COLLOIDAL PHOSPHORUS TRANSPORT DURING STORM EVENTS IN THE MAUMEE RIVER WATERSHED

One important driver of eutrophication in aquatic ecosystems is bioavailable P loading. The most abundant form of bioavailable P is soluble reactive P (SRP), which is commonly assumed to be all phosphate even though standard methods measure any P molecule which passes through a 450 nm filter and binds with molybdate under acidic conditions. In lotic systems, colloidal particles (~5 – 450 nm) can be important inorganic and organic P carriers; however, the bioavailability of colloidal P can be lower than phosphate, suggesting that we may overestimate bioavailable P concentrations when colloidal-SRP is high. Thus, it is important to understand the spatial and temporal patterns in colloidal-SRP concentrations. Since colloid exports from agricultural systems are generally highest following a drying-rewetting cycle, and one of the effects of climate change in the Midwest U.S. is stronger storms with higher rainfall amounts, we predicted that stream colloidal-SRP concentrations would be highest during storm events. We combined biweekly monitoring of three streams with storm event sampling in 12 different tributaries throughout the Maumee River watershed (NW Ohio). We measured dissolved and colloidal-SRP, along with the concentrations of potential P-binding elements and compared it to periods of no rainfall. The fraction of SRP in the colloidal fraction was very low during low to moderate flow periods, but higher during storm events. Understanding the spatiotemporal variation in colloidal P concentrations will advance our knowledge of P cycles and improve eutrophication management.

Primary Presenter: Ashlynn Boedecker, Ohio State University (boedecker.4@osu.edu)

Authors:

Ashlynn Boedecker, Ohio State University  (boedecker.4@osu.edu)

Matthew Sens, Ohio State University  (sens.25@osu.edu)

Katarina Funk, Ohio State University  (funk.193@osu.edu)

Morgan Shaw, Ohio State University  (shaw.759s@osu.edu)

John Lenhart, Ohio State University  (lenhart.49@osu.edu)

Michael Brooker, Ohio State University  (brooker.26@osu.edu)

Justin Chaffin, Ohio State University  (chaffin.46@osu.edu)

Benjamin Colman, University of Montana  (ben.colman@mso.umt.edu)

Laura Johnson, Heidelberg University  (ljohnson@heidelberg.edu)

Vinayak Shedekar, Ohio State University  (shedekar.1@osu.edu)

James Hood, Ohio State University  (hood.211@osu.edu)