Long-term trends in sodium and chloride in the Mohawk River, New York: the effect of fifty years of road-salt application

摘要

Ecological studies have demonstrated the adverse effects of road-salt, primarily NaCl, on water quality, flora, and fauna. In this study, we quantified changes in ionic composition and solute flux of water draining the Mohawk River Basin (9103 km~2) in New York State, from 1952 to 1998. Using various statistical, graphical, and modeling techniques, we showed that concentrations of Na~+ and Cl~- have increased by 130 and 243%, respectively, while other constituents have decreased or remained constant. The use of de-icing salt on roads within the watershed, which we estimate at 39 kg km~(-2) day~(-1), appears to be the primary mechanism responsible for reported increases, accounting for the increase in NaCl export from 16 to 46 kg km~(-2) day~(-1) over the 47-year period. Moreover, despite population decline within this rural upstate watershed, increased environmental stewardship, and The Clean Water Act, concentrations of Na~+ and Cl~- still increased during the 1990s.