Interests
Trace elements in natural waters; marine and estuarine chemistry; chemistry of rivers and weathering; oil spill effects on ocean chemistry; global carbon system; sedimentary fluxes.
At present, most of the work in my lab involves trace element studies, though we are also involved in some oil spill and sediment studies as well as examinations of methane and carbon dioxide. Over the years I have worked in many different areas of geochemistry ranging from sediment studies to radionuclide studies to studies of the oceanic carbon dioxide system. Thus, I am prepared to help students interested in most any sort of geochemically-oriented project.
Current Research
Trace elements in rivers and streams. Surprisingly little is known about the concentrations of many dissolved trace elements in rivers and what processes control those concentrations. Our work has examined the mechanisms of seasonal concentration variations in the Mississippi River, the effect of landscape differences on trace elements in the Yukon River Basin, and the global variability of concentrations. Our work has been supported by the Environmental Protection Agency, the National Science Foundation, the US Dept. of Agriculture, and the US Geological Survey. Current work involves studies of the Mississippi, Yukon, and Pearl Rivers.
Trace element and nutrient behavior in the outflow region of the Mississippi River along the Louisiana Shelf. This is a dynamic and highly productive coastal region. Also, the region is interesting because most of the river water enters the northern Gulf of Mexico near the shelf break while the rest of the water enters the Gulf through a shallow bay and broad shelf. Hence, we can study the effect of the physiographic setting on biogeochemical processes. We are also working in Mississippi coastal waters on the east side of the birdfoot delta. The work is supported by the National Science Foundation, NOAA, and MS Dept. of Marine Resources.
Reactive trace elements in the Atlantic Ocean. We've been examining the distributions of certain trace elements which have air-borne sources, including manganese, lead, aluminum, and gallium. The work should shed light on input of dust, pollutants, and trace nutrients to the ocean. This work is part of an international program called Geotraces which is sponsored by the National Science Foundation.
Composition of colloids. Colloids are sub-micron particles and macromolecules and they are an important factor regulating trace element transport and bioavailability/toxicity. In some of our work we utilize small pore size (20 nm) filters to process samples in remote field sites. In other work we use a technique called field flow fractionation that allows colloidal particles to be size fractioned for further analysis.
Chemical effects of the Deepwater Horizon oil spill. We have examined distributions of trace elements, nutrients, polycyclic aromatic hydrocarbons (PAH’s), and methane in submerged plumes in the spill area. The work is funded by the National Science Foundation and the NGI/BP Gulf Research Initiative.
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