Current Research
The Aqueous Geochemistry and Mineralogy Group studies geochemical processes controlling mineral transformations and the fate of trace elements, nutrients, and contaminants in terrestrial and planetary aquatic systems. Our work focuses on topics of relevance to environmental biogeochemistry, planetary geochemistry, and geobiology. A summary of our current research projects is listed below.
ENVIRONMENTAL BIOGEOCHEMISTRY
RESEARCH
Structural and Interfacial Geochemistry of Rare Earth
and Platinum Group Elements
Funded by the
Department of Energy
Collaborators:
Prof. Daniel Giammar (Wash. U.), Dr. Eugene Ilton (PNNL), Dr. Eric
Bylaska (PNNL)
Critical
elements are essential to key technologies that underlie energy storage
and generation, transportation, communications, and computing. The
availability of the rare earth elements (REEs) and the platinum group
elements (PGEs) are of particular concern because of the lack of
adequate U.S. domestic production and, especially for PGEs, their
overall low abundance in Earth’s crust. REEs and PGEs in deposits
formed by rock weathering represent new potential resources for future
exploitation. However, the fundamental geochemical processes that
dictate the migration and enrichment of REEs and PGEs during weathering
are poorly constrained. The mechanisms controlling how REEs and PGEs
bind to the surfaces of mineral, become trapped inside the structures
of minerals, and are mobilized from mineral surfaces and structures in
weathering environments represent major areas of uncertainty. The
foundational scientific knowledge required to accurately predict the
formation and occurrence of deposits of REEs and PGEs formed via
weathering is currently inadequate. This project seeks to elucidate the
roles of mineral surfaces and structures in controlling the migration
and enrichment of REEs and PGEs in weathering environments. Through
coordinated laboratory experiments, synchrotron-based X-ray techniques,
and advanced computational studies, this project will obtain
fundamental new insight into the basic chemical processes controlling
the formation of rare earth and platinum group element deposits near
Earth’s surface.
Dynamic Recrystallization and Trace Element
Redistribution at Mineral Surfaces
Funded by the National
Science Foundation
Current
Participants:
Greg Ledingham
Components in
water have been demonstrated to cause the recrystallization of iron and
manganese oxide minerals, affecting the fate of micronutrients and
contaminants associated with these phases. This project explores trace
element fate during iron oxide
recrystallization and the mobility of adsorbed heavy metals.
Heavy Metal Hazard and Soil Quality in Peace Park, St.
Louis
Funded by Washington University
Current
Participants:
Elaine Flynn
Partners: Green City Coalition, St. Louis
Development Corporation, The Nature Conservancy, Missouri Department of
Conservation
Unoccupied land
in the College Hill neighborhood of St. Louis is being repurposed to
create a new place for the community to gather for events,
entertainment, and recreation. The planned Peace Park seeks to health,
well-being, and overall landscape of this community. We are working to
assess soil heavy metal hazards that may exist in the vacant urban land
that is the home for Peace Park and also assessing aspects of soil
health to aid in implementing the park design and maintenance.
PLANETARY GEOCHEMISTRY RESEARCH
Extracting Trace Element Concentrations
from Mars Exploration Rover APXS Data: Implications for Alteration
Processes and Crustal Composition
Funded by the National
Aeronautics and Space Administration
Current
Participants: Abigail Knight
Collaborators: Dr. Scott VanBommell (Wash.
U.)
Alpha Particle
X-ray Spectrometer (APXS) instruments on the Mars Exploration Rovers
(MER) Opportunity and Spirit amassed a large collection of data from
two distinct landing sites. Existing analysis of these data have
provided the abundance of Cr, Mn, Ni, Zn, and Br, but a wide array of
trace elements have not be quantified to date. Principal investigator
Scott VanBommel has recently developed new data processing methods for
the Mars
Science Laboratory mission to quantify a diverse array of additional
trace elements, and under his leadership this project seeks to port
this capability to the large archive of APXS data from the MER
missions. This project will develop Ga and Ge abundances as well as
Ga/Al and Ge/Si ratios as indicators of petrogenesis, hydrothermal
alteration, and acidic leaching on Mars. We will also utilize a
collection of redox-active and redox-inactive trace elements to provide
new insight in aqueous alteration processes at the MER landing site.
GEOBIOLOGY RESEARCH
Reconciling Prebiotic Paradigms: Mapping
Planetary Reality onto Experimental Strategies
Funded by the National
Aeronautics and Space Administration
Current
Participants: Emily Millman
Collaborators: Prof. Karyn Rogers (RPI) plus 14 other
scientists at multiple institutions
Project Website: http://earthfirstorigins.rare.rpi.edu/
The
large collaborative project consists of one of the major teams involved
in NASA's Prebiotic Chemistry and Early Earth Environments Consortium
supported by the NASA Astrobiology Program. The overarching goal is to
develop a new understanding of conditions on the early Earth and the
prebiotic chemistry that occurred with rocks, minerals, and fluids
actually present during this period. The Washington University team is
specifically focused on phyllosilicates that formed on the early Earth
from mafic and ultramafic crystal alteration and how key prebiotic
compounds bound to and were selectively concentrated by these phases.