GEOCHEMICAL ANALYSIS OF A KETTLE LAKE IN UPSTATE NEW YORK

Mud Lake is a kettle lake, a remnant of the last glaciation, sitting on the top of a hill at approximately 1800 ft elevation in the Robert V. Riddell State Park near Davenport, NY. The lake is surrounded by a bog and no fish live in the lake. The only known water input to the lake is meteoric water and the only outlet is of anthropogenic origin. The bedrock is mainly sandstone and siltstone with some interbedded shale providing low acid buffering capacity. Mud Lake is an acidic lake with an approximate open water surface area of 7850 m² and 5 m maximum depth at the middle of the lake. The goals of this study are to determine the inorganic geochemical properties of the lake and investigate the seasonal changes of the lake. The results of two sampling campaigns in spring and summer are reported. Water samples were collected along a North-South cross-section of the lake at several depths. Temperature, dissolved oxygen, pH and total dissolved solids were measured on site using a handheld multi-probe instrument. Cation and anion concentrations were determined using inductively coupled plasma optical emission spectrometry and ion chromatography, respectively. Spring and summer results are similar. Temperature decreases to 10 ^oC by 2.5 m depth and remains constant to maximum depth. Dissolved oxygen concentrations decrease rapidly, dropping below 5 mg/L at 1 m depth and reaching nearly zero mg/L by 1.5 m depth. The pH is consistently between 4.2 and 5.3 through the seasons. The values of the total dissolved solids, 12-18 mg/L, are indicating very low dissolved ion content of the lake, which are consistent with the low cation and anion concentration results. Nitrate and sulfate are the dominant anions reaching 1.2 and 2.8 mg/L concentrations in the surface waters and decrease to 0.6 and 1.6 mg/L at the bottom, respectively. Chloride is below 1 mg/L in all samples, but it increases with depth. Calcium, sodium and magnesium are present below 1 mg/L concentrations and other metals are below 0.2 mg/L for all samples. The low amount of dissolved species support that the lake’s only water input comes from meteoric water and weathering processes of the surrounding bedrock only add small quantities of cations and anions to the water. Further sampling and monitoring is required to understand seasonal changes of the lake.