Road salt in the environment: loads, lags and consequences.
Monday, 15 December 2014
Increased use of road salt over the past few decades has, not surprisingly, led to higher Na and Cl concentrations in dispersed parts of the environment. We have tracked these changes over southeastern New York for the past 20+ years and can show a clear link to road density as an explanatory factor for local concentrations. The unexpected findings center around retention of Cl in streams and shallow groundwaters long after the winter season has passed and this can result in average summertime concentrations as high as monthly mean concentrations during the snoa and ice season. These persisten concentrations have consequences for aquatic life as well as local water resources. Literature suggests these high summer values may cause harm to some sensitive organisms.Experiments show both susceptibility and adaptation by local stream algal communities. Analysis of reported data from private drinking water wells shows a sub-set has Cl levels above the EPA secondary standard and these exceedances are apparently associated with local salt application rates. The problems of rising salt are significant given the magnitude of salt release to the environment but also tractable in the sense that there are multiple motivations for minimizing application rates while maintaining public safety. The salinization issue has also proven a useful tool for public engagement since the problem is widespread yet comprehensible.