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Biogeochemistry and Paleoenvironmental Studies

The role of the geological sciences in our society has undergone important changes in recent years, resulting in a shift to basic research in areas that will result in a better understanding of natural hazards, natural resource management, and the environmental impact of both natural processes and human activities. The subdisciplines that are most critical in evaluating the nation's strategic problems are those that pertain to near-surface processes. Links between geology and the biosphere are especially important. Active areas of research pursued by our faculty include the following:
 

Environmental Geochemistry
Faculty: C. Kelley, K. Rogers, M. Schulte

Many research projects directly or indirectly relate to hydrogeology and environmental geochemistry. The fate of organic chemicals in aqueous environments (ocean, estuary, groundwater, and lake environments) is also studied, with particular emphasis on the carbon cycle. Redox geochemistry, specifically the coupling between the S and Fe cycles, is another area of active research.

Geomicrobiology
Faculty: C. Kelley, K. Rogers, M. Schulte

Microorganisms catalyze chemical reactions in order to live, and the existence of bacteria and archaea, which thrive at temperatures greater than 80°C in the absence of light and feed on the geochemical energy provided by seafloor hydrothermal systems, is a remarkable example of the close connections between biology and geology. No longer can we think of life as independent of the geophysical and geochemical environment that it inhabits. The discovery of these organisms has revolutionized thinking in both biology and geology, and our research provides a quantitative link between these fields. The same connections between biology and geology extend to all other locations where life is found. Organisms that inhabit lakes, rivers, the oceans, oil-field brines and groundwater all make use of the geochemistry of their environment, and this is especially true in the subsurface biosphere. Geological and geochemical processes provide the metabolic energy and nutrients that microbes need.

Paleoenvironments
Faculty: K. MacLeod

Paleoenvironments play a role in most of the research conducted in the field of Biogeochemistry and Paleontology. Environmental conditions influence the distribution of organisms and cycling of chemical species and, thus, are important in projects ranging from the distribution of fossils on geologic time scales to microbial activity and carbon cycling on biologic time scales. A number of ongoing projects, though, are focused specifically on documenting and understanding the causes and effects of paleoenvironmental variations.

• Extinction is a common theme of studies examining the interplay of environmental, physical, and biological systems over the last 500 million years. Oxygen, carbon, sulfur, and strontium isotopes are being used to understand changes across major disruptions to the Earth system, such as mass extinctions at the end of the Paleozoic and Mesozoic.
• For the Quaternary, cave calcite deposits (speleothems) are being studied to provide high-resolution terrestrial records of glacial-interglacial environmental changes.

Stable Isotope Geochemistry
Faculty: C. Kelley, K. MacLeod, P. Nabelek, K. Shelton

The use of stable isotopic analyses as a tool for studying geological and biogeochemical processes has led to a greater understanding of the complexities of these processes. The research that uses stable isotope analyses is wide and varied, spanning from microbial processes to high temperature geochemistry and economic geology. Stable isotope analyses can be used to understand past environmental climates and as well as to understand the modern day cycling of carbon and sulfur during early diagenesis.

Oceanography
Faculty: C. Kelley, K. MacLeod, M. Schulte, M. Underwood

Approximately 70% of the Earth is covered by oceans. The study of the ocean is truly an interdisciplinary science, including the subfields of biological, chemical, geological and physical oceanography. Many of our researchers have sailed on oceanographic cruises, including legs of the Ocean Drilling Project and on the Atlantis II, which houses the deep-sea submersible, ALVIN, to study various aspects of oceanographic processes. Studies of processes occurring during the modern day include microbial interactions and carbon processing in the water column and surface sediments, elemental cycling studies of anoxic basins, and sedimentary mineralogy and physical transport near plate boundaries. Information obtained from these modern day studies lead to better understanding of processes and the environmental controls on those processes that occurred in the geologic past.

M. Underwood (left) in core description laboratory aboard JOIDES Resolution.

Last Modified: summer 2009