EES Seminar: Phosphorus Cycling in Coastal Waters and Sediments, Deb Jaisi, U. Delaware

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Nutrient contamination in open water bodies has increasingly been one of the lingering issues in water quality restoration because of the multitude of sources, temporally and spatially variable inputs, and complex interacting factors. In this talk, outcomes from the stable isotope [phosphate oxygen (18OP)] will be combined with that of NMR, Raman, and IR spectroscopies to characterize phosphorus (P) sources and species in dissolved and particulate matter in the water column, discriminate external input and recycled sources, and connect biogeochemical processes in shallow sediment with overlying water column. Some of the key highlights include coupled carbon-phosphorus (C-P) cycling and dominance of the remineralization pathway of P cycling supporting late-stage eutrophication in the Chesapeake Bay. It will also include the most recent advances made in tandem mass spectrometry based position-specific isotope analysis (PSIA) in intact P molecules and fragments and insights derived for selective hydrolysis and synthesis of P compounds in natural environment. These outcomes are useful for high-resolution studies on P process as well as have implications for testing efficacy of nutrient management plans in agricultural runoff-dominated watersheds.

Dr. Jaisi is an environmental and isotope biogeochemist specializing in the high-resolution oxygen isotopic analysis of phosphate across diverse scales and ecosystems. His earned PhD degree in Geological Sciences from Miami University, postdoc as Interdepartmental Bateman Fellow from Yale University and NSF Fellow from California Institute of Technology. Dr. Jaisi has published 117 peer reviewed papers and book chapters.