Monitoring Chloride Concentrations of the Pike River in Southeastern Wisconsin
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Scientists are revisiting the effects of road salt on aquatic ecosystems.1,2 According to the US Environmental Protection Agency, chronic chloride contamination occurs at 230 ppm and acute chloride contamination results at levels exceeding 860 ppm.3 Since Fall 2007, the chloride ion concentration of six sites on the lower Pike River has been quantified with a chloride ion selective electrode. The Pike River empties into Lake Michigan and it is adjacent to several major roadways. To obtain a more representative sample of the river, five new sites were added along the entire Pike River, including the headwaters of the Pike River where the river is narrow and shallow. The chloride ion concentration was consistently higher near the headwaters of the Pike River except after heavy rain events. Overall, river data for Spring 2010 shows a baseline chloride ion concentration of 57.00 ± 2.19 ppm for early March, which spikes to 221.2 ± 25.3 ppm by the end of March due to melting snow and runoff into the river. The readings in early May remained high at 131.7 ± 19.7 ppm and finally dropped to 75.1 ± 1.7 ppm by May 14, 2010. The lack of rainfall during Spring 2010 may be the cause of the stagnant high chloride concentration levels in the Pike River. Future research will model the flow and hydrological characteristics of the river, including seasonal changes of river depth, width, and velocity to better understand the movement of chloride in the Pike River.