Conductivity of Runoff and Percolation Water during Winter and Spring Storm Events.

Salt is added to Rhode Island roadways to improve road conditions during winter storms. However, salt adversely affects roadside communities and may impact aquatic ecosystems. The current project measures salt concentration in run-off and percolation water from road side verges with the goal to provide information to conduct trials that test the salt resistance of native grass species. Six sites were set up with suction cup lysimeters, installed at 25 cm depth, from October to November 2007. These sites were on heavy traffic interstates (I95, two at I295) and busy state routes used for commuting (RI 146, RI4 and RI1). Three of the sites were in the northern part of Rhode Island that receives more intense and more frequent snow storms than the Southern part where lysimeters were installed at three locations. The conductivity of snow (thawed), snowmelt and percolation water was measured on storm events and snow melt days from December 2007 to March 2008. Snow itself displayed conductivities of 200 to 3000 uS/cm during the measurement period. Overland flow and soil water at 25 cm depth had conductivities of between 400 to greater than 20000 uS/cm. Several surface waters downstream from the roadside had elevated salt concentrations. Conductivity of soil water rapidly decreased after early March and was variable both along the road side and as a function of distance from the roadside. Concentrations in soil water increased again in May.