Chloride Toxicity to Native Freshwater Species in Natural and Reconstituted Prairie Pothole Waters.

Oil and gas extraction in the Prairie Pothole Region (PPR) of the northern USA has resulted in elevated chloride concentrations in ground and surface water due to widespread contamination with highly saline produced water, or brine. The toxicity of chloride is poorly understood in the high hardness waters characteristic of the region. We evaluated the toxicity of chloride to two endemic species, Daphnia magna (water flea) and Lemna gibba (duckweed), exposed in field-collected waters (hardness ~ 3000 mg/L as CaCO) and reconstituted waters (hardness 370 mg/L as CaCO) intended to mimic PPR background waters.