A5079530473- Marine and coastal ecosystems
- Marine Biology and Ecology Research
- Geochemistry and Elemental Analysis
- Geology and Paleoclimatology Research
- Mercury impact and mitigation studies
- Methane Hydrates and Related Phenomena
- Oceanographic and Atmospheric Processes
- Ocean Acidification Effects and Responses
- Atmospheric and Environmental Gas Dynamics
- Isotope Analysis in Ecology
- Heavy metals in environment
- Paleontology and Stratigraphy of Fossils
- Geochemistry and Geologic Mapping
- Groundwater and Isotope Geochemistry
- Arctic and Antarctic ice dynamics
- Radioactive contamination and transfer
- Geological Studies and Exploration
- Radioactive element chemistry and processing
- Hydrocarbon exploration and reservoir analysis
- Calcium Carbonate Crystallization and Inhibition
- Ionosphere and magnetosphere dynamics
- Atmospheric chemistry and aerosols
- Marine Bivalve and Aquaculture Studies
- Arctic and Russian Policy Studies
- Coral and Marine Ecosystems Studies
University of California, Santa Cruz
2016-2025
Higher Institute of Mining, Industry and Geology
2023
Colorado School of Mines
2023
Ruhr University Bochum
2023
National Postdoctoral Association
2022
Cooperative Institute for Research in Environmental Sciences
2022
University of Washington
2022
Brookhaven National Laboratory
2022
Bigelow Laboratory for Ocean Sciences
2022
Woods Hole Oceanographic Institution
2007-2018
The oceanic biological pump drives sequestration of carbon dioxide in the deep sea via sinking particles. Rapid consumption and remineralization âtwilight zoneâ (depths between euphotic zone 1000 meters) reduce efficiency sequestration. By using neutrally buoyant sediment traps to sample this chronically understudied realm, we measured a transfer particulate organic 150 500 meters 20 50% at two contrasting sites. This large variability is poorly represented biogeochemical models. If...
Here we show that labile particulate iron and manganese concentrations in the upper 500 m of Western Subarctic Pacific, an iron‐limited High Nutrient Low Chlorophyll (HNLC) region, have prominent subsurface maxima between 100–200 m, reaching 3 nM 600 pM, respectively. The concentration Fe are characterized by a more reduced oxidation state, suggesting source from primary volcagenic minerals such as Kuril/Kamchatka margin. systematics these profiles suggest consistently strong lateral...
Abstract A major surface circulation feature of the Arctic Ocean is Transpolar Drift (TPD), a current that transports river‐influenced shelf water from Laptev and East Siberian Seas toward center basin Fram Strait. In 2015, international GEOTRACES program included high‐resolution pan‐Arctic survey carbon, nutrients, suite trace elements isotopes (TEIs). The cruises bisected TPD at two locations in central basin, which were defined by maxima meteoric dissolved organic carbon concentrations...
Heightened biological activity was observed in February 1996 the high‐nutrient low‐chlorophyll (HNLC) subarctic North Pacific Ocean, a region that is thought to be iron‐limited. Here we provide evidence supporting hypothesis Ocean Station Papa (OSP) received lateral supply of particulate iron from continental margin off Aleutian Islands winter, coincident with bloom. Synchrotron X‐ray analysis used describe physical form, chemistry, and depth distributions size fractionated matter samples....
[1] We have compiled a global data set of 62 open ocean profiles particulate organic carbon (POC), CaCO3, and opal concentrations collected by large volume in situ filtration the upper 1000 m over last 30 years. define concentration-based metrics for strength (POC concentration at depth) efficiency (attenuation POC with depth mesopelagic) biological pump. show that pump are dynamic characterized regime constant high transfer low to moderate surface bloom where height is weak deep efficiency....
The concentration and the major phase composition (particulate organic matter, CaCO3, opal, lithogenic iron manganese oxyhydroxides) of marine particles is thought to determine scavenging removal particle-reactive TEIs. Particles are also vector for transferring carbon from atmosphere deep ocean via biological pump, their may efficiency strength this transfer. Here, we present first full depth section size-fractionated (1–51 µm, >51 µm) suspended particulate matter (SPM) US GEOTRACES North...
Abstract The Great Calcite Belt (GCB) is a region of elevated surface reflectance in the Southern Ocean (SO) covering ~16% global ocean and thought to result from elevated, seasonal concentrations coccolithophores. Here we describe field observations experiments two cruises that crossed GCB Atlantic Indian sectors SO. We confirm presence coccolithophores, their coccoliths, associated optical scattering, located primarily subtropical, Agulhas, Subantarctic frontal regions....
We present full‐depth zonal sections of total dissolved cobalt, iron, manganese, and labile cobalt from the South Atlantic Ocean. A basin‐scale plume African coast appeared to be a major source metals this region, with high concentrations in oxygen minimum zone Angola Dome extending 2500 km into subtropical gyre. Metal were elevated along coastal shelf, likely due reductive dissolution resuspension particulate matter. Linear relationships between N 2 O, O , as well low surface aluminum...
In this paper, we present, describe, and model the first size-fractionated (0.8–51 µm; >51 µm) water-column particulate trace metal results from US GEOTRACES North Atlantic Zonal Transect in situ pumping survey, with a focus on lithogenic tracer elements Al, Fe Ti. This examination of basin-wide, full-depth distributions elucidates many inputs processes—some for bulk material, others element-specific—which are presented via concentration distributions, elemental ratios, size-fractionation...
We deployed the Multiple Unit Large Volume in‐situ Filtration System (MULVFS) to simultaneously sample 12 depths between 10 and 900 m during US GEOTRACES Atlantic Pacific intercalibration experiments. Sampling was designed compare large (>51 µm) small (micron or sub‐micron 51 size particulates collected by four classes of 142 mm filter holders against those using main MULVFS holder. evaluated Whatman “QMA,” Pall “Supor” (0.8, 0.45, 0.2 µm), Millipore “MF” (0.45 filters. Paired QMA filters...
Ocean export production is a key constituent in the global carbon cycle impacting climate. Past ocean commonly estimated by means of barite and Barium proxies. However, precise mechanisms underlying precipitation undersaturated marine water column are not fully understood. Here we present detailed mineralogical crystallographic analysis from size-fractionated particulate material collected using multiple unit large volume in-situ filtration systems North Atlantic Southern Ocean. Our data...
Deposition of continental mineral aerosols (dust) in the Eastern Tropical North Atlantic Ocean, between coast Africa and Mid-Atlantic Ridge, was estimated using several strategies based on measurement aerosols, trace metals dissolved seawater, particulate material filtered from water column, particles collected by sediment traps sediments. Most data used this synthesis involve samples during US GEOTRACES expeditions 2010 2011, although some results literature are also used. Dust deposition...
The sinking of organic matter to the deep ocean leaves extremely low concentrations major and trace nutrients for photosynthetic organisms at sunlit surface. As a result, marine phytoplankton make use alternative sources essential elements have evolved substitute some by others in various biochemical processes. A particularly intriguing example is that Zn, which used many functions but often depleted down picomolar surface seawater. Laboratory data show species are able achieve high growth...
Abstract Observations of dissolved cadmium (dCd) and phosphate (PO 4 ) suggest an unexplained loss dCd to the particulate phase in tropical oxyclines. Here, we compile existing observations Cd phosphorus (P), present new data from US GEOTRACES GP15 Pacific Meridional Transect examine this phenomenon a perspective. We use simple algorithm reproduce station depth profiles P via regeneration possible subsurface accumulation. Our examination reveals decoupling driven by variable partitioning...
Abstract. The sinking of particulate organic carbon (POC) is a key component the ocean cycle and plays an important role in global climate system. However, processes controlling fraction primary production that exported from euphotic zone (export ratio) how much it survives respiration mesopelagic to be sequestered deep (transfer efficiency) are not well understood. In this study, we use three-dimensional, coupled physical–biogeochemical model (CCSM–BEC; Community Climate System Model–ocean...
Abstract Summertime carbon, nitrogen, and biogenic silica export was examined using 234 Th: 238 U disequilibria combined with free floating sediment traps fine scale water column sampling in situ pumps (ISP) within the Eastern Tropical North Pacific Gulf of California. Fine ISP provides evidence that this system, particulate carbon (PC) nitrogen (PN) concentrations were more rapidly attenuated relative to Th activities small particles compared large particles, converging 1–5 µmol dpm −1 by...
Abstract. Cobalt is the scarcest of metallic micronutrients and displays a complex biogeochemical cycle. This study examines distribution, chemical speciation, biogeochemistry dissolved cobalt during US North Atlantic GEOTRACES transect expeditions (GA03/3_e), which took place in fall 2010 2011. Two major subsurface sources to were identified. The more prominent two was large plume emanating from African coast off eastern tropical coincident with oxygen minimum zone (OMZ) likely due...