USING HALOGENS AND DISCRIMINANT ANALYSIS TO DISTINGUISH AMONG SOURCES OF SALINITY IN THE TIOUGHNIOGA RIVER, CENTRAL NEW YORK

Road salt is an emerging contaminant that is a prominent focus of numerous water quality studies. The Tioughnioga River, located in central New York, is a headwater of the Susquehanna River, which flows into the Chesapeake Bay. In central New York, road salts are applied heavily during winter months. The two branches of the Tioughnioga River with contrasting land-use types provide an ideal opportunity to test and apply novel approaches for detecting different sources of salinity.

From September 10^th, 2012 to November 29^th, 2014 flow measurements were conducted and water samples were collected weekly at the East and West Branches of the Tioughnioga River. Samples were analyzed for major ions using Ion Chromatography, for I^- and Br^- on ICP-MS, and for δ²H and δ ¹⁸O on a Picarro Water Isotope Analyzer. The purpose of this study is to characterize the sources of salinity in the East and West Branches of the Tioughnioga River primarily through the use of the unique chemical ratios of I^-, Br^-, and Cl^-. Concentrations of major ions, I^‑, and Br^- were used in a multivariate statistical model to determine the most probable sources of salinity for each sample. Furthermore, we compare these classifications to those derived from linear discriminant analysis.

Halogen ratios suggest that in addition to de-icing salts, groundwater is another source of salinity. Concentrations of ions are relatively low in the East Branch, with the exception of I^-, suggesting deep, saline groundwater (e.g. Appalachian brine) is a salinity source. The West Branch appears to be a glacial aquifer system where de-icing salts serve as the primary source of salinity. Discriminant analysis indicates Appalachian Basin Brines are mixing with stream water in the East Branch, whereas road salt is the dominant source of salinity in the West Branch.