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ARS Home » Midwest Area » Columbus, Ohio » Soil Drainage Research » Research » Publications at this Location » Publication #366028
Research Project: Agricultural Water Management in Poorly Drained Midwestern Agroecosystems

Location: Soil Drainage Research

Title: Internal phosphorus storage in two headwater agricultural streams in the Lake Erie basin

Author
item CASILLAS-ITUARTE, NADIA - The Ohio State University
item SAWYER, AUDREY - The Ohio State University
item DANNER, KELSEY - The Ohio State University
item King, Kevin
item COVAULT, ALEXANDRA - The Ohio State University

Submitted to: Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2019
Publication Date: 11/25/2019
Citation: Casillas-Ituarte, N.N., Sawyer, A.H., Danner, K.M., King, K.W., Covault, A.J. 2019. Internal phosphorus storage in two headwater agricultural streams in the Lake Erie basin. Environmental Science and Technology. 54:176-183. https://doi.org/10.1021/acs.est.9b04232.
DOI: https://doi.org/10.1021/acs.est.9b04232

Interpretive Summary: Eutrophication or nutrient enrichment of both coastal and inland water bodies continues to plague many parts of the world. The Gulf of Mexico and Lake Erie highlight the eutrophication issues in the United States. With respect to Lake Erie, phosphorus is the primary nutrient responsible for the resurgence in harmful and nuisance algal blooms. The source of that phosphorus has been the topic of much debate by the research, action agency, and stakeholder communities. Legacy phosphorus or that amount of phosphorus that has been built up in the field and stream sediments is thought to be a significant source of phosphorus to Lake Erie. Analyses from two agricultural drainage ditches within the Lake Erie watershed revealed that internal phosphorus can account for a substantial amount P delivery. Furthermore, the amount of internal phosphorus loss varied with stream hydrologic characteristics and did not appear to be as influenced by upland production or conservation practices. These findings should be beneficial to Lake Erie stakeholders in identifying practices and approaches to meet the 40% binational phosphorus reduction goals and address the eutrophication issue.

Technical Abstract: Internal phosphorus (P) in aquatic sediment plays an important role in the nutrient dynamics of lakes, sometimes long after external loads have been reduced. Similarly, internal P sources may drive the nutrient dynamics of small agricultural streams that feed larger eutrophic rivers and lakes, despite best management practices intended to reduce external P loads from adjacent farm fields. Here, internal P concentrations were measured on cores from two small agricultural streams during spring and summer in the drainage basin of Lake Erie, a large, eutrophic lake experiencing increasing SRP loads. Average total extractable P concentrations were similar to within 5% during spring and summer, but mobile P binding fractions nearly doubled in summer, possibly due to accelerated rates of organic matter mineralization or iron reduction beneath suboxic, stagnant surface waters. One site had chronically greater internal P concentrations by 25 to 75%, despite the implementation of best management practices such as grass buffers. The site also had more aquatic vegetation that restricted flow, less dissolved oxygen in surface water, and greater organic matter in sediment during both seasons, suggesting that variations in hydrology, sediment composition, and vegetation influence hot spots of P retention throughout small agricultural streams.