Under the influences of natural climate variations and anthropogenic disturbance, ecosystems on earth are experiencing a lot of changes. Our research goals are to understand these changes in carbon (c) and nitrogen (n) cycles as well as food web structures in present ecosystems and reconstruct past variations preserved in sediment records. Our main research tools are compound and position specific isotope analysis (CSIA and PSIA) of amino acids and volatile fatty acids. We take advantage of the synergy among observational, experimental, and modeling approaches to enhance our ability to quantitatively describe and simulate biogeochemical cycles and trophic structures in food webs. We study a variety of research topics:
• Amino acids degradation in oxic and anoxic benthic environments and how diagenesis affects the sedimentary N isotope records.
• C and N flow through different trophic levels in food webs and corresponding stable isotope fractionations.
• Greenhouse gases cycling in Alaskan peatlands in response to permafrost melting.
• Transport and environmental fate of organochlorine pollutants in the remote oceans.