Research Interests:

My research focuses on the biogeochemistry of organic matter, with an emphasis on lipid biomarkers, in aquatic environments. Lipid biomarkers provide a link between biological sources of organic matter and organic compounds preserved in sediments. Biomarkers are used as tracers of processes that produce, transport, and alter organic matter in water columns and sediments, and we use biomarker distributions to determine rates and mechanisms for these processes. Most biomarkers in the ocean are produced by phytoplankton in surface waters via photosynthesis, although terrigenous biomarkers in deep-sea sediments verify that organic compounds from continental sources also reach the sea. The fate of organic compounds is affected by biological food web dynamics, by chemical alteration such as photolysis, by association with mineral particles, and by physical transport by currents. Although most work in our laboratory is directed at understanding the behavior of biogenic organic substances, organic pollutants are affected by the same processes.

Understanding the behavior of organic substances in rivers, lakes, estuarine salt marshes, and coastal and open ocean areas is vital because organic matter is intimately involved in life processes on Earth. Biogeochemical cycling of organic matter is a major determinant of the composition of the global atmosphere and ocean: the photosynthetic production of organic matter produces oxygen and consumes carbon dioxide, while the degradation of organic matter utilizes oxygen and releases carbon dioxide. Preservation of organic matter in sediments provides a link to ancient environments, including those environments and geological processes that produce coal and oil that are critical sources of energy in today's society. If we can better understand how biogenic compounds behave in aquatic environments, we may better be able to predict the fate of pollutants, and vice versa.