AN ELEMENTAL AND MINERALOGICAL COMPARISON OF LAKE SEDIMENTS TO WATERSHED SOILS IN WESTERN NEW YORK

This study aims to assess the sedimentary record of the north basin of Conesus Lake with its corresponding watershed soils. Conesus Lake is the westernmost lake of the Finger Lakes (Livingston County, NY) and has been undergoing remediation efforts after experiencing cultural eutrophication in the mid-late 20th century. The northeast watershed of Conesus Lake is a subwatershed and is the main source of sediment and water delivery for the northeastern portion of the lake. The sediments in the north Conesus Lake basin are distinct from the rest of the lake. Using ArcGIS and LIDAR, the northeast watershed was mapped using the New York State GIS Program Office data. From the bedrock and surficial geology of the watershed, three locations were selected for soil cores. A sedimentary core from a single location in the north basin was used for comparison with the soil cores from the northeastern subbasin. Using techniques of X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF), this study aims to determine the origin of north basin sediment delivered to the north basin of Conesus Lake.

At each watershed location, soil probes collected ~30cm of sediment. Smear slides were used to classify the texture and organic composition of the soils. A Thermo Scientific™ Niton™ XL5 Plus handheld XRF analyzer was used to quantify the abundance of elements in the soil at 3-6 cm increments. Scanning electron microscope (SEM) stubs of soil were analyzed for texture and composition using SEM-EDS. XRD analysis of samples were assessed to add confidence in identification. The soil elemental, mineralogical, and textural compositions were compared to the elemental and mineralogical data collected from the lake basin core. A piston core collected at 11.13 m water depth from the north basin of Conesus Lake resulted in 145.5 cm of core. The core was split, imaged, and analyzed using a Geotek multi-sensor core logger. XRD data was collected from the sediments at 6 cm intervals.

Preliminary results identified that the mineralogy of the soil and lake cores are compositionally aligned. Concentrations of dolomite occur in the soil and lake cores as a detrital mineral. Calcite appears authigenically in the soil and lake cores. Soil diatoms only appear distal from the lake with low diversity and abundances. Similarly, aquatic diatoms are sparse throughout the lake core.