Year Established: 2018 Start Date: 2018-07-01 End Date: 2019-06-30
Total Federal Funds: $41,299 Total Non-Federal Funds: $96,580
Principal Investigators: Joel Moore
Abstract: A growing number of studies have documented increasing chloride concentrations, [Cl–], in streams and lakes across the northern US. Chloride concentrations have been rising over the last several decades though researchers only started focusing on study of this subject in the last 15-20 years. The increase in [Cl–] in the northern US, and in other cold regions of the world, has largely been driven by the application of sodium chloride (NaCl) as a deicing salt. Rising [Cl–] raise a number of concerns including detrimental effects on organisms in aquatic ecosystems, diminished drinking water quality, and emerging evidence showing correlations with increased fluxes of organic carbon and nitrogen from soils. In many urban locations, [Cl–] frequently exceed the chronic criterion of 230 mg/L for ambient water quality set by US Environmental Protection Agency (EPA), which established with the goal of protecting aquatic life. Additionally, alteration of aquatic communities has been observed in streams with [Cl–] substantially lower than 230 mg/L. In fact, the Maryland Department of Environment (MDE) has reported that chloride is an important stressor resulting in biological impairment in a number of watersheds across Maryland. Most research on [Cl–] has focused on the use of grab samples collected on a biweekly to annual basis. Grab sampling has been quite useful for illustrating the long-term trends in [Cl–] and for beginning to understand the chronic exposure of aquatic organisms to chloride. However, chloride is often delivered in pulses from impervious surfaces to streams and lakes as the result of road salt application and weather conditions, e.g., snow melt. Given that grab sampling occurring as often as every 1–2 weeks is uncommon, it is unclear to both scientists and regulators assess how frequently the chronic criterion of 230 mg/L (based on four-day average) acute or the acute criterion of 860 mg/L (based on one-hour average) are exceeded within a three-year period. This project will focus on using continuous measurement of electrical conductivity (referred to as conductivity, hereafter, and collected as specific conductance [μS/cm]) by in-situ sensors in in combination with grab sample data for conductivity and [Cl–] to assess the temporal and spatial variations in chloride resulting from road salt inputs to Maryland streams. The US Geological Survey (USGS) and MDE have collected a substantial amount of continuous conductivity data along with complementary grab sample data across Maryland but do not have the resources to conduct in-depth analysis of some or all of these data. The synthesis of these data with water chemistry data collected by the PI’s lab from Maryland streams ranging from forested to urban settings will be used to develop insights on the extent of short-duration road salt inputs into streams. These data will be useful to regulators and resource managers focused on protecting Maryland’s freshwater resources.