Keywords

groundwater, road salt pollution, piezometer installation, Cokriging, freshwater salinization

Mentor

Alan Steinman

Abstract

Salinization of freshwater ecosystems through the use of road de-icing salts has altered both the chemical and biological structures of these systems. In addition to the contamination of surface waters, there are also increasing concerns about how groundwater is being affected by road salt pollution and its role as a potential pathway for salt to reach other freshwater systems. This study focused on an area in eastern Grand Rapids, MI where salt pollution from winter applications to the East Beltline Highway is affecting a string of three residential lakes. To assess the potential role of groundwater in the pollution of this system, this study 1) assessed the presence of groundwater seepage using field data and ArcMap, and 2) collected groundwater and surface water samples from all three lakes with drive-point piezometers. Groundwater samples were tested for chloride, an element of road salt, and soluble reactive phosphorus to assess road salt and nutrient pollution. Although baseline levels of chloride before exposure to road salt are unknown, all chloride measurements were above the Michigan chronic limit. This included the western end of the system (farthest from East Beltline), suggesting an east to west groundwater plume of salt may be responsible for the elevated chloride levels in this tri-lake system. Additional testing, perhaps including dye injections, is required to determine if groundwater is acting as a pollution pathway.

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