Chloride hydrogeochemistry of the finger lakes in Central and Western New York, USA

Abstract

Road deicing salts have impacted the hydrogeochemistry of lakes throughout the snow-belt region of the globe. This paper advances our understanding of the historical change in salt concentrations in, and sources to, the Finger Lakes of western and central New York state, and compares the results to other lakes across the globe. Surface water samples from Honeoye, Canandaigua, Keuka, Seneca, Cayuga, Owasco, Skaneateles and Otisco lakes were analyzed for chloride (Cl) concentrations, and augmented with published and unpublished decade, and for the first time, century-scale Cl data for these lakes and Hemlock Lake. A mass-balance model estimated the Cl flux required to match the measured Cl concentrations in each lake. Cl concentration and flux trends defined two groups of lakes. Group 1: A mid-1900′s peak in Cl concentrations was detected in Seneca and Cayuga lakes, that resulted from a short but significant spike of Cl, most likely from salt mine wastes during pre-Environmental Protection Agency times. Group 2: Hemlock, Honeoye, Canandaigua, Keuka, Owasco, Skaneateles and Otisco lakes, revealed smaller yet increasing concentrations and fluxes over time that were interpreted to reflect increasing use of road deicing salts in their watersheds and supported by correlations to their state and federal road lengths, percentage of impervious surfaces, water residence times in each watershed and the production of road salt in the US, but not to their trophic status, nor their percentage of agricultural land. Estimated Cl inputs from municipal wastewater treatment facilities, individual septic systems and the atmosphere (precipitation) were also insignificant in the Finger Lakes region. These results help clarify the processes responsible for increasing Chloride concentrations in lakes globally.