Organic biogeochemistry

Biomarkers, or molecular fossils, are organic compounds preserved in geologic materials that can be traced back to a specific source organism or process. Although only a small amount of organic matter produced is eventually preserved in geologic materials, the geochemical properties of this organic matter can provide information regarding environmental conditions at the time of deposition. For example, molecular fossils can be used to examine past vegetation assemblages (C3 vs. C4 plants), past primary productivity in lakes or oceans, past hydrological fluctuations, or to reconstruct past sea or lake surface temperatures. My research involves utilizing multiple organic geochemical and isotopic proxies to investigate outstanding questions in paleoclimate and paleoceanography through examining contributions to sedimentary organic matter from archaea, bacteria and eukarya, the three domains of life. I am also interested in developing and refining new techniques for paleoenvironmental reconstructions. For more information, please visit the UMass Amherst Biogeochemistry Laboratory homepage.

A number of compounds such as the long-chain n-alkanes, n-alkanoic acids and n-alkanols form the major constituents of plant leaf waxes. These compounds are transported to oceans and lakes by wind and fluvial erosion and eventually become buried in sediments. The carbon isotopic composition of plant leaf waxes provides information regarding the composition of past vegetation assemblages (C3 vs. C4 plants) while the deuterium isotopic composition of plant leaf waxes can provide information regarding past hydrology.