IDENTIFYING SOURCES OF SALINITY IN THE TIOUGHNIOGA RIVER USING HALOGENS AS A SENSITIVE TRACER

Concentrations of halogens in surface water and groundwater have risen since the application of deicing salts to roadways began, but how much of the salinity changes can be attributed to anthropogenic sources? The Tioughnioga River is the headwater of the Chesapeake Bay system, where water quality has become an ongoing problem. The Tioughnioga River begins as two branches, in central New York, where road salts are applied heavily during winter months. The West Branch runs parallel to an interstate highway (I-81) and boasts an approximately 10% greater urbanized land use than the East. From September 10^th 2012 to November 29^th 2014 flow measurements were conducted and weekly water samples were collected at East and West Branches. Sampling of the rivers longitudinally was completed six times in 2014. Samples were analyzed for major ions using Ion Chromatograph, and for I^- and Br^- on ICP-MS. The purpose of this study is to characterize the sources of salinity in the watershed primarily through the use of the unique chemical ratios of I^-, Br^-, and Cl^-to distinguish among sources. Dilution effects are evident during high flow conditions. Ratios of I/Br suggest that in addition to de-icing salts, groundwater is another source of salinity. Water in the East Branch is typically more pristine, however offers indications of the influence of a deeper source. The water of the West Branch resembles a glacial aquifer system affected by deicing agents. The respective ratios of halogens, including iodine, demonstrate the potential of serving as a novel and sensitive approach to identifying the sources of salinity in water.