Widespread and increasing use of road deicing salt is a major driver of increasing lake chloride concentrations, which can negatively impact aquatic organisms and ecosystems. We used a simple model to explore the controls on road salt concentrations and predict equilibrium concentrations in lakes across the contiguous United States. The model suggests that equilibrium salt concentration depends on three quantities: salt application rate, road density, and runoff (precipitation minus evapotranspiration). High application combined with high road density leads to high equilibrium salt concentrations regardless of runoff. Yet if application can be held at current rates or reduced, concentrations in many lakes situated in lightly to moderately urbanized watersheds should equilibrate at levels below currently recommended thresholds. In particular, our model predicts that, given 2010–2015 road salt application rates, equilibrium chloride concentrations in the contiguous United States will exceed the current regulatory chronic exposure threshold of 230 mg L⁻¹ in over 2000 lakes; will exceed 120 mg L⁻¹ in over 9000 lakes; and will be below 120 mg L⁻¹ in hundreds of thousands of lakes. Our analysis helps to contextualize current trends in road salt pollution of lakes, and suggests that stabilization of equilibrium chloride concentrations below thresholds designed to protect aquatic organisms should be an achievable goal.

中文翻译：

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湖泊道路盐污染上限

道路除冰盐的广泛使用和不断增加是导致湖泊氯化物浓度增加的主要驱动因素，这会对水生生物和生态系统产生负面影响。我们使用一个简单的模型来探索对道路盐浓度的控制，并预测美国本土湖泊的平衡浓度。该模型表明，平衡盐浓度取决于三个量：盐施用率、道路密度和径流（降水量减去蒸散量）。无论径流如何，高应用与高道路密度相结合都会导致高平衡盐浓度。然而，如果可以按目前的速度保持或减少施用量，位于轻度至中度城市化流域的许多湖泊的浓度应平衡在低于当前建议阈值的水平。特别是，我们的模型预测，考虑到 2010-2015 年道路盐的施用率，美国本土的平衡氯化物浓度将超过 2000 多个湖泊目前监管的长期暴露阈值 230 mg L -1 ^；9000多个湖泊将超过120 mg L ^{−1 ；}数十万个湖泊的浓度将低于 120 mg L ^{-1 。}我们的分析有助于了解当前湖泊道路盐污染的趋势，并表明将平衡氯化物浓度稳定在旨在保护水生生物的阈值以下应该是一个可实现的目标。