Molecular
Geochemistry
and Nanoscience Group
Projects:
Synchrotron
Based Studies
Simulations
Selenium
Distribution and Fluxes in Intertidal Wetlands, San Francisco
Bay, CA
Studies
in this group address issues of environmental contaminant sequestration,
migration, dissolution and oxidation-reduction via a variety of
natural and anthropogenic operants. Recent work has included characterization
of the selenium speciation, transport and reaction rates within
soil horizons at the Kesterson Reservoir, where national attention
has focused on the selenium poisoning of wildlife from buildup of
agricultural runoff. Other work has determined inorganic chemical
processes that reduce the dangerous selenite species to elemental
selenium. Related investigations have examined arsenic transport
and redox reactions in soils, and microbial effects on the speciation
of selenium in hydrologic systems. The important but overlooked
effects of the vadose zone air-water interface on the transport
of colloids has been identified and quantified by department scientists.
Fundamental
studies on the nature of the aqueous solution/mineral interface,
and on the structure of near-aqueous solvated ions and colloids
are also being performed, with the aim to provide improved modeling
capability for contaminant migration and other surface processes,
such as weathering, sediment transfer, ion exchange and the biogeochemistry
of nutrient cycles. Current work includes: state-of-the-art molecular
dynamics modeling of the interlayer solvated cations in clays; studies
of the solvation environment of contaminant and nutrient molecular
units in aqueous solution; determination of the molecular identity
of initial iron oxide precipitates on quartz surfaces; and characterization
of the "acid-mine-drainage" mineral schwertmannite via simulation,
x-ray scattering and x-ray spectroscopy methods. Many of these efforts
involve newly developed capabilities utilizing synchrotron x-ray
sources. Important new work on the aqueous behavior of humic and
fulvic acids, hydroxyl speciation near cations in water, and the
nature of organic contaminants on mineral surfaces has been carried
out recently at Berkeley LabŐs Advanced Light Source.
|
For
more information about the Molecular Geochemistry & Nanoscience
Group, contact:
Glenn Waychunas
Molecular Geochemistry
& Nanoscience Group Leader
ph: 510-486-2224
email:gawaychunas@lbl.gov
|
