Recent Sedimentary History of Lake Mendota, Wis.
The chemical composition of several sediment cores taken from Lake Mendota, Madison, Wis., has been investigated to determine changes in the flux of various chemicals to this lake. The uppermost sediments consist of approximately 1/2 meter of black gyttja. The chemical stratigraphy of a 9.9 meter-long core indicates that stable conditions existed in Lake Mendota and its watershed prior to the settlement of the area surrounding the lake by white man in the mid to late 1800s. Since that time, there has been an appreciable increase in the amounts of phosphorus, iron, manganese, aluminum, and potassium in the uppermost sediments. The organic carbon content of the sediments has fluctuated several times in the past with the most recent sediments showing slightly higher values than the older sediments. This study has demonstrated the feasibility of using the chemical composition of lake cores to estimate the influence of cultural activities of man on the rate of eutrophication of a lake.