In many areas of the United States (US), application of deicing salts is a major contributor to elevated and increasing chloride concentrations and specific conductance. Elevated chloride concentrations can negatively affect aquatic ecosystems and drinking water quality. Understanding the factors that control chloride (and sodium) concentrations is essential to inform efforts to improve deicing salt application practices and reduce impacts on ecosystems and drinking water quality. Short-term variations in chloride concentrations over days to seasons are most influenced by direct inputs to streams and other surface water, frequently entering via stormwater drains. As a result, in many places chloride concentrations are higher in the winter. In-stream sensors measuring on the time scale of minutes often provide useful information on concentrations, especially during the winter. Long-term variations in chloride concentrations over years to decades are caused by indirect inputs to surface water, typically entering via groundwater inputs at baseflow. Over the long-term, concentrations have been increasing for years to decades in many locations. An unintended but related consequence of stormwater management is increasing chloride concentrations in groundwater, which causes stream concentrations to increase over the long-term. A key wrinkle in understanding the susceptibility of aquatic communities is that the negative effects of chloride are connected to both background conditions (surface waters with low versus high dissolved solids) and to the mix of ions present in surface water.
Joel Moore, Professor of Geosciences; Interim Director for Environmental Science & Studies; Coordinator for Urban Environmental Biogeochemistry Laboratory; Department of Physics, Astronomy, and Geosciences; Towson University, Towson, MD
Joel Moore is a Professor of Geosciences at Towson University near Baltimore, Maryland. He received his Ph.D. in Geosciences from Penn State University and was a postdoctoral fellow at Northwestern University. Since starting at Towson in 2011, a major focus for his research lab has been geochemistry in urban systems, including deicing salt impacts on streams and groundwater. Since 2020 he has served as Deputy Director of the Urban Critical Zone Cluster, 1 of 9 National Science Foundation projects funded for 5 years to conduct research on the critical zone (the region from the tree tops to the bottom of groundwater flow). He and others in the Urban Critical Zone Cluster are investigating how urbanization affects the export of water, solutes, and sediments in urban centers on the east coast of the US from Philadelphia to Raleigh (and beyond). Joel has served on the board of the Maryland Water Monitoring Council and was involved in a multi-year Salt Management Strategy project organized by the Virginia Department of Environmental Quality, including serving on the steering committee. His research is informed by regular conversations with the Maryland Department of Environment, Maryland Department of Natural Resources, reservoir technical groups, and groups involved in stormwater management (e.g., the Chesapeake Stormwater Network).