The Origin and Distribution of Phosphorus in Western Lake Erie

The phosphate phosphorus distribution in western Lake Erie in May 1951 and the average concentration throughout 1950–1951 are shown to be a result of the drift current pattern and the discharge of the Maumee and Detroit Rivers. The bed rock in the lake appears to provide negligible quantities. The Detroit River supplies 405 metric tons per year at an average concentration of 2.6 µg PO4‐P/L, and the Maumee River supplies 125 tons at an average concentration of 43 µg PO4‐P/L. The remaining streams supply 39 tons at a concentration of 16 µg PO4‐P/L. There is a loss of soluble phosphorus, possibly as precipitating ferric phosphate and by adsorption onto ferric hydroxide. The bottom sediments are considerably enriched in phosphorus. Phosphate phosphorus and turbidity in the lake are positively correlated (r = +0.65), and evidence from turbidity data indicates that the lake is enriched by a thin‐layered tongue of water from the south shore streams which flow over or under the clearer, nutrient poor water, and then mixes vertically with it. Removal of fish by man accounts for an annual loss of 29 metric tons, or six per cent of the average annual input of phosphorus. Approximately 94 metric tons, 20 per cent of the average annual input, may be held temporarily as phytoplankton. Although phosphorus is probably never limiting in the southern waters of western Lake Erie, the accompanying turbidity sometimes prevents any significant phytoplankton growth.