BATCH EXPERIMENTS TO UNDERSTAND PHOSPHOROUS AND FINE PARTICLE TRACER INTERACTIONS

Small agricultural streams connect cropland to large water bodies like Lake Erie, which is experiencing steady dissolved phosphorus (P) enrichment from agricultural activities. The travel times of P from croplands to large eutrophic water bodies are uncertain and depend in part on dissolved P interactions with fine particles in the water column and streambed. In the last decade, new tracers have emerged to help quantify the movement of particulates, and opportunities abound to use those tracers in combination with traditional K₃PO₄ injections in small streams. To do so, it is first necessary to quantify the sorption behavior of dissolved P on particle tracers. We are performing a series of batch experiments using dissolved P and Dayglo fine particles under a range of concentrations with both deionized water and natural agricultural stream water. Samples are being analyzed for dissolved P concentration using a Skalar SAN++ Continuous Flow Analyzer and for particle concentrations based on fluorescence using a Horiba Scientific Aqualog spectrofluorometer. From batch experiments, we will quantify adsorption isotherms and adsorption kinetics over timescales of hours, or the typical duration of stream tracer experiments. This information will help advance new tracer experimental methods and mathematical models for P transport in small agricultural streams.