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Algal blooms in the Western Basin of Lake Erie are dependent upon nutrients provided by major rivers within Northwest Ohio. To develop more accurate methods of defining which of these waterways is the largest contributor, a proof of concept study is being conducted using δ18O of phosphate molecules. In the summer of 2016, under relatively low stream flow conditions, 10-20L samples of water were collected at the several major branches within the Portage River, at the mouths of the Portage, Maumee, and Sandusky Rivers, and at two locations within the Western Basin. In the spring of 2017, these collections were repeated during high flow or flood conditions. Silver phosphate was then precipitated from these water samples for δ18O analysis.For comparison of our water collections with possible PO4 sources, δ18O of various fertilizers, wastewater effluents, and manures were also analyzed.Water samples that were collected during low flow conditions supported our expectation of lower δ18O, a reflection of higher biological processing and values near that of equilibrium calculations. Water collections at high flows exhibit a reciprocal pattern with much higher δ18O. This was again expected as lower retention time within streams restricts biological processing and allows the δ18O of potential sources to be more evident. These δ18O values, collectively, will provide insight into the validity of this novel method of tracking inorganic phosphorus.
Biology | Ecology and Evolutionary Biology
Marshall , M. M., Metzner , G. K., & McCluney , K. E. (2020). Using δ18O to track PO4 entering the Western Basin of Lake Erie. .