Water Resources Research Act Program

Details for Project ID 2017LA112B

Determination of chloride, nitrate and other ion concentrations in Mississippi Alluvial Aquifer in Northeast Louisiana

Institute: Louisiana
Year Established: 2017 Start Date: 2017-03-01 End Date: 2019-02-28
Total Federal Funds: $15,080 Total Non-Federal Funds: $31,595

Principal Investigators: Douglas Carlson

Abstract: Previous workers have observed areas of elevated chloride concentrations within the Mississippi Alluvial Aquifer. In general, these areas of elevated chloride concentrations lie in an axis from eastern Morehouse Parish to central Franklin Parish to central Concorida Parish. The areas with elevated chloride concentrations appear to have increased in area from the early 1970s to the early 2000s. However, the more recent study is small, includes only about 25 wells. The 1970s study by comparison includes chloride values from approximately 125 wells. The proposed study will include collection of approximately 150 samples, which will have Chloride, Nitrate and Total Dissolved Solids (TDS) values determined, plus any recent values of Chloride, Nitrate and TDS values from community wells monitored as part of the Department of Health and Hospitals (DHH) program, Department of Environmental Quality (DEQ) and U.S. Geological Survey (USGS) monitoring programs. This data set of approximately 200 to 220 values will be compared to results from the 1970s to see if there has been a measurable expansion of high chloride concentration regions in the past approximately 35 years, and if nitrate concentrations have increased between 1993 and 2017. The proposed study will include a set of samples collected from approximately 150 wells selected from within the study area’s nine parishes: Catahoula, Concordia, East Carroll, Franklin, Madison, Morehouse, Richland, Tensas and West Carroll Parishes (Figure 1). The sampling will include samples collected from wells that are screened across mainly the lower portion of the Mississippi River Alluvial Aquifer. Analysis will include gravimetric determination of TDS and ion chromatography determination for chloride, bromide, fluoride, nitrate, nitrite, phosphate and sulfate concentrations.