A5014193444- Marine and coastal ecosystems
- Arctic and Antarctic ice dynamics
- Geology and Paleoclimatology Research
- Oceanographic and Atmospheric Processes
- Mercury impact and mitigation studies
- Geochemistry and Elemental Analysis
- Methane Hydrates and Related Phenomena
- Groundwater and Isotope Geochemistry
- Marine Biology and Ecology Research
- Isotope Analysis in Ecology
- Atmospheric chemistry and aerosols
- Heavy metals in environment
- Water Quality and Resources Studies
- Geochemistry and Geologic Mapping
- Climate change and permafrost
- Marine and fisheries research
- Radioactivity and Radon Measurements
- Analytical chemistry methods development
- Electrochemical Analysis and Applications
- Food Industry and Aquatic Biology
- Atmospheric and Environmental Gas Dynamics
- Analytical Chemistry and Sensors
- Water Quality and Pollution Assessment
- Geological Studies and Exploration
- Water Quality Monitoring and Analysis
University of Alaska Fairbanks
2012-2024
National Oceanography Centre
2024
University of Southampton
2024
Old Dominion University
2024
Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
2024
Scripps Institution of Oceanography
2023
University of Arkansas at Fayetteville
2020
International Arctic Research Center
2008
University of California, Santa Cruz
2006-2007
[1] The Ross Sea polynya is among the most productive regions in Southern Ocean and may constitute a significant oceanic CO2 sink. Based on results from several field studies, this region has been considered seasonally iron limited, whereby "winter reserve" of dissolved (dFe) progressively depleted during growing season to low concentrations (∼0.1 nM) that limit phytoplankton growth austral summer (December–February). Here we report new data for 2005–2006 (27 December–22 January) following...
Atmospheric deposition of trace elements and isotopes (TEI) is an important source metals to the open ocean, impacting TEI budgets distributions, stimulating oceanic primary productivity, influencing biological community structure function. Thus, accurate sampling aerosol TEIs a vital component ongoing GEOTRACES cruises, standardized analysis procedures allow comparison data from different sites investigators. Here, we report results intercalibration study by seventeen laboratories for...
Abstract Atmospheric dust is an important source of the micronutrient Fe to oceans. Although relatively insoluble mineral assumed be most component dust, a small yet highly soluble anthropogenic may also significant. However, quantifying importance global oceans requires tracer which can used identify and constrain aerosols in situ. Here, we present isotope (δ 56 Fe) data from North Atlantic aerosol samples GEOTRACES GA03 section. While collected near Sahara have near-crustal δ Fe, America...
Observational and modeling studies in the Bering Sea indicate that changes seasonal ice cover time of retreat influence open‐water productivity. In particular, timing spring bloom its phytoplankton community composition are affected. Dissolved iron (DFe) data water column cores collected during 2007‐ Ecosystem Study (BEST) cruise melting provided substantial DFe to column. The additional input from sea could be biologically important along outer shelf break where ice‐free areas insufficient...
The international GEOTRACES program was developed to enhance knowledge about the distribution of trace elements and their isotopes (TEIs) in ocean reduce uncertainty sources, sinks, internal cycling. Recognizing importance intercalibration from outset, implemented efforts early program, consensus materials were generated that included full range TEIs dissolved seawater, suspended particles, aerosols. section cruises include “crossover station(s)” are occupied by two or more sections whereby...
For the past 20 years, GEOTRACES program (www.geotraces.org) has produced transformative insights into cycling of trace elements and isotopes (TEIs) in ocean. Be they bioactive essential for sea life (e.g., Fe, Ni, Cu, Zn…); contaminants Pb, Hg); or tracers processes like particle settling velocity (e.g. Th, Pa), source matter Nd, Pb isotopes) deep vertical diffusion Ra, Ac), TEI marine concentrations range from nanomol to attomole per litre, making their measurements particularly...
Factors influencing concentrations of nitrate, silicic acid, dissolved Fe, and Mn in the near‐field Columbia River plume were examined during late spring summer from 2004 to 2006 as part Influences on Shelf Ecosystems program. Under upwelling‐active phases, cold, high‐nitrate coastal seawater was entrained plume, nitrate 16–19 μ M observed with much 90% a origin. downwelling‐relaxation warm, nutrient‐depleted forming 2.5–6 M, river only source. Elevated acid is dominant source, 60–80 plume....
Concentrations of soluble (<0.025 μ m), dissolved (<0.4 m) and total (unfiltered) iron (Fe) were measured over the continental shelf slope northern Gulf Alaska (GoA) during spring‐summer. Large cross‐shelf gradients surface water Fe concentrations observed in these productive waters both seasons. Most particulate (>0.4 colloidal (0.025–0.4 size fractions removed from within inner mid shelf. As a result contribution to concentration increased break/slope waters. Surface on GoA higher...
Abstract The surface waters of the Arctic Ocean include an important inventory freshwater from rivers, sea ice melt, and glacial meltwaters. While some freshwaters are mixed directly into ocean, cryospheric reservoirs, such as snow, ice, melt ponds act incubators for trace metals, well potential sources to ocean upon melting. availability reactivity these metals depends on their speciation, which may vary across each pool or undergo transformation mixing. We present here baseline...
Abstract Atmospheric deposition has been suggested to be an important source of reactive nitrogen stored in Northern Hemisphere land‐fast ice, contrast Antarctic sea where bulk nutrients originate predominantly from underlying seawater. A paucity ice studies the open Arctic Ocean limits our understanding potential for melting contribute primary production N‐deplete waters Arctic. As part U.S. western GEOTRACES 2015 expedition, samples pack overlying snow, atmospheric aerosols, and seawater...
The sensitive, laboratory‐ and ship‐based, flow‐injection (FI) method for the determination of dissolved manganese in seawater developed by Resing Mottl ( Anal. Chem . 1992;64:2682‐2687) has been significantly modified improved incorporating five significant changes. three major changes are use a commercially available iminodiacetate (IDA) resin (Toyopearl AF‐chelate 650M) place 8‐hydroxyquinoline on‐line preconcentration matrix removal, addition nitrilotriacetic acid as an activator ligand...