GROUNDWATER CHLORIDE EXPOSURE TO URBAN FRESHWATER (ENDO)BENTHIC ECOSYSTEMS

Chloride is also one of the most ubiquitous contaminants of groundwater in urban areas, with sources including road de-icing salts, industrial discharges, water softeners, domestic waste, landfill leachate, road dust suppressants, and fertilizers. The discharge of chloride-contaminated groundwater to urban surface water bodies poses a risk to freshwater ecosystems, especially to endobenthic organisms (buried or burrowing in the benthic zone) because they may experience less diluted concentrations than organisms on the sediment surface or in the overlying water. But the available information on such concentrations for urban freshwater bodies is limited. Here we collate and analyze sediment pore-water / discharging groundwater data from 11 different urban sites across Canada (3 lake shores, 8 streams/rivers) to provide broader context to the threat posed by chloride in groundwater to aquatic endobenthic ecosystems of urban water bodies. These data are discussed in relation to their different sources, the spatial variation at different scales, toxicity endpoints, and in comparison to literature findings for wells and urban surface waters.