Sources and pathway of phosphorus cycling in the Chesapeake Bay: Results from isotope, EXAFS, NMR, and Mossbauer analyses

Deb P Jaisi

Department of Plant and Soil Sciences, University of Delaware

531 S College Ave., Newark, DE 19716

E-mail: jaisi@udel.edu; Tel: (302) 831-1376; Fax: (302) 831-0605

Webpage: http://sites.udel.edu/ebl/

Coastal regions of the world are suffering from increasinglywater quality issues fuelled by both point and non–point nutrient sources. My research team pairs phosphate oxygen isotope technique with a suite of mineralogical (XRD), microscopic (SEM and TEM), and spectroscopic (¹H and ³¹P NMR, ⁵⁷Fe Mossbauer, and Synchrotron X-Rayabsorption) methods to identify sources, compositions, degradation and recycling of phosphorus in the water and sediment columns. In our recent study, remineralization efficiency of particulate P in water column and pathway of sediment P cycling inthe sediment was analysed. It was found that significant remineralization of particulate P occurs in the water column with consistent decrease in diester-to-monoester ratios with water depth. In the sediment column, remineralization of organic P was found to be the predominant pathway of P cycling and generating inorganic P that precipitates into authigenic apatite as well as effluxes out of the sediment-water interface. Overall, these findings provide new scientific insights on the sources and pathways of P cycling in nutrient rich ecosystem.