Salt Concentration Measurement Using Re-usable Electric Conductivity-based Sensors

Human activities alter salt concentration of water sources such as lakes, ponds, wetlands and streams, which will have detrimental impacts on water quality and aquatic ecosystems. We developed electrical conductivity (EC)-based sensors to measure salt concentrations in water bodies. We calibrated and validated sensors using standard sodium chloride (NaCl) solutions. Furthermore, we validated sensors in a laboratory (using standard solutions) and field settings. The errors for the laboratory validation varied from 0 to 13% with an average of 6%. We deployed 35 sensors in the Madison County, Illinois, USA and measured high-resolution (15 min) salt concentration for 6 months (December, 2018 to May, 2019) in water bodies in urban stream, parking lot drain, road-side drain, and creek. The average errors between sensor and field measurements were 11% for sensor field validation. Sensors were able to predict salt concentrations in the field settings within a precision level required to quantify salt concentration in water bodies. Therefore, the study would be helpful to monitor the change in salt concentrations in water sources as an impact of human activities benefiting water managers, researchers, and agencies working on water quality and ecosystems.