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In this article by G. C. Bortleson and G. F. Lee [Environ. Sci. Technol., 6 (9), 799-808 (1972)], in Figure 4, the date at the 40-cm level should read 1895 rather than 1875.

Depositional patterns of iron, manganese, and phosphorus in one central and five northern Wisconsin lakes ranging from oligotrophic to eutrophic, primarily from natural causes, have been investigated.One-meter cores from one or more locations within each lake were analyzed.The historical pattern of iron and manganese deposition is closely related to the pattern of phosphorus deposition in most of the cores. Four of the nine cores show a strong positive correlation coefficient between P and Fe and seven between P and Mn. Manganese has more predictive value than iron for determining the concentration of phosphorus in a given core; however, the iron content appears to be the dominant factor in the phosphorus sorptive and retentive capacity of sediments.

Analysis of 32 surface sediment samples from different areas of Lake Mendota, Wis., indicated a high positive statistical correlation between Mn, Fe, and P concentration in the sample and the depth of water overlying the point of sample recovery. An inverse correlation was found for Mg and K. No statistical correlation between concentration and depth of sample recovery was found for Ca and Na. urface sediment samples were collected from Lake S Mendota, Wis., during the summer and early fall of 1967.The purpose of the sampling was to assess the chemical composition of the sediments with respect to water depth and location in the lake. Studies conducted during the early 1950's reported by Rohlich (1963) indicate that N, P, and Fe concentrations become greater with increasing depth of water, Later work by Nriagu (1968) showed a correlation between the concentration of total-and sulfide-S and depth of overlying water for seven sediment samples collected from the central area of Lake Mendota, with depths ranging from approximately 11 to 25 meters. Gravity core sediment samples from different areas of Lake Mendota were collected by Murray (1956). The sediments in the deeper areas of the lake were typically black sludge or gyttja, resting on top of buff-colored marl deposits. The average CaC03 content of the black sludge is 32 x (dry weight basis). The sludge in the deeper area of the lake generally showed a higher carbonate content than sludge in shallower areas. Lee (1962) summarized previous studies that found shifting of the bottom muds in University Bay, located in the southcentral part of the lake. This was determined by plotting concentration contours for the summer and winter seasons. The variations in the element distribution contours were attributed to the effects of bottom currents induced by strong winds which prevail during fall and winter. An extensive survey of the circulation of Lake Mendota was conducted by Bryson and Suomi (1952). They found that wind-driven epilimnetic waters resulted in a depression of the thermocline in the downwind portion of the lake. A resultant upward release of this depression created measurable hypolimnetic currents. These hypolimnetic currents would be sufficient to disturb the extremely flocculent surface sediments. Gardner and Lee (1965) reported that scuba divers operating in the waters above the surface sediments created sufficient water currents to agitate the sediments, resulting in highly turbid bottom water conditions. Thus, continuous wind-driven circulation of the epilimnion, followed by hypolimnetic circulation, would account for the displacement and partial alteration of sedimentary element distribution patterns.The study reported here extends the available information Present address, Department of Chemistry (DFC), USAF Academy, Colo. 80840. about the distribution of certain elements in the surface sediments of Lake Mendota. The results show the effect of depth and possibly bottom morphology on the concentration of elements in surface sediments, and thus can ...