteristics of aerosols. I am also extending take about a week to reach equilibrium in labora- these investigations to evaluate the organic molecule compo- tory microcosms. Rachel Zwillinger, a senior in my sition and mineralogical variation of aerosols trapped in ice research group, began this project this year and will cores (in collaboration with Dr. Lonnie Thompson, Ohio submit a senior thesis next year. State University). We began these studies very recently. We To investigate the biogeochemical processes involved in hope to obtain information on natural organohalogens asso- organic molecule halogenation in soil systems and their rates ciated with the modern and ancient aerosols and their impact in detail, we built two fi eld stations in Pine Barrens (NJ) and on the ozone depletion. in Princeton University campus. We are also monitoring the In summary, my research group is developing into a speciation of C, N, and S in organic molecules to evaluate diverse and interdisciplinary research group to address the the association of these elemental cycles with the Cl-cycle. fundamental biogeochemical processes in the environment. Two-Year Bibliography Functional Group Chemistry of Natural Organic Mol- Refereed articles: ecules. To understand the chemistry of complex natural Strathmann T., Myneni SCB. Speciation of aqueous Ni(II)-Car- organic molecules, we are investigating the functional group boxylate and Ni(II)-Fulvic Acid Solutions: Combined ATR- chemistry of small chain model organic ligands and their FTIR and XAFS Analysis, Geochim. Cosmochim. Acta 68: metal complexes in aqueous solutions and at the mineral- 3441-1458, 2004. Xue S., Leri A., Myneni SCB., Jaffe P. Uptake of bromide by water interfaces (Geochim. Cosmochim. Acta 2004). GraduateGraduate two wetland plants (Typha latifolia and Phragmites australis students, David Edwards and Wei Jiang, are examining the (Cav.) Trin. Ex Steud), Environ. Sci. Technol..38: 5642-5648, chemistry of selected biomacromolecules (Langmuir 2004; 2004. Geochim. Cosmochim. Acta, In review); and Michael Hay Reina R., Leri A, Myneni SCB. Cl K-edge X-ray spectroscopic and Dr. Deshmukh are investigating the types of carboxylic investigation of enzymatic formation of organochlorines in acid groups associated with biomacromolecules found in weathering plant material, Env. Sci. Technol. 38: 783-789, 2004. aquatic and soil systems using infrared, NMR, and X-ray Maria S, Russell LM, Gilles MK, Myneni SCB. Organic aerosol spectroscopy methods. A summary of these studies are as growth mechanisms and their climate forcing implications, follows: Science, 306: 1921-1924, 2004. • Complete speciation of C, N, P, S, Cl, and Br func- Wei J. Saxena A., Song B., Ward BB., Beveridge TJ., Myneni tionalities of stable fractions of natural organic SCB. Elucidation of functional groups on Gram-positive and Gram-negative bacterial surfaces using infrared spectros- molecules in soils and fl uvial systems using X-ray copy, Langmuir, 20: 11433-11442, 2004. absorption spectroscopy. Naslund LA, Cavalleri M, Ogasawara H, Nilsson A, Pettersson • Carboxylic groups, which are important reactive LGM, Wernet P, Edwards DC, Sandstrom M, Myneni SCB groups in biomacromolecules, occur as aliphatic car Direct evidence of orbital mixing between solvated transi- boxylic acids, as opposed to the assumed aromatic tion-metal ions: An Oxygen 1s XAS and DFT study of aque- ous systems, J. Phys. Chem A, 107: 6869-6876 (Cover page carboxylic acids (such as salicylic acid). We also article), 2003. fi nd that a majority of carboxylic groups have an electron withdrawing group on the adjacent C- Articles in press or submitted Majzlan J., Myneni SCB. Speciation of sulfate in acid waters and atom (in the �- and �-positions), which makes the its infl uence on mineral precipitation, Environ. Sci. Technol., carboxyl group much more reactive and promotes the in press. formation of strong complexes (chelates) with aqueous Edwards DC., Nielsen SB., Jarzecki AA., Spiro TJ., Myneni SCB. metals and mineral surfaces. This information is Experimental and theoretical vibrational spectroscopy stud- important in understanding the reactivity of common ies of acetohydroxamic acid and desferrioxamine B in aque- ous solution: Effects of pH and iron complexation, Geochim. stable biomacromolecules and their origin in aquatic Cosmochim. Acta., being revised. systems. White SJO, Hay M., Marcus M., Lanzirotti A., Myneni SCB.

• The soluble and insoluble organic carbon in terrestrial Constraints for sequestering CO2 in geologic formations systems is primarily derived from plants, as opposed (Submitted for consideration as a research article in Environ. to the recently emerging idea that organic molecules Sci. Technol.). Strathmann TJ., Myneni SCB. Effect of soil fulvic acid on Ni(II) from bacterial biofi lms play a major role in the biogeo- sorption and bonding at the aqueous-boehmite (‟-AlOOH) chemical reactions in soils. interface, Environ. Sci. Technol, in review. • Organic molecules fractionate in soils, and our prelim- Li W., Seal S., Rivero C., Lopez C., Richardson K., Pope A., inary data suggest that this chemical fractionation is Schulte A., Myneni SCB., Jain H., Antoine K., Miller A. Role universal irrespective of mineralogy and climate. of S/Se ratio in chemical bonding of As-S-Se glasses inves- tigated by Raman, XPS, and EXAFS spectroscopies, J. App. Some of these results will be submitted for a publication Phys., in review. shortly. Using the X-ray spectral signatures of organic molecules in soils and sediments, I am investigating the chemistry of 15 Guust Nolet and S waves from shallow earthquakes. She is ready to start George J. Magee Professor of applying this. Geophysics and Geological See geoweb.princeton.edu/people/faculty/nolet/research. Engineering html for up-to-date information on equally interesting as Ph.D., 1976, University of Utre- well as less spectacular results. cht (The Netherlands) email: [email protected] Two-Year Bibliography Refereed articles: Montelli, R., G. Nolet, F.A. Dahlen, G. Masters, E.R. Engdahl, S.- H. Hung, Global P and PP travel time tomography: rays vs. waves, Geophys. J. Int., 158, 637-654, 2004. Zhou, Y., F.A. Dahlen and G. Nolet, 3-D sensitivity kernels for surface wave observables, Geophys. J. Int., 158, 142-156, 2004. Lebedev, S. and G. Nolet, Upper mantle beneath Southeast Asia from S velocity tomography, J. Geophys. Res., 108, With Raffaella Montelli and Tony Dahlen, we continued the 10.1029/2000JB000073, 2003. exploration of the effects of fi nite frequency – introduced by Margerin, L. and G. Nolet, Multiple scattering of high-frequency us four years ago – into the imaging of the Earth’s interior. seismic waves in the deep Earth: Modeling and numerical An investigation of long period S, ScS and SS waves led to examples, J. Geophys. Res., 108, 10.1029/2002JB001974, a spectacular confi rmation of the earlier results that showed 2003. Tibuleac, I., G. Nolet, C. Michaelsson and I. Koulakov, P wave a number of mantle plumes reach deep down into the lower amplitudes in a 3D Earth, Geophys. J. Int., 155 , 1-10, 2003. mantle. This fi nding has important implications for the geo- Zhou, Y., G. Nolet and F.A. Dahlen, Surface sediment ef- dynamics of the Earth, and I am exploring the consequences fects on teleseismic P waves, J.Geophys.Res., 108, DOI of that with Raffaella Montelli and Shun Karato (Yale). It 10.1029/2002JB002331, 2003. seems that we are for the fi rst time able to directly infer the Montelli, R., G. Nolet, F.A. Dahlen, G. Masters, E.R. Engdahl, S.- H. Hung, Finite-frequency tomography reveals a variety of speed by which plumes rise in the mantle, that we can put plumes in the mantle, Science, 303, 338-343, 2004. constraints on the lower mantle viscosity and it also seems Margerin L., G. Nolet, Multiple scattering of likely the lower mantle is enriched with a heavy element, high‐frequency seismic waves in the deep Earth: probably iron. With Nick Arndt (Grenoble) and Claude PKP precursor analysis and inversion for mantle granu- Herzberg (Rutgers) we are exploring the consequences of larity, J. Geophys. Res., 108 (B11), 2514, doi:10.1029/ the observed plume temperatures for the petrology of ocean 2003JB002455, 2003. Montelli, R., J. Virieux, G. Nolet, A. Lomax and A.Zollo, 3D island basalts. linearized delay travel time tomography of Mt. Vesuvius with Also with Raffaella Montelli, we put the parameteriza- adapted grids, in: The internal structure of Mt. Vesuvius, ed. P. tion of tomographic models on a surer footing in the theory Capuano, P. Gasparini, A. Zollo, J. Virieux, R. Casale and M. of nonlinear optimization. We are now able to adapt the Yeroyanni, 203-215, Liguori Editore, Napoli 2003. node density of models to the local resolution. Articles in press or submitted With Frederik Simons and Jeff Babcock (Scripps), we Nolet, G. and R. Montelli, Optimal parameterization of tomo- did a second test of the MERMAID diver, designed to graphic models, subm . to Geophys. J. Int., 2004. Zhou, Y., G. Nolet, F.A. Dahlen and G. Laske, Global upper record earthquakes while fl oa ting autonomously at a depth mantle structure from fi nite-frequency surface-wave tomog- of 1000 m or more in the oceans. We were able to recognize raphy, subm. to Geophys. J. Int., 2004. clearly the signal of a magnitude 6.1 earthquake at teleseis- Zhou, Y., F.A. Dahlen, G. Nolet and G. Laske, Finite-frequency mic distances. This is a great success, and we hope to use it effects in global surface wave tomography, subm. to Geo- to obtain funding for further development of this prototype. phys. J. Int., 2004. Though Simons has left Princeton for a faculty position at Nolet, G., F.A. Dahlen and R. Montelli, Traveltimes and am- plitudes of seismic waves: a re-assessment, subm. to A. UC London, he will remain strongly involved. Levander and G. Nolet (eds.), Analysis of broadband seis- Karen Sigloch has completed and perfected new software mograms, AGU Monograph Series, 2003. to measure arrival times and amplitudes of complicated P

16 Tullis C. Onstott Over the past year as part of our IPTAI astrobiology Professor effort we performed a reconnaissance of an arctic Au mine, Ph.D., 1980, Princeton University Lupin Mine, that accesses brine situated beneath 500 meters email: [email protected] of permafrost and rock. The geochemical and microbial analyses from the survey revealed conditions that indicate it represents the most accessible, Mars-like environment on Earth. The subpermafrost brines are rich in methane and with the discovery of methane in the Martian atmosphere this past year, makes the site even more relevant to Mars exploration. The investigators involved in research at this site will be gathering this January to share the results of this fi rst reconnaissance and plan a drilling campaign for this coming spring. The lead IPTAI investigator, Prof. Pratt of Indiana University, and I are preparing a proposal to the NAI During the spring I also organized and ran a seminar series to support the drilling. This campaign will be the fi rst of on Extrasolar Planets and Astrobiology with some support several designed to develop the technology required for locat- from our department. The seminar primarily tapped faculty ing subsurface brines beneath deep permafrost on Mars, for and research staff from Princeton and Rutgers universities retrieving samples of permafrost and brine with little organic who were actively involved in many facets of this topic from or microbial contamination, for performing life detection mass spectrometers for Mercury to deep sea robotic vessels. experiments on these same samples in the fi eld or in the During the reunions, I joined engineering faculty (Kas- borehole and to determine how sensitive the organic and in- din) and astrophysics faculty (Turner) in a 1 hour presenta- organic constituents are to the thermal histories that Martian tion to the alumni on searching for life in the universe. samples will be subjected to upon their return from Mars be During the spring and summer I worked with Ed Turner robotic craft. It is anticipated that such a mission would take (AST) primarily and with Laura Landweber (EEB), Chuck place in the 2013-15 time frame and none of the technology Dismukes and Ed Stiefel (Chem) on a proposal to the Soph- required has reached fl ight capability as of yet. No progress more Initiative for a new sophomore level course in Astrobi- was made on the development of a down hole instrument for ology called Life in the Universe (GEO/AST/EEB 255). The life detection as this was not supported by Princeton Uni- proposal was funded. We used most of the funds to support versity for an MRI proposal. IPTAI is, however, planning to a fi eld trip to Yellowstone National Park and to cover the submit a proposal to NASA’s ASTEP, Astrobiology Science acquisition of a telescope and microscope. The department and Technology Engineering Program in July 05 to initiate kicked in additional funds for a digital camera that can be this activity. We have also developed a proposal to NASA’s mounted on the microscope. As a result we now have a fi eld ASTID, Astrobiology Science and Technology Instrument microscope with suffi cient resolution to image microbes that Development, program for perfecting the means of contami- can be used for other GEO and PEI courses. I also organized nant removal on the surface of Mars by Mars rovers that will the syllabus, selected the texts, organized the fi eld trip, taught be submitted later this year. 6 of the 24 lectures, graded the mid-terms and fi eld note- During the past two years I developed the concept of books and developed and graded four problem sets. free energy fl ux or FEF in calculating the maximum amount The intention of the spring seminar series, the presenta- of energy available to microbial cells for the production of tion to the alumni and GEO/AST/EBB 255 course was to ATP (published in Onstott, 2004). This simple calculation determine the level of interest among the Princeton Univer- combines the concentrations and diffusivities of gaseous sity students, faculty and alumni in the topic of astrobiology. and aqueous geochemical species determined for the envi- The response to all three venues has been very enthusiastic ronment with ~80 microbial redox reactions to determine and has convinced Turner, Kadin and I to pursue submission which microbial phenotype should be dominant in that of a proposal to Provost for the support and development of environment. This calculation for the fi rst time effectively Princeton University Planets and Life Institute. This in- couples the geochemical characterization of the environment stitute would foster interdepartmental research in the areas with the phylogenetic characterization from analyses of the related to the search for extrasolar planets and exobiology and environmental DNA using the 16SrDNA gene. In applying the origin of life. It would provide certifi cates in Astrobiol- this approach to the results from ~200 sites in South Africa ogy to undergraduate and graduate students. Proposals to I observed that the biodiversity and phenotype predicted NASA for the Terrestrial Planet Finder Mission Science Cen- by the genetic analyses was comparable to that predicted by ter and to NASA’s Astrobiology Institute would be among FEF analyses. Surprisingly, however, the magnitude of FEF the principal funded initiatives. If the former is successful, increased with depth while the biomass diminished. In other then a new building would be required to house the institute words, the deeper you go in the crust the greater the bioavail- in order to support the ~100 FTE’s required to process the able energy and the less the microbial biomass. Furthermore, satellites data. the FEF is so high that it is unsupportable over the 10’s of

17 million year lifetimes of the environments we sampled in such a presumption. The search for hyperthermophiles in South Africa. This apparent contradiction in observations the deep subsurface, however, requires access to samples may be due to one or all of the following possibilities: with in situ temperatures of ~100°C. For this reason we 1. Most of the biomass is located within the rock matrix submitted a proposal to NSF’s Earthscope Program to obtain and not within the fi ssure water and energy substrates microbial samples from the San Andreas Fault where drilling are slowly diffusing from the fi ssure water into the rock and coring at depths of 3 kilometers accesses rock and fl uid matrix. at such temperatures. This proposal to NSF is still pending 2. Most of the biomass was recently introduced into the but results based upon samples collected by Mark Davidson environment by mining activity (which is not consis- during the stage 1 drilling appear promising. If funded, this tent with the gaseous geochemical results or the DNA research project, the monitoring program in South Africa and of the mining contaminants). a project being carried out by my former graduate student, 3. Most of the gaseous and aqueous geochemical constit- Li-Hung Lin, in Taiwan where they are coring into an active uents were recently introduced into the fractures by fault zone will be the fi rst projects to examine the relation- mining activity or specifi cally due to fracture propaga- ships between tectonic activity and subsurface microbial den- tion into the rock matrix. sity, diversity and activity predicted by my former graduate 4. Some other factors inhibit the utilization of the abun- student, Hsin-Yi Tseng in 1996. dant energy resources by the organisms within this My interactions with the SAFOD program and our de- environment. velopment of a drilling program for the Canadian permafrost environment have reinforced my perception, one shared by Recent analyses of core samples retrieved from 2.0 kmbls many of my colleagues, that many subsurface processes can- in South Africa by my graduate students, Mark Davidson not be adequately characterized by boreholes drilled from the and Bianca Mislowack, do not support the fi rst possibility. surface. Subsurface processes operate at spatial scales ranging DNA analyses of these rock cores are in progress to further from microns to 100’s of meters and time scales of minutes test the second possibility. The third possibility is consistent to years. In performing deep subsurface experiments using with the observed elevated concentrations of energy nutri- kilometer long boreholes it is virtually impossible to examine ents within the rock matrix, but we have no direct observa- the short time and length scale mechanisms. To do so would tions that fracture propagation leads to enhanced fl uences require having a deep underground cavity from which several of energy substrates into the fracture or whether microbial km3 blocks of crust can be characterized and instrumented communities are affected by such fl uxes if they occur. For in 4D. Such an experimental cavity can only rarely exist this reason we submitted a proposal to NSF in conjunction within operating mines because they require years of dedi- with geophysicists interested in monitoring crustal seismicity cated time and isolation. For these reasons we have joined in South Africa to core across an active fault zone at a depth forces with the high energy physicists and astrophysicists that of 3.7 km. The boreholes resulting from this activity would have been developing a proposal for a program within NSF be instrumented not only with motion detectors and strain funded at the congressional level for a Deep Underground gauges, but one borehole will be devoted to monitoring Science and Engineering Laboratory (DUSEL). Currently I gaseous and aqueous geochemical fl uctuations and changes in am one of six P.I.’s (3 physicists and 3 earth scientists) sup- microbial communities during a magnitude 3-4 earthquake ported by phase 1 of an NSF program to select a site and that is anticipated along the fault zone during the next 2 fund the installation of the DUSEL. Our role at this initial years of mining operations. This NSF proposal was success- phase it so promote the concept to our communities and ful and plans for development of the site during the spring of hold workshops to develop the infrastructure requirements, ’05 are underway. The observations obtained from this site the priority experimental clusters and monetary requirements will hopefully provide conclusive evidence regarding the third for DUSEL. The factors will be used by NSF to select from possibility. To examine the fourth possibility, my graduate among 6 candidate DUSEL sites. student, Mark Davidson, has been developing a “retentostat” Two-Year Bibliography the low metabolic activities and growth rates in an apparently Refereed articles: nutrient rich environment are reproducible in the lab. This Ward, J.A., Slater, G.F., Lacrampe-Couloume, G., Lin, L.-H., device will enable him to monitor the population density and Hall, J.A., Moser, D.P., Bonin , A., Bellamy, R.E.S., Onstott, genetic composition of a thermophilic sulfate reducing bacte- T.C. and Sherwood Lollar, B., Microbial Hydrocarbon Gases ria under in situ conditions as he alters the nutrient fl ux. in the Witwatersrand Basin, South Africa: Implications for The maximum extent to which the biosphere penetrates Deep Biosphere, Geochim. Cosmochim. Acta, 68; 3239- 3250, 2004. the crust is presumably based upon the maximum tempera- Onstott, T.C. Impact of CO2 Injections on Deep Subsurface ture limit for life, currently 123°C for laboratory isolates. Microbial Ecosystems and Potential Ramifi cations for the

The general perception based primarily upon the absence of Surface Biosphere. In The CO2 Capture and Storage Project, petroleum biodegradation in reservoirs above 80°C is that Vol. II, D.C. Thomas and S.M. Benson, eds., 1207-1239. hyperthermophiles do not exist in the subsurface. Their 2004. Baker, B.J., Moser, D.P., MacGregor, B.J., Fishbain, S., Wagner, absence is attributed to the lack of suffi cient energy resources M., Fry, N.K., Jackson, B., Speolstra, N., Loos, S., Takai, to maintain cell integrity at such high temperatures. Our K., Sherwood-Lollar, B., Fredrickson, J.K., Balkwill, D. L., results on the energy fl ux in South Africa do not support Onstott, T.C., Wimpee, C.F. and Stahl, D.A., Related As- 18 semblages of Sulfate-reducing Bacteria Associated with Balkwill, D. L., T.L. Kieft, T. Tsukuda, H.M. Kostandarithes, T.C. Ultradeep Gold Mines of South Africa and Deep Basalt Onstott, S. Macnaughton, J. Bownas, T.J. Bailey, and J.K. Aquifers of Washington State, Environmental Microbiology, Fredrickson, Thermus multireducens sp. nov., a globally 5, 267-277, 2003. distributed metal-reducing species associated with thermal Omar, G., Onstott, T.C. and Hoek, J., The Origin of Deep Sub- ground and spring waters, Extremophiles, 8;37-44, 2003. surface Microbial Communities in the Witwatersrand Basin, Articles in press or submitted South Africa as Deduced from Apatite Fission Track Analy- Lin, L-H, Hall, J.A., Lippmann, J., Ward, J.A., Sherwood-Lollar, ses, Geofl uids, 3, 69-80, 2003. B. and Onstott, T.C., Radiolytic H in the continental crust: Moser, D.P., Onstott, T. C., Fredrickson, J.K., Brockman, F. J., 2 Nuclear power for deep subsurface microbial communities, Balkwill, D. L., Drake, G.R., Pfi ffner, S., White, D.C., Takai, Chem. Geol., submitted.(this is an article that was submit- K., Pratt, L.M., Fong, J., Sherwood-Lollar, B., Slater, G., ted twice to Science and then twice to Nature, but wasn’t Phelps, T.J., Spoelstra, N., DeFlaun, M., Southam, G., Welty, accepted by either), 2004. A.T., Baker, B. J., and Hoek, J., Temporal shifts in Microbial Hall, J.A., Mailloux, B.J., Onstott, T.C., Scheibe, T.D., Fuller, Community Structure and Geochemistry of an Ultradeep M.E., Dong, H. and DeFlaun, M.F., Physical versus chemical South African Gold Mine Borehole, Geomicrobiology Jour- effects on bacterial transport as determined during in situ nal, 20, 1-32, 2003. sediment core pulse experiments, Jour. Cont. Hydrology, in Mailloux, B.J., Fuller, M.E., Rose, G.F., Onstott, T.C., DeFlaun, press, 2004. M.F., Alvarez, E., Hemingway, C., Hallet, R.B., Phelps, T.J., Choi, K.-H., F.C. Dobbs, L.G. Kampschmidt, T. Scheibe, B. and Griffi n, T. Design of a Modular Injector, Multi-level Mailloux, P. Zhang, M. Fuller, W.P. Johnson, T.C. Onstott, M. Sampler, and Sampling Manifold for Groundwater Tracer DeFlaun. Response of protists following a bacterial injection Experiments, Groundwater, 41, 816-827, 2003. at an oxic coastal sandy aquifer. To be submitted to Appl. Musslewhite, C.L., McInerney, M.J., Dong, H., Onstott, T.C., Environ. Microbiol, 2004. Green-Blum, M.X., Swift, D., Macnaughton, S., The factors Mailloux, B. J., Devlin, S., Fuller, M. E., Onstott, T. C., DeFlaun, controlling microbial distribution and activity in the shallow M. F., Choi, K-H, Green, M., Swift, D. J.P. and McCarthy, J. subsurface, Geomicrobiology Journal, 20, 245-261, 2003. The Role of Aquifer Heterogeneity on Metal Reduction in an Lippmann, J., Stute, M., Torgersen, T., Moser, D.P., Hall, J., Atlantic Coastal Plain Aquifer, Geochim. Cosmochim. Acta, Lihung, L-H, Borcsik, M. Bellamy, R.E.S. and Onstott, T.C., submitted, 2004. Dating ultra deep mine waters with noble gases and 36Cl, Sherwood Lollar, B., Lacrampe-Couloume, G., Slater, G.F., Ward, Witwatersrand Basin, South Africa, Geochim. Cosmochim. J., Moser, D.P. , Lin, L.-H. and Onstott, T.C., Abiogenic Acta., 67, 4597-4619, 2003. gases support H -based autotrophy and methanogenesis in Mailloux, B.J., Fuller, M.E., Onstott, T.C., Hall, J., Dong, H., 2 the deep subsurface, Science, submitted, 2004. DeFlaun, M.F., Streger, S.H., Rothmel, R.K., Green, M., Lin, L-H, Slater, G. F., Sherwood Lollar, B., Lacrampe-Couloume, Swift, D.J.P. and Radke. J., The role of physical heteroge- G. and Onsott, T. C., Yields and hydrogen isotopic composi- neity on the fi eld-scale transport and attachment of bac- tions of radiolytic H and the implications for deep biosphere teria, Water Resources Research, 39(6) 1142,doi:10.1029/ 2 in continental crust, Geochim. Cosmochim. Acta, in press, 2002WR001591, 2003. 2004. Mormile, M.R., Biesen, M.A., Gutierrez, M.C., Ventosa, A., Pav- Fuller M. E., Mailloux B. J., Streger S., Hall J. A., Zhang P., lovich, J.B., Onstott, T.C. and Fredrickson, J.K., Isolation Vainberg S., Johnson W. P., Onstott T. C., and DeFlaun of Halobacterium salinarum Retrieved Directly from Halite M. F. Application of a vital fl uorescent staining method for Brine Inclusions, Environmental Microbiology, 5, 1094-1102, simultaneous, near-real-time concentration monitoring of 2003. two bacterial strains in an Atlantic Coastal Plain aquifer in Onstott, T.C., Moser, D.P., Fredrickson, J.K., Brockman, F.J., Oyster, Virginia, Applied and Environmental Microbiology, in Pfi ffner, S.M., Phelps, T.J., White, D.C., Peacock, A., Balk- press, 2004. will, D., Hoover, R., Krumholz, L.R., Borscik, M., Kieft, T.L. and Wilson, R.B., Indigenous versus contaminant microbes in ultradeep mines, Env. Microbiol., 5, 1168-1191, 2003.

19 Michael Oppenheimer On past temperatures and anomalous late-20th century warmth (with 12 co-authors), Eos, 84, 256-8, 2003. (Woodrow Wilson School and Response (to comments on, On past temperatures and anoma- Department of Geosciences) lous late-20th century warmth, with 12 co-authors), Eos, 84, Albert G. Millbank Professor of 473-4, 2003. Geosciences and International Book Review: Atmospheric Pollution: History, Science, and Affairs Regulation, Physics Today 56, 65-66, 2003. Ph.D., 1970, University of Chi- Published (or in review) chapters in books: cago What is the Economic Value of Information about Climate Thresholds? (with K. Keller, S-R Kim, J. Baehr, and D. F. Bradford), Integrated Assessment of Human-Induced Cli- mate Change, M. Schlesinger, ed., submitted October 14, 2004. Global Warming: The Intersection of Long-Term Goals and Near- Term Policy (with A. Petsonk), in Michel, D. (ed.), Climate Policy for the 21st Century: Meeting the Long Term Chal- Two-Year Bibliography lenge of Global Warming, Center for Transatlantic Relations, Refereed Articles: Johns Hopkins University, Washington, pp.79-112, 2003. The West Antarctic Ice Sheet and Long Term Climate Policy (with Miscellaneous publications: R.B. Alley), Climatic Change, 64, 1-10, 2004. Defi ning Dangerous Anthropogenic Interference: The Role of Article 2 of the UNFCCC: Historical Origins, Recent Interpre- Science, the Limits of Science, Prepared for the Workshop tations (with A. Petsonk), submitted to Climatic Change, Perspectives on Dangerous Climate Change, Tyndall Centre, February, 2004. Norwich, UK, 28 June 2004, 2004. Climate Change Impacts Sensitive to Path to Stabilization (with Reinvigorating the Kyoto System and Beyond: Maintaining B.C. O’Neill), Proc. Nat. Acad. Sci., 101, 16,411-16,416, the Fundamental Architecture, Meeting Long-Term Goals, 2004. prepared for Leaders’ Summit on Post-Kyoto Architecture: Book Review: The Discovery of Global Warming, J. Environmen- Toward an L20?, Council on Foreign Relations, September tal Hist., 9, 327-8, 2004. 20-21, 2004. The Infl uence of Climate on In-stream Removal of Nitrogen (with Climate Change: The Case for Long Term Targets, prepared for S.D. Donner and C. J. Kucharik), Geophys. Res. Letters, 31, High-Level Transatlantic Dialogue on Climate Change, Ger- L20509, doi:10.1029/2004GL020477, 2004. man Institute for International and Security Affairs and the Ice Sheets, Global Warming, and Article 2 of the UNFCCC (with Brookings Institution, October 17, 2003. R.B. Alley), Climatic Change, in press, 2004. Global Climate Change, prepared for Old Rules and New Avoiding Dangerous Anthropogenic Interference with the Climate Threats, Council on Foreign Relations, September 19, 2003. System (with K.Keller, M. Hall, S.-R. Kim, and D. F. Brad- ford), Climatic Change, in press, 2004.

Fedorov A.V., R.C. Pacanowski, S. G. Philander and G. Boc- S. George H. caletti, The effect of salinity on the wind-driven circulation Philander and the thermal structure of the upper ocean, J. Phys. Professor Oceanogr, 31, 1949-1966, 2004. Ph.D., 1970, Harvard University Fedorov A.V., S.L. Harper, S.G. Philander, B. Winter and A. Wit- tenberg, How Predictable is El Niño? Bull. Amer. Met. Soc., email: [email protected] 84, 911-919, 2003. Philander S.G. and A.V. Fedorov, Is El Niño Sporadic or Cyclic?, Annual Reviews of Earth and Planetary Sciences, 31, 579- 594, 2003. Philander, S. G., and A. V. Fedorov, Role of tropics in chang- ing the response to Milankovich forcing some three million years ago, Paleoceanography, 18(2), 1045, doi:10.1029/ 2002PA000837, 2003. Philander S.G., On dipoles and Spherical Cows, Bull. Amer. Meteorol. Soc. 84, 1424, 2003. Other miscellaneous publication Two-Year Bibliography Philander S.G., El Niño and the Uncertain Science of Global Books Warming., Daedalus, Journal of the American Academy of Our Affair with El Niño (How we transformed an Enchanting Arts and Sciences, pp 105-108, Spring, 2004. Peruvian Current into a Global Climate Hazard) Princeton Philander S.G.: Science in an Uncertain World, News from ICTP, University Press, 2004 Trieste, Italy, Autumn, 2004. Refereed articles: Articles in press or submitted: Boccaletti G., R. Pacanowski, S.G. Philander and A. Fedorov, Boccaletti G., R. Pacanowski, and S.G. Philander: A diabatic The Thermal Structure of the Ocean, J. Phys. Oceanogr., 34, mechanism for decadal 888-902, 2004. variability in the tropics. Dynamics of Atmospheres and Oceans, 2004, in press.

20 Allan Rubin distances larger than about twice the mainshock radius, and Associate Professor for mainshock-aftershock time lags greater than ~1 day. For Ph.D., 1988, Stanford University a vertical, planar fault in a homogeneous medium there is no email: [email protected] mechanism for generating such asymmetry. However, there is a 10%-20% contrast in seismic velocity across the central San Andreas fault, with the North American rocks being the slower. This introduces a symmetry-breaking heterogeneity, to which we ascribe the asymmetry in aftershock occurrence. Consistent with this, the nearby Calaveras fault exhibits es- sentially no across-fault velocity contrast and no aftershock asymmetry. Over the last year we have pursued this topic using both numerical models and additional observations. On the numerical front, we have been modeling elastodynamic Because the number of earthquakes increases exponentially ruptures on an interface separating differing materials. Such with decreasing magnitude, earthquakes near the detection models demonstrate a pronounced tendency for the ruptures threshold of a given seismic network represent a potential to propagate preferentially in one direction, that being the wealth of data for both structural geology and seismol- direction of motion of the more compliant rocks abutting ogy. A major impediment to exploiting such datasets in the fault (for the San Andreas this would be the SE-mov- the past has been that location errors are typically ~1 km, ing North American plate located to the NE). The cause a value that exceeds both the earthquake dimensions (tens is a large reduction in fault-normal compression near the of meters for magnitude 1 events) and the length scales of SE-propagating rupture front, an effect that is absent in a signifi cant structures within fault zones. By cross-correlating homogeneous body. While this result is not new, no previous the seismograms of “similar” earthquakes (those with similar modeling efforts have been directed toward understanding locations and focal mechanisms), it is possible to determine what happens when such ruptures stop. This is the central relative arrival times with errors that are less than one-tenth issue for understanding the aftershock asymmetry, and this the sampling rate. From such measurements I and students asymmetry remains the best observational evidence to date of and post-docs working with me have relocated many thou- an effect of a material contrast. sands of microearthquakes recorded by the USGS Northern We have identifi ed two processes that could be respon- California Seismic Network. Errors in relative location are sible for the dearth of aftershocks to the SE. First, as the only meters to tens of meters for events separated by tens to SE-propagating front is slowed and stopped by a barrier, for hundreds of meters. This increased resolution allows us to a wide range of conditions a slip “pulse” detaches from the image fault-zone structures that previously were invisible. main rupture and continues to the SE before dying. This The most impressive of these structures are the slip-parallel slip pulse “smooths” the stress fi eld and leaves the region “streaks” of seismicity, up to kilometers in length and as little immediately to the SE of the rupture farther from failure as 100 m and 10 m in height and width, that seem to be than the region immediately to the NW. Second, as the slip ubiquitous along creeping faults in central California. pulse dies, the propagating pulse of reduced normal stress The high-precision catalog also allows us to study that sustained it continues along the fault. Conceivably, this earthquake interaction on an unprecedented scale, result- pulse could trigger slip on any patch of fault close enough to ing in new and surprising insights into the mechanics of failure to otherwise have produced an aftershock, making it rupture. Because of the obvious implications for seismic instead part of the mainshock. hazards, geologists have long asked how earthquakes stress or These models have identifi ed an additional observa- de-stress the nucleation zones of potential future earthquakes. tion that could help constrain the modeling and distinguish However, location errors previously restricted such studies to between the above scenarios. As the rupture front slows and earthquakes larger than magnitude 5 or 6, of which only a stops, the region to the SE experiences its peak stress essen- modest number exist in any given region on a timescale of a tially instantaneously (with the arrival of the local normal few decades. We now have a catalog of many thousands of stress reduction), while the region to the NW must wait until earthquakes with errors in relative location that are a small the stopping phases from the opposite side of the rupture fraction of the rupture dimensions. Because these are mostly arrive. This introduces much larger delays for potential magnitude 1-3 events each may have only a few (or zero) “immediate aftershocks” located to the NW. No aftershocks catalogued aftershocks, but by “stacking” all the aftershocks triggered by stress waves arriving from the mainshock can be robust statistics are easily obtained. identifi ed by the seismic network, because their signals would Along the NW-SE trending San Andreas fault in cen- be buried in the mainshock coda. However, the signature tral California, we have found that the nearest aftershocks of any such aftershocks is still present in the archived wave- of microearthquakes are nearly three times more likely to forms. Because the waveforms of both mainshocks and after- occur to the northwest of the mainshock than to the south- shocks would be essentially identical to those of other nearby east. This asymmetry disappears for mainshock-aftershock earthquakes, it is possible to identify the aftershocks by

21 deconvolving the waveforms of all earthquakes in the region no relation to the previously-identifi ed minimum size, and by those to which they are similar. Post-doc Jean-Paul Am- have determined what that size is for the most commonly- puero has devised a new technique for doing this on a large used frictional law. scale, and of a test population of 2000 earthquakes from The larger interest in this work stems from the fact that Parkfi eld, CA, has identifi ed 10 clear examples of immediate suffi ciently large nucleation zones would make early earth- aftershocks occurring within a few hundredths of seconds of quake detection feasible. While observational evidence for the mainshock. All but one of these are located to the NW a detectable nucleation phase has been mixed and contro- of the mainshock, on a timescale consistent with trigger- versial, previous theoretical estimates have been uniformly ing by the arrival of the stopping phase, as was suggested by pessimistic (the predicted nucleation zone size is meters or the numerical modeling. Aftershocks to the SE would be less). We have shown that the most common friction law expected to dominate if the propagating pulse of low normal predicts much larger nucleation zones for a restricted (but stress were the cause of the catalog asymmetry. We will be geologically quite reasonable) range of parameters. However, expanding this study in the upcoming year. we have also shown that this friction law has some possibly As part of our modeling effort, we took an unexpected unreasonable attributes, and have outlined a simple series of detour and in so doing settled a long-standing question lab experiments that should be able to demonstrate unequiv- regarding the size of earthquake nucleation zone on faults ocally whether it requires modifi cation. I am now collabo- obeying “rate-and-state” friction. Earthquakes do not begin rating with Chris Marone at Penn State, who is conducting at a point; rather, they nucleate over a fi nite region whose some exploratory tests in his rock friction lab. size depends upon the constitutive properties of the surface Two-Year Bibliography on which they occur. For over two decades experimentalists Refereed articles: have been trying to determine these properties in the labora- Ziv, A., A.M. Rubin, and D. Kilb, Spatio-temporal analyses of tory, and the constitutive laws they have proposed have been earthquake productivity and size distribution: Observations well-studied in the context of simple systems (a block being and simulations, Bull. Seism. Soc. Am., 93, 2069-2081, 2003. pulled by an elastic spring, for example). This has given rise Ziv, A., and A.M. Rubin, Implications of rate-and-state friction to the identifi cation of a maximum spring stiffness and (ap- for properties of aftershock sequences: Quasi-static inher- proximately) a minimum nucleation size that would allow an ently discrete simulations, J. Geophys. Res., 108, B1, doi: earthquake instability to occur. However, in the Earth the 10.1029/2001JB001219, 2003. analog of the “spring stiffness” is not simple, depending as Other miscellaneous publications: it does upon elastic interaction between neighboring points Detournay, E., L.G. Mastin, J.R.A. Pearson, A.M. Rubin, and along the fault, each moving at its own velocity. Through a F.J. Spera, Final Report of the Igneous Consequences Peer combination of numerical and analytical work, Jean-Paul and Review Panel, 86 pp. plus 86 pp. appendices, prepared for the Offi ce of Civilian Radioactive Waste Management of the I have shown that the nucleation size on an elastic fault bears U.S. Department of Energy, Feb. 2003.

Jorge L. Sarmiento Modeling and Observational Constraints on Carbon Professor Sinks One of the major research directions that my group Ph.D., 1978, Columbia University has taken in the past years is estimation of the magnitude, email: [email protected] spatial distribution, and temporal variability of carbon sources and sinks by inverse modeling of atmospheric and oceanic CO2 observations and by evaluation of models with the major new data sets that were gathered by global surveys during the last decade. This work has culminated during the past two years in several papers that converge on an estimate for the oceanic carbon sink of 2.0 ± 0.4 Pg C yr—1 for the 1990’s (e.g., Gloor et al., 2003; McNeil et al., 2003; Matsu- moto et al., 2004; and Jacobson et al., in preparation). The uncertainty is half that which we would have given for the oceanic carbon sink estimate a decade ago. My group is now The primary focus of my research is on the global carbon working hard to explore the implications of this oceanic con- cycle, with particular attention to the role of the ocean in straint for our estimates of land carbon sources and sinks. A controlling atmospheric carbon dioxide levels. My recent paper in preparation by Jacobson et al. suggests that the large publications can be categorized into three broad areas: (1) CO2 fertilization sink postulated to exist in the tropics might modeling and observational constraints on ocean and land in fact be nonexistent. The absence of this CO2 fertilization carbon sinks for anthropogenic carbon; and (2) stabilization sink has major negative implications for the future growth of atmospheric carbon dioxide; (3) ocean biogeochemical rate of atmospheric CO2. processes and modeling. Each of these areas is discussed Stabilization of carbon dioxide. We wrapped up several below, with attention primarily to papers published during projects on enhancing the uptake of anthropogenic car- 2004. bon by the ocean either by iron fertilization or by deep-sea 22 Two-Year Bibliography sequestration. Gnanadesikan et al. (2003) examined a new Books: scenario for iron fertilization that involves small-scale patch Sarmiento, J. L., and N. Gruber, Ocean Biogeochemical Dynam- fertilization. We found that patch fertilization was extremely ics, Princeton University Press, in press. ineffi cient (only a tiny fraction of the organic carbon ex- Refereed articles or book chapters ported from the surface ocean comes from the atmosphere) Sarmiento, J. L., N. Gruber, M. A. Brzezinski, and J. P. Dunne, and probably impossible to verify due to the small size of the High latitude controls of the global nutricline and low lati- signal relative to natural variability. Irina Marinov’s Ph.D. tude biological productivity, Nature, 427: 56-60, 2004. thesis completed in December of 2004 examined the funda- 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. mental processes that control the air-sea balance of CO2 and Dutay, M. Follows, Y. Gao, A. Gnanadesikan, N. Gruber, how removal of nutrients might affect biological production A. Ishida, F. Joos, K. Lindsay, E. Maier-Reimer, J.C. Mar- in lower latitudes. Mignone et al. (2004) examined deep shall, R.J. Matear, P. Monfray, A. Mouchet, R. Najjar, G.-K. sequestration of carbon, with the main emphasis being on Plattner, R. Schlitzer, R. Slater, P.S. Swathi, I.J. Totterdell, how the large differences in ocean circulation models lead to M.-F. Weirig, Y. Yamanaka, A. Yool, J.C. Orr, Evaluation of ocean carbon cycle models with data-based metrics, Geo- correspondingly large variations of a factor of 2x or more in phys. Res. Lett., 31, L07303, doi:10.1029/2003GL018970, sequestration effi ciency. Edmonds et al. (2004) used a com- 2004. bination of integrated assessment and carbon cycle models Mignone, B. K., J. L. Sarmiento, R. D. Slater, and A. Gnanadesi- to examine some of the major issues that would need to be kan, Sensitivity of sequestration effi ciency to mixing pro- resolved in order to stabilize atmospheric carbon dioxide. cesses in the global ocean, Energy, 29: 1467-1478, 2004. Greenblatt, J. B., and J. L. Sarmiento, Variability and climate

Ocean Biogeochemical Processes and Modeling. My feedback mechanisms in ocean uptake of CO2, In: The research in this area has two major goals, the fi rst being to Global Carbon Cycle, ed. C. B. Field and M. R. Raupach, develop an understanding of what controls ocean biogeo- Island Press, Washington, D.C., pp. 257-275, 2004. Edmonds, J., F. Joos, N. Nakicenovic, R. G. Richels, and J. L. chemistry, and the second related goal being to develop the Sarmiento, Scenarios, targets, gaps, and costs, In: The capability to predict the response of ocean biogeochemistry Global Carbon Cycle, ed. C. B. Field and M. R. Raupach, to climate change. The major accomplishment of 2004 was Island Press, Washington, D.C., pp. 77-102, 2004. the fi nal completion of the textbook I have been working Sarmiento, J. L., R. Slater, R. Barber, L. Bopp, S. C. Doney, A. on for 10 years (Sarmiento and Gruber, Ocean Biogeochemi- C. Hirst, J. Kleypas, R. Matear, U. Mikolajewicz, P. Mon- cal Dynamics, in press, Princeton University Press). The fray, V. Soldatov, S. A. Spall, and R. Stouffer, Response of ocean ecosystems to climate warming, Global Biogeochem. book will likely appear in early 2005. Another important Cycles, 18, GB3003, doi:1029/2003GB002134, 2004. milestone was the publication in Nature of SarmientoSarmiento et Marinov, I., and J. L. Sarmiento, The role of the oceans in the al. (2004), which describes a major new insight about how global carbon cycle: An overview, In: The Ocean Carbon nutrients are returned from the deep ocean to the main Cycle and Climate, ed. M. Follows and T. Oguz, NATO ASI, thermocline. This supply of nutrients to the thermocline of Ankara, Turkey, Kluwer Academic Publishers, pp. 251-295, 2004. the world ocean, which occurs by formation of Subantarctic Doney, S. C., K. Lindsay, K. Caldeira, J.-M. Campin, H. Drange, Mode Water, appears to be responsible for about three-quar- J.-C. Dutay, M. Follows, Y. Gao, A. Gnanadesikan, N. ters of the biological productivity in the global ocean to the Gruber, A. Ishida, F. Joos, G. Madec, E. Maier-Reimer, J.C. north of the Southern Ocean. Marshall, R.J. Matear, P. Monfray, A. Mouchet, R. Naj- As regards the development of a prediction model, over jar, J.C. Orr, G.-K. Plattner, J. Sarmiento, R. Schlitzer, R. Slater, I.J. Totterdell, M.-F. Weirig, Y. Yamanaka, and A. Yool, the past few years, my group has collaborated with GFDL Evaluating global ocean carbon models: The importance of to develop and test a new model of ocean biogeochemistry, realistic physics, Global Biogeochem. Cycles, 18, GB3017, including iron delivery by dust from the atmosphere (Gao et doi:10.1029/2003GB002150, 2004. al., 2003) and ecosystem models for biological production Gnanadesikan, A., J. P. Dunne, R. M. Key, K. Matsumoto, J. L. and export of organic matter from the surface of the ocean Sarmiento, R. D. Slater, and P, S. Swathi, Oceanic ventilation and biogeochemical cycling: Understanding the physical (e.g., Gnanadesikan et al., 2004). Meanwhile, I undertook mechanisms that produce realistic distributions of tracers an independent study to analyze 6 global warming predic- and productivity, Global Biogeochem. Cycles, 18, GB4010, tions of the next century from which I hoped to be able doi:10.1029/2003GB002097, 2004. to infer how biology might change in response to global Gloor, M., N. Gruber, J. L. Sarmiento, C. S. Sabine, R. Feely, and warming. As part of this study we developed a new empiri- C. Rödenbeck., A fi rst estimate of present and pre-industrial cal modeling approach to predict ocean biology and applied air-sea CO2 fl ux patterns based on ocean carbon measure- ments, Geophys. Res. Lett., 30(1): 10.1029/2002GL015594, it to the climate warming simulations from the 6 models 2003. (Sarmiento et al., 2004, Global Biogeochemical Cycles). McNeil, B. I., R. J. Matear, R. M. Key, J. L. Bullister, and J. L. My group participated in an ocean carbon model inter- Sarmiento, Anthropogenic CO2 uptake by the ocean based comparison study (OCMIP), results from which are now on the global chlorofl uorocarbon dataset, Science, 299: starting to be published (Watson et al., 2003; Doney et al., 235-239, 2003. Toggweiler, J. R., A. Gnanadesikan, S. Carson, R. Murnane, and 2004; see also Matsumoto et al, 2004). I also was asked to J. L. Sarmiento, Representation of the carbon cycle in box write two overview papers on modeling ocean biogeochemis- models and GCMs, Part 1, the solubility pump, Global Bio- try, which I wrote with two members of my group (Greenb- geochem. Cycles, 17(1): 1026, doi:10.1029/2001GB001401, latt and Sarmiento, 2004; Marinov and Sarmiento, 2004). 2003. 23 Toggweiler, J. R., R. Murnane, S. Carson, A. Gnanadesikan, Patra, P. K., S. Maksyutov, and TransCom-3 Modelers, Sensitivity and J. L. Sarmiento, Representation of the carbon cycle in of optimal extension of observation networks to the model box models and GCMs, Part 2, the organic carbon pump, transport, Tellus, 55B (2): 498-511, 2003. Global Biogeochem. Cycles, 17(1): 1027, doi:10.1029/ Maksyutov, S., T. Machida, H. Mukai, P. Patra, T. Nakazawa, G. 2001GB001841, 2003. Inoue, and TransCom-3 Modelers, Effect of recent obser- Gnanadesikan, A., J. L. Sarmiento, and R. D. Slater, Effects of vations on Asian CO2 fl ux estimates with transport model patchy ocean fertilization on atmospheric carbon dioxide inversions, Tellus 55B (2): 522-529, 2003. and biological production, Global Biogeochem. Cycles, 17 Gao, Y., S.-M. Fan, and J. L. Sarmiento, Aeolian iron input to (2), doi: 10.1029/2002GB001940, 2003. the ocean through precipitation scavenging: a modeling Law, R. M., Y.-H. Chen, K. R. Gurney, and TransCom 3 mod- perspective and its implication for natural iron fertilization in

ellers, TransCom 3 CO2 inversion intercomparison: 2. Sensi- the ocean, J. Geophys. Res., 108(D7), 4221, doi:10.1029/ tivity of annual mean results to data choices, Tellus, 55B (2): 2002JD002420, 2003. 580-595, 2003. Watson, A. J., J. C. Orr, O. Aumont, K. G. Caldeira, J.-M. Gurney, K. R., R. M. Law, A. S. Denning, P. J. Rayner, D. Baker, Campin, S. C. Doney, H. Drange, M. J. Follows, Y. Gao, A. P. Bousquet, L. Bruhwiler, Y.-H. Chen, P. Ciais, S. Fan, I. Y. Gnanadesikan, N. Gruber, A. Ishida, F. Joos, R. M. Key, K. Fung, M. Gloor, M. Heimann, K. Higuchi, J. John, E. Kow- Lindsay, F. Louanchi, E. Maier-Reimer, R. J. Matear, P. Mon- alczyk, T. Maki, S. Maksyutov, P. Peylin, M. Prather, B. C. fray, A. Mouchet, R. G. Najjar, G.-K. Plattner, C. L. Sabine, Pak, J. Sarmiento, S. Taguchi, T. Takahashi, and C-W. Yuen, J. L. Sarmiento, R. Schlitzer, R. D. Slater, I. Totterdell, M.-F.

TransCom 3 CO2 inversion intercomparison: 1. Annual mean Weirig, M. E. Wickett, Y. Yamanaka, and A. Yool, Carbon di- control results and sensitivity to transport and prior fl ux oxide fl uxes in the global ocean, In: Ocean Biogeochemistry, information, Tellus, 55B (2): 555-579, 2003. ed. M. J. R. Fasham, Springer-Verlag, Publishers, New York, pp. 123-143, 2003.

Daniel Sigman Laboratory studies of biological transformations of nitrogen. Assistant Professor Ongoing studies in my lab and in collaboration with gradu- Ph.D., 1997, MIT and Woods Hole ate students Julie Granger and Joe Needoba from University Oceanographic Institution of British Columbia make use of laboratory culture experi- email: [email protected] ments to characterize the isotope discriminations caused by specifi c biological transformations of nitrogen. This is a nec- essary starting point for isotope studies of the environment, and it has also yielded insights into the transformations themselves. Measuring the changes in N and O isotope com- position of nitrate in the medium of growing algal cultures and comparing the isotopic composition of the medium nitrate with the nitrate inside the cells of these algae, we have built on earlier work to develop a model for the controls on the isotope effect expressed during nitrate assimilation by In order to develop a predictive understanding of the Earth’s algae. In this model, the dominant isotope discriminating environment, new disciplines have arisen that seek to be process is the reduction of nitrate within the cell, and the quantitative in both measurement and theory. Biogeochem- degree of isotope discrimination actually observed in the en- istry represents one such discipline, in which environmental vironment is controlled by the fraction of nitrate that is taken processes are generalized and abstracted in terms of under- up into the cell, witnesses the isotope discrimination associ- lying chemistry and elemental mass balance. To succeed, ated with nitrate reduction, but then leaks back out into the biogeochemistry and related disciplines must overcome two environment. The fraction of back-leakage to gross nitrate fundamental challenges. First, the environment is spatially uptake appears to depend on what properties are limiting and temporally complex, obscuring integrated fl uxes. Sec- algal growth, with the largest fraction of leakage when algae ond, it is exceedingly diffi cult to quantify the sensitivities of are limited by light. Such a dependency is consistent with biogeochemical fl uxes to the point of developing a predic- a physiological strategy in which algae up-regulate nitrate tive understanding of how the fl uxes interact. Much of my uptake in the darkness to be prepared for any future increase research has involved the development of subject-specifi c in the availability of light; light availability in the ocean can solutions to these broad challenges. With regard to the fi rst, I be extremely variable, so such a strategy is plausible. Look- have advanced the use of the isotopic composition of dis- ing forward, this offers the possibility that we can use the - amplitude of isotope fractionation (an index of nitrate back- solved N species in the ocean (nitrate (NO3 ) and dissolved organic N in particular) to provide integrative constraints on leakage) to identify light limitation in the ocean (as opposed N cycle processes. With regard to the second, I am among to other limitations on growth, such as from iron). However, those who treat the sediment record as an archive of natural the above model regarding light limitation arises from ob- experiments from which the underlying controls on the N servations of only a single cultured species of diatom. Thus, cycle can be determined; I seek to derive information from they may not apply broadly among oceanic phytoplankton. the N isotopic composition of sediments and organic matter This is among the issues that will be explored in future work. bound within sedimentary microfossils. Another important observation from this culture work is

24 of a constant ratio of O-to-N isotope fractionation by enzy- a large nitrate N and O isotope sample set from the Ber- matic nitrate reduction. This invariance is observed at various ing Sea. These data indicate that a previously recognized amplitudes of isotope fractionation, over a range of growth nitrate defi cit in the deep Bering Sea is due to nitrate respira- conditions for a given algal species, for a number of algal spe- tion (also known as denitrifi cation) by bacteria in the deep cies (both eukaryotic and prokaryotic), and in both nitrate seafl oor sediments; denitrifi cation is the dominant loss of assimilating and nitrate respiring organisms. This raises the biologically available N from the ocean. Combining this O-to-N isotope fractionation ratio as an important constraint observation with other constraints on circulation, Lehmann on the enzyme mechanism of nitrate reductases and suggests estimates extremely high rates of denitrifi cation, much higher that, with regard to the chemical properties that set the N than is normally measured by direct methods for deep sea and O isotope effects, diverse nitrate reductases operate via sediments. We suggest that the extremely steep slopes of the same basic chemical mechanism. We have only begun to the Bering basin channel organic matter into the deep sea, explore the direction; nevertheless, it is a promising one. driving these high rates. This study may reconcile a stand- Studies of the modern nitrogen cycle. ing discrepancy among different approaches to estimating My group’s measurements of the modern environment have sedimentary denitrifi cation rates in the ocean. involved diverse materials, such as samples from the ocean EEB graduate student Ben Houlton (advisor: Lars water column, sediment pore waters, soil and stream wa- Hedin) has analyzed Hawaiian rain waters, soil waters, soil ters, rain waters, surface snow, and glacial ice cores. Most of extracts, and stream waters for the isotopic composition of these studies are relevant for both the modern ocean and the nitrate and dissolved organic N. In a submitted manuscript, interpretation of the geologic and glacialogic records. The he combines his results with simple steady state models of following is a summary list of recently completed studies, for the terrestrial nitrogen cycle to argue that denitrifi cation is which there is a manuscript published, submitted, or in a late an under-appreciated mechanism of bioavailable N loss in stage of preparation. tropical forest ecosystems; previous paradigms have focused Graduate student Meredith Hastings has completed the on loss by surface and ground water fl ow. fi rst thorough study of nitrate N and O isotopes in surface I will soon submit a manuscript describing a large nitrate snow, which she conducted on a sample suite that she col- N and O data set from the water column of the eastern North Pacifi c. This data set reveals with remarkable clarity lected at the summit of the Greenland ice cap, from which 18 16 15 14 important ice core records have been retrieved. Meredith’s an anomaly in nitrate O/ O and N/ N from the covaria- study provides a basis for downcore nitrate isotope studies tion expected from our culture studies of the denitrifi cation to reconstruct past changes in the reactive N chemistry and process. While it is too early in the development of this fi eld to defi nitively explain this anomaly, it may well be the result oxidation state of the atmosphere, indicating that the isotopic 15 14 composition of nitrate being deposited at the snow surface of a previously unrecognized input of (low- N/ N) nitrate from recent and local cyanobacterial N fi xation. This would is preserved as the snow is buried. This study also reveals a 2 seasonal cycle in the N and O isotopic composition of nitrate run against the current paradigm for where one expects to fi nd high N fi xation in the ocean, but there are good geo- deposited on the Greenland ice cap, which she uses to test 2 ideas regarding seasonal changes in nitrate source and atmo- chemical arguments for its plausibility. spheric processing. Hastings is in the process of writing up My collaborators and I recently published a study of the N isotope dynamics in the Cariaco Basin, an O -defi cient two other major projects: (1) a downcore study of nitrate iso- 2 topic composition in Greenland ice cores indicating dramatic marine basin off the coast of Venezuela. The Cariaco is one of the best studied O -defi cient basins and is thus an impor- changes in the past, and (2) a year-long data set of nitrate N 2 and O isotopic composition (15N/14N, 18O/16O, and 17O/16O) tant model system for redox reactions and their infl uence on in Princeton rain water collected at the top of Fine Tower. the N cycle and the N isotopes. Coring in the basin has also Angela Knapp is measuring the N isotopic composi- provided a remarkable sedimentary record of the past, but tion of dissolved organic matter and the N and O isotopic downcore studies of N isotopes are in need of groundtruth- composition of nitrate in the tropical/subtropical Atlantic ing in the modern ocean. We observe that the sharp depth transition to O defi ciency in the deep Cariaco basin leads and Pacifi c, and she has one manuscript in press and one in 2 preparation on her Atlantic results. Dissolved organic nitro- to complete consumption of nitrate at the transition where gen is the dominant form of bio-available nitrogen in the denitrifi cation occurs. As a result, in this system, the nor- nutrient-poor low-latitude ocean, but its role in biological mally highly isotope-fractionating process of denitrifi cation productivity has been a mystery. Her work to date suggests has no isotopic impact. This informs models that use the N that much of the DON pool is so recalcitrant that it is ho- isotopes of nitrate to describe and quantify denitrifi cation in mogenized by the upper ocean circulation in large regions of the global ocean. On the basis of seasonally distributed water column sam- the subtropical gyres. At the same time, her combined nitrate 15 14 N and O isotope data indicate that much of the nitrate above pling, we have developed a seasonal picture of the N/ N of 500 m in the tropical Atlantic has recently been added to the nitrate across the Subantarctic Zone of the Southern Ocean, ocean, through cyanobacterial N fi xation and its subsequent south of Australia. Despite only modest seasonal changes 2 in surface nitrate concentration ([NO -]), nitrate 15N/14N oxidation to nitrate. 3 Postdoc Moritz Lehmann has completed the analysis of increases dramatically from winter to summer. The nitrate

25 15 14 - N/ N:[NO3 ] relationship of the Antarctic surface to the diatom-bound N isotopic composition from the Subantarctic south of the Subantarctic surface is very different from that Zone, the region to the north of the Antarctic in the South- of the Subantarctic thermocline below the Subantarctic ern Ocean. Surprisingly, the records indicate the opposite surface. Thus, the seasonal change in Subantarctic surface sense of change that had been inferred from bulk sediment N nitrate 15N/14N indicates a winter/summer difference in the isotope measurements in the Subantarctic. The most robust source of nitrate to the Subantarctic surface, with vertical explanation for the records is that the degree of nitrate con- mixing supplying nitrate from the Subantarctic thermocline sumption was much higher in the Subantarctic during the during the winter and Ekman transport supplying Antarctic last ice age than today, most likely because of iron fertiliza- nitrate from the south during the summer. At the same time, tion during ice ages, an established but unproven hypothesis. the completeness of the apparent wintertime “reset” of the Unfortunately, we currently cannot rule out an alternative Subantarctic surface to thermocline characteristics introduces potential explanation for the glacial/interglacial N isotope the surface salinity of the Subantarctic as a constraint on change, a northward migration of Antarctic conditions the amount of Antarctic nitrate input during the summer. lowering the isotope effect of nitrate assimilation. Because of For the nitrate isotope data to be consistent with the salinity the potential importance of a glacial change in Subantarctic constraint, the isotope effect for nitrate assimilation in the nutrient conditions, resolving this uncertainty in our inter- Subantarctic must be signifi cantly higher than we observe in pretation is a focus of ongoing activity. the seasonally ice covered Antarctic. A higher isotope effect As our collaboration with the lab of Gerald Haug at in the Subantarctic is also suggested by our studies of sinking GFZ Potsdam continues, we are developing a progressively N [Lourey et al., 2003]. When combined with other regional stronger case for a link between climate cooling and polar studies from the Subarctic Pacifi c and equatorial Pacifi c, these ocean stratifi cation over the last three million years of Earth data argue that the Subantarctic Zone is home to a uniquely history. I have recently become interested in a new physical high isotope effect for algal nitrate assimilation. This may be mechanism for this link that involves the reduced tempera- due to a uniquely important role for light limitation of algal ture sensitivity of ocean density at low temperatures, which growth in this region (see summary of culture work above). I describe in the context of new evidence in a 2004 manu- Earth history studies. script. The motivation for this new interest is that our data in Based on Angie Knapp’s work on dissolved organic nitro- hand indicate that (1) the Antarctic in the Southern Ocean gen, postdoc Becky Robinson Graham and graduate student and the Subarctic North Pacifi c show the same response of Brigitte Brunelle have developed a method for the N isotopic upper ocean stratifi cation to climate cooling, and (2) there analysis of organic matter trapped within microfossils that are appears to be a relatively linear response of upper ocean buried in deep sea sediments. This is a specialized measure- stratifi cation to climate in both of these regions. These obser- ment, but it offers the potential to expose changes in nutrient vations are diffi cult to explain by other (e.g., sea ice- or wind- cycling through Earth history. Our work to date has focused related) mechanisms, which are likely to have different effects on sediment cores from polar ocean regions, where the nutri- in the two hemispheres and to cause threshold responses. ent status of the surface has a major effect on atmospheric Postdoctoral researcher Agatha DeBoer has been per- forming model experiments to test the potential role of the CO2. Becky Robinson Graham has demonstrated that previous non-linear dependence of density on temperature in the bulk sediment and diatom-bound N isotope records from the observed link between climate and polar ocean overturning. Antarctic have major fl aws. Based on her results, changes in In order to carry out these long time scale experiments, she the surface nitrate concentration of the Antarctic were much has adapted a computationally effi cient model developed by more modest than the previous records suggested, with some GFDL’s Robbie Toggweiler, the “water planet” model, which evidence for spatial variations. These results fi t with studies has simplifi ed bathymetry and basin geometry and is coupled suggesting that signifi cant iron fertilization of the Antarctic to a simple energy balance model of the atmosphere. DeBoer by enhanced dust transport is diffi cult to achieve even dur- has recently obtained extremely encouraging results for our ing the peak of the last ice age, partially because glacial dust cooling-driven stratifi cation hypothesis. These involve model deposition is expected to occur mostly in the lower latitude experiments in which we “lie” to the density calculation Subantarctic Zone, which shares a common latitude range protocol in the model, such that density and its gradients in with expected dust sources. While the data continue to sup- the model are calculated as if the ocean were homogenously port a previous hypothesis of Antarctic stratifi cation during warmer or colder than it really is. This has proven to be an glacial times, which would have reduced the escape of deeply effective strategy for isolating the temperature effects on den- sity structure from the other effects that temperature change sequestered CO2 to the atmosphere, the new data suggest a less important role for Antarctic nutrient drawdown in has in a model. In the “pseudo-warming” experiments, we glacial/interglacial CO2 changes. Given the limited evidence fi nd a remarkable spin-up of polar ocean overturning. In for patchiness in glacial nutrient drawdown, this study sug- the “pseudo-warming” experiments, polar ocean overturn- gests that each of the zonal sectors of the Antarctic must be ing decreases markedly. Follow-up experiments are currently studied to get an adequate view of nutrient status during the being run to improve our understanding of these results and last ice age. to compare the strength of this effect with other likely infl u- Becky has also generated three downcore records of ences on polar ocean overturning that arise in the context

26 of climate change (most critically, changes in the poleward nated by the 15N/14N of intracellular nitrate, Journal of Phy- water vapor transport in the atmosphere). A manuscript is in cology, 40, 517–522, DOI: 10.1111/j.1529-8817.2004.03172. preparation. x, 2004. Sigman, D.M., S.L. Jaccard, and G.H. Haug, Polar ocean stratifi - Lastly, recent Ph.D. graduate Curtis Deutsch (advisor: cation in a cold climate, Nature, 428, 59-63, 2004. Jorge Sarmiento) and I have modeled the expected effects of Hastings, M.G., D. M. Sigman, and F. Lipschultz, Isotopic hypothesized glacial/interglacial changes in the nitrogen cycle evidence for source changes of nitrate in rain at Bermuda, on the isotopic composition of oceanic nitrate. Comparison Journal of Geophysical Research – Atmospheres, 108(D24), of his model results with sedimentary nitrogen isotope data 4790, doi:10.1029/2003JD003789, 2003. suggest that negative (stabilizing) feedbacks in the ocean Sigman, D.M., and G.H. Haug, Biological Pump in the Past, in Treatise On Geochemistry, edited by H.D. Holland and K.K. nitrogen cycle have prevented large changes in the oceanic Turekian (H. Elderfi eld, volume editor), Elsevier Science, nitrogen reservoir over the last glacial/interglacial transition. Oxford, 2003. Saito, M.A., D.M. Sigman, and F.M.M. Morel, The bioinorganic Method development. chemistry of the ancient ocean: the co-evolution of cyano- The foundation for nearly all of the ongoing analytical work bacterial metal requirements and biogeochemical cycles in my lab is the method we developed for measurement of at the Archean/Proterozoic boundary? Inorganica Chimica the isotope ratios of nitrogen (15N/14N) and oxygen (18O/16O) Acta, 356C, 308-318, 2003. in nitrate (NO -) dissolved in diverse aqueous solutions (e.g., Sigman, D.M., S.J. Lehman, and D.W. Oppo, Evaluating mecha- 3 13 freshwater, seawater, sediment porewater, culture media). Ni- nisms of nutrient depletion and C enrichment in the inter- mediate-depth Atlantic during the last ice age, Paleocean- trate in itself is a central part of the nitrogen cycle, especially ography, 18(3), 1072, doi:10.1029/2002PA000818, 2003. in the ocean. Moreover, other forms of nitrogen can be con- Lourey, M.J., T.W. Trull, D.M. Sigman, Sensitivity of d15N of verted to nitrate in the lab, so that their isotopic composition nitrate, surface suspended and deep sinking particulate can also be determined. In previous years, I have described nitrogen to seasonal nitrate depletion in the Southern the nitrate method and our derivative methods for measur- Ocean, Global Biogeochemical Cycles, 2003, 17(3), 1081, doi:10.1029/2002GB001973, 2003. ing dissolved organic N and the organic N bound within Casciotti, K.L., D.M. Sigman, and B.B. Ward, Linking diversity sedimentary microfossils. We have added two new analytical and stable isotope fractionation in ammonia-oxidizing bac- capabilities this year. Graduate student Ben Houlton and teria, Geomicrobiology Journal, 20, 335–353, 2003. postdoc Moritz Lehmann developed a technique to measure Sigman, D.M., R. Robinson, A.N. Knapp, A. van Geen, D.C. the 15N/14N of ammonium in natural samples with roughly McCorkle, J.A. Brandes, and R.C. Thunell, Distinguishing between water column and sedimentary denitrifi cation in 100 times higher sensitivity than previous methods. Postdoc the Santa Barbara Basin using the stable isotopes of nitrate, Jan Kaiser and graduate student Meredith Hastings devel- Geochemistry, Geophysics, Geosystems, 4(5), 1040 , doi: oped a new technique to measure the 17O/16O of nitrate, with 10.1029/2002GC000384, 2003. probably a 1000-fold improvement in sensitivity relative to Karsh, K.L., T.W. Trull, M.J. Lourey, and D.M. Sigman, Relation- previous methods and a major reduction in the labor require- ship of nitrogen isotope fractionation to phytoplankton size and iron availability during the SOIREE Southern Ocean Iron ments of the measurement. RElease Experiment (SOIREE), Limnology and Oceanogra- Two-Year Bibliography phy, 48, 105-106, 2003. Refereed articles: Haug, G.H., D. Günther, L.C. Peterson, D.M. Sigman, and K.A. Hastings, M.G., E.J. Steig, and D.M. Sigman, Seasonal varia- Hughen, Climate and the collapse of Maya civilization, Sci- tions in N and O isotopes of nitrate in snow at Summit, ence, 299, 1731-1735, 2003. Greenland: Implications for the study of nitrate in snow and Articles in press or submitted: ice cores, Journal of Geophysical Research – Atmospheres, Haug, G.H., A. Ganopolski, D.M. Sigman, A. Rosell-Mele, G.E.A. 109, D20306, 10.1029/2004JD004991, 2004. Swann, R. Tiedemann, S.L. Jaccard, J. Bollmann, M.A. Deutsch, C., D.M. Sigman, R.C. Thunell, N. Meckler, and G.H. Maslin, M.J. Leng, and G. Eglinton, North Pacifi c seasonality Haug, Isotopic constraints on glacial/interglacial changes in and the glaciation of North America 2.7 million years ago, the oceanic nitrogen budget, Global Biogeochemical Cycles, Nature, in press. 18, GB4012, 10.129/2003GB002189, 2004. Knapp, A.N., D.M. Sigman, and F. Lipschultz, The N isotopic Granger, J., D.M. Sigman, J.A. Needoba, and P.J. Harrison, composition of dissolved organic nitrogen and nitrate at the Coupled nitrogen and oxygen isotope fractionation of nitrate Bermuda Atlantic Time-series Study site, Global Biogeo- during assimilation by cultures of marine phytoplankton, chemical Cycles, in press. Limnology and Oceanography, 49 (5), 1763-1773, 2004. Robinson, R.S., D.M. Sigman, P.J. DiFiore, M.M. Rohde, T.A. Robinson, R.S., B.G. Brunelle and D.M. Sigman, Revisiting nutri- Mashiotta, D. Lea, Diatom-bound 15N/14N: New support for ent utilization in the glacial Antarctic: Evidence from a new enhanced nutrient consumption in the ice age Subantarctic, method for diatom-bound N isotopic analysis, Paleoceanog- Paleoceanography, in review. raphy, 19, 3, PA3001 10.1029/2003PA000996, 2004. Houlton, B.Z., D.M. Sigman, and L.O. Hedin, Isotopic evidence Thunell, R.C., D.M. Sigman, F. Muller-Karger, Y. Astor and R. for large gaseous nitrogen losses from tropical rainforests, Varela, The nitrogen isotope dynamics of the Cariaco Basin, Nature, in review. Venezuela, Global Biogeochemical Cycles, 18, 3, GB3001 Sigman, D.M., J. Granger, P. DiFiore, M.F. Lehmann, A. van 10.1029/2003GB002185, 2004. Geen, D. Karl, R. Ho, G. Cane, Coupled nitrogen and oxy- Lehmann, M.F., D.M. Sigman, and W.M. Berelson, Coupling the gen isotope measurements of nitrate along the North Pacifi c 15 14 18 16 N/ N and O/ O of nitrate as a constraint on benthic margin, Global Biogeochemical Cycles, in review. nitrogen cycling, Marine Chemistry, 88, 1-20, 2004. Jaccard, S.L., Haug, G.H., Sigman, D.M., Pedersen, T.F., Thier- Needoba, J.A., D.M. Sigman, P.J. Harrison, The mechanism of stein, H.R., Röhl. U., Glacial/interglacial changes in Subarc- isotope fractionation by algal nitrate assimilation as illumi- tic North Pacifi c stratifi cation, Science, in review. 27 John Suppe southern California, Taiwan and the Tianshan mountains of Blair Professor of Geology western China. Ph.D., 1969, Yale University For example, graduate student Lifan Yue has combined a email: [email protected] detailed 3D image he has developed of the classic thrust fault of the major Chi-Chi earthquake in Taiwan with an equally detailed coseismic displacement fi eld to get an unparalleled image of the relationships between complex earthquake slip and complex fault geometry in a major earthquake. The Chi-Chi earthquake is a unique opportunity because it is the best instrumented earthquake ever and for unusual reasons we are able to independently map the fault in detail in 3D. Furthermore we have shown that borehole measurements of pore-fl uid pressures surrounding this fault are entirely hydro- static in contrast with the classic hypothesis of Hubbert & We are working to understand the rich variety of processes Rubey (1959) that high pore-fl uid pressures are the solution by which the upper crust deforms, particularly by studying to the problem of fault weakness. Also I have obtained a sur- actively deforming mountain belts such as Taiwan, the Tian- prising result in critical-taper wedge theory which allows one shan of western China and the Transverse Ranges of southern to determine absolute fault strength from wedge taper data, California. For the fi rst 150 years of Geology the study of independent of signifi cant assumptions about material prop- active deformation moved rather slowly because of “data erties. This is an important contribution to the longstanding starvation” caused by diffi culties in seeing into the complex controversy over the strength of major plate-boundary faults deforming interiors of mountain belts. The subject fi nally because they have been largely inaccessible to measurement. began to take off about 1980 because of improved seismic Results using this new theory indicate very weak basal de- imaging. Since then my students and I have been at the fore- tachments in Taiwan, Japan and Niger delta. front of a successful effort to use these new data to develop Graduate student Ramon Gonzalez is making signifi cant fault-related fold theory which has shown, surprisingly, that advances in the understanding of detachment folding based the vast richness of deformed structures that we observe are on precise analysis of well-imaged examples from the Tian- formed by simple processes of displacement and propaga- shan, Nankai trough, Cascadia accretionary wedge and Niger tion of non-planar faults. In the last few years we have made delta. breakthroughs in insight, developing shear fault-bend folding I am fi nishing with former postdoc Aurélia Hubert-Fer- and detachment folding theories, which explain in detail rari of University of Neuchatel a major paper on “the link large classes of previously misunderstood structures. between the surface and the subsurface” in active tectonics, I am working hard at completing a book on fault-related in which we have been able to establish close relationships fold theory to be published by Princeton University Press and between surface deformation and geomorphology and the I have joined with former students John Shaw at Harvard subsurface structure in the Tianshan of western China. With and Chris Connors at Washington & Lee to write and edit a Dr. Dengfa He I have been working on what may be the major volume on interpretation of seismic images in light of longest active intact thrust sheet in the world which is on the fault-related fold theory, which about to be published with northern margin of Tibet and extends ~250km out into the AAPG. In addition I am a co-organizer of a major interna- Tarim basin to the north. In addition I went to China last tional conference on Theory and application of Fault-related summer to initiate a new multiyear project on active defor- folding in Foreland Basins which will be held in China this mation in the Junggar basin on the northern margin of the summer. It is an unusual conference because the list of par- Tianshan. ticipants includes a very large number of well-known scien- Two-Year Bibliography tists from diverse fi elds ranging from structural geology, to Books active tectonics to petroleum geologists. We will have three (with J. Shaw, C. Connors), editors, Seismic Interpretation of days of meeting in Beijing after which we all fl y to western Contractional, Fault-Related Folds: an AAPG Seismic Atlas. China for a one-week fi eld trip to see actively growing struc- American Association of Petroleum Geologists, in press, tures in the Tianshan Mountains. 2004. I feel that Active Tectonics in the midst of a new ac- Refereed articles: celeration of understanding driven by new data that can be (with S. Carena, and H. Kao), Lack of continuity of the San Andreas fault in southern California: Three-dimensional fault brought to bear on upper crustal deformation, especially: models and earthquake scenarios, Journal of Geophysical [1] precise earthquake locations, [2] dense geodetic data, Research, v. 109, B04313, 17 pp, 2004. [3] tectonic geomorphology (which provides an integral of Essay Review of John Rodgers “The Company I Kept,” American deformation of the land surface over the last 10,000-100,000 Journal of Science, v. 304, p. 285-286, 2004. years), and [4] seismic imaging. We are engaged in a number (with Erickson, S. G., and Strayer, L. M.), Numerical modeling of of projects that are at the forefront of using all these new data hinge-zone migration in fault-bend folds. . In McClay, K. ed., Thrust Tectonics and Hydrocarbon Systems, American As- for new insight, working in areas of active deformation in sociation of Petroleum Geologists Memoir, 82, p. 438-452, 2004. 28 (with L. M. Strayer and S. G. Erickson), Infl uence of growth strata 2005. on the evolution of fault-related folds: Distinct-element mod- (with J. H. Shaw and S. C. Hook), Pitas Point anticline, Cali- els. In McClay, K. ed., Thrust Tectonics and Hydrocarbon fornia, USA. In J. Shaw, C. Connors, J. Suppe, editors, Systems, American Association of Petroleum Geologists Seismic Interpretation of Contractional Fault-Related Folds, Memoir, 82, p. 413-437, 2004. American Association of Petroleum Geologists, in press, (and Chris Connors and Yikun Zhang), Shear fault-bend fold- 2005. ing. In McClay, K. ed., Thrust Tectonics and Hydrocarbon (with J. H. Shaw and C. D. Connors), Part 1: Structural Interpre- Systems, American Association of Petroleum Geologists tation Methods. In J. Shaw, C. Connors, J. Suppe, editors, Memoir, 82, p. 303-323, 2004. Seismic Interpretation of Contractional Fault-Related Folds, Exponential growth of geology, mathematics, and the physical American Association of Petroleum Geologists, in press, sciences for the last two hundred years and prospects for 2005. the future, Journal of Nanjing University, v. 38, p. 76-86, (with F. Corredor and J. H. Shaw), Shear fault-bend fold, deep 2003. water Niger Delta. In J. Shaw, C. Connors, J. Suppe, edi- tors, Seismic Interpretation of Contractional Fault-Related Other miscellaneous publications Folds, American Association of Petroleum Geologists, in With Li-Fan Yue, Mapping active faults in southern California in press, 2005. 3D using small earthquakes: southern San Andreas, San (with A. Hubert-Ferrari and Jerome Van Der Woerd), Irregular Jacinto and Elsinore fault systems, NEHRP Annual Project earthquake cycle along the southern Tianshan, China (Aksu Summary, vol 5, 7 pp, 2003. http://erp-web.er.usgs.gov/re- area), Journal of Geophysical Research, in press, 2005. ports/annsum/vol45/sc/sc_vol45.htm (with Kauan-Yin Lai,Yue-Gau Chen, Jih-Hao Hung and Ya-Wen Articles in press or submitted: Chen), Fault geometry related surface deformation of an ac- (with A. Ferrari, X. Wang and C. Jia), The Yakeng detachment tive fault: evidence from geomorphic features and coseismic fold, China. In J. Shaw, C. Connors, J. Suppe, editors, slip, Quaternary International, in press, 2005. Seismic Interpretation of Contractional Fault-Related Folds, (with Li-Fan Yue and Jih-Hao Hung), Structural geology of a American Association of Petroleum Geologists, in press, classic thrust belt earthquake: the 1999 Chi-Chi earthquake Taiwan (Mw7.6), Journal of Structural Geology, in review,

Bess B. Ward isms involved in transformations of inorganic and organic Professor of Geosciences nitrogen in the ocean and in sediment environments. This Ph.D., 1982 University of Wash- research makes use of technical approaches that range from ington molecular biology to stable isotope biogeochemistry. The email: [email protected] two main bacterial groups we study are the nitrifi ers, auto- trophs that oxidize ammonium to nitrite and nitrate, and the denitifi ers, heterotrophs that can respire nitrate in the absence of oxygen. The linked activities of these two groups can be crucial in determining the chemical form and supply of nitrogen to planktonic communities and in determining the net nitrogen budget of ecosystems. Ward lab has a web page where all of this is described. http://geoweb.princeton.edu/research/ecomicrobio/ecomi- crobio.html

My research concerns the marine and global nitrogen cycle, Summary of Progress During the Past Year on Each Project: using molecular and immunological probes for marine 1. “Biocomplexity of Aquatic Microbial systems: Relat- bacteria and bacterial processes (especially nitrifi cation and ing diversity of Microorganisms to Ecosystem Function” denitrifi cation), and measuring the rates of N transforma- (O’Mullan, Adhitya) (http://geoweb.princeton.edu/research/ tion processes. We have ongoing research on denitrifi cation biocomplexity/index.html) in Antarctica and the Arabian Sea, the genes involved in 2004 was the fourth year of this collaborative project, involv- nitrogen assimilation by phytoplankton, diversity of func- ing several other institutions, all working in Chesapeake Bay tional guilds of bacteria involved in the nitrogen cycle of and coordinated through Princeton as the lead institution. Chesapeake Bay, and the role of metals in nitrogen redox Microbial biogeochemical cycling of the elements regulates biogeochemistry. Some of the main projects are summarized a dynamic environment in which the cycles of different ele- explicitly below. ments are linked through the physiology of microorganisms. Microbes control many of the important biogeochemical Our present understanding of ecosystem function has been processes that occur in the oceans as well as on land. They gained through physical/chemical approaches to measure- contribute to the trace gas cycles that infl uence climate; they ment and modeling of the net transformations. These ap- utilize and produce nutrients that are involved in eutrophica- proaches necessarily rely on gross simplifi cations about the tion; and they are even capable of cleansing the environment role and regulation of the various functional groups (guilds) by degrading a vast variety of chemical compounds, both involved. Recent advances in molecular microbial ecology naturally occurring and anthropogenically produced. My have shown the microbial world to contain immense diversi- research focuses on the nitrogen cycle and the microorgan- ty and complexity at every level: redundancy and duplication of functional genes within a single organism; molecular di- 29 versity among functional genes that encode the same process reductase (NR) in eukaryotic phytoplankton were used in in different organisms; large genetic diversity among different the fi rst successful second generation array to analyze phy- organisms apparently engaged in the same biogeochemical toplankton communities in the English Channel. This array function within single communities; great variability in the detected both community composition (DNA) and gene species composition of different communities that apparently expression (mRNA) in natural assemblages and demonstrated perform equally well. the power of the approach. Papers are in prep and submitted. The goal of this project is to investigate the functional The second generation version of the nirS and amoA arrays relationship between complexity in microbial communi- have been constructed and will be deployed in the coming ties and the physical/chemical environment at a range of year. biological and ecological scales. Previously, such analysis The macroarray project is based at UCSC (Zehr lab); the was technologically limited by the inability to assay large fi rst macroarrays were tested with nitrogenase genes (nifH) numbers of samples simultaneously for a large number of and found to have discriminatory power and sensitivity simi- genes and phylotypes. Using gene array technology, we will lar to that of the microarrays (Steward et al., 2004; Jenkins be able to detect the distribution and differential expression et al., 2004). Both kinds of arrays are able to distinguish of functional genes in natural systems. The results of this different community compositions of denitrifi ers, nitrifi res or study will constitute the fi rst step towards application of nitrogen fi xers, respectively, in sediment and water samples DNA chip technology for gene expression of “exotic” (i.e., from different stations. not of biomedical importance) processes and organisms in 2. “What limits denitrifi cation and bacterial production the environment. The gene arrays, along with a full suite of in Lake Bonney, Antarctica?” (Tuit) ecosystem process measurements, are deployed along a tran- The second three-year period of this project initially focused sect that spans the eutrophic - oligotrophic gradient from the on experiments with denitrifying laboratory cultures grown inland waters of the Chesapeake Bay out to the Sargasso Sea. under trace metal clean denitrifying conditions in trilami- Experiments and functional gene studies focus on key trans- nate bags. The ongoing experiments are designed to test the formations in the carbon and nitrogen cycles (C fi xation, N copper hypothesis, which grew out of our previous work on fi xation, nitrifi cation, denitrifi cation, urea assimilation). The this project. The copper hypothesis suggests that lack of Cu diversity of guilds will be interpreted in terms of ecosystem can limit denitrifi cation and lead to build up of inorganic function, assessed using geochemical data and tracer experi- nitrogen intermediates in the water column. Field work in ments. In addition to fi eld studies designed to investigate and the dry valley lakes of Antarctica is planned for 2004 and dissect the natural system, we have also performed perturba- 2005. During the fi rst season (ongoing at the time of this tion experiments using mesocosms. The goal of these experi- writing), we developed and tested a series of fl ow cytometric ments is to determine how microbial species diversity affects assays for bacterial abundance and physiological state in the the major energy and nutrient fl ows within ecosystems, and lake samples. to assess the degree of stability or instability associated with changes in redundancy within guilds of microorganisms 3. “Center for Environmental Bioinorganic Chemistry” responsible for major nitrogen and carbon pathways. (Jayakumar, Tuit) To date, about 20 fi eld trips/research cruises have been The two forms of dissimilatory (respiratory) nitrite reductase, completed in Chesapeake Bay, the Choptank River and the cd-NiR (nirS gene) and Cu-NiR (nirK gene), are dis- the Sargasso Sea. Both microarrays (using 70-bp oligomer tributed across the Bacterial and Archaeal domains in a great probes) and macroarrays (using ~350 bp PCR products) de- diversity of microorganisms. Because trace metal availability rived from functional genes, which we extracted from Chesa- can limit denitrifi cation in the lab, we hypothesized that peake Bay sediments, plus a few representative genes from metal distributions might infl uence the type of nir found in cultured organisms. The fi rst generation microarrays contain- natural marine assemblages. The fi rst step in addressing this ing oligos for nitrite reductase genes (nirS) were characterized hypothesis is to describe the distribution and diversity of nir in terms of their specifi city and sensitivity using simple and genes in marine systems. One paper (Jayakumar, Francis and complex mixtures of known genes, and complex environ- Ward, 2004) describes the diversity and distribution of nirS mental samples from Chesapeake Bay (Taroncher-Oldenburg genes in the low oxygen coastal waters of the Arabian Sea in et al, 2003). Sequence differences of 13-15% can be distin- the continental shelf region of India. The sequences found guished and the detection limit is 107 copies of a particular here are the fi rst reported for a water column environment, target. These results appear to be robust for all genes, due to and are quite different from those previously reported from the uniform behavior of oligomer probes. A similar microar- sediment environments. Jayakumar and Tuit participated in a ray, containing oligo probes for ammonia monooxygenase month long cruise in Nov-Dec 2003 in the Eastern Tropical (amoA) genes has been used to characterize sediment and North Pacifi c which visited the strong oxygen minimum zone water column samples along the complete transect from April in that region. They conducted Cu perturbation experiments 2001. and hope to detect a response by the indigenous denitrifying The second generation of microarrays employed a new community based on nitrous oxide production. Samples were labeling protocol and a new quantifi cation procedure. Genes also collected for analysis of both nirS and nirK genes. The encoding the essential enzymes RuBisCO (rbcL) and nitrate only defi nitive results of the cruise experiments were that 1) denitrifi catio rates were overall very low and 2) denitrifi ca- 30 tion rates were stimulated by the addition of organic carbon samples for DNA and RNA will be analyzed to determine but not by the addition of Cu, Fe or Cu chelators. the kinds of denitrifying genes present, and to investigate 4. “Draft Level Sequencing of a Selection of Nitrifying their patterns of expression under different conditions. Bacteria” (O’Mullan) and “Microbial genome sequencing; Two-Year Bibliography The complete genome sequence of a mini consortium of Refereed articles: marine ammonia oxidizers” Song, B., and B. B. Ward, Molecular characterization of the as- similatory nitrate reductase gene and its expression in the DOE has agreed to sequence the entire genome of fi ve am- marine green alga, Dunaliella tertiolecta. Journal of Phycol- monia- and nitrite-oxidizing bacteria. Nitrobacter hambur- ogy, 40: 721-731, 2004. gensis 14X was grown in our lab and I extracted the DNA Jenkins, B. D., G. F. Steward, S. M. Short, B. B. Ward and J. P. that was used for sequencing. Ward lab is the lead on the N. Zehr, Fingerprinting diazotroph communities in the Chesa- hamburgensensis genome and annotation is currently under- peake Bay by using a DNA macroarray, Applied and Envi- ronmental Microbiology, 70: 1767-1776, 2004. way. In the NSF project, we are sequencing two additional Steward, G. F., B. D. Jenkins, B. B. Ward and J. P. Zehr, Devel- ammonia oxidizers, including Nitrosococcus oceanus. The opment and testing of a DNA macroarray to assess nitro- Moore foundation microbial genome project has agreed to genase (nifH) gene diversity, Applied and Environmental sequence another N. oceanus genome, and we are growing Microbiology, 70: 1455-1465, 2004. the cells for that project. Jayakumar, D. A., C. A. Francis, S. W. A. Naqvi and B. B. Ward, Diversity of nitrite reductase genes in the denitrifying water 5. “Diversity and distribution of denitrifying bacteria in column of the coastal Arabian Sea, Aquatic Microbial Ecol- relation to chemical distributions in theoxygen minimum ogy, 34: 69-78, 2004. zone of the Arabian Sea” (Jayakumar, Tuit, Rich) Francis, C. A., G. D. O’Mullan and B. B. Ward, Diversity of am- monia monooxygenase (amoA) genes across environmental The Arabian Sea is one of three regions in the open ocean gradients in Chesapeake Bay sediments, Geobiology, 1: where signifi cant denitrifi cation occurs in the water column. 129¬140, 2003. Nitrous oxide is an intermediate in the denitrifi cation path- Ward, B. B., Signifi cance of anaerobic ammonium oxidation in way, and is also produced during aerobic nitrifi cation at low the ocean, Trends in Microbiology, 11: 408-410, 2003. oxygen tensions. It is very effective as a greenhouse gas, and Casciotti, K. L., D. M. Sigman and B. B. Ward, Linking diversity and biogeochemistry in ammonia-oxidizing bacteria, Geomi- what controls its production and release from marine systems crobiology Journal, 20: 335-353, 2003. is not well understood. Nitrous oxide accumulates in a char- Taroncher-Oldenburg, G, E. Griner, C. A. Francis and B. B. Ward, acteristic pattern in oxygen minimum zones (OMZs), such Oligonucleotide microarray for the study of functional gene as that found in the Arabian Sea. In previous work (Granger diversity of the nitrogen cycle in the environment, Applied and Ward, 2003), we showed that denitrifi cation by cultured and Environmental Microbiology, 69: 1159-1171, 2003. Ward, B. B., J. Granger, M. T. Maldonado and M. L. Wells, What bacteria in the lab could be limited by copper availability, limits bacterial production in the suboxic region of per- leading to the accumulation of denitrifi cation intermediates manently ice-covered Lake Bonney, Antarctica? Aquatic in the medium. We hypothesized that copper availability in Microbial Ecology, 31: 33-47, 2003. OMZs might be quite low, low enough in fact to limit de- Caffrey, J. M., N. E. Harrington, I. P. Solem and B. B. Ward, nitrifi cation at the nitrous oxide reduction step, thus leading Biogeochemical Processes in a Small California Estuary, to accumulation of nitrous oxide. Copper limitation might Elkhorn Slough, CA.: 2. Nitrifi cation Activity, Community Structure and Role in Nitrogen Budgets, Marine Ecology also lead to accumulation of nitrite in denitrifying bacteria Progress Series, 248: 27-40, 2003. that possess the copper type nitrite reductasae, rather than Song, B. and B. B. Ward, Nitrite reductase genes in haloben- the iron enzyme. Thus, if copper limitation were a fact of life zoate degrading denitrifyng bacteria and related species, in the OMZ, we might expect that the iron NiR should be FEMS Microbial Ecology, 34: 349-357, 2003. more common than the copper NiR. Granger, J. and B. B. Ward, Accumulation of nitrogen oxides in copper-limited cultures of denitrifying bacteria, Limnology In September 2004, Carrie Tuit, Amal Jayakumar, and and Oceanography, 48: 313-318, 2003. Jeremy Rich participated in a month long cruise in the Arabi- Articles in press or submitted: an Sea in collaboration with Indian colleagues on the Indian Submitted research vessel Sagar Kanya. Preliminary results indicate Ward, B. B., Diversity and functional dynamics in a marine phy- that, unlike the Eastern Tropical North Pacifi c where similar toplankton community uncovered by gene arrays, Nature. experiments were performed in November 2003, denitrifi ca- Ward, B. B., Temporal variability in nitrifi cation rates and related tion was NOT carbon limited. Nitrate disappeared from the biogeochemical factors in Monterey Bay, California, Marine bags over the course of a few days, and the entire denitrifi ca- Ecology-Progress Series. Bronk, D. A. and B. B. Ward, Inorganic and organic nitrogen cy- tion sequence was observed in most bags. We suspect that cling in the Southern California Bight., Deep-Sea Research. a large, basin-wide dinofl agellate bloom may have supplied Ward, B. B. and G. D. O’Mullan, Community level analysis: organic matter to the OMZ at an unusually high rate. The Genetic and biogeochemcial approaches to investigate results suggest that denitrifi cation rates can be very variable community composition an function in aerobic ammonia and episodic, implying that conventional areal and annual oxidation. In: Method in Enzymology. Ed: J. Leadbetter. denitrifi cation rate estimates may be unreliable. In Press Anammox (Jeremy Rich), denitrifi cation (Al Devol, Ward, B. B., J. Granger, M. T. Maldonado, K. L. Casciotti, S. Harris and M. L. Wells, Denitrifi cation in the hypolimnion of University of Washington) and trace metal distributions (Jim permanently ice-covered Lake Boney,Antarctica, Aquatic Moffett, WHOI) were also investigated on the cruise. Our Microbial Ecology. 31 Ward, B. B., Molecular approaches to marine microbial ecology and the marine nitrogen cycle. In: Annual Review of Earth and Planetary Science, 33:X-XX Allen, A. E., B. Song and B. B. Ward, Characterization of diatom (Bacillariophyceae) nitrate reductase genes and detection of eukaryotic nitrate reductase genes from marine waters, Journal of Phycology. O’Mullan, G. D. and B. B. Ward, Comparison of temporal and spatial variability of ammonia-oxidizing baceria to nitrifi ca- tion rates in Monterey Bay, CA, Applied and Environmental Microbiology. Casciotti, K. L. and B. B. Ward, Nitric oxide reductase (norB) genes identifi ed in ammonia-oxidizing bacteria, FEMS Mi- crobial Ecology. Song, B., and B. B. Ward, Diversity of benzoyl-CoA reductase genes n aromatic compound degrading denitrifying bacteria and in environmental samples, Applied and Environmental Microbiology. Jiang, W., A. Saxena, B. Song, B. B. Ward, T. J. Beveridge, S. C. B. Myneni, Elucidation of functional groups on Gram-posi- tive and Gram-negative bacterial surfaces using infrared spectroscopy, Langmuir.

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