Salt Levels up in Northeast

The salt levels in freshwater in the northeastern U.S. are rising thanks to increases in the number of roads and in the use of deicers in the winter.

A team led by Sujay S. Kaushal, Peter M. Groffman, and Gene E. Likens at the Institute of Ecosystem Studies, Millbrook, N.Y., measured chloride levels in streams in Maryland, New York, and New Hampshire (Proc. Natl. Acad. Sci. USA, published online at www.pnas.org/cgi/doi/10.1073/pnas.0506414102). They found an increase in the baseline chloride concentration over the past 30 years, exceeding 100 mg/L on a seasonal basis in some places.

Assuming a linear rate of increase, the authors estimate that chloride levels in some streams will exceed 250 mg/L in the next century, making them toxic to sensitive freshwater life and not potable for humans.