HYDROLOGICAL-MICROBIAL INTERACTIONS CONTROLLING LANDSCAPE PHOSPHORUS MOBILITY

Freshwater eutrophication from anthropogenic phosphorus sources is a persistent and acute global water quality problem. Despite decades of effort to improve water quality, nonpoint sources of phosphorus continue to be implicated as the major source in many watersheds, which suggests there are critical mechanisms controlling phosphorus transport that are not well understood. One critical knowledge gap is the disconnection between hydrologic sciences and environmental microbiology. The immediate goal of this project is to improve the scientific understanding of how the interactions between hydrology and microbial processes affect phosphorus mobility and retention in the landscape. This project focuses on phosphorus mobilization-retention roles played by microbial activities unique to parts of the landscape prone to different patterns of saturating-drying cycles, from nearly perennially-saturated (e.g., in streams) to rarely saturated (e.g., steep upland areas). The specific objectives are to determine the relative roles of several microbially-mitigated phosphorus release-retention processes in agricultural watersheds. The long-term objective of this research is to develop better land- and water-management strategies that capitalize on improved hydro-microbiological insights for reducing nonpoint source nutrient enrichment of freshwater bodies.