Biotic and Abiotic Factors Contributing to P Movement in the Landscape.
Jane E. Hill1, Barbara Cade-Menun2, and Menachem Elimelech1. (1) Yale Univ, Dept of Chemical Engineering, 9 Hillhouse Ave, New Haven, CT 06520, (2) Stanford Univ, Dept Geological & Envl. Sci., Stanford, CA 94305-2115
Phosphorus flux from agriculture into water bodies contributes to algal blooms (some harmful), anoxia, and fish kills every year in regions host to intensive agricultural operations, like the Chesapeake Bay. The major culprit is the animal waste that is often composted and then spread onto croplands as a fertilizer. While the nitrogen sources are relatively bioavailable (and often, in their own right, a eutrophication agent), P sources are usually bound by metals and organic carbon in a complex interplay of sorption and desorption kinetics. The Phosphorus Site Index (PSI)--a relatively inexpensive and easy-to-use tool to predict the risk associated with soils in this region–-is helpful, but does not adequately capture one of the major potential contributors to phosphorus pollution, myo inositol hexakisphosphate (phytate). Indeed, little is known about its fate in these systems and elsewhere. My work seeks to link the incidence of phytate and the population of microbes that transform the compound, influencing its fate and that of other P forms in soil and sediment systems. In this presentation, I communicate a case study at two impacted sites on the Delmarva Peninsula where a rigorous analysis of soil chemistry, P species, molecular biology, and enzymology have been at least partially married, to reveal microbes from specific redox zones (like thiosulfate at the aerobic/anaerobic interface) that are particularly adept at transforming phytate. The implications of this have consequences not only for the Chesapeake Bay and other impacted regions, but also, for understanding ways to influence soil fertility, as well.