A5023442531- Marine and coastal ecosystems
- Paleontology and Stratigraphy of Fossils
- Marine Biology and Ecology Research
- Geology and Paleoclimatology Research
- Geochemistry and Elemental Analysis
- Ocean Acidification Effects and Responses
- Isotope Analysis in Ecology
- Methane Hydrates and Related Phenomena
- Microbial Community Ecology and Physiology
- Groundwater and Isotope Geochemistry
- Oceanographic and Atmospheric Processes
- Mercury impact and mitigation studies
- Atmospheric and Environmental Gas Dynamics
- Coral and Marine Ecosystems Studies
- Hydrocarbon exploration and reservoir analysis
- Calcium Carbonate Crystallization and Inhibition
- Geological and Geochemical Analysis
- Radioactive element chemistry and processing
- Radioactive contamination and transfer
- Coastal and Marine Dynamics
- Coastal wetland ecosystem dynamics
- CO2 Sequestration and Geologic Interactions
- Geomagnetism and Paleomagnetism Studies
- Air Quality Monitoring and Forecasting
- Geological formations and processes
University of Southern California
2016-2025
Southern California University for Professional Studies
2010-2025
Southern California Earthquake Center
2014-2024
University of California, Los Angeles
2004
Moss Landing Marine Laboratories
1988-1996
Old Dominion University
1996
Duke University
1984-1985
The flux of dissolved iron from sediments to the water column was measured with chambers along California coast over a five‐year period. High fluxes were observed on continental shelf. an average 75 times larger than values derived pore‐water gradients. significantly correlated oxidation organic matter, which allows extrapolation global input shelf is at least as significant aerosols, has been presumed be dominant external source. Evidence this seen 100's kilometers offshore where it can...
The end-Triassic mass extinction overlapped with the eruption of Central Atlantic Magmatic Province (CAMP), and release CO2 other volcanic volatiles has been implicated in extinction. However, timing marine biotic recovery versus CAMP eruptions remains uncertain. Here we use Hg concentrations isotopes as indicators volcanism continental shelf sediments, primary archive faunal data. In Triassic–Jurassic strata, Muller Canyon, Nevada, levels rise interval, peak before appearance first Jurassic...
Research Article| August 01, 2006 Authigenic molybdenum isotope signatures in marine sediments Rebecca L. Poulson; Poulson 1College of Oceanic and Atmospheric Sciences, Oregon State University, 104 Ocean Administration Building, Corvallis, 97331-5503, USA Search for other works by this author on: GSW Google Scholar Christopher Siebert; Siebert James McManus; McManus William M. Berelson 2Department Earth University Southern California, Los Angeles, California 90089-0740, Author Article...
The global CaCO 3 budget is constrained by new estimates of standing stocks, fluxes through the water column, and dissolution in column on sea floor. Previous carbonate production export are indistinguishable within a large range values, 0.4–1.8 Gt PIC yr −1 . Globally, excess alkalinity (TA*) mass tracers indicate 1.0 between 200 1500 m, suggesting must at least equal this amount. Most occurs high latitudes, from outer shelf upper slope sediments (100–1500 m) only support 5–10% TA*...
B vitamins are some of the most commonly required biochemical cofactors in living systems. Therefore, cellular metabolism marine vitamin-requiring (auxotrophic) phytoplankton and bacteria would likely be significantly compromised if (thiamin 1 , riboflavin 2 pyridoxine 6 biotin 7 cobalamin 12 ) were unavailable. However, factors controlling synthesis, ambient concentrations, uptake these key organic compounds environment still not well understood. Here, we report vertical distributions five...
Chemical and biological sensor technologies have advanced rapidly in the past five years. Sensors that require low power operate for multiple years are now available oxygen, nitrate, a variety of bio-optical properties serve as proxies important components carbon cycle (e.g., particulate organic carbon). These sensors all been deployed successfully long periods, some cases more than three years, on platforms such profiling floats or gliders. Technologies pH, pCO2, inorganic maturing well....
We present molybdenum isotope and concentration data from 14 sites in the eastern Pacific central California to Peru margin. The environments studied have been chosen represent a broad range oxidation‐reduction (redox) potential, which provide framework for behavior of this redox‐sensitive element. Manganese‐rich hemipelagic sediments tropical mean characteristic Mo signature ( δ 98/95 = −0.49 ± 0.04‰, two times standard deviation (2 SDOM) with n 14) that reflects fractionation between ocean...
Climate warming is expected to reduce oxygen (O2) supply the ocean and expand its minimum zones (OMZs). We reconstructed variations in extent of North Pacific anoxia since 1850 using a geochemical proxy for denitrification (δ(15)N) from multiple sediment cores. Increasing δ(15)N ~1990 records an expansion anoxia, consistent with observed O2 trends. However, this was preceded by longer declining trend that implies anoxic zone shrinking most 20th century. Both periods can be explained changes...
An extensive region of the Eastern Tropical South Pacific (ETSP) Ocean has surface waters that are nitrate-poor yet phosphate-rich. It been proposed this distribution nutrients provides a geochemical niche favorable for N2fixation, primary source nitrogen to ocean. Here, we present results from two cruises ETSP where rates N2fixation and its contribution export production were determined with suite biological measurements. was only detectable using isotopic mass balances at six stations,...
Abstract The cycling of biologically produced calcium carbonate (CaCO 3 ) in the ocean is a fundamental component global carbon cycle. Here, we present experimental determinations situ coccolith and foraminiferal calcite dissolution rates. We combine these rates with solid phase fluxes, dissolved tracers, historical data to constrain alkalinity cycle shallow North Pacific Ocean. coccolithophores demonstrate nonlinear dependence on saturation state. Dissolution all three major calcifying...
Abstract Planktonic calcifying organisms play a key role in regulating ocean carbonate chemistry and atmospheric CO 2 . Surprisingly, references to the absolute relative contribution of these calcium production are lacking. Here we report quantification pelagic North Pacific, providing new insights on three main planktonic groups. Our results show that coccolithophores dominate living (CaCO 3 ) standing stock, with coccolithophore calcite comprising ~90% total CaCO production, pteropods...