THE GEOHISTORICAL RECORD OF ANTHROPOGENIC EFFECTS IN THE SOUTH BASIN OF CONESUS LAKE, WESTERN NEW YORK

This study aims to establish a geohistorical record of the south basin of Conesus Lake, a small Finger Lake in western New York (Livingston County, NY). Conesus Lake is categorized as a mesotrophic lake that experienced cultural eutrophication, causing harmful cyano-algal blooms in the mid-late twentieth century. Since 1999, stakeholders have made a concerted effort to reduce nutrient loading. This remediation resulted in Conesus overcoming its 2002 listing as phosphorus impaired and 2006 listing as oxygen impaired. In order to track pre-and post-European impacts on the environment of the lake, it is necessary to consult the geohistorical record. The geohistorical record will be assessed using analytical techniques that will illustrate the mineralogy, elemental composition, organic and sedimentary signal of anthropogenic influence.

Piston and Bolivia cores were collected from sites in the south basin of Conesus lake. A Piston core was collected at 17 m in depth and resulted in 127 cm of cored sediments. Additional Piston and Bolivia cores were collected at 1.8 m in depth resulting in a composite core of 154 cm. All three cores were split, imaged, and analyzed using a Geotek multi-sensor core logger at Syracuse University for magnetic susceptibility (MS) and X-ray fluorescence (XRF). X-ray diffraction (XRD) was assessed at key intervals to compare to XRF trends. Smear slides and sediments were sub-sampled and processed for diatoms at six cm intervals. One core was sub-sampled at one cm increments for 210Pb dating at St. Croix Watershed Research Station along with loss on ignition analysis.

Changes in mineralogy and elemental trends coincide with significant historical events such as European settlement in the 1790’s and the introduction of industrial practices in the 1850’s. XRF data indicates the introduction of lead at 55 cm through its use in paint and gasoline in 1920, and the increase in concentration as its uses became common, then decreasing concentration towards the present as it was phased out. The abundance of anthropogenic related elements in the lake are minimal but show increases from 63 cm to 30 cm corresponding to multiple MS peak accumulations in the lake. Towards the present, the mineralogy and elemental trends display a gradual decline in concentrations caused by the past 25 years of local remediation efforts.