Guyot Science 2003

Department of Geosciences, Princeton University

1 2 Guyot Science 2003

A Summary of the Research Progress and Accomplishments Made by the Faculty Members of the Department of Geosciences During the Year 2003

Last year, January-December 2003, was another good year for the Princeton Department of Geosciences. As usual, a number of individual faculty members received outside honors and awards in recognition of the overall excellence of their research. Jason Morgan was awarded a 2002 National Medal of Science, the nation’s highest honor for scientists and engineers, presented annually by the President of the United States. This is a fitting end to Jason’s remarkable 44-year career as a geoscientist at Princeton. In October 2003, the department hosted a two-day MorganFest symposium, in honor of Jason’s retirement. Isaac Held of the Program in Atmospheric and Oceanic Sciences was elected a Member of the National Academy of Sciences, and George Philander was elected a Fellow of the American Academy of Arts and Sciences. Tony Dahlen was awarded the 2003 Inge Lehmann Medal of the American Geophysical Union; this medal is presented biennially for outstanding contributions to the understanding of the structure, composition and dynamics of the earth. Danny Sigman will be one of the recipients of the 2004 AGU Macelwane Medal; this medal recognizes signifi- cant contributions to the geophysical sciences by an outstanding young scientist (less than 36 years of age). Danny is the first member of the geosciences department to receive this coveted award. Jorge Sarmiento was inducted as a 2003 Fellow, and Allan Rubin was elected as a 2004 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. Maia Schweizer, a departmental concentrator who will receive her B.A. Degree in 2004, has been awarded a Marshall Fellowship, to pursue graduate studies in biogeosciences at Oxford Univer- sity. 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, 2002-2003, 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 ingassing due to temperature-driven solubility changes, and Professor also to atmospheric mixing. Ph.D., 1970, Columbia University email: [email protected] Highlights of our research of last year include:

1. Assembling and analyzing our atmospheric O2/N2 records of the past 5 years. The results show that oceans have been

responsible for about 70% of fossil CO2 sequestration, and the land biosphere 30%. They also confirm that the most

interannual variability in CO2 uptake is associated with the diminution of land biosphere sequestration during El Nino events.

2. Assembling about 8 years of O2/N2 data in air over the equatorial Pacific, collected intermittently using automated samplers installed on ships. These results show a maximum

The activities of my laboratory focus on studies of the in O2/N2 ratios, but it is considerably smaller than predicted by a variety of ocean circulation/biogeochemistry models. geochemistry of O2, with applications to understanding the global carbon cycle and glacial-interglacial climate change. The results call into question aspects of these models. The geochemical properties we study are the concentration 3. Matt Reuer’s rapid progress with the analysis of Southern Ocean samples for the isotopic composition and concentra- of O2 in air (which we measure to very high precision), and 16 the relative abundance of the three stable O isotopes ( O, tion of O2, to constrain rates of net and gross production. 17 18 The results show that ocean productivity is highest in the O, and O) in O2. There are two subjects for the isotopic northern end of the Southern Ocean and decreases to the studies: O2 in fossil air extracted from ice cores, and dis- south. This result agrees with satellite studies of chlorophyll solved O2 in seawater. Three processes affect the concentra- distribution but contradicts inversion studies of the produc- tion and isotopic composition of O2: photosynthesis, tivity distribution, as well as hypotheses that net production respiration, and isotope exchange between O2 and CO2 in the stratosphere. in the Southern Ocean is limited by the availability of nutrients, or favored by cold temperature. Studies of the O2 concentration (or ratio of O2/N2) in 4. There were three significant analytical advances during the air constrain the fate of fossil fuel CO2 that does not remain in the atmosphere: these measurements allow us to partition past year: (a) Jan Kaiser developed the basis of a method for the “missing” CO2 between the oceans and the land bio- sphere. They also constrain rates of seasonal biological making continuous measurements of O2/Ar ratios of production by the oceans. Finally, they provide a test of dissolved gases in surface waters, along ships’ cruise models describing the global interaction of ocean circulation tracks. He recently participated in an oceanographic and biogeochemistry: These models predict that there should cruise in the eastern equatorial Pacific, and made his first measurements. Jan’s technique will give rates of net be a relatively large maximum in the atmospheric O2/N2 ratio in air over the tropical Pacific. biological production in the upper ocean at far greater resolution than any previous experimental approach. The isotopic measurements of O2 in ice core trapped gases reflect the relative fertility of Earth’s biosphere, aver- The method is a significant advance in constraining the aged over about 1,000 years. The triple isotope composition fertility of ocean ecosystems and addressing other problems of interest concerning the ocean carbon cycle. of O2 in seawater reflects the fraction of dissolved O2 from (b) We have continued to build and install auto- photosynthesis. O2 supersaturation reflects net production (photosynthesis in excess of respiration); by combining mated air samplers. We now have a record from Cape Grim (Tasmania) that is over 1 year long. It shows that measurements of O2 concentrations and isotopes, we can determine rates of photosynthesis, respiration, and net samples are collected with much better integrity, yield- production in aquatic ecosystems. Of course rate determina- ing cleaner records of atmospheric variations. This tions of these processes in seawater have been made for many improvement is particularly important for Ar/N2 years; what makes our work new is that our approach does measurements, whose amplitude of annual variability is not require labor-intensive bottle incubations at sea, and our only 10-25 parts per million. measurements can be made on large numbers of samples (c) Makoto Suwa and Bruce Barnett have built an collected by colleagues on cruises of opportunity, and automated extraction line for Makoto’s ice core samples, returned to the lab. and he has begun his thesis measurements. We have also begun planning or doing 3 new projects. Supplementing the O2 studies are studies of Ar. In seawater samples, Ar gives a measure of physical supersatura- The first is a collaboration with Chuck Dismukes, tion due to warming of waters and bubble entrainment. In Department of Chemistry, to investigate the source of O produced during photosynthesis (it is primarily from air samples, the Ar/N2 ratio reflects seasonal outgassing and 2 water but there is reason to think that some comes from

4 bicarbonate). The second, and potentially most interest- Bender, M. L., Climate-biosphere interactions on glacial-interglacial ing, is a study with Larry Edwards of the possibility of timescales, Global Biogeochemical Cycles, in press, 2003. helium/uranium dating of speleothems, which have Battle, M., M. Bender, M. Hendricks, D. T. Ho, R. Mika, G. McKinley, S. Fan, T. Blaine, and R. Keeling, Measurements terrific high-resolution climate records. The third, with and models of the atmospheric Ar/N2 ratio, Geophysical Lonnie Thompson, is an attempt to use gas stratigraphy Research Letters, 30 (15), 1786, doi:10.1029/2003GL017411, to data a critical portion of one of his tropical ice cores. 2003. Bender, M. L. (Chair) and 14 co-authors, A large Scale CO Two-Year Bibliography 2 Observing System: Oceans and Atmosphere, National Keller, K. R. D. Slater, M. Bender and R. M. Key, Possible biological Oceanic and Atmospheric Administration, 214 pp + 9 or physical explanations for decadal scale trends in North Appendices, 2002. Pacific nutrient concentrations and oxygen utilization, Deep- (Note: this document presents a 5-10 years implementation plan, Sea Research Part II - Topical Studies in Oceanography, 49, commissioned by the NOAA Office of Global Program, for 345-362, 2002. systematic observation of CO and related properties in the Blunier, T., B. Barnett, M. L. Bender and M. B. Hendricks, Biological 2 oceans and atmosphere). oxygen productivity during the last 60,000 years from triple Hendricks, M. B., M. L. Bender, and B. Barnett, Net and gross O oxygen isotope measurements, Global Biogeochemical 2 production in the Southern Ocean from measurements of Cycles, 16 (3), art. No. 1029, July-August, 2002. biological O saturation and its triple isotope composition, Bender, M. L., Orbital tuning chronology for the Vostok climate 2 submitted to Deep Sea Research. record supported by trapped gas composition, Earth and Planetary Science Letters, 204, 275-289, 2002.

F. Anthony Dahlen Research on finite-frequency (banana-doughnut) Department Chair tomography also proceeded on a number of other fronts in Professor 2003. Graduate student Adam Baig completed his compre- Ph.D., 1969, University of hensive theoretical and computational study of finite- California, San Diego frequency acoustic wave propagation in weakly heteroge- email: [email protected] neous, 3-D, Gaussian and exponential random media. Ensemble averaging methods were used to deduce the expected dependence of statistical observables, such as the root-mean-square traveltime and amplitude and the absolute (second-order) traveltime, upon the heterogeneity strength and correlation scale length of the random medium, the wavelength, and the source-receiver geometry. These results extend the statistical results previously obtained by previous investigators, using classical ray theory. The excellent During 2003, my long-standing collaboration with Guust agreement between Adam’s ground-truth numerical simula- Nolet, to account for finite-frequency wavefront healing tions and our finite-frequency random medium theory effects in global seismic traveltime tomography, finally came shows that we have a complete theoretical understanding of to fruition, with the first successful imaging of deep-mantle the fundamental physics of diffractive wavefront healing in thermal convection plumes by graduate student Raffaella the linear (weak heterogeneity, moderate propagation Montelli. Raffa’s P-wave velocity images show at least six distance) regime. Small-scale wavespeed heterogeneities, well-resolved plumes — Ascension, Azores, Canary, Easter, which are most susceptible to wavefront healing, will tend to Samoa and Tahiti — that originate in the vicinity of the be suppressed in ray-theoretical inversions; finite-frequency core-mantle boundary, as originally proposed by Jason (banana-doughnut) sensitivity kernels enable us to image Morgan more than thirty years ago. Other less well-resolved small-scale features, such as Raffa’s plumes, in the earth’s plumes, including Hawaii, may also extend into the lower- mantle with greater fidelity, because they properly account most mantle. Several other plumes, including Iceland, are for such diffractive effects. Adam also defended his Ph.D. clearly confined to the upper mantle, suggesting that convec- dissertation in September 2003, and is now a Canadian tion may be partially separated into two depth regimes. All NSERC Postdoctoral Fellow, working with Professor of the observed plumes have a diameter of several hundred Michael Bostock at the University of British Columbia. kilometers, indicating that plumes convey a substantial Graduate student Ying Zhou has completed a major fraction of the internal heat escaping from the earth. Raffa theoretical effort, to develop both 3-D and 2-D sensitivity successfully defended her Ph.D. dissertation in September kernels for the measured phases, arrival angles, and ampli- 2003, and is now working in the Department of Geosciences tudes of waves that travel along the earth’s surface rather as a postdoc, to invert S-wave traveltimes using finite- than through its interior. A long paper describing these frequency sensitivity kernels, to provide an independent results has been accepted for publication in Geophysical check on her very exciting P-wave results. Journal International. Ying is presently making use of her

5 newly developed surface-wave kernels to invert Love and blurred, or spread laterally, as a result of wavefront healing Rayleigh phase measurements collected by Gabi Laske at the and other finite-frequency diffraction effects. The 1-D Scripps Institution of Oceanography. Ying will complete her spreading varies as the cube root of the amplitude reduction, Ph.D. dissertation in 2004. so that the total volume-integrated slowness is conserved. Second-year graduate student Tarje Nissen-Meyer has Two-Year Bibliography initiated a project to compute exact waveform and traveltime Dahlen, F.A. & Baig, A.M., Fréchet kernels for body wave sensitivity kernels in a background spherical earth model, amplitudes, Geophys. J. Int., 150, 440-466, 2002. using an axially symmetric spectral element method. The Baig, A.M. & Dahlen, F.A., Traveltimes in 3-D random media, method should also be capable of computing the response of Geophys. J. Int., 153, 1-16, 2002. a spherical earth to a moment tensor or point force source Zhou, Y., Nolet, G. & Dahlen, F.A., Surface sediment effects on up to 1 Hz frequency, substantially better than can be teleseismic P wave amplitudes, J. Geophys. Res., 108 (B9), 2417, doi:10.1029/2002JB002331, 2003. achieved with normal-mode summation codes. This work is Montelli, R., Nolet, G. Dahlen, F. A., Masters, G., Engdahl, E. R. & being conducted in collaboration with Alex Fournier, Hung, S.-H, Finite-frequency tomography reveals a variety of who defended his Ph.D. dissertation in December 2003, and plumes in the mantle, Science, 303, 338-343, 2004. who is now working at the Institut de Physique du Globe in Dahlen, F. A., Resolution limit of traveltime tomography, Geophys. Paris. Graduate student Paul McGee has begun to make J. Int., in press, 2003. progress on his first-year research project, to investigate the Montelli, R., Nolet, G., Masters, G., Dahlen, F.A. & Hung, S.-H., Global P and PP traveltimes: rays versus waves, Geophys. J. influence of near-field terms on sub-receiver waveform and Int., in press, 2003. traveltime sensitivity kernels in a uniform halfspace, using Nolet, G. Dahlen, F. A. & Montelli, R., Travel times of seismic the Cagniard-de Hoop method. waves: a reassessment, in Data Analysis and Imaging with Finally, in 2003, I was able to shirk my administrative Global and Local Arrays, edited by Levander, A. & Nolet, G., duties as department chair for long enough to conduct a American Geophysical Union, Washington, D.C., in press, modest investigation of the diffractive resolution limit of 2003. traveltime tomography. I derived an explicit formula relating Baig, A. M. & Dahlen, F. A., Statistics of traveltimes and amplitudes of waves in random 3-D media, Geophys. J. Int., in press, a recovered 3-D seismic slowness image to the actual seismic 2003. slowness under the assumption that a tomographically Zhou, Y., Dahlen, F. A. & Nolet, G., 3-D sensitivity kernels for complete collection of finite-frequency traveltime shifts is surface-wave observables, Geophys. J. Int., in press, 2003. inverted using linearized ray theory. The tomographically Baig, A. M. & Dahlen, F. A., Traveltime biases in random media and recovered image is blunted, or diminished in amplitude, and the S-wave discrepancy, Geophys. J. Int., submitted, 2003.

Thomas S. Duffy materials composing the region. We are using the diamond Associate Professor anvil cell together with laser-heating techniques to produce Ph.D., 1992, California Institute pressures and temperature comparable to the deep mantle. of Technology Using these tools, we are exploring crystal structures, phase email: [email protected] relations, 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. Brillouin scattering is a method whereby one can measure the complete elastic tensor My research program focuses on understanding the large- by recording the frequency shift induced in scattered laser scale behavior of Earth and other planets through experi- light by thermally generated sound waves. We have recently mental study of geological materials directly under extreme used this technique to investigate the elastic properties of a pressure and temperature conditions. The study of planetary suite of natural garnets including andradite, almandine and interiors is currently progressing rapidly as a result of grossular to pressures corresponding to 300-400 km depth. observational advances including new three-dimensional The results provide new constraints on compositional images of the deep Earth. These new observations have the dependence of elasticity in this chemically diverse system. potential to answer fundamental questions about the Earth’s Our study of the elastic properties of fayalite to 12 GPa origin, evolution, and structure. Progress in this area is place strong new constraints on the effect of iron content on dependent on coupling the new observations with a detailed olivine elasticity at pressures of the upper mantle. The results knowledge of the physical and chemical properties of the have direct application to interpretation of seismic tomogra-

6 phy. We’ve also recently examined calcium oxide elasticity Speziale, S., F. Jiang, C. L. Caylor, S. Kriminski, C.-S. Zha, R. E. using both Brillouin scattering and lattice strain anisotropy Thorne, and T. S. Duffy, Sound velocity and elasticity of measurements. Finally, we have carried out the first measure- tetragonal lysozyme crystals by Brillouin spectroscopy, Biophysical Journal, 85, 3202-3213, 2003. ment of single-crystal elasticity of a protein crystal Kavner, A., and T. S. Duffy, Elasticity and rheology of platinum (lysozyme) using this method. under high pressure and non-hydrostatic stress, Physical Review B, 68, 144101, 2003. Crystal structures at ultrahigh pressures Yin, H., K. D. Hobart, F. J. Kub, S. R. Shieh, T. S. Duffy, and J. C. Sturm, Strain partition of Si/SiGe and SiO /SiGe on compliant Silica, SiO2, is a fundamental compound in the geosciences 2 substrates, Applied Physics Letters, 82, 3853-3855, 2003. and materials science. The crystal structure of SiO2 at ultra- high pressures (P>70 GPa or approx. 1700 km depth) has Shim, S.-H., R. Jeanloz, and T. S. Duffy, Tetragonal structure of CaSiO3 perovskite above 20 GPa, Geophysical Research been controversial as theoretical studies predict a number of Letters, 10.1029/2002GL016148, 2002. energetically competitive high-pressure phases. We have Shieh, S. R., T. S. Duffy, and B. Li, Strength and Elasticity of SiO2 conducted in situ laser-heated diamond cell experiments across the stishovite - CaCl-type structural phase boundary, using synchrotron x-ray diffraction under quasi-hydrostatic Physical Review Letters, 89, 25507, 2002. Shieh, S. R., and T. S. Duffy, Raman spectroscopy of Co(OH) to conditions to determine the high-pressure phase of SiO2 at 2 temperatures up to 2500 K and pressures up to 130 GPa. 30 GPa: Implications for amorphization and structural frustration, Physical Review B, 66, 134301, 2002. These are challenging experiments due to the extreme Shim, S.-H., T. S. Duffy, and K. Takemura, Equation of state of gold pressure-temperature conditions involved. We have focused and its application to phase boundaries near 660-km depth in on improving the sample environment as well as testing the Earth’s mantle, Earth and Planetary Science Letters, 203, 729- effects of different starting materials. Results to date indicate 739, 2002. Speziale, S., and T. S. Duffy, Single-crystal elastic constants of that the CaCl2 form of SiO2 is stable all the way to depth fluorite (CaF ) to 9.3 GPa, Physics and Chemistry of Minerals, conditions corresponding to the Earth’s core-mantle bound- 2 ary. We are also carrying out finite element simulations of 29, 465-472, 2002. Yin, H., R. Huang, K. D. Hobart, Z. Suo, T. S. Kuan, C. K. Inoki, S. the thermal structure of the laser-heated diamond cell. R. Shieh, T. S. Duffy, F. J. Kub, and J. C. Sturm, Strain Through these simulations we hope to develop a better relaxation of SiGe islands on compliant oxide, Journal of understanding of heat flow in our laser-heating experiments, Applied Physics, 92, 9716-9722, 2002. and to use this tool to develop improved experimental Bo, X.-Z., N. Yao, S. R. Shieh, T. S. Duffy, S. Wagner, and J. C. techniques. Sturm, Large-grain polycrystalline silicon films with low intragranular defect density by low-temperature solid-phase Strength of mantle silicates crystallization without underlying oxide, J. Appl. Phys., 91, In the radial x-ray diffraction technique, a sample is com- 2910-2915, 2002. pressed under intentionally non-hydrostatic conditions and Shim, S.-H. and T. S. Duffy, Raman spectroscopy of Fe2O3 to 62 the lattice strain is measured as a function of angle from the GPa, American Mineralogist, 87, 318-326, 2002. loading axis using synchrotron x-rays. Such studies can yield Sean R. Shieh, Thomas S. Duffy and Baosheng Li, Superhard Materials Under Pressure: Strength and Elasticity of constraints on elastic moduli, strength, equations of state, Stishovite, National Synchrotron Light Source Science texture development, and other fundamental properties Highlights, July, 23, 2002, http://nslsweb.nsls.bnl.gov/nsls/ without the severe sample limitations of other techniques. sci&tech/science/2003/07-Shieh.htm. We have used this method recently to study the behavior of Shim, S.-H., T. S. Duffy, R. Jeanloz, C.-S. Yoo, and V. Iota, Raman spectroscopy and x-ray diffraction of phase transitions in Cr O CaSiO3 perovskite, cubic silicon nitride (a superhard solid), 2 3 and a hydrous magnesian silicate (phase D). In future work to 61 GPa, Physical Review B, submitted, 2003. we hope to extend these studies to simultaneous high Jiang, F., S. Speziale, S. R. Shieh, and T. S. Duffy, Single-crystal elasticity of andradite garnet to 11 GPa, Journal of Physics pressures and temperatures and to obtain a more complete Condensed Matter, submitted, 2003. description of the rheology under these conditions. Shieh, S. R., T. S. Duffy, and G. Shen, Elasticity and strength of Two-Year Bibliography calcium silicate perovskite at lower mantle pressures, Yin, H. Z., R. Huang, K. D. Hobart, J. Liang, Z. Suo, S. R. Shieh, T. Physics of the Earth and Planetary Interiors, in press, 2003. S. Duffy, F. J. Kub, and J. C. Sturm, Buckling suppresion of SiGe islands on compliant substrates, Journal of Applied Physics, 94, 6875-6882, 2003.

7 Lincoln S. Hollister seismology, geochemistry, structural geology, and petrology. Professor Bhutan Ph.D., 1966, California Institute With my colleague Djordje Grujic at Dalhausie University, of Technology we have defined a process in mountain building, based on email: [email protected] our studies in Bhutan. This process involves the rapid extrusion of a low viscosity, partially melted orogenic channel from lower crustal depths. It was published in 2002. 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 poten- tial. 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 How are mountains and continental crust made? These are with geologic features exposed at the surface. the major questions driving my research and teaching. I interpret the pressure-temperature-time-strain history of Lamellar magnetism rocks in the context of the tectonic processes operating on With Robert Hargraves, I worked on using properties of the continental crust. My contributions are based on direct lamellar magnetism for interpreting discordant paleomag- observation of the products of mountain building. I have netic inclinations of plutons in western British Columbia. forged collaborations with people in other disciplines and We managed to get a paper submitted prior to Robert’s work in an interdisciplinary mode where the objective is to death in March. Co- workers include Tom James of the achieve results unattainable by individual investigators. I also Geological Survey of Canada and Paul Renne of the Berkeley continue to work on ways to help students use the power of Geochronology Center. This paper is now in press; it making observations in the field. proposes a solution to understanding enigmatic paleomag- Currently, my research is on three fronts: the origin of netic data pertaining to the on-going Baja British Columbia the Coast Mountains of British Columbia, the origin of the controversy. Himalayas in Bhutan, and the application of lamellar Two-Year Bibliography magnetism for resolving the Baja British Columbia contro- Grujic, D., L.S. Hollister, and R.R. Parrish, Himalayan metamorphic versy. sequence as an orogenic channel: insight from Bhutan. Earth and Planetary Science Letters, 198, 171-191. Batholiths Morozov, I.B., N. L. Christensen, S. B. Smithson, and L. S. My biggest research commitment for the next five years is a Hollister, 2003, Seismic and laboratory constraints on crustal new multidisciplinary collaboration which proposes to formation in a former continental arc (ACCRETE, southeastern resolve the continental crust composition paradox: although Alaska and western British Columbia). Journal Geophysical Research continental crust begins as accreted island arcs the average , 108(B1), 2, doi:10.1029/2001JB001740. 9pp. Andronicos, C. L., D. H. Chardon, L. S. Hollister, G. E. Gehrels, composition of continental crusts is more silicic than that of and G. J. Woodsworth, 2003, Strain partitioning in an obliquely island arcs. Before becoming stable continental crust, the convergent orogen, plutonism, and synorogenic collapse: The original island arc composition is modified by processes that Coast Mountains batholith, British Columbia, Canada. are not understood. This is a fundamental problem in the Tectonics, 22(2), 1012, doi:10.1029/2001TC00312, 24pp. earth sciences. Daniel, C. G., L. S. Hollister, R. R. Parrish, and D. Grujic, 2003, The new project is located in the Coast Mountains of Extrusion of the Main Central Thrust zone from lower crustal depths, eastern Bhutan Himalaya. Journal Metamorphic British Columbia. It is called BATHOLITHS. The name Geology, v. 21, 317-334. comes from the hypothesis that the formation of batholiths Hollister, L.S., R.B. Hargraves, T.S. James, P.R.Renne, in press, is a major factor in making typical continental crust. Our The paleomagnetic effects of reheating the Ecstall pluton, toolbox of techniques includes active and passive source British Columbia. Earth and Planetary Science Letters.

8 Gerta Keller Abramovich, S. and Keller, G., 2002. High stress late Maastrichtian Paleoenvironment in Tunisia: Inference from planktic Professor foraminifera. Paleogeogr., Paleoclimatol., Paleoecol., 178, Ph.D., 1978, Stanford University 145-164, 2002. email: [email protected] Abramovich, S., Keller, G., Adatte, T., Stinnesbeck, W., Hottinger, L., Stueben, D., Berner, Z., Ramanivosoa, B. and A. Randriamanantenasoa,2002. Age and Paleoenvironment of the Maastrichtian-Paleocene of the Mahajanga Basin, Madagascar: a multidisciplinary approach. Marine Micropaleontology, 47, 17-70, 2002. Stueben, D., Kramar, U., Berner, Z., Leosson, M., Keller, G., Adatte, T., and W. Stinnesbeck, 2002. High resolution carbon and oxygen isotope profiles of foraminifera and the Ca- normaized Sr curve of the late Maastrichtian at Elles, Tunisia. Paleogeogr., Paleoclimatol., Paleoecol., 178, 321-345, 2002. Adatte, T., Keller, G., Stinnesbeck, W., 2002. Late Cretaceous to During the past year the 10-year-long research project on the early Paleocene climate and sea-level fluctuations. Cretaceous-Tertiary boundary impact and mass extinction Paleogeogr., Paleoclimatol., Paleoecol., 178, 165-198, 2002. has culminated in spectacular success with the coming Keller, G. and Stinnesbeck, W., 2002. Slumping and a sandbar deposit at the Cretaceous-Tertiary boundary in the El Tecolote together of empirical evidence from sedimentology, stratigra- section (northeastern Mexico): An impact-induced sediment phy, paleontology, mineralogy, geochemistry and paleomag- gravity flow – Comment. Geology, 30, 382-383, 2002. netic stratigraphy. The environmental history revealed by all Wolfgang Stinnesbeck, Gerta Keller, Peter Schulte, Doris Stueben, of these disciplines is that the current impact mass extinction Zsolt Berner, Utz Kramar, José Guadalupe Lopez-Oliva, 2002. scenario can no longer be supported. The evidence indicates The Cretaceous-Tertiary (K/T) Boundary transition at that Chicxulub predates the KT boundary and that there Coxquihui, state of Veracruz, Mexico: evidence for an early Danian impact event? Am. J. S. Amer. Res. 15, 497-509, were multiple impact events that together with major 2002. volcanism caused a longterm crisis beginning in the late Keller, G., Guembelitria dominated late Maastrichtian planktic Maastrichtian and lasting well into the early Tertiary. foraminiferal assemblages mimic early Danian in the Eastern This new theory and its supporting evidence has been Desert of Egypt. Marine Micropaleontology, 47(l-2), 71-99, carried by news outlets in many countries and international 2002. magazines including Nature and The Economist, and the Keller, G., Adatte, T., Burns, S.J., and A. Tantawy, Hight stress Geological Society of London has sponsored a debate on my paleoenvironment during the late Maastrichtian to early Paleocene in Central Egypt. Paleogeogr., Paleoclimato., team’s work (Geoscientist, November, 2003). Paleoecol., 187, 35-60, 2002. A 2000-word summary of our results is published in the Abramovich S., and Keller, G., 2003. Planktic foraminiferal Geoscientist and can be downloaded at response to latest Maastrichtian abrupt warm event a case study from midlatitude DSDP Site 525. Marine http://www.geolsoc.org.uktemplate.cfm?name=NSG2349857238495 Micropaleontology 48, 225-249, 2002. Two-Year Bibliography Schulte, P., Stinnesbeck, W., Stueben, D., Kramar, U., Berner, Z., Keller, G., Adatte, T., Stinnesbeck, W., Affolter, M. Schilli, L. and Keller, G., andAdatte, T., 2003. Fe-rich an K-rich mafic Lopez-Oliva, J.G., 2002. Multiple Spherule Layers in the late spherules from slumped and channelized Chicxulub ejecta Maastrichtian of northeastern Mexico. GSA Special Vol. 356, deposits in the northern La Sierrita area, NE Mexico.Int. 145-162, 2002. J.Earth Sci. 92, 114-142, 2002. Stueben, D., Kramer, U., Berner, Z., Eckhardt, J.D., Stinnesbeck, Stueben, D., Kramar, U., Berner, Z.A., Meudt, M., Keller, G., W., Keller, G., Adatte, T. and Heide, K. 2002. Two anomalies of Abramovich, S.,Adatte, T., Hambach, U., and Stinnesbeck, W., platinum group elements above the Cretaceous-Tertiary 2003. Late Maastrichtian paleoclimatic and paleoceanographic boundary at Beloc, Haiti: Geochemical context and changes inferred from Sr/Ca ratio and stable isotopes. consequences for the impact scenario: Geological Society of Paleoclimatol. Paleoecol. Paleogeogr., 199, 107-127, 2002. America, Special Volume, 356, 163-188, 2002. Keller, G., Stinnesbeck, W., Adatte, T. and Stueben, D., 2003. Adatte, T. Keller, G., Burns, S., Stoykova, K.H., Ivanov, M.I., Multiple Impacts across the Cretaceous-Tertiary boundary. Vangelov, D., Kramer, U. and Stueben, D., 2002. Earth Science Reviews, 62, 327-363, 2003. Paleoenvironment across the Cretaceous-Tertiary (K-T) Keller, G., Stinnesbeck, W., Adatte, T., Holland, B., Stueben, D., transition at Bjala, eastern Bulgaria. GSA Special Paper 356, Harting, M., C. de Leon and J. de la Cruz, 2003. Spherule 231-252, 2002. deposits in Cretaceous-Tertiary boundary sediments in Belize Keller, G., Adatte, T., Stinnesbeck, W., Luciani, V., Karoui, N., and Guatemala. J. Geol. London, 160, 1-13, 2003. Zaghbib-Turki, D., 2002. Paleoecology of the Cretaceous- Keller G. 2003. Biotic effects of impacts and volcanism. Earth and Tertiary mass extinction in planktic foraminifera. Paleogeogr., Planetary Science Letters 215, 249-264, 2003. Paleoclimatol., Paleoecol., 178, 257-298, 2002. Gerta Keller, Thierry Adatte and Wolfgang Stinnesbeck, 2003. The Karoui-Yaakoub, N., Zaghbib-Turki, D. and Keller, G., 2002. The non-smoking gun, Geoscientist 13 (11), 8-11, 2003. Cretaceous-Tertiary (K-T) mass extinction in planktic Abramovich, S., Keller, G., Stueben, D. and Berner, Z., 2003. foraminifera at Elles I and El Melah, Tunisia. Paleogeogr., Characterization of late Campanian and Maastrichtian planktic Paleoclimatol., Paleoecol., 178, 233-256, 2002. foraminiferal depth habitats and vital activities based on stable isotopes. Paleoclimatol. Paleoecol. Paleogeogr, 2003.

9 Keller, G., 2004. Paleoecology of Late Maastrichtian-early Danian Late Maastrichtian and K/T paleoenvironment of the eastern planktic foraminifera in the eastern Tethys (Israel and Egypt). Tethys (Israel): mineralogy, trace element and platinum group J. Foram. Res., 2004. elements, biostratigraphy and faunal turnovers, in press. Keller, G. and Pardo, A., 2004. Paleoecology of the Cenomanian- Tantawy, A.A.A. and Keller, G., in press. Biotic effects of volcanism Turonian Stratotype Section (GSSP) at Pueblo, Colorado. on calcareous nannofossils and planktic foraminifera: Marine Micropleontology, 2004. Ninetyeast Ridge, Indian Ocean. Egyptian Journal of Geology, Keller, G., Stueben, D., Berner, Z. and Adatte, T., in press. in press. Cenomanian-Turonian δ13C, δ18O, sea-level and salinity Keller, G., in press. Biotic effects of late Maastrichtian mantle plume variations at Pueblo, Colorado. Paleoclimatol. Paleoecol. volcanism: implications for impacts and mass extinctions. Paleogeogr., in press. Lithos, in press. Adatte, T. Keller, G., Stueben, D., Harting, M., Kramar, U., Stinnesbeck, W., Abramovich, S. and Benjamini, C., in prep.

François M. M. nutrients in the sea. We have obtained mounting evidence from laboratory and field work that cadmium is an impor- Morel tant micronutrient for marine phytoplankton. From our Blanke Professor of Geosciences previous work, we know that Cd promotes the growth of Director, Princeton Environmental diatoms under low zinc conditions as the result of the Institute synthesis of a Cd-carbonic anhydrase. Cadmium thus Director, Center in Environmental BioInorganic Chemistry catalyses the acquisition of inorganic carbon for photosyn- Ph.D., 1971, California Institute of thesis. Having now obtained the full DNA sequence for this Technology enzyme (the first Cd enzyme discovered) and over-expressed email: [email protected] it in a bacterial host, we are in the process of characterizing it in collaboration with protein chemists at Pen. Our next goal is to elucidate the biochemical/physiological role of Cd in coccolithophores which we have found to accumulate unusually high concentrations of this metal. The biochemi- Marine phytoplankton are responsible for about half of the cal utilization of cadmium by diatoms and coccolithophores global primary production and for a major fraction of reverse is, we believe, the key to the ocean biogeochemistry of Cd weathering on the Earth. Some of the carbon dioxide they and also, perhaps, to the ecology of these dominant phy- toplankton taxa. fix is exported to the deep sea; some of the SiO2 precipitated In collaboration with John Reinfelder (at Rutgers by diatoms and of the CaCO3 precipitated by coccolithophores is accumulated in sediments and eventually University) we have continued our work on the mechanism subjected to diagenesis. What physical and chemical factors of inorganic carbon uptake and fixation in diatoms. By control the growth and activity of phytoplankton is the following the rates of CO2 uptake and O2 evolution in the overarching question addressed in my research group. Our presence of various inhibitors, we have obtained convincing focus is on trace metals, some of which are essential for data supporting our earlier (and controversial) report of phytoplankton growth (e.g., Fe), some are toxic (e.g., Hg), unicellular C4 photosynthesis —a pathway that involves some are both (e.g., Cd). accumulation of carbon as a C4 compound prior to fixa- An outstanding question of oceanography is why tion— in these organisms. This project, in concert with our phytoplankton precipitate hard parts: what physiological and work on Cd-carbonic anhydrase and on the physiological ecological benefits diatoms obtain from their silica frustule? role of the silica frustule indicate that a particularly effective and coccolithophores from their calcite liths? We’ve been carbon acquisition system may be in part responsible for the working on the hypothesis that the hard parts of phy- ecological success of diatoms in the oceans. toplankton are important in key extracellular enzymatic After a hiatus of several years (during which iron became processes. We have shown that the silica frustule of diatoms the fashionable element in oceanography), we have reacti- is an excellent buffer for hydrogen ion that enables the rapid vated our research on the iron physiology of marine phy- - toplankton. Our present foci are the mechanism of uptake of conversion of HCO3 to CO2 through the activity of an extracellular carbonic anhydrase enzyme, a key step in the iron complexed in organic chelates or precipitated as colloi- acquisition of inorganic carbon by diatoms. We have now dal oxides (the major form of iron in the oceans), and obtained evidence that the calcium carbonate liths of intracellular Fe storage. 1) Fe uptake. We have known for coccolithophores likewise enhance the activity of extracellu- some time that diatoms are able to reduce Fe(III) and release lar alkaline phosphatase –an enzyme that liberates ortho- Fe(II) from compounds, but the mechanism has remained phosphate from organic compounds. unclear. Our new data support the hypothesis that this - The biogeochemistry of cadmium continues to be a reduction is mediated by the release of superoxide (O2 ) by research focus in our group. Because of its excellent correla- the organisms. This finding explains a number of observa- tion with phosphate, cadmium is used as a paleotracer of tions about the remarkable range of metal complexes that

10 - effects on taxonomic composition and nutrient utilization in an can be reduced by diatoms. (In addition, the release of O2 may serve an effective bactericidal function.) 2) Fe storage. Equatorial Pacific phytoplankton assemblage. MEPS, 236: 37- We have identified in the recently published genome of the 43, 2002. Tortell, P.D. and F.M.M. Morel. Sources of inorganic carbon for marine cyanobacterium Trichodesmium two sequences with phytoplankton in the Eastern Subtropical and Equatorial high homology to genes known to code for ferritin, the Pacific Ocean. Limnol. Oceanogr., 47: 1012-1022, 2002. major iron storage protein in living organisms. This is the Morel, F.M.M., E.H. Cox, A.M.L. Kraepiel, T.W. Lane, A.J. Milligan, first evidence of ferritin in marine microorganisms and we I. Schaperdoth, J.R. Reinfelder and P.D. Tortell. Acquisition of are in the process of isolating and characterizing this protein inorganic carbon by the marine diatom Thalassiosira to study its role in the ecology of Trichodesmium, the organ- weissflogii. Functional Plant Biology, 29: 2,3 p. 301-308, 2002. ism thought to be responsible for the bulk of N fixation in Morel, F.M.M., A.J. Milligan and M.A. Saito. “Marine Bioinorganic 2 Chemistry: The Role of Trace of Metals in the Oceanic Cycles the ocean. of Major Nutrients” in Treatise on Geochemistry edited by KK. Our continuing work on the biogeochemistry of mer- Turekian, H.D. Holland, Elsevier Science Ltd, Cambridge, UK, cury is presently focused on mercury methylation. Since 2003. methyl mercury is the species accumulated in fish via the Ekstrom, E.B., F.M.M. Morel, J.M. Benoit. Mercury Methylation food chain, this is a key transformation, but it has received Independent of Acetyl-CoA Pathway in SRB. Appl. and surprisingly little attention over the past 20 years. The two Environ. Microbiol 69 (9) 5414 – 5422, 2003. Quigg, A., Z.V. Finkel, A.J. Irwin, Y. Rosenthal, T.-Y.Ho, J.R. questions we are trying to answer are: 1) where is methyla- Reinfelder, O. Schofield, F.M.M. Morel, P.G. Falkowski, The tion occurring in the ocean and by what mechanism? and 2) evolutionary inheritance of elemental stoichiometry in marine what controls the rate of methylation by sulfate reducing phytoplankton. Nature 425: 291-294, 2003. bacteria in freshwater systems? New data on the concentra- Ho, T.-Y., A. Quigg, Z.V. Finkel, A.J. Milligan, K. Wyman, P.G. tion of mercury in tuna caught off Hawaii show that this Falkowski, F.M.M. Morel. The Elemental Composition of Some concentration has not changed in thirty years. Mercury in Marine Phytoplankton. J. Phycol. 39, 1-15, 2003. tuna thus does not respond to the increase in mercury in the Saito, M. A., D.M. Sigman and F.M.M. Morel. The Bioinorganic Chemistry of the Ancient Ocean: The Co-Evolution of atmosphere and in the surface of the oceans caused by Cyanobacterial Metal Requirements and Biogeochemical anthropogenic inputs. We thus propose that methyl mercury Cycles at the Archean-Proterozoic Boundary. Inorganica in the open ocean may originate from the deep sea, perhaps Chimica Acta 356C, 312-322, 2003. from hydrothermal vents. Our biochemical work with Morel, F.M.M. and N.M. Price, The Biogeochemical Cycles of Trace sulfate reducing bacteria has shown that, contrary to what is Metals in the Oceans. Science, 300: 944-947, 2003. commonly believed, the acetylCoA pathway is not necessary Kraepiel, A.M.L., K. Keller, H.B. Chin, E.G. Malcolm, F.M.M. Morel, Sources and Variations of Mercury in Tuna Environ. Sci. for Hg methylation in these organisms. We are now trying to Technol., in press. elucidate what enzymes are actually involved in methylation Milligan, A. J. and F.M.M. Morel. Dynamics of silicon metabolism and what control their activity in these organisms. and silicon isotopic discrimination in a marine diatom as a function of pCO Limnol. Oceanogr., in press . Two-Year Bibliography 2 Lalonde, J.D. , M. Amyot, J. Orvoine, F.M.M. Morel, J-C. Auclair Milligan, A.J. and F.M.M. Morel. A proton buffering role for silica in and P.A. Ariya, Photo induced oxidation of Hg0 in the waters diatoms. Science, 297: 1848-1850, 2002. (aq) from the St. Lawrence estuary. Environ. Sci. Technol., in press. Tortell, P.D., G.R. DiTullio, D.M. Sigman, and F.M.M. Morel. CO2

Satish Myneni between various components of the Earth’s surface environ- Assistant Professor ment, which includes mineral oxides, biota and their Ph.D., 1995, Ohio State byproducts, and the atmosphere. One of the challenging University aspects in environmental sciences is to gain a better under- email: [email protected] standing of interactions between these different compart- ments in nature, and to use this to predict a variety of biogeochemical processes such as elemental cycling, biologi- cal chemistry of elements, and the fate and transport of contaminants in the environment. The focus of my research is on understanding the: • Coordination chemistry of geochemical species of interest, and their energetics in aqueous solutions and at the natural interfaces, and • Chemistry of natural organic molecules and their role in Water is essential for the origin and survival of life on our biogeochemical processes and elemental cycles planet and perhaps plays a pivotal role on the existence of life on other planetary bodies as well. In several different Geochemistry of aqueous systems forms, water mediates the physical and chemical interactions The goals of this research project are to evaluate H-bonding 11 environment in liquid water, and how this modifies ion phases in acid systems. Our studies (a combination of solvation and complex formation in aqueous solutions and at infrared, Raman and X-ray spectroscopy) on these systems natural interfaces. I began collaborations with researchers at provided unequivocal evidence for the occurrence of H- the Stockholm University (Anders Nilsson and Lars bonding complexes with Fe(III)oxyhydroxide polymers. Pettersson) several years ago, and I have been trying to These results will be submitted for a publication in the next establish a similar collaboration with the theoreticians (Dr. couple of weeks. Future investigations will focus on the Roberto Car) at Princeton University. Our initial efforts at speciation of Fe(III) and Al(III) polymers in aqueous Princeton University took a setback because of the immigra- solutions, and their influence on Al-, and Fe-bioavailability. tion issues of a post-doctoral associate who we wanted to Chemistry of natural organic molecules hire to conduct these investigations. However, Car’s group is Organic molecules are found everywhere on the surface of making significant progress on theoretical calculations on the Earth, and their composition, molecular structure and the H-bonding networks in liquid water as a function of pH, concentration modifies the biogeochemical processes in the and these calculations are critical to interpret our experimen- environment. One of the bottlenecks in our understanding tal spectra completely. We hope to take graduate students of the elemental cycles is related to the speciation of C, N, this coming year to continue these theoretical investigations. and S associated with the organic molecules, and their Results from some of our previous collaborations have been variation in the environment. For the past several years, my published in the past few months, and these are on the: research group has been using and developing X-ray spec- • H-bonding interactions in liquid water (J. Phys. 2002), troscopy and spectromicroscopy methods for studying the chemistry of natural organic molecules in their pristine state and (Rev. Mineral., 2002). Using these methods I am investigat- • Chemical state of ion-solvated water (J. Phys. Chem. ing the: 2003) • Functional group chemistry and macromolecular structure My studies on water will continue and the future of natural organic molecules in soils and sediments, emphasis will be on the nature of water at the mineral-water • Role of minerals in the retention and fractionation of interfaces as a function of water-film thickness and pH, and organic molecules in the environment, the nature of surface hydroxyls. Design of synchrotron • Chemistry of natural organohalogens in the environment: endstation to conduct these investigations is completed, and coordination chemistry, rates of formation in the environ- the fabrication and the first set of experiments will be ment and their role in various biogeochemical reactions, conducted during April (2004). Michael Hay and Laura and Harrington, graduate students in my group, will focus on • Interfacial reactions on microorganism surfaces. these studies. Using these new tools, we hope to understand With my group members, I made a significant progress in how water solvates functional groups of mineral surfaces, several different areas of this research. The highlights are as and how surface hydration changes with variations in the follows. composition of water films. There are major developments in my investigation of the Chemistry of natural organohalogens. Several researchers have inner-sphere (IS, direct interactions of ions) and outer- shown that simple organochlorine compounds, which are sphere (OS, bonding of ions through intermediate solvated toxic and have deleterious effects on atmospheric chemical water molecules) complexation of ions in aqueous solutions reactions, are formed from the biogeochemical reactions in and at interfaces. It is not clear why certain ions form OS the environment. My recent studies provided unequivocal complexes and certain others form IS complexes until now. evidence for their occurrence in soils and sediments (Science, What chemical variables modify these interactions? My 2002). With the help of seniors, graduate students and post- studies (X-ray and infrared) indicate that protonation of ions doctoral scholars, I am expanding this study into several (in the case of anions, for example) alters their complexation different directions. These are: characteristics and coordination environments. According to • Using haloperoxidase enzymes common to all soils and my investigation, anions tend to exhibit significant “H- sediments, we have successfully halogenated plant materi- bonding” interactions above the pH at which anions are als. The products of these reactions are similar to those present in unprotonated forms. However, the concentration found in naturally weathered plant material, which of IS complexes increases significantly once the anions are implicates their role in extensive organohalogenation in protonated. Polymerization of anions also follows the same the nature (Rachel Reina, M. E Thesis; Environ. Sci. behavior. These results explain the observed variations in the Technol, 2003). sorption and redox kinetics of anions as a function of pH • A majority of chlorinated organic molecules in weathering and sample drying. My post-doctoral scholar (Dr. Juraj plant material are associated with the most soluble Majzlan) and I have applied these results to understand polyphenol fraction, but not in stable lignins, as thought sulfate speciation in acidic soils and waters. Existing thermo- by several previous investigators. Current focus is on the dynamic models fail to explain speciation of sulfate (the size fractionation of these molecules, and the coordination most common anion in these systems) in aqueous and solid

12 environment of halogens in them, which will ultimately organic molecules in modern aerosols (in collaboration with help in the evaluation of their toxicity and role in elemen- Dr. Lynn Russell, Scripps; Geophys. Res. Let. 2002). This tal cycles (Dr. Ashish Deshmukh, a post-doctoral scholar molecular information is useful to predict the light scattering in my group is conducting this investigation). and water absorption characteristics of aerosols. I am also • We extended these molecular investigations to explore extending these investigations to evaluate the organic organobromines in the environment. Studies of my group molecule composition and mineralogical variation of indicate a very high concentration of organobromines at aerosols trapped in ice cores (in collaboration with Dr. the sediment-water interface in shallow and deep marine Lonnie Thompson, Ohio State University). We hope to sediments (Jacqueline Hakala, senior thesis in Geosciences; obtain information on natural organohalogens associated Alessandra Leri, Graduate Student). Ms. Leri will continue with these ancient aerosols and their impact on the ozone these investigations and try to find out the abiotic and depletion. biotic pathways involved in the halogenation of organic In summary, my research group is developing into a molecules, and differences in their reaction rates and diverse and interdisciplinary research group to address the products. fundamental biogeochemical processes in the environment. A field station is built in Pine Barrens (NJ) to identify the Two-Year Bibliography processes involved in the formation of organohalogens, and Myneni SCB, Soft X-ray spectroscopy and spectromicroscopy their rates. We are also monitoring the speciation of C, N, studies of organic molecules in the environment. In Rev. and S in organic molecules to evaluate the association of Mineral. Geochem. Applications of Synchrotron Radiation in Low-Temperature Geochemistry and Environmental Science, these elemental cycles with Cl-cycle. Ed P. Fenter, M. Rivers, N. Sturchio, S. Sutton, V 49: 485-579, Functional group chemistry of natural organic molecules. 2002. To understand the chemistry of complex natural organic Russell LM, SF Maria, SCB Myneni, Mapping organic coatings on atmospheric particles. Geophys. Res. Let. 29: 10.1029/ molecules, we are investigating the functional group chemis- 2002GL014874, 2002. try of small chain model organic ligands and their metal Myneni SCB, Formation of stable chlorinated hydrocarbons in complexes in aqueous solutions and at the mineral-water weathering plant material. Science, 295, 1039-1041. (Science interfaces. Graduate students, David Edwards and Wei Jiang, Express, published online 17 January 2002; 10.1126/ are examining the chemistry of selected biomacromolecules; science.1067153), 2002. and Timothy Strathmann, a former post-doctoral scholar in Myneni SCB, Y. Luo, LA Naslund, L Ojamae, H. Ogasawara, A. my group, is investigating the metal complexation behavior Pelmenshikov, P. Vaterlain, C. Heske, LGM. Pettersson, A. Nilsson, Spectroscopic evidence for unique hydrogen bonding of various carboxylic acids using infrared and X-ray spectros- structures in water. J. Phys.: Condens. Matter, 14, L213-L219, copy methods. Some of these results are submitted for a 2002. publication. Using this information, we are investigating the Naslund LA, M. Cavalleri, H. Ogasawara, A. Nilsson, LGM. chemistry of natural organic molecules and organo-mineral Pettersson, P. Wernet, DC. Edwards, M. Sandstrom, SCB. interactions in soils and sediments. A summary of these Myneni, Direct evidence of orbital mixing between solvated studies are as follows: transition-metal ions: An Oxygen 1s XAS and DFT study of aqueous systems. J. Phys. Chem A, 107: 6869-6876 (Cover • Complete speciation of C, N, P, S, Cl, and Br page article), 2003. functionalities of resistant fractions of natural organic Reina R., A. Leri, SCB. Myneni, Cl K-edge X-ray spectroscopic molecules in soils and fluvial systems. investigation of enzymatic formation of organochlorines in • Carboxylic groups, which are the dominant reactive weathering plant material. Env. Sci. Technol. 10.1021/ es0347336, 2003. groups, occur as simple aliphatic monocarboxylic acids, as Strathmann T., SCB. Myneni, Speciation and complexation in opposed to the assumed aromatic carboxylic acids (such as aqueous Ni(II) Carboxylate and Ni(II)-Fulvic Acid Solutions: salicylic acid) in fluvial and soil humic substances. Combined ATR-FTIR and XAFS Analysis. Geochim. • The soluble and insoluble organic carbon in terrestrial Cosmochim. Acta, in review. systems is primarily derived from plants, as opposed to the Majzlan J., SCB. Myneni, Speciation of sulfate in acid waters and recently emerging idea that organic molecules from its influence on mineral precipitation. Nature, in review. Li W., C. Rivero, SCB. Myneni, A. Schulte, KA. Richardson, S. bacterial biofilms play a major role in the biogeochemical Seal, Structural properties of glass system As-S-Se studied by reactions in soils. Raman, XPS and EXAFS. J. Non Crystalline Solids., in review. • Organic molecules fractionate in soils, and our preliminary Myneni SCB, Chemistry of natural organic molecules on mineral data suggest that this chemical fractionation is universal surfaces. In Environmental Catalysis, Ed: V. Grassian. Marcel irrespective of mineralogy and climate. Dekker Pub, to be published in 2004. Myneni SCB, GA. Waychunas, SJ. Traina, GE. Brown Jr., Some of these results will be submitted for a publication Predicting oxoanion complexation in aqueous solutions and at in the next few months. In the next year, my field investiga- mineral-water interfaces. To be submitted to Science shortly. tions will focus on the biogeochemical cycling of organic White SJO, MJ. Hay, SCB. Myneni, Consequence of elevated soil- CO on plant growth: A constraint for geological sequestration forms of C, N, and S in soils of Pine Barrens in New Jersey 2 of CO . To be submitted to Nature shortly. Using the X-ray spectral signatures of organic molecules 2 in soils and sediments, I am investigating the chemistry of

13 Guust Nolet Two-Year Bibliography Hung, S.-H., F.A. Dahlen and G. Nolet, Wavefront healing: a George J. Magee Professor of banana-doughnut perspective, Geophys. J. Int. 146, 289-312, Geophysics and Geological 2001 (this paper was accidentally omitted in earlier annual Engineering reviews). Ph.D., 1976, University of Allen, R.M., G. Nolet., W.J. Morgan, K. Vogfjord, M. Nettles, G. Utrecht (The Netherlands) Ekstrom, B.H. Bergsson, P. Erlendsson, G.R. Foulger, S. email: [email protected] Jakobsdottir, B.R. Julian, M. Pritchard, S. Ragnarsson, R. Stefansson, Plume driven plumbing and crustal formation on Iceland, J. Geophys. Res., 107, 10.029/2001JB000584, 2002. Du, Z., Foulger, G.R., Julian, B.R., Allen, R.M., Nolet, G., Morgan, J.W., Bergsson, B.H., Erlendsson, P., Jakobsdottir, S., Ragnarsson, S., Stefansson,R. & Vogfjord, K., Crustal structure beneath western and eastern Iceland from surface waves and receiver functions, Geophys. J. Int.,149, 349-363, 2002. We (i.e. Raffaella Montelli, Tony Dahlen and myself) made Lebedev, S. and G. Nolet, Upper mantle beneath Southeast Asia the first images ever of the plumes hypothesized by Jason from S velocity tomography, J. Geophys. Res., 108, 10.1029/ 2000JB000073, 2003. Morgan more than 30 years ago: Margerin, L. and G. Nolet, Multiple scattering of high-frequency seismic waves in the deep Earth: Modeling and numerical examples J. Geophys. Res., 108, 10.1029/2002JB001974, 2003. Tibuleac, I., G. Nolet, C. Michaelsson and I. Koulakov, P wave amplitudes in a 3D Earth, Geophys. J. Int., 155, 1-10, 2003. Articles in press or submitted: Zhou, Y., G. Nolet and F.A. Dahlen, Surface sediment effects on teleseismic P waves, J.Geophys.Res., 108, DOI 10.1029/ 2002JB002331, 2003. Margerin and G. Nolet, Multiple scattering of high frequency seismic waves in the deep Earth -II: PKP precursors analysis and inversion for mantle granularity, J. Geophys. Res, 108, 10.029/ 2003JB002455, 2003. Zhou, Y., F.A. Dahlen and G. Nolet, 3-D sensitivity kernels for surface wave observables, subm. to Geophys. J. Int., 2003. Montelli, R., G. Nolet, G. Masters, F.A. Dahlen and S.H.-Hung, P Recent work with Ludovic Margerin on multiple scattering and PP global traveltime tomography: Rays versus waves, has resulted in a new estimate of the size and strength of subm. to Geophys. J. Int., 2003. Montelli, R., G. Nolet, F.A. Dahlen, G. Masters, E.R. Engdahl and small scatteres in the lower mantle. S.H.-Hung, Finite-frequency tomography reveals a variety of With Frederik Simons and Jeff Babcock at Scripps, we plumes in the mantle, Science, in press, 2003. did the first test of the MERMAID diver, designed to record Nolet, G., F.A. Dahlen and R. Montelli, Traveltimes and amplitudes earthquakes while floating autonomously at a depth of 1000 of seismic waves: a re-assessment, subm. to A. Levander and m or more in the oceans. We recovered the instruments and G. Nolet (eds.), Analysis of broadband seismograms, AGU acquired a valuable set of ambient noise data. Monograph Series, 2003. See geoweb.princeton.edu/people/faculty/nolet/research.html for up-to-date information on equally interesting as well as less spectacular results.

14 Tullis C. Onstott coenzyme M (CoM), which is known to be present in all Professor methanogenic bacteria. We will adapt a commercial bore- Ph.D., 1980, Princeton University hole probe designed to measure the pH, Eh, conductivity, email: [email protected] pressure and temperature at depth. We also propose to develop a cassette filtration system for recovering biomass for molecular analyses. This will employ a high pressure circulating pump connected to the fluid sampler and a modified, commercially available, bulk water borehole sampler. As a continuation of our South Africa deep microbiol- ogy project we are proposing to instrument two boreholes that cut across active fault zones. In collaboration with our South African colleagues we will monitor these boreholes for two years during which we anticipate several magnitude 3-4 Deep subsurface microbiology, earthquake and astro- earthquakes. These experiments will provide the first biology observation regarding the role of seismicity in enhancing Over the past decade analyses of rock cores and groundwater nutrient fluxes to subsurface microbial communities as well have identified the presence of a subsurface biosphere that as the role, if any, played by microorganisms in the nucle- mitigates many of the geochemical processes long thought to ation of seismic events. be abiotic. The existence of this biosphere has significant As part of our recently awarded Astrobiology Center, we implications for groundwater quality, remediation of con- will begin field work in mines located in the Canadian Arctic taminated aquifers, degradation of petroleum reservoirs, where permafrost is currently ~500 meters think and overlie

CO2 subsurface sequestration and the search for life beneath brine-bearing Precambrian rocks. Such sites provide an the surface of Mars and other planetary bodies. During the environment more analogous to that of the Martian subsur- course of our South African LExEn project we collected face and provide an interesting contrast to our much warmer ~200 samples of these environments, which are from fluid South African subsurface environments. We will thus be filled fractures within rocks hundreds of meters beneath the able to directly assess the role of temperature on microbial surface. These samples are limited to water emanating from a activity. We also hope that with help from the department borehole. Just how representative these bulk water samples and the university we will be able to initiate an Astrobiology are of the in situ conditions within these fractures is a source program for undergraduates that will attract students to the of speculation and can only be addressed by probing these natural sciences. fractures directly. Two-Year Bibliography Borehole logging has a log history in the petroleum Dong H., T.C. Onstott, M.F. DeFlaun, S.H. Streger, R.K. Rothmel industry as the standard means of characterizing subsurface and B.J. Mailloux, Relative Dominance of Physical vs. structure. More recently, borehole imaging tools, such as Chemical Effects on the Transport of Adhesion Deficient video cameras and radar, and borehole probes for pH, Eh, Bacteria in Intact Cores from South Oyster, Va., Environ. velocity and conductivity are becoming widely used in Science & Tech. 36:891-900, 2002. geophysical and hydrological studies. Voltametric sensors Dong, H., T.C. Onstott, C.H. Ko, M. Elimelech, A.D. Hollingsworth, M.F. DeFlaun, D.G. Brown and B.J. Mailloux, Theoretical have recently become available for measuring trace metals in Prediction of Collision Efficiency Between an Adhesion- ocean water and boreholes. Deficient Bacterium and Aquifer Sediments. Colloids and In the coming year we plan to develop the first borehole Surfaces B: Biointerfaces, 24:229-245, 2002. probe for the detection, sampling and analyses of specific Dong, H., R. Rothmel, T.C. Onstott, M.E. Fuller, M.F. DeFlaun, S.H. enzymes utilized by anaerobic microorganisms. The probe Streger, R. Dunlap, and M. Fletcher,. Simultaneous Transport will employ a multi-wavelength spectrometer and photomul- of Two Bacterial Strains in Intact Cores from Oyster, Virginia: Biological Effects and Numerical Modeling. Applied and tiplier fitted for fluorescent measurements. It will be Environmental Microbiology 68:2120-2132, 2002. designed to function at pressures up to 200 bars and tem- Baker, B.J., D.P. Moser, B.J. MacGregor, S. Fishbain, M. Wagner, peratures up to 60oC. The probe will be designed to collect N.K. Fry, B. Jackson, N. Speolstra, S. Loos, K. Takai, B. fluorescent data on fracture surfaces and from fluid samples. Sherwood-Lollar, J.K. Fredrickson, D.L. Balkwill, T.C. Onstott, The latter will require development of a sampling tool for C.F. Wimpee. and D.A. Stahl, Related Assemblages of extracting fluid samples from these fractures zones and Sulfate-reducing Bacteria Associated with Ultradeep Gold pumping the fluid into fluorescent analysis chamber. We Mines of South Africa and Deep Basalt Aquifers of Washington State, Environmental Microbiology, 5, 267-277, 2003. will utilize a bioluminescent based detection system as this Omar, G., T.C. Onstott and J. Hoek, The Origin of Deep Subsurface affords the greatest sensitivity for what will be low biomass/ Microbial Communities in the Witwatersrand Basin, South low activity samples. Firefly luciferase will be used to assay Africa as Deduced from Apatite Fission Track Analyses, ATP and the bacterial luciferase reaction will be used assay Geofluids, 3, 69-80, 2003. for and NAD(P)H. We will also test the feasibility of using Moser, D.P., T.C. Onstott, J.K. Fredrickson, F.J. Brockman, D.L. a fluorescent assay for quantification of the thiol biomarker Balkwil, G.R. Drake, S. Pfiffner, D.C. White, K. Takai, L.M. Prat, 15 J. Fong, B. Sherwood-Lollar, G. Slater, T.J. Phelps, N. Vainberg, W.P. Johnson, T.C. Onstott,. and M.F. DeFlaun, Field Spoelstra, M. DeFlaun, G. Southam, A.T. Welty, B.J. Baker, J. validation of a vital fluorescent staining method for near-real- Hoek, Temporal shifts in Microbial Community Structure and time concentration monitoring of two bacterial strains at the Geochemistry of an Ultradeep South African Gold Mine South Oyster Focus Area of the NABIR bacterial transport field Borehole, Geomicrobiology Journal, 20, 1-32, 2003. site. Applied and Environmental Microbiology, submitted, 2003. Mailloux, B.J., M.E. Fuller, G.F. Rose, T.C. Onstott, M.F. DeFlaun, Lin, L-H, J.A. Hall, J. Lippmann, J.A. Ward, B. Sherwood-Lollar and

E. Alvarez, C. Hemingway, R.B. Hallet, T.J. Phelps, and T. T.C. Onstott, Radiolytic H2 in the continental crust: Nuclear Griffin, Design of a Modular Injector, Multi-level Sampler, and power for deep subsurface microbial communities, Science, Sampling Manifold for Groundwater Tracer Experiments. submitted, 2003. Groundwater, 41, 816-827. 2003. Balkwill, D. L., T.L. Kieft, T. Tsukuda, H.M. Kostandarithes, T.C. Musslewhite, C.L., M.J. McInerney, H. Dong, T.C. Onstott, M.X. Onstott, S. Macnaughton, J. Bownas, T.J. Bailey, and J.K. Green-Blum, D. Swift, S. Macnaughton, The factors controlling Fredrickson, Thermus multireducens sp. nov., a globally microbial distribution and activity in the shallow subsurface. distributed metal-reducing species associated with thermal Geomicrobiology Journal, 20, 245-261, 2003. ground and spring waters. Extremophiles, in press, 2003. Lippmann, J., M. Stute, T. Torgersen, D.P. Moser, J. Hall, L-H. Lin, Hall, J.A., B.J. Mailloux, T.C. Onstot, T.D. Scheibe, M.E. Fuller, H. M. Borcsik R.E.S. Bellamy and T.C. Onstott, Dating ultra-deep Dong, and M.F. DeFlaun, Physical versus chemical effects on mine waters with noble gases and 36Cl, Witwatersrand Basin, bacterial transport as determined during in situ sediment core South Africa, Geochim. Cosmochim. Acta., 67, 4597-4619, pulse experiments, Jour. Cont. Hydrology, in review, 2003. 2003. Mailloux, B. J., S. Devlin, M.E. Fuller, T.C. Onstott , M.F. DeFlaun, Mormile, M.R., M.A. Biesen, M.C. Gutierrez, A. Ventosa, J.B. K-H. Choi, M. Green, D.J.P. Swift, and J. McCarthy, The Role Pavlovich, T.C. Onstott and J.K. Fredrickson, Isolation of of Aquifer Heterogeneity on Metal Reduction in an Atlantic Halobacterium salinarum Retrieved Directly from Halite Brine Coastal Plain Aquifer. Geochim. Cosmochim. Acta, submitted, Inclusions. Environmental Microbiology, 5, 1094-1102, 2003. 2003. Onstott, T.C., D.P. Moser, J.K. Fredrickson, F.J. Brockman, S.M. Ward, J.A., G.F. Slater, G. Lacrampe-Couloume, L.-H. Lin, J.A. Pfiffner, T.J. Phelps, D.C. White, A. Peacock, D. Balkwill, R. Hall, D.P. Moser, A. Bonin, R.E.S. Bellamy, T.C. Onstott, and Hoover, L.R. Krumholz, M. Borscik, T.L. Kieft. and R.B. Wilson, B. Sherwood Lollar, Microbial Hydrocarbon Gases in the Indigenous versus contaminant microbes in ultradeep mines, Witwatersrand Basin, South Africa: Implications for Deep Env. Microbiol., 5, 1168-1191, 2003. Biosphere, Geochim. Cosmochim. Acta, submitted, 2003. EarthLab-A Subterranean Laboratory and Observatory to Study Sherwood Lollar, B., G. Lacrampe-Couloume, G.F. Slater, J. Ward, Microbial Life, Fluid Flow and Rock Deformation-NSF agency D.P. Moser, L.-H. Lin and T.C. Onstott, Abiogenic gases

report-72 pp. support H2-based autotrophy and methanogenesis in the deep Mailloux, B.J., M.E. Fuller, T.C. Onstott, J. Hall, H. Dong, M.F. subsurface. Nature submitted, 2003. DeFlaun, S.H. Streger, R.K. Rothme, M. Green, D.J.P. Swift. Lin, L-H, G.F. Slater, B. Sherwood Lollar, G. Lacrampe-Couloume, and J. Radke, The role of physical heterogeneity on the field- and T.C. Onsott, Yields and hydrogen isotopic compositions of

scale transport and attachment of bacteria. Water Resources radiolytic H2 and the implications for deep biosphere in Research, in press. 2003. continental crust. Geochim. Cosmochim. Acta, submitted, Fuller, M.E., B.J. Mailloux, S.H. Streger, J.A. Hal, P. Zhang, S. 2003.

Michael Oppenheimer Framework Convention on Climate Change as a means to (Woodrow Wiilson School and avoid dangerous warming. Understanding past climate Department of Geosciences) changes including paleo-temperatures and the history of the Albert G. Millbank Professor of major ice sheets, provides important context for projecting Geosciences and International future changes and understanding their significance to Affairs society. In addition, I have investigated the relation of US Ph.D., 1970, University of Chicago policy on climate change to other elements of US foreign email: [email protected] and domestic policy on environment, energy, and trade.

Most recent research and future research plans Recent research continues to focus on the question of dangerous climate change with a new emphasis on the nitrogen cycle, and its perturbation by climate changes. Collaborating with Steve Pacala’s group and GFDL, we are developing the nitrogen component for the Earth Systems My research over the past 3 years has focused largely on the Model. Our objective is to investigate changes in nitrogen question of what may constitute dangerous climate impacts. delivery to estuaries (which causes eutrophication) and Accordingly, I have investigated both the potential physical future increases in nitrous oxide emissions that may follow and ecological consequences of a changing climate, such as from climate change, that in turn affect both the ozone layer disintegration of the major ice sheets, political and institu- and future warming. Assessment of the future of the West tional approaches to averting such impacts, and the costs of Antarctic ice sheet continues with emphasis on processes that doing so. Research has emphasized the origin, interpreta- could lead to rapid disintegration. A collaboration with tions, and potential implementation of Article 2 of the UN NOAA is aimed at assessing current climate-induced changes 16 in coral reef systems and projecting future impacts of climate Response (to comments on, On past temperatures and anomalous change on reefs. late-20th century warmth, with 12 co-authors). Eos, 84, 473-4, Policy responses under investigation include elaboration 2003. Global Warming: Formulating Long Term Goals (with A. Petsonk), of Article 2 of the UNFCCC and institutional issues related in Climate Policy Beyon Kyoto: Meeting the Long Term to Article 2 such as the role of nongovernmental organiza- Challenge of Global Warming (Johns Hopkins School of tions, the scientific community, and firms in its implementa- Advanced International Studies, Center for Transatlantic tion; the cost and environmental consequences of delaying Relations, Washington, DC) December, 2003. action to reduce emissions; the relation of US policy on Book Review: The Carbon War: Global Warming and the End of climate change to other elements of US foreign policy; the the Oil Era. Climatic Change, 54, 497-505, 2002. Atmospheric Pollution: History, Science, and appropriate role of government in providing incentives for Book Review: Regulation. Physics Today 56, 65 66, 2003. development of a hydrogen economy; and means to monitor Avoiding dangerous anthropogenic interference with the climate and account for sequestration of carbon in biological system (with K. Keller, M. Hall, S.-R. Kim, and D. F. Bradford). reservoirs. Submitted to Climatic Change, October, 2003. Two-Year Bibliography The West Antarctic Ice Sheet and Long Term Climate Policy (with R.B. Alley). Submitted to Climatic Change, November, 2003. Dangerous climate impacts and the Kyoto Protocol (with B.C. O’Neill).Science 296, 19712002. On past temperatures and anomalous late-20th century warmth (with 12 co-authors). Eos 84, 256-8, 2003.

S. George H. The shallowness of the thermocline is of enormous importance to the earth’s climate. For example, El Niño Philander would be a permanent rather than intermittent phenomenon Professor if the depth of the thermocline were to increase by merely a Ph.D., 1970, Harvard University few tens of meters. Why is the thermocline so shallow, and email: [email protected] hence the ocean so cold? Our studies indicate that the depth of the thermocline depends critically on the constraint of a balanced heat budget for the ocean. The oceanic heat-loss, mainly in high latitudes, depends on atmospheric condi- tions, but its heat-gain depends on the depth of the ther- mocline in the upwelling zones of low sea surface tempera- tures in the tropics. A change in the heat loss requires an adjustment of the depth of the thermocline so that the gain can balance the loss. This implies that if global warming The ocean is surprisingly cold. Even in the western equato- should decrease the oceanic heat loss, then the equatorial rial Pacific where sea surface temperatures are at a maximum, thermocline could deepen. The degree to which this happens the average temperature of a water column is barely above depends on the relative importance of the two main freezing because the warm surface waters are confined to a components of the oceanic circulation: the deep, slow, very shallow layer (of approximately a hundred meters) that thermohaline circulation, and the shallow, rapid, wind- floats on very cold abyssal waters that extend to depths of driven circulation of the upper ocean. We are currently 4000 meters and more. The interface between the warm and investigating the factors that determine the relative impor- the cold is known as the thermocline. Studies of the ocean tance of these components – oceanic diffusivity is one – in in motion can be divided into two categories: those that order to explain why different models of the ocean give explore the consequences of the very shallow thermocline, different results. How will we decide which model is relevant and those that attempt to explain why the thermocline is so to reality? shallow today. This distinction is possible because the Measurements are essential for the testing of any theo- processes that maintain the thermocline have time-scales of ries. When dealing with phenomena that have a timescale of decades and longer. Hence the basic thermal structure of the decades and longer – global climate changes for example — ocean can be regarded as a given in studies of phenomena we face a serious problem because the available instrumental with time-scales of a few years at most. Those phenomena records are too short to provide checks for models. Fortu- include various types of waves that propagate on the ther- nately records of paleo-climates do provide tests. Of special mocline, the seasonal cycle, the Southern Oscillation interest are the climate changes that occurred around 3 between El Niño, La Niña... Our studies cover such phe- million years ago. El Niño was a permanent phenomenon nomena, including the predictability of El Niño, and also up to that time, but then became intermittent. Furthermore, cover phenomena with time-scales of decades and more that the response of the climate to Milankovich forcing (periodic involve the processes that maintain the oceanic thermal variations in the distribution of sunlight associated with structure. variations in orbital parameters) changed markedly: the 17 response to variations in obliquity amplified significantly Two-Year Bibliography while the response to precession remained unchanged. Our Our Affair with El Niño (How we transformed an Enchanting theories for the thermal structure of the ocean provide Peruvian Current into a Global Climate Hazard) Princeton explanations for these different climate changes in terms of a University Press 2004 Fedorov A.V., S.L. Harper, S.G. Philander, B. Winter and A. gradual shoaling of the thermocline associated with increased Wittenberg, How Predictable is El Niño? Bull. Amer. Met. Soc. oceanic heat loss as the earth cooled gradually during the 84, 911-919, 2003. Cenozoic. Some 3 million years ago the depth of the Philander S.G. and A.V. Fedorov, Is El Niño Sporadic or Cyclic? thermocline reached a critical value that permitted the winds Annual Reviews of Earth and Planetary Sciences 31, 579-594, to bring cold, deep water to the surface in certain upwelling 2003. zones, thus terminating permanent El Niño conditions. At Philander, S. G., and A. V. Fedorov, Role of tropics in changing the response to Milankovich forcing some three million years ago, that stage ocean-atmosphere interactions of the type that Paleoceanography, 18(2), 1045, doi:10.1029/2002PA000837, characterize interannual El Niño today came into play and 2003. strongly influenced climate and the response to Milankovich Philander S.G., On dipoles and Spherical Cows. Bull. Amer. forcing. Meteorol. Soc. 84, 1424, 2003. The oceanic thermal structure depends not only on the Boccaletti G., R. Pacanowski, S.G. Philander and A. Fedorov, The heat fluxes across the surface but also on the salinity varia- Thermal Structure of the Ocean, J. Phys. Oceanogr.,in press tions induced by precipitation and evaporation. Heavy 2004. Fedorov A.V., S.G. Philander, R. Pacanowski, G. Boccaletti, ”The rainfall in high latitudes freshens the surface waters and effect of salinity on the wind-driven circulation and the thermal counters the effect of low temperatures on density. If rainfall structure of the upper ocean.” J. Phys. Oceanogr., in press, is sufficiently heavy it can negate the effect of temperature 2004. on surface density gradients with profound consequences for the oceanic circulation and its conveyor belts. We are currently studying the associated phenomena.

Robert A. Phinney signal/noise ratios are, justifiably, the most valuable inputs to Professor the different science processing planned by community Ph.D., 1961, California Institute of members. Technology With the great increase in data flows to the Data email: [email protected] Management Center occasioned by Earthscope, the impor- tance of near-real-time processing will increase. Thus, earthquake signals will need to be subject to preliminary location and source characterization, quality control, and screening for use by research teams, to permit the science to keep up with the flow of data from the Earthscope instru- ments. Under this scenario, most (perhaps 90%) of the wave- form data will consist of background noise that shows no obvious events on any single instrument. Although the role of wind, oceanic waves, and cultural disturbances is well- I have been developing a new initiative to study the spatial established, the proposition that some of this background behavior of background seismic noise from modern digital consists of sub-detectable waveforms from seismic events at networks. A recently submitted proposal to the NSF the low end of the Gutenberg-Richter distribution has not Earthscope initiative, and an abstract submitted to the received much attention. This proposition matters, specifi- Seismological Society of America follow: cally with Earthscope, because the large number of network 1. NSF project abstract: data channels raises the possibility of applying multichannel Planning for the flow and processing of Earthscope seismic waveform filters for detection of such events. We can cite data streams is well under way, through Earthscope work- scattered examples of studies that work with multichannel shops. The community is, justifiably, principally interested data, but propose that interest in these issues is timely only in the wise management of event waveforms which are to be now that the Earthscope capability is coming online. utilized for imaging and seismic source studies along lines [1] I propose to implement prototype noise processing which are well-established, and for which Earthscope algorithms using existing networks, in 3 genres: local area represents a major enhancement of capability due to the its nanoearthquakes, regional catalogs for sparsely covered technology design and its comprehensive scope. In such regions, and nearteleseismic detection/matched filtering for mainstream data flow, earthquake signals with the larger small events in the North American cordillera.

18 [2] I propose to build a modeling capability for estimat- ization of individual seismic events. Such events are defined ing the composition of the noise field, based on an by a single channel detection at several stations which passes Earthscope network design, on existing seismicity catalogs, an association process. For small events with magnitudes and incorporating parametric specifications of the spectra of near the detection threshold, the catalog is arguably incom- small sources and the effects of Q and scattering on propa- plete, and fails completely at lower magnitudes. gating signals. Archambeau, in an unpublished technical report, has shown Given the multiple spatial scales and heterogeneous that noise intervals where no network detections occur can makeup of the Earthscope facility, it is expected that a be processed by stacking to build up signal/noise ratio and to number of instances of this kind of processing may evolve. It detect seismic emission by what I call “sub-detectable” will be necessary, therefore, for the scientific planning to events. Stacking over stations is done by a migration extend well beyond this single inquiry. I propose that this set algorithm, in which the detection channel is tuned, in turn, of topics be taken up in appropriate workshops in the for each subsurface volume element. Stacking over time is Earthscope community. For this project, I propose a single critical to building an adequate S/N; in our experiments, workshop to begin the process of focusing on the issues. windows of 1-4 hours are used. By stacking over time, The scientific-intellectual focus of this proposal is the individual subdetectable events are traded-off for reliable opportunity presented by the Earthscope technology to detection of emission by clusters of events. I report on mobilize tools for detection and characterization of smaller- experiments with this process using the Anza network of magnitude events throughout the Earthscope region, and UCSD, which is available in near-real time, and which is beyond. In the PBO - SAFOD tectonically active region it situated directly over nests of local events. would be focused on connecting the energy release from The goal of this kind of study is to develop ways of small events to tectonic issues. In broader areas of the utilizing the noise from a modern digital network. In the intermontane West and the continental interior, this would experiments, noise windows preceding well-detected (ml work with the transportable and deployable arrays to greatly around 1.5) local events are studied. Images of seismic improve our knowledge of crustal seismicity. emission from sub-detectable seismicity are localized as The broader impact of this project lies in the idea that expected near the reference event. I show analysis experi- near-real-time processing of the Earthscope data stream can ments designed to establish the statistical validity of the provide new products which integrate nicely into the emission images; typically this is done by taking the test Earthscope Education and Outreach plan, and are useful for interval for the network and replacing the data phases by schools, governments, and the media. Such products might randomized phases, and reprocessing. The performance of serve as an extension of traditional seismicity reporting. this scheme depends on the selection of meaningful algo- 2. Abstract submitted to spring 2004 Seismological rithms for noise balancing, filtering, and stacking. Society Bulletin Local networks and arrays in seismically active areas are normally utilized for the detection, location, and character-

Allan Rubin exceeds both the earthquake dimensions (tens of meters for Associate Professor magnitude 1 events) and the length scales of significant Ph.D., 1988, Stanford University structures within fault zones. By cross-correlating the email: [email protected] seismograms of “similar” earthquakes (those with similar locations and focal mechanisms), it is possible to determine relative arrival times with errors that are less than one-tenth the sampling rate. From such measurements I and students and post-docs working with me have relocated many thousands of microearthquakes recorded by the USGS Northern California Seismic Network. Errors in relative location are now only tens of meters for events separated by hundreds of meters, and, with improvements we have recently introduced, as little as meters for neighboring events. This increased resolution allows us to image fault- Because the number of earthquakes increases exponentially zone structures that previously were invisible. The most with decreasing magnitude, earthquakes near the detection impressive of these structures are the slip-parallel “streaks” of threshold of a given seismic network represent a potential seismicity, up to kilometers in length and as little as 100 m wealth of data for both structural geology and seismology. A and 10 m in height and width, that seem to be ubiquitous major impediment to exploiting such datasets in the past has along creeping faults in central California and that have been that location errors are typically ~1 km, a value that since been discovered elsewhere.

19 The high-precision catalog also allows us to study to failure at the time of the mainshock, but not too close (or earthquake interaction on an unprecedented scale, resulting it would become part of the mainshock). Perhaps any region in new and surprising insights into the mechanics of rupture. far enough from failure to resist the extra dynamic “kick” Because of the obvious implications for seismic hazards, (normal stress reduction) associated with the SE-propagating geologists have long asked how earthquakes stress or de-stress rupture front will be too far from failure, once that transient the nucleation zones of potential future earthquakes. How- stress disappears, to produce an early aftershock. Assessing ever, location errors previously restricted such studies to this hypothesis requires running models of bimaterial earthquakes larger than magnitude 5 or 6, of which only a ruptures that stop. Post-doc Jean-Paul Ampuero and I have modest number exist in any given region on a timescale of a found that the transient dynamic stress field associated with few decades. We now have a catalog of many thousands of rupture arrest has the necessary ingredients to be consistent earthquakes with errors in relative location that are a small with the scenario outlined above. Under a wide range of fraction of the rupture dimensions. Because these are mostly conditions, as the SE-propagating rupture front is slowed by magnitude 1-3 events each may have only a few (or zero) a stress barrier unfavorable for slip, the region of normal catalogued aftershocks, but by “stacking” all the aftershocks stress reduction continues propagating at seismic velocities, robust statistics are easily obtained. and carries with it a small slip “pulse” detached from the Along the NW-SE trending San Andreas fault in central main rupture. This slip pulse can propagate a considerable California, we have found that the nearest aftershocks of distance into the stress barrier, such that when slip stops microearthquakes are nearly three times more likely to occur (and the normal stress reduction disappears), the fault at the to the northwest of the mainshock than to the southeast. location of the rupture front lies far below the threshold for This asymmetry disappears for mainshock-aftershock frictional slip. This is unlike the fate of the NW-propagating distances larger than about twice the mainshock radius, and rupture front, which, as with homogeneous bodies, lies on for mainshock-aftershock time lags greater than ~1 day. For the failure threshold at the cessation of slip (and which is a vertical, planar fault in a homogeneous medium there is no thus more likely to produce an early aftershock). In the mechanism for generating such asymmetry. However, along future we will incorporate more realistic (“rate-and-state”) the central San Andreas there is a 10%-20% contrast in friction laws in the dynamic models, to try to understand seismic velocity across the fault, with the North American more quantitatively the observed temporal and spatial limits rocks being the slower. This introduces a potentially symme- (~1 day and ~2 mainshock radii) of the aftershock asymme- try-breaking heterogeneity, to which we ascribe the asymme- try. try in aftershock occurrence. Consistent with this, the More important than any particular question to be nearby Calaveras fault exhibits essentially no across-fault addressed, perhaps, is the idea that this is a rare opportunity velocity contrast and no aftershock asymmetry. Most of my to test theoretical rupture models and laboratory-derived research effort over the last year has been directed at under- friction laws with real data. Already there has been one standing this asymmetry more quantitatively. unanticipated spin-off of the numerical models – in addition Within the last 5 years, several groups have developed to an asymmetry in aftershock productivity, the simulations elastodynamic models of rupture on an interface separating are suggestive of an asymmetry in rupture complexity; that differing materials. In addition to being perhaps the norm is, the “coughing and sputtering” that a modest fraction of rather than the exception for large-displacement (i.e., earthquakes seem to undergo during growth or arrest. We hazardous) faults, ruptures on such bimaterial interfaces are had previously found evidence for such asymmetry in a very important for seismic risk. The models demonstrate a small dataset, and Jean-Paul Ampuero is currently undertak- pronounced tendency for the ruptures to propagate preferen- ing a much more ambitious search of the data from the tially in one direction, that being the direction of slip of the Parkfield borehole seismic network (which has a greater mechanically less stiff rocks abutting the fault (which for the dynamic range than the USGS NCSN network and that also San Andreas would be the SE-moving North American plate covers a region with a large across-fault velocity contrast). located to the NE). The cause is a large reduction in fault- The hope is that asymmetry in rupture complexity will form normal compression near the SE-propagating rupture front, an independent dataset, complimentary to the asymmetry in an effect that is absent in a homogeneous body. Because aftershock occurrence, that will be available to constrain rupture velocities approach seismic wave speeds, such prevailing theories of earthquake rupture. “directivity” would concentrate potentially damaging ground I have also continued to pursue my interests in dike shaking in the direction of propagation. Evidence for such propagation, in conjunction with a study of volcanic hazards preferential directivity is scarce, but earthquakes that (1) are associated with the proposed US nuclear waste storage large enough for directivity to be detectable, and (2) that facility at Yucca Mountain, Nevada. The most significant occur on faults whose velocity structure is known, are very result has been the identification of a previously-unrecog- few. nized elastic instability at the tip of ascending dikes, that We interpret the aftershock asymmetry we observe as an results from the accumulation of a low-density gas phase unanticipated byproduct of this preferential propagation. between the magma front (which brings a continual supply Our reasoning is as follows: For a potential earthquake of fresh, undegassed magma) and the crack tip. The instabil- nucleation site to generate an aftershock, it should be close ity is not expected to operate for the laterally-propagating 20 dikes that are well-known from Iceland and Hawaii, but it is Ziv, A., and A.M. Rubin, Implications of rate-and-state friction for an attractive explanation for the observed transition from properties of aftershock sequences: Quasi-static inherently (crack-like) diamond-bearing kimberlite dikes to (rifle- discrete simulations, J. Geophys. Res., 108, B1, doi: 10.1029/ 2001JB001219, 2003. barrel-like) kimberlites plugs and diatremes at depths of ~1 Budnitz, R.J., E.M. Detournay, L. Mastin, J.R.A. Pearson, A.M. km. Rubin, and F.J. Spera, Yucca Mountain Igneous Two-Year Bibliography Consequences Peer Review Panel Interim Report, 75 pp. plus Rubin, A.M., Aftershocks of microearthquakes as probes of the appendices, prepared for the Office of Civilian Radioactive mechanics of rupture, J. Geophys. Res., 107, B7, doi:10.1029/ Waste Management of the U.S. Department of Energy, August 2001JB000496, 2002. 2002. Rubin, A.M., Using repeating earthquakes to correct high-precision Detournay, E., L.G. Mastin, J.R.A. Pearson, A.M. Rubin, and F.J. earthquake catalogs for time-dependent station delays, Bull. Spera, Final Report of the Igneous Consequences Peer Seism. Soc. Am., 92, 1647-1659, 2002. Review Panel, 86 pp. plus 86 pp. appendices, prepared for the Kilb, D., and A.M. Rubin, 2002, Implications of diverse fault Office of Civilian Radioactive Waste Management of the U.S. orientations imaged in relocated aftershocks of the Mount Department of Energy, Feb. 2003. Lewis, ML 5.7, California, earthquake, J. Geophys. Res., 107, B11, 2294, doi:10.1029/2001JB000149, 2002.

Jorge L. Sarmiento for predicting the chlorophyll distribution in the ocean and Professor its response to global warming, and by additional smaller Ph.D., 1978, Columbia University grants. email: [email protected] Modeling and observational constraints on carbon sinks One of the major research directions that my group has taken in the past years is estimation of the spatial distribu- tion and temporal variability of carbon sources and sinks by

inverse modeling of atmospheric and oceanic CO2 observa- tions and by evaluation of models with the major new data sets that were gathered by global surveys during the last decade. The long-term goal is to better understand the mechanisms of terrestrial and oceanic carbon source and sink distributions. Gloor et al. (2003) applied the inverse modeling methodology developed for atmospheric inversions The primary focus of my research is on the global carbon in order to estimate air-sea CO2 fluxes from the rich new cycle, with particular attention to the role of the ocean in data set of oceanic dissolved inorganic carbon concentra- controlling atmospheric carbon dioxide levels. My recent tions. McNeil et al. (2003) published a paper in Science publications can be categorized into four broad areas: (1) that used chlorofluorocarbon observations to provide new modeling and observational constraints on ocean and land constraints on the oceanic uptake of CO2. All of these carbon sinks for anthropogenic carbon; (2) stabilization of constraints on air-sea fluxes converge on similar total oceanic atmospheric carbon dioxide; (3) ocean biogeochemical uptake estimates, but there are significant differences in the processes and modeling; and (4) processes that caused the spatial distribution of these, particularly in the Southern lower pCO2 of the ice ages. Each of these areas is discussed Ocean. Matsumoto et al. (in press) used chlorofluorocarbon below, with attention primarily to papers published or in and radiocarbon observations in combination to evaluate a press during 2003. group of 19 ocean circulation models. Only about a quarter At the end of 2003, my research group consisted of 3 of the models are able to fit the observations in both the graduate students, 5 post-docs, 2 research staff members, Southern Ocean and outside it. These models give very and 2 technical staff members. My research was supported similar anthropogenic carbon uptake. by grants from BP Amoco and Ford Motor Company for the We participated in an atmospheric carbon transport Carbon Mitigation Initiative, from NOAA for analysis of model and inverse modeling comparison study aimed at carbon observations and earth system model development, improving our methodology for estimating carbon sources from the Department of Energy for research on the seques- and sinks from atmospheric observations (TRANSCOM). tration of carbon in the ocean via fertilization of phy- Results from this study are now appearing in press (Law et toplankton, from the National Science Foundation for al., 2003; Gurney et al., 2003; Patra et al., 2003; and research on improved methods for detecting the penetration Maksyutov et al., 2003). Ongoing research in this area by of anthropogenic carbon dioxide into the ocean and for the my group includes new inverse models combining atmo- role of the Southern Ocean in thermocline nutrient ventila- spheric and oceanic observations into a single analysis, with tion, from NASA for the development of empirical models preliminary results suggesting that the ocean fluxes can be

21 determined with great precision, and that the combination to obtain funding from NASA in order to further develop of the oceanic with atmospheric constraints provides strong this approach. limits on land carbon uptake estimates. My group participated in an ocean carbon model Stabilization of carbon dioxide intercomparison study (OCMIP), results from which are We have put considerable effort into studying the possibility now starting to be published (Watson et al., in press; Doney of enhancing the uptake of anthropogenic carbon by the et al., submitted; see also Matsumoto et al, in press). I also ocean either by iron fertilization or by deep-sea sequestra- was asked to write two overview papers on modeling ocean tion. Gnanadesikan et al. (2003) examined a new scenario biogeochemistry, which I wrote with two members of my for iron fertilization that involves small-scale patch fertiliza- group (Greenblatt and Sarmiento, in press; Marinov and tion. We found that patch fertilization was extremely Sarmiento, in press). inefficient (only a tiny fraction of the organic carbon Paleoceanography exported from the surface ocean comes from the atmo- A major challenge for oceanographers working on the sphere) and probably impossible to verify due to the small carbon cycle is to understand why carbon dioxide was lower size of the signal relative to natural variability. Mignone et during the ice ages, a phenomenon that remains to be al. (in press) examined deep sequestration of carbon, with explained despite almost 20 years of research. While this has the main emphasis being on how the large differences in not been a central core of my research, my group continues ocean circulation models lead to correspondingly large to contribute insights and model simulations. Two recent variations of a factor of 2x or more in sequestration effi- publications we were involved with (Toggweiler et al., 2003a ciency. Edmonds et al. (in press) used a combination of & b) provide fresh new insights on the role of the solubility integrated assessment and carbon cycle models to examine and biological pumps and suggest a completely new hypoth- some of the major issues that would need to be resolved in esis for the ice age CO2 reduction involving changes in ocean order to stabilize atmospheric carbon dioxide. circulation with no change in the biological pump. Ocean biogeochemical processes and modeling Two-Year Bibliography My research in this area has two major goals, the first being Brzezinski, M. A., C. J. Pride, V. M. Franck, D. M. Sigman, J. L. to develop an understanding of what controls ocean bio- Sarmiento, K. Matsumoto, N. Gruber, G. H. Rau, and K. H. Coale, A switch from Si(OH) to NO - depletion in the glacial geochemistry, and the second related goal being to develop 4 3 Southern Ocean. Geophys. Res. Lett., 29 (12): 10.1029/ the capability to predict the response of ocean biogeochemis- 2001GL014349, 2002. try to climate change. I have a paper that will appear in the Doney, S. C., J. A. Kleypas, J. L. Sarmiento, and P. G. Falkowski, January 1, 2004, issue of Nature (Sarmiento et al., in press) The U. S. JGOFS Synthesis and Modeling Project — An that describes a major new insight about how nutrients are introduction. Deep-Sea Res. II, 49: 1-20, 2002. returned from the deep ocean to the main thermocline. This Dutay, J.-C., J. L. Bullister, S. C. Doney, J. C. Orr, R. Najjar, K. supply of nutrients to the thermocline of the world ocean, Caldeira, J.-M. Campin, H. Drange, M. Follows, Y. Gao, N. which occurs by formation of Subantarctic Mode Water, Gruber, M. W. Hecht, A. Ishida, F. Joos, K. Lindsay, G. Madec, E. Maier-Reimer, J. C. Marshall, R. J. Matear, P. Monfray, A. appears to be responsible for about three-quarters of the Mouchet, G.-K. Plattner, J. Sarmiento, R. Schlitzer, R. Slater, I. biological productivity in the global ocean to the north of J. Totterdell, M.-F. Weirig, Y. Yamanaka, A. Yool, Evaluation of the Southern Ocean. Based on this result, and other work ocean model ventilation with CFC-11: comparison of 13 global that we have done at Princeton and GFDL, we recently ocean models. Ocean Modelling, 4(2): 89-120, 2002. received new funding from the National Science Foundation Gnanadesikan, A., R. D. Slater, N. Gruber, and J. L. Sarmiento, for a more detailed modeling and data analysis study of the Oceanic vertical exchange and new production: a comparison between models and observations. Deep-Sea Res. II, 49: role of Southern Ocean processes in the global ocean 363-402, 2002. circulation and nutrient resupply to the main thermocline. Gruber, N, and J. L. Sarmiento, Large –scale biogeochemical- As regards the development of a prediction model, over physical interactions in elemental cycles. In: The Sea, ed. A. the past few years, my group has collaborated with GFDL to R. Robinson, J. J. McCarthy, and B. J. Rothschild, John Wiley develop and test a new model of ocean biogeochemistry, & Sons, Inc. pp. 337-399, 2002. including iron delivery by dust from the atmosphere (Gao et Gurney, K. R., R. M. Law, A. S. Denning, P. J. Rayner, D. Baker, P. Bousquet, L. Bruhwiler, Y. H. Chen, P. Ciais, S. Fan, I. Y. Fung, al., 2003) and ecosystem models for biological production M. Gloor, M. Heimann, K. Higuchi, J. John, T. Maki, S. and export of organic matter from the surface of the ocean Maksyutov, K. Masarie, P. Peylin, M. Prather, B. C. Pak, J. (Gnanadesikan et al., submitted; Dunne et al., submitted). Randerson, J. Sarmiento, S. Taguchi T. Takahashi, and C.-W.

Meanwhile, I undertook an independent study to analyze 6 Yuen, Towards more robust estimates of CO2 fluxes: control global warming predictions of the next century from which I results from the TransCom3 inversion intercomparison. hoped to be able to infer how biology might change in Nature, 415: 626-630, 2002. response to global warming. As part of this study we Iglesias-Rodriquez, M. D., R. Armstrong, R. Feely, R. Hood, J. Kleypas, J. D. Milliman, C. Sabine, and J. Sarmiento, The developed a new empirical modeling approach to predict marine calcium carbonate budget in a changing ocean. EOS ocean biology and applied it to the climate warming simula- Transactions, 83 (34): 365, 374-375, 2002. tions from the 6 models. A paper describing this work is Matsumoto, K., J. L. Sarmiento, and M. A. Brzezinski, Silicic acid now in press (Sarmiento et al., submitted) and we were able leakage from the Southern Ocean as a possible mechanism 22 for explaining glacial atmospheric pCO2. Global Biogeochem. Gnanadesikan, N. Gruber, A. Ishida, F. Joos, R. M. Key, K. Cycles, 16 (10): 10.1029/2001GB001442, 2002. Lindsay, F. Louanchi, E. Maier-Reimer, R. J. Matear, P. Peylin, P., D. Baker, J. Sarmiento, P. Ciais, P. Bousquet, Influence Monfray, A. Mouchet, R. G. Najjar, G.-K. Plattner, C. L. Sabine, of transport uncertainty on annual mean and seasonal J. L. Sarmiento, R. Schlitzer, R. D. Slater, I. Totterdell, M.-G.

inversions of atmospheric CO2 data. J. Geophys. Res., Weirig, M. E. Wickett, Y. Yamanaka, and A. Yool, Carbon 107(D19), 4385, doi:10.1029/2001JD000857, 2002. dioxide fluxes in the global ocean. In: Ocean Sarmiento, J. L. and N. Gruber, 2002. Sinks for anthropogenic Biogeochemistry: A JGOFS Synthesis, ed. M. J. R. Fasham, J. carbon. Physics Today, August pp. 30-36, 2002. Field, T. Platt, and B. Zeitzschel, Springer-Verlag, Publishers, Sarmiento, J. L., J. Dunne, A. Gnanadesikan, R. M. Key, K. New York, pp. XX, in press.

Matsumoto, and R. Slater, A new estimate of the CaCO3 to Sarmiento, J. L., N. Gruber, M. A. Brzezinski, and J. P. Dunne, High organic carbon export ratio. Global Biogeochem. Cycles, 16 latitude controls of the global nutricline and low latitude (4), 1107, doi:10.1029/2002GB001919, 2002. biological productivity, Nature, in press. Gloor, M., N. Gruber, J. L. Sarmiento, C. S. Sabine, R. Feely, and Matsumoto, K., J.L. Sarmiento, R.M. Key, O. Aumont, J.L. Bullister, C. Rˆdenbeck, A first estimate of present and pre-industrial air- K. Caldeira, J.-M. Campin, S.C. Doney, H. Drange, J.-C.

sea CO2 flux patterns based on ocean carbon measurements. Dutay, M. Follows, Y. Gao, A. Gnanadesikan, N. Gruber, A. Geophys. Res. Lett., 30(1): 10.1029/2002GL015594, 2003. Ishida, F. Joos, K. Lindsay, E. Maier-Reimer, J.C. Marshall, McNeil, B. I., R. J. Matear, R. M. Key, J. L. Bullister, and J. L. R.J. Matear, P. Monfray, R. Najjar, G.-K. Plattner, R. Schlitzer,

Sarmiento, Anthropogenic CO2 uptake by the ocean based on R. Slater, P.S. Swathi, I.J. Totterdell, M.-F. Weirig, Y. the global chlorofluorocarbon dataset Science, 299: 235-239, Yamanaka, A. Yool, J.C. Orr, Evaluation of ocean carbon cycle 2003. models with data-based metrics, Geophys. Res. Let., in press. Toggweiler, J. R., A. Gnanadesikan, S. Carson, R. Murnane, and J. Mignone, B., J. L. Sarmiento, R. D. Slater, A. Gnanadesikan, L. Sarmiento, Representation of the carbon cycle in box Sensitivity of sequestration efficiency to mixing processes in models and GCMs, Part 1, the solubility pump, Global the global ocean, Energy, in press. Biogeochem. Cycles, 17(1): 1026, doi:10.1029/ Greenblatt, J. B., and J. L. Sarmiento, Variability and climate

2001GB001401, 2003. feedback mechanisms in ocean uptake of CO2. In: Toward

Toggweiler, J. R., R. Murnane, S. Carson, A. Gnanadesikan, and J. CO2 Stabilization: Issues, Strategies, and Consequences, A L. Sarmiento, Representation of the carbon cycle in box SCOPE/GCP Rapid Assessment Project, ed. C. Field and M. models and GCMs, Part 2, the organic carbon pump, Global Raupach, Island Press, in press. Washington, D.C. Biogeochem. Cycles, 17(1): 1027, doi:10.1029/ Edmonds, J., F. Joos, N. Nakicenovic, R. Richels, and J. L. 2001GB001841, 2003. Sarmiento, Scenarios, targets, gaps, and costs. In: Toward

Gnanadesikan, A., J. L. Sarmiento, and R. D. Slater, Effects of CO2 Stabilization: Issues, Strategies, and Consequences, A patchy ocean fertilization on atmospheric carbon dioxide and SCOPE/GCP Rapid Assessment Project, ed. C. Field and M. biological production. Global Biogeochem. Cycles, 17 (2), doi: Raupach, Island Press, Washington, D.C., in press. 10.1029/2002GB001940, 2003. Gnanadesikan, A., J. P. Dunne, R. M. Key, K. Matsumoto, J. L. Law, R. M., Y.-H. Chen, K. R. Gurney, and TransCom 3 modellers, Sarmiento, R. D. Slater, and P. S. Swathi, Oceanic vertical

TransCom 3 CO2 inversion intercomparison: 2. Sensitivity of exchange and particulate export: Comparisons between annual mean results to data choices. Tellus, 55B (2): 580-595, models and new observational estimates, Global Biogeochem. 2003. Cycles, submitted. Gurney, K. R., R. M. Law, A. S. Denning, P. J. Rayner, D. Baker, P. Marinov, I., and J. L. Sarmiento, The role of the oceans in the Bousquet, L. Bruhwiler, Y. H. Chen, P. Ciais, S. Fan, I. Y. Fung, global carbon cycle: An overview. In: Ocean Carbon Cycle and M. Gloor, M. Heimann, K. Higuchi, J. John, E. Kowalczyk, T. Climate, ed. M. Follows and T. Oguz, NATO ASI, Ankara, Maki, S. Maksyutov, P. Peylin, M. Prather, B. C. Pak, J. Turkey. Sarmiento, S. Taguchi, T. Takahashi, and C-W. Yuen, J. L. Sarmiento, R. Slater, R. Barber, L. Bopp, S. C. Doney, A. C.

TransCom 3 CO2 inversion intercomparison: 1. Annual mean Hirst, J. Kleypas, R. Matear, U. Mikolajewicz, P. Monfray, V. control results and sensitivity to transport and prior flux Soldatov, S. A. Spall, and R. Stouffer, Response of Ocean information. Tellus, 55B (2): 555-579, 2003. Ecosystems to Climate Warming, Global Biogeochem . Patra, P. K., S. Maksyutov, and TransCom-3 Modelers, Sensitivity Cycles, submitted. of optimal extension of observation networks to the model Doney, S. C., K. Lindsay, K. Caldeira, J.-M. Campin, H. Drange, J.- transport. Tellus, 55B (2): 498-511, 2003. C. Dutay, M. Follows, Y. Gao, A. Gnanadesikan, N. Gruber, A. Maksyutov, S., T. Machida, H. Mukai, P. Patra, T. Nakazawa, G. Ishida, F. Joos, G. Madec, E. Maier-Reimer, J.C. Marshall, Inoue, and TransCom-3 Modelers, Effect of recent R.J. Matear, P. Monfray, A. Mouchet, R. Najjar, J.C. Orr, G.-K. observations on Asian CO2 flux estimates with transport Plattner, J. Sarmiento, R. Schlitzer, R. Slater, I.J. Totterdell, M.- model inversions. Tellus 55B (2): 522-529, 2003. F. Weirig, Y. Yamanaka, and A. Yool, Evaluating global ocean Gao, Y., S.-M. Fan, and J. L. Sarmiento, Aeolian iron input to the carbon models: The importance of realistic physics, Global ocean through precipitation scavenging: a modeling iogeochem. Cycles, submitted. perspective and its implication for natural iron fertilization in the Dunne, J. P., R. A. Armstrong, A. Gnanadesikan, J. L. Sarmiento, ocean. (J. Geophys. Res., 108(D7), 4221, doi:10.1029/ and R. D. Slater, Empirical and mechanistic models for particle 2002JD002420, 2003. export ratio, Global Biogeochem. Cycles, submitted. Watson, A. J., J. C. Orr, O. Aumont, K. G. Caldeira, J.-M. Campin, S. C. Doney, H. Drange, M. J. Follows, Y. Gao, A.

23 Daniel Sigman research. My main analytical tool in this effort is the stable Assistant Professor isotope composition of nitrogen-bearing compounds. In the Ph.D., 1997, MIT and Woods Hole modern environment, the isotope ratios of different chemi- Oceanographic Institution cal forms of nitrogen provide a constraint on the occurrence email: [email protected] and rates of important processes in the nitrogen cycle. Looking into the past, the ice age cycle represents a host of natural perturbations, the responses to which may provide a clear indication of the dominant feedbacks in the nitrogen cycle. Isotope measurements on appropriate nitrogen- bearing materials from the sedimentary or glaciological records may be used to reconstruct the relevant changes in the nitrogen cycle. This reconstruction can, in turn, provide insight into the history of other elemental cycles, ocean circulation and climate. Despite this great promise, nitrogen The biologically important elements turn over so rapidly at isotope geochemistry is a relatively young field and sorely the surface of the Earth that modest differences between lacks adequate methods for many types of measurements. input and output in large reservoirs such as the ocean could The initial focus of my research at Princeton has been to completely remove them or double their concentration in develop a new generation of analytical methods for nitrogen the relatively short span of thousands to millions of years. isotope geochemistry. While method development continues Despite this precarious situation, the evidence indicates that to be a major part of my research program, my group has the Earth has been remarkably stable in its habitability. The begun to put our new methods to work, to understand the chain of multi-cellular life has been continuous for more nitrogen cycle, its history, and its interaction with other than a half billion years. While mass extinctions have elemental cycles and with climate. occurred, none have been associated with the internally Below, I describe isotope studies in my lab that have driven collapse of an elemental cycle. This continuity been completed over the last year or studies underway that requires a conspiracy of feedbacks within the Earth system have already yielded significant insights. Given the delay that stabilizes the availability of life’s key ingredients. Yet we between completing a project and shepherding it through know little about these feedbacks or the constraints that they publication, this work includes projects that are not reflected impose on the environment and life. Biologically available in this year’s publications, and (or “fixed”) nitrogen is one of the most important nutrients vice-versa. to primary producers, and its residence time in the environ- Isotopic studies of the modern nitrogen cycle ment is among the shortest of the biologically important Based on methods described below, my group’s analytical constituents. However, the terrestrial and oceanic budgets of work has focused on diverse modern materials, such as fixed nitrogen have uncertainties of greater than a factor of samples from the ocean water column, sediment pore waters, two. Moreover, there is no agreement on the feedbacks that soil and stream waters, and laboratory experiments with stabilize the fixed nitrogen reservoir, especially in the ocean; cultured organisms. However, most of these studies are some investigators favor input-based feedbacks (involving relevant for both the modern ocean and the interpretation of “N fixation”), while others focus on the output (“denitrifi- 2 the geologic record. The following is a list of these recently cation”). completed studies, for which a manuscript has been submit- Earth’s climate is similarly vulnerable to change, and ted or will be submitted within the next month or so. feedbacks are also at work. However, these feedbacks do not 1) Graduate student Meredith Hastings has analyzed a all lead to stability. A good example is provided by the cycle year-long sample set of Bermuda rainwater for nitrate N and of ice ages that has dominated the last two million years of O isotopic composition, which reveals a seasonal, transport- Earth history. Our understanding of these cycles is that driven change in the rainwater source of nitrate to Bermuda subtle variations in Earth’s orbit and rotation are amplified that had not been recognized from previous nitrate concen- by internal feedbacks, yielding dramatic climate change over tration measurements (paper in press). Nitrate in rain is hundreds to thousands of years. Atmospheric carbon dioxide essentially a record of one of the main sources of rain acidity appears to represent one such feedback, being abundant and also affects the fertility of the biosphere. Meredith’s during warm interglacial periods (thus causing further results suggest that there are previously under-appreciated warming) and scarce during ice ages (thus causing further natural sources of atmospheric nitrate in the North Atlantic cooling). However, we do not know what caused atmo- Basin. spheric carbon dioxide to change. Some suspect a role for the 2) Angela Knapp is measuring the N isotopic composi- photosynthetic extraction of carbon dioxide from the surface tion of dissolved organic matter in several oceanic environ- ocean and atmosphere by algae and the sequestration of this ments. Dissolved organic nitrogen is the dominant form of carbon in the ocean interior. bio-available nitrogen in the nutrient-poor low-latitude Understanding the feedbacks acting on Earth’s environ- ocean, but its role in biological productivity is a mystery. ment, both chemical and physical, is the core goal of my 24 Her work to date suggests that much of the DON pool is Earth history studies recalcitrant on the time scale of months. Moreover, her data Based on Angie Knapp’s work on dissolved organic nitrogen, appear to provide a constraint on the importance of cyano- postdoc Becky Robinson Graham and graduate student bacterial N2 fixation as a source of bioavailable N to the Brigitte Brunelle have developed a method for the N isotopic well-studied ocean region in the more northern Sargasso Sea. analysis of organic matter trapped within microfossils that 3) Postdoc Moritz Lehmann has completed an N and O are buried in deep sea sediments. This is a specialized isotopic study of nitrate loss in the Santa Monica Bay (paper measurement, but it offers the potential to expose changes in in press). This work indicates that denitrification (bacterial nutrient cycling through Earth history. Our work to date has nitrate-based respiration) expresses very little fractionation in focused on sediment cores from polar ocean regions, where Santa Monica Bay sediments. The results also require that the nutrient status of the surface has a major effect on these shallow marine sediments, despite being vigorously atmospheric CO2. irrigated by organisms, are “tight” with respect to nitrate Becky Robinson Graham has demonstrated that previ- efflux: a given nitrate ion that is transported in from bottom ous bulk sediment and diatom-bound N isotope records water or produced by nitrification within the sediment will from the Antarctic have major flaws. Based on her results, most likely be consumed before it has the opportunity to changes in the surface nitrate concentration of the Antarctic exit the sediment. more much modest than the previous records suggested, 4) EEB graduate student Ben Houlton (advisor: Lars with some evidence for spatial variations (paper in review). Hedin) has analyzed Hawaiian rain waters, soil waters, and These results fit with studies suggesting that significant iron stream waters for the isotopic composition of nitrate and fertilization of the Antarctic by enhanced dust transport is dissolved organic N. In a manuscript nearing completion, he difficult to achieve even during the peak of the last ice age, combines his results with simple steady state models of the partially because glacial dust deposition is expected to mostly terrestrial nitrogen cycle to argue that denitrification is an in the Subantarctic, which shares a common latitude range under-appreciated mechanism of bioavailable N loss in with expected dust sources. However, the data also suggest a tropical forest ecosystems; previous paradigms have focused less important role for Antarctic nutrient drawdown in on hydrological loss. glacial/interglacial CO2 changes. Given the limited evidence 5) University of British Columbia graduate student Julie for patchiness, this study suggests that each of the zonal Granger is carrying out the first incubation experiments to sectors of the Antarctic must be studied to get an adequate characterize the relationship between N and O isotopic view of nutrient status during the last ice age. fractionation in algal nitrate uptake. This work shows the Becky has also generated three downcore records of strongest relationship between the N and O isotopes of diatom-bound N isotopic composition from the Subantarc- nitrate ever observed, provides a constraint on the biological tic Zone, the region to the north of the Antarctic in the mechanisms of isotope fractionation during nitrate assimila- Southern Ocean. Surprisingly, this record indicates the tion, and will be the basis for our use of coupled N and O opposite sense of change that had been inferred from bulk isotopes to study surface ocean processes (paper in review). sediment N isotope measurements in the Subantarctic. Her 6) University of British Columbia graduate student results indicate that, during the last ice age, the high flux of Joseph Needoba has extracted the internal pool of nitrate biogenic detritus that occurred in the Subantarctic was from phytoplankton cells, which my group is analyzing for associated with more complete consumption of the nitrate N and O isotopic composition. The results show that the supply to the region, as would occur with iron fertilization. dominant control on the isotope effect of nitrate assimilation This represents the most direct evidence I know of for a by phytoplankton (or at least those in culture) is the degree change in productivity driven by a natural change in iron to which nitrate can leak back out of the phytoplankton cell supply; we are currently working on a manuscript that we (paper in review). plan to submit before the end of the year. In addition, my lab is generating data sets for the N Recent Ph.D. graduate Curtis Deutsch (advisor: Jorge isotopic composition of nitrate from various regions of the Sarmiento) has modeled the expected effects of hypothesized ocean and for several small basins that provide good model glacial/interglacial changes in the nitrogen cycle on the systems (e.g., a manuscript in review on the Cariaco Basin in isotopic composition of oceanic nitrate (paper in review). the tropical Atlantic). Despite this diversity of projects, most Comparison of his model results with sedimentary nitrogen of the studies described above share several central goals. isotope data suggest that negative (stabilizing) feedbacks in First, they help to characterize the controls on the isotopic the ocean nitrogen cycle have prevented large changes in the fractionation of discrete nitrogen transformations, to study oceanic nitrogen reservoir over the last glacial/interglacial both the natural environment and the biochemical transfor- transition. mations themselves. Second, they seek to use the isotopes of Two-Year Bibliography nitrate as an integrative signal of spatially and temporally Sigman, D.M., S.J. Lehman, and D.W. Oppo, Evaluating variable processes in the environment. Third, they pioneer mechanisms of nutrient depletion and 13C enrichment in the the use of oxygen isotopes in nitrate as a complement to the intermediate-depth Atlantic during the last ice age, nitrogen isotopes. Paleoceanography, 18(3), 1072, doi:10.1029/2002PA000818, 2003. 25 Lourey, M.J., T.W. Trull, D.M. Sigman, An unexpected decrease of Southern Ocean, Geophysical Research Letters, 29, 10.1029/ δ15N of surface and deep organic nitrogen accompanying 2001GL014349, 2002. Southern Ocean seasonal nitrate depletion, Global Karl, D., A. Michaels, B. Bergman, D. Capone, E. Carpenter, R. Biogeochemical Cycles, 2003, 17(3), 1081, doi:10.1029/ Letelier, F. Lipschultz, H. Paerl, D. Sigman, and L. Stal, 2002GB001973, 2003. Dinitrogen fixation in the world’s oceans, Biogeochemistry, 57/ Casciotti, K.L., D.M. Sigman, and B.B. Ward, Linking diversity and 58, 47–98, 2002. stable isotope fractionation in ammonia-oxidizing bacteria, Hastings, M.G., D. M. Sigman, and F. Lipschultz, Isotopic evidence Geomicrobiology Journal, 20, 335–353, 2003. for source changes of nitrate in rain at Bermuda, Journal of Sigman, D.M., R. Robinson, A.N. Knapp, A. van Geen, D.C. Geophysical Research Ð Atmospheres, in press. McCorkle, J.A. Brandes, and R.C. Thunell, Distinguishing Sigman, D.M., and G.H. Haug, “Biological Pump in the Past”, in between water column and sedimentary denitrification in the Treatise On Geochemistry, edited by H.D. Holland and K.K. Santa Barbara Basin using the stable isotopes of nitrate, Turekian (H. Elderfield, volume editor), Elsevier Science, Geochemistry, Geophysics, Geosystems, 4(5), 1040 , doi: Oxford, in press. 10.1029/2002GC000384, 2003. Saito, M.A., D.M. Sigman, and F.M.M. Morel, The bioinorganic Karsh, K.L., T.W. Trull, M.J. Lourey, and D.M.Sigman, Relationship chemistry of the ancient ocean: the co-evolution of of nitrogen isotope fractionation to phytoplankton size and iron cyanobacterial metal requirements and biogeochemical cycles availability during the SOIREE Southern Ocean Iron RElease at the Archean/Proterozoic boundary? Inorganica Chimica Experiment (SOIREE), Limnology and Oceanography, 48, Acta, in press. 105-106, 2003. Lehmann, M.F., D.M. Sigman, and W.M. Berelson, Benthic nitrogen Haug, G.H., D. G¸nther, L.C. Peterson, D.M. Sigman, and K.A. cycling and the 15N/14N and 18O/16O of oceanic nitrate, Hughen, Climate and the collapse of Maya civilization, Marine Chemistry, in press. Science, 299, 1731-1735, 2003. Needoba, J.A., D.M. Sigman, P.J. Harrison, Evidence for a Carillo, J.H., M.G. Hastings, D.M. Sigman, and B.J. Huebert, mechanism of nitrogen isotope fractionation by marine Atmospheric deposition of inorganic and organic nitrogen and phytoplankton during growth on nitrate, Journal of Phycology, base cations in Hawaii, Global Biogeochemical Cycles, 16 (4), in review. 1076, doi:10.1029/2002GB001892, 2002. Granger, J., D.M. Sigman, J.A. Needoba, and P.J. Harrison, Pantoja, S., D.J. Repeta, J.P. Sachs, and D.M. Sigman, Stable Coupled nitrogen and oxygen isotope fractionation of nitrate isotope constraints on the nitrogen cycle of the Mediterranean during assimilation by cultures of marine phytoplankton, Sea water column, Deep-Sea Research I,. 49, 1609 –1621, Limnology and Oceanography, in review. 2002. Deutsch, C., D.M. Sigman, R.C. Thunell, N. Meckler, and G.H. Casciotti, K.L., D.M. Sigman, M. Galanter Hastings, J.K. Bohlke, Haug, Isotopic constraints on glacial/interglacial changes in the and A. Hilkert, Measurement of the oxygen isotopic oceanic nitrogen budget, Global Biogeochemical Cycles, in composition of nitrate in seawater and freshwater using the review. denitrifier method, Analytical Chemistry, 74 (19), 4905-4912, Thunell, R.C., D.M. Sigman, F. Muller-Karger, Y. Astor and R. 2002. Varela, The nitrogen isotope dynamics of the Cariaco Basin,

Tortell, P.D., G.R. DiTullio, D.M.Sigman, and F.M.M. Morel, CO2 Venezuela, Global Biogeochemical Cycles, in review. effects on taxonomic composition and nutrient utilization in an Robinson, R.S., B. Brunelle and D.M. Sigman, Revisiting nutrient Equatorial Pacific phytoplankton assemblage, Marine Ecology utilization in the glacial Antarctic: Evidence from a new method Progress Series, 236, 37-43, 2002. for diatom-bound N isotopic analysis, Paleoceanography, in Brzezinski, M.A., C.J. Pride, V.M. Franck, D.M. Sigman, J.L. review. Sarmiento, K. Matsumoto, N. Gruber, G.H. Rau, and K.H. Sigman, D.M., S.L. Jaccard, and G.H. Haug, Cold climates and - Coale, A switch from Si(OH)4 to NO3 depletion in the glacial polar stratification, Nature, in review.

John Suppe southern California. For the first 150 years of Geology the study of active deformation moved rather slowly because of Blair Professor of Geology Ph.D., 1969, Yale University “data starvation” caused by difficulties in seeing into the email: [email protected] complex deforming interiors of mountain belts. The subject finally began to take off about 1980 because of improved seismic imaging. Since then my students and I have been at the forefront of a successful effort to use these new data to develop fault-related fold theory which has shown, surpris- ingly, that the vast richness of deformed structures that we observe are formed by simple processes of displacement and propagation of non-planar faults. In the last few years we have made breakthroughs in insight, developing shear fault- bend folding and detachment folding theories, which explain in detail large classes of previously misunderstood structures. I am working hard at completing a book on fault-related fold We are working to understand the rich variety of processes theory to be published by Princeton University Press and I by which the upper crust deforms, particularly by studying have joined with former students John Shaw at Harvard and actively deforming mountain belts such as Taiwan, the Chris Connors at Washington & Lee to write and edit a Tianshan of western China and the Transverse Ranges of major volume on interpretation of seismic images in light of 26 fault-related fold theory, which is in press with AAPG. satellite data. In addition Ramon Gonzalez is making I feel that Active Tectonics in the midst of a new accelera- significant advances in the understanding of detachment tion of understanding driven by new data that can be folding based on precise analysis of well-imaged examples brought to bear on upper crustal deformation, especially: [1] from the Tianshan, Nankai trough, Cascadia accretionary precise earthquake locations, [2] dense geodetic data, [3] wedge and Niger delta. tectonic geomorphology (which provides an integral of Two-Year Bibliography deformation of the land surface over the last 10,000- (with J. Shaw, C. Connors, editors) Seismic Interpretation of 100,000 years), and [4] seismic imaging. We are engaged in Contractional, Fault-Related Folds: an AAPG Seismic Atlas. a number of projects that are at the forefront of using all American Association of Petroleum Geologists, 2004, in press. these new data for new insight, working in areas of active Progress in active foreland tectonics. Actas del XV Congreso deformation in southern California, Taiwan and the Geologico Argentino, v. 3, p. 254-256, 2002. (with L. M. Strayer) 3D mechanical modeling of thrust propagation : Tianshan mountains of western China. distinct-element method. Journal of Structural Geology, v. 24, For example Sara Carena, who just completed her PhD, p. 637-650, 2002. has for the first time developed techniques for mapping (with S. Carena) 3D imaging of active structures using earthquake active faults based on the locations of tens of thousands of aftershocks: the Northridge thrust. Journal of Structural small earthquakes. Now large earthquake catalogues that Geology, v. 24, p. 887-904, 2002. have accumulated data over many years can be used to image (with S. Carena and H. Kao) The active detachment of Taiwan illuminated by small earthquakes and its control on first-order active faults in 3D detail in previously inaccessible regions of topography. Geology, v. 30, 935-938, 2002. the crust. Carena has mapped active faults to depths of (with Lu, HF, Wang, SL, Jia, D, J, Hubert-Ferrari, A, Yin, DH, Yan, 60km in Taiwan using 110,000 small earthquakes, including FL, Chen, J) Quaternaryfolding in the south piedmont of tracing the master fault on which the mountains slide under central segment of Tianshan Mountains: Chinese Science the entire mountain belt and into the mantle (Oct. 2002 Bulletin, v. 47. 1907-1911, 2002. Geology). This has allowed us to show through the Davis, Exponential growth of geology, mathematics, and the physical Suppe & Dahlen (1983) theory of critical-taper wedge sciences for the last two hundred years and prospects for the future. Journal of Nanjing University, v. 38, p. 76-86, 2003. mechanics (the theory that mountain belts are like deform- (with Sara Carena) 3-D Mapping of Active Faults in Southern ing wedges of soil in front of bulldozers) that the first-order California: Eastern Ventura Basin and San Gorgonio Pass - topographic shape of the mountain belt is controlled by the San Bernadino Regions (2002). NEHRP Annual Project shape of the basal sliding surface. The reversal in surface Summary vol 44, 7 pp, 2002. http://erp-web.er.usgs.gov/ slope at the crest of Taiwan mountains is produced mechani- reports/annsum/vol44/sc/sc_vol44.htm cally by the bending of the sliding surface as it dives into the (with Li-Fan Yue) Mapping active faults in southern California in 3D using small earthquakes: southern San Andreas, San Jacinto mantle, plus critical-taper wedge mechanics. Previously, critical- and Elsinore fault systems NEHRP Annual Project Summary taper wedge mechanics had only been applied to the margins of vol 5, 7 pp, 2003. http://erp-web.er.usgs.gov/reports/annsum/ mountain belts and it surprised just about everyone that it vol45/sc/sc_vol45.htm would work for the full width of a mountain belt. (and Chris Connors and Yikun Zhang) Shear fault-bend folding. In other work graduate student Lifan Yue has combined Memoir American Association of Petroleum Geologists, 2003, a detailed 3D image he has developed of the classic thrust in press. fault of the major Chi-Chi earthquake in Taiwan with an (with Erickson, S. G., and Strayer, L. M.) Numerical modeling of hinge-zone migration in fault bend folds. Memoir American equally detailed coseismic displacement field to get an Association of Petroleum Geologists, 2003, in press. unparalleled image of the relationships between complex (with L. M. Strayer and S. G. Erickson) Influence of growth strata earthquake slip and complex fault geometry in a major on the evolution of fault related folds: Distinct-element models. earthquake. The Chi-Chi earthquake is a unique opportu- Memoir American Association of Petroleum Geologists, 2003, nity because it is the best instrumented earthquake ever and in press. for unusual reasons we are able to independently map the (with A. Ferrari, X. Wang and C. Jia) The Yakeng detachment fold, China. In J. Shaw, C. Connors, J. Suppe, editors, Seismic fault in detail in 3D. Interpretation of Contractional Fault-Related Folds. American I am finishing with former postdoc Aurélia Hubert- Association of Petroleum Geologists, 2003, in press. Ferrari of University of Neuchatel a major paper on “the link (with J. Shaw, C. Connors,) Part I Structural interpretation methods, between the surface and the subsurface” in active tectonics, In J. Shaw, C. Connors, J. Suppe, editors, Seismic in which we have been able to establish close relationships Interpretation of Contractional , Fault-Related Folds: an AAPG between surface deformation and geomorphology and the Seismic Atlas. American Association of Petroleum Geologists, subsurface structure in the Tianshan of western China. 2003, in press. (with A. Hubert-Ferrari, Jerome Van Der Woerd, X. Wang, H. Lu) Finally we began a new project on active deformation of the Irregular earthquake cycle along the southern Tianshan, China Tianshan involving graduate student Ramon Gonzalez, a (Aksu area). Journal of Geophysical Research, postdoctoral visitor Dengfa Hu arriving in the spring from 2003,submitted. the research lab of PetroChina and former postdocs Xin (with S. Carena, and H. Kao) Continuity of the San Andreas fault Wang of Zhejiang University. In support of this new effort between Cajon Pass and San Gorgonio Pass, California. Ramon Gonzalez has developed the ability to obtain quanti- Journal of Geophysical Research, 2003, submitted. tative structural data from high-resolution stereo Corona 27 Bess B. Ward microorganisms. Our present understanding of ecosystem Professor of Geosciences function has been gained through physical/chemical ap- Ph.D., 1982 University of Wash- proaches to measurement and modeling of the net transfor- ington mations. These approaches necessarily rely on gross simplifi- email: [email protected] cations about the role and regulation of the various func- tional groups (guilds) involved. Recent advances in molecu- lar microbial ecology have shown the microbial world to contain immense diversity and complexity at every level: redundancy and duplication of functional genes within a single organism; molecular diversity among functional genes that encode the same process in different organisms; large genetic diversity among different organisms apparently engaged in the same biogeochemical function within single communities; great variability in the species composition of My research concerns the marine and global nitrogen cycle, different communities that apparently perform equally well. using molecular and immunological probes for marine The goal of this project is to investigate the functional bacteria and bacterial processes (especially nitrification and relationship between complexity in microbial communities denitrification). We have ongoing research on denitrifica- and the physical/chemical environment at a range of biologi- tion in Antarctica, chlorinated aromatic degradation genes in cal and ecological scales. Previously, such analysis was denitrifying bacteria, the genes involved in nitrogen assimila- technologically limited by the inability to assay large num- tion by phytoplankton, diversity of functional guilds of bers of samples simultaneously for a large number of genes bacteria involved in the nitrogen cycle of Chesapeake Bay, and phylotypes. Using gene array technology, we will be able and the role of metals in nitrogen redox biogeochemistry. to detect the distribution and differential expression of Some of the main projects are summarized explicitly below. functional genes in natural systems. The results of this study Microbes control many of the important biogeochemical will constitute the first step towards application of DNA processes that occur in the oceans as well as on land. They chip technology for gene expression of “exotic” (i.e., not of contribute to the trace gas cycles that influence climate; they biomedical importance) processes and organisms in the utilize and produce nutrients that are involved in eutrophica- environment. The gene arrays, along with a full suite of tion; and they are even capable of cleansing the environment ecosystem process measurements, will be deployed along a by degrading a vast variety of chemical compounds, both transect that spans the eutrophic - oligotrophic gradient naturally occurring and anthropogenically produced. My from the inland waters of the Chesapeake Bay out to the research focuses on the nitrogen cycle and the microorgan- Sargasso Sea. Experiments and functional gene studies will isms involved in transformations of inorganic and organic focus on key transformations in the carbon and nitrogen nitrogen in the ocean and in sediment environments. This cycles (C fixation, N fixation, nitrification, denitrification, research makes use of technical approaches that range from urea assimilation). The diversity of guilds will be interpreted molecular biology to stable isotope biogeochemistry. The in terms of ecosystem function, assessed using geochemical two main bacterial groups we study are the nitrifiers, au- data and tracer experiments. In addition to field studies totrophs that oxidize ammonium to nitrite and nitrate, and designed to investigate and dissect the natural system, we the denitifiers, heterotrophs that can respire nitrate in the will also perform perturbation experiments using absence of oxygen. The linked activities of these two groups mesocosms. The goal of these experiments is to determine can be crucial in determining the chemical form and supply how microbial species diversity affects the major energy and of nitrogen to planktonic communities and in determining nutrient flows within ecosystems, and to assess the degree of the net nitrogen budget of ecosystems. stability or instability associated with changes in redundancy Ward lab has a web page where all of this is described. within guilds of microorganisms responsible for major nitrogen and carbon pathways. http://geoweb.princeton.edu/research/ecomicrobio ecomicrobio.html To date, about 15 field trips/research cruises have been 1. Biocomplexity of aquatic microbial systems: Relat- completed in Chesapeake Bay, the Choptank River and the ing diversity of microorganisms to ecosystem function Sargasso Sea. The first papers on this work have recently (O Mullan) been published or accepted (Taroncher-Oldenburg et al., (http://geoweb.princeton.edu/research/biocomplexity/index.html) 2003; Francis et al., 2003; Steward et al., in press). Both 2003 was the third year of this collaborative project, microoarrays (using 70-bp oligomer probes) and macroarrays involving several other institutions, all working in Chesa- (using ~350 bp PCR products) derived from functional peake Bay and coordinated through Princeton as the lead genes, which we extracted from Chesapeake Bay sediments, institution. Microbial biogeochemical cycling of the ele- plus a few representative genes from cultured organisms. ments regulates a dynamic environment in which the cycles The microarrays containing oligos for nitrite reductase genes of different elements are linked through the physiology of (nirS) were characterized in terms of their specificity and

28 sensitivity using simple and complex mixtures of known great diversity of microorganisms. Both NiRs are well genes, and complex environmental samples from Chesapeake known in denitrifying bacteria, and the nitric oxide reduc-

Bay. Sequence differences of 13- 15% can be distinguished tase (NoR, which produces N2O) in denitrifiers has also and the detection limit is 107 copies of a particular target. been characterized. It is also well known that nitrifying These results appear to be robust for all genes, due to the bacteria, obligate aerobic autotrophs, also produce both NO uniform behavior of oligomer probes. The second set of and N2O under some conditions, but the enzymology and microarrays, containing oligo probes for ammonia genetics of these transformations in nitrifiers was not monooxygenase (amoA) genes has been characterized and is understood. We discovered a nitrite reductase in nitrifying being used to characterize sediment and water column bacteria that is homologous with the nirK of denitrifiers samples. The third generation of microarrays will employ a (Casciotti and Ward, 2001). Similarly, we also recently new labeling protocol and a new quantification procedure, discovered a norB gene in nitrifiers which is highly homolo- both of which are being optimized in our lab. The gous with the norB gene from denitrifiers (Casciotti and macroarray project is based at UCSC (Zehr lab); the first Ward, in preparation). macroarrays were tested with nitrogenase genes (nifH) and We further investigated the similarities in the genes found to have discriminatory power and sensitivity similar to between denitrifiers and nitrifiers by determining the that of the microarrays. Both kinds of arrays are able to isotopic effects of the enzymes in whole cell and lysate distinguish different community compositions of assays. For the residual nitrite, the isotopic effect is deter- denitrifiers, nitrifirs or nitrogen fixers, respectively, in mined by the kind of NiR present, but is not influenced by sediment and water samples from different stations. whether the process is performed by a nitrifier or a 2. What limits denitrification and bacterial production denitrifier. The isotopic effect must result from the mode of in Lake Bonney, Antarctica? (Tuit) action of the iron vs. the copper enzyme, and perhaps the The second three year period of this project has just begun degree of exchange that occurs between the cell and the and work so far has focused on experiments with denitrify- environment. The implication is that the significance of ing cultures in the lab. Cultures are grown under trace metal isotopic signatures of inorganic and gaseous nitrogen species clean denitrifying conditions in trilaminate bags. The in the ocean may be more complicated than previous ongoing experiments are designed to test the copper hypoth- suspected, if the effects of nitrification and denitrification esis, which grew out of our previous work on this project. cannot be distinguished. One manuscript describing the The copper hypothesis suggests that Cu limitation can limit relationship between gene phylogeny and isotope effect has denitrification and lead to build up of in organic nitrogen been published (Casciotti et al., 2003). A model is being intermediates in the water column. Field work in the dry developed to help sort out the expected isotopic fraction- valley lakes of Antarctica is planned for 2004 and 2005. ation in different environmental scenarios (Casciotti et al., in preparation). 3. The coupling between carbon and nitrogen cycles in Because trace metal availability can limit denitrification coastal upwelling ecosystems; biogeochemical in the lab (see above), we hypothesized that metal distribu- cycling and its molecular basis (Song, Allen) tions might influence the type of nir found in natural marine This research has focused on the search for a nitrate reduc- assemblages. The first step in addressing this hypothesis is to tase gene in marine diatoms, which was finally successful last describe the distribution and diversity of nir genes in marine year. Nitrate reductase genes from several diatoms have now systems. One manuscript (Jayakumar, Francis and Ward, in been sequenced and their phylogenetic relationships are press) describes the diversity and distribution of nirS genes congruent with those described by others using 18S rRNA in the low oxygen coastal waters of the Arabian Sea in the genes, but in agreement with those results that the conven- continental shelf region of India. The sequences found here tional morphologically based taxonomy is not phylogeneti- are the first reported for a water column environment, and cally based. A manuscript describing the phylogeny of NR is are quite different from those previously reported from cultures and in samples retrieved from coastal sites in both sediment environments. Jayakumar and Tuit participated in the Atlantic and Pacific is in preparation (Allen, Song and a month long cruise in Nov-Dec 2003 in the Eastern Ward). A manuscript (Song and Ward, submitted) describ- Tropical North Pacific which visited the strong oxygen ing the first nitrate reductase gene from a marine alga minimum zone in that region. They conducted Cu perturba- (Dunaliella tertiolecta, a green alga) and its expression has tion experiments and hope to detect a response by the been completed. Sequences for nitrate transporters, ammo- indigenous denitrifying community based on nitrous oxide nium transporters and nitrate reductases from green algae production. Samples were also collected for analysis of both and diatoms have been retrieved from several cultures and nirS and nirK genes. from seawater samples and are undergoing analysis. 5. Draft Level Sequencing of a Selection of Nitrifying 4. Center for Environmental Bioinorganic Chemistry Bacteria (Jayakumar, Tuit) DOE has agreed to sequence the entire genome of five The two forms of dissimilatory (respiratory) nitrite reduc- ammonia- and nitrite-oxidizing bacteria. Nitrobacter tase, the cd-NiR (nirS gene) and Cu-NiR (nirK gene), are hamburgensis 14X is being grown in our lab in order to distributed across the Bacterial and Archaeal domains in a 29 produce the DNA required for sequencing. We will also be Caffrey, J. M., N. E. Harrington and B. B. Ward. Biogeochemical involved in the annotation of all five genomes. Processes in a Small California Estuary: 1. Benthic Fluxes and Pore Water Constituents Reflect High Nutrient Freshwater Two-Year Bibliography Inputs, Marine Ecology Progress Series, 233: 39-53, 2002. Francis, C. A., G. D. O’Mullan and B. B. Ward. Diversity of Ward, B. B. Nitrification in Aquatic Systems. Encyclopedia of ammonia monooxygenase (amoA) genes across Environmental Microbiology, D. A. Capone, Ed., Wiley & Sons, environmental gradients in Chesapeake Bay sediments. New York, Pp. 2144-2167, 2002. Geobiology, 1: 129-140, 2003. Zehr, J. P, and B. B. Ward. Nitrogen cycling in the ocean: new Ward, B. B. Significance of anaerobic ammonium oxidation in the perspectives on processes and paradigms. Applied and ocean. Trends in Microbiology, 11: 408-410, 2003. Environmental Microbiology, 68: 1015-1024, 2002. Casciotti, K. L., D. M. Sigman and B. B. Ward. Linking diversity Jayakumar, D. A., C. A. Francis, S. W. A. Naqvi and B. B. Ward. and biogeochemistry in ammonia-oxidizing bacteria Diversity of nitrite reductase genes in the denitrifying water Geomicrobiology Journal, 20: 335-353, 2003. column of the coastal Arabian Sea, Aquatic Microbial Ecology, Taroncher-Oldenburg, G, E. Griner, C. A. Francis and B. B. Ward. in press. Oligonucleotide microarray for the study of functional gene Steward, G. F., B. D. Jenkins, B. B. Ward and J. P. Zehr. diversity of the nitrogen cycle in the environment, Applied and Development and testing of a DNA macroarray to assess Environmental Microbiology, 69: 1159-1171, 2003. nitrogenase (nifH) gene diversity, Applied and Environmental Ward, B. B., J. Granger, M. T. Maldonado and M. L. Wells. What Microbiology, in press. limits bacterial production in the suboxic region of permanently O’Mullan, G. D. and B. B. Ward. Diversity of ammonia-oxidizing ice-covered Lake Bonney, Antarctica? Aquatic Microbial bacteria based on the genes encoding ammonia Ecology, 31: 33-47, 2003. monooxygenase (AmoA) and 16S ribosomal RNA in Monterey Caffrey, J. M., N. E. Harrington, I. P. Solem and B. B. Ward. Bay, CA., Applied and Environmental Microbiolog, submitted. Biogeochemical Processes in acSmall California Estuary, Casciotti, K. L. and B. B. Ward. Nitric oxide reductase (norB) Elkhorn Slough, CA.: 2. Nitrification Activity, Community genes identified in ammonia oxidizing bacteria, Applied and Structure and Role in Nitrogen Budgets, Marine Ecology Environmental Microbiology, submitted. Progress Series, 248: 27-40, 2003. Song, B., and B. B. Ward. Diversity of benzoyl-CoA reductase Song, B. and B. B. Ward. Nitrite reductase genes in halobenzoate genes n aromatic compound degrading denitrifying bacteria degrading denitrifyng bacteria and related species. FEMS and in environmental samples, Applied and Environmental Microbial Ecology, 34: 349-357, 2003. Microbiology, submitted. Granger, J. and B. B. Ward. Accumulation of nitrogen oxides in Song, B., and B. B. Ward. Molecular characterization of the copper-limited cultures of denitrifying bacteria. Limnology and assimilatory nitrate reductase gene and its expression in the Oceanography, 48: 313-318, 2003. marine green alga Dunaliella tertiolecta, Journal of Phycology, Ward, B. B. and G. D. O’Mullan. Worldwide distribution of marine submitted. ammonia-oxidizing Gamma-Proteobacteria detected in Jenkins, B. D., G. F. Steward, S. M. Short, B. B. Ward and J. P. seawater by PCR and sequencing of 16S rRNA and AmoA Zehr. Shifts in diazotroph community composition in the genes, Applied and Environmental Microbiology, 68: 4153- Chesapeake Bay estuary revealed by a DNA macroarray 4157, 2002. approach, Applied and Environmental Microbiology, submitted. Ward, B. B. How many species of prokaryotes are there? Proceedings of the National Academy of Sciences, US. 99:10234-10236, 2002.

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