WATER QUALITY MONITORING OF KARST SPRINGS IN SOUTHWEST MISSOURI BASED ON PFAS, NITRATE AND MAJOR IONS

In karstic areas, fractures provide conduits for contaminants to reach deeper aquifers. The purpose of the study was to analyze the water quality of springs in the Springfield Plateau aquifer. The water quality analyzed was in proximity to faults to determine the variation in chemistry with time as well as its potential to contaminate the deeper Ozark aquifer. Eleven springs were sampled monthly within Lawrence (rural) and Greene (urban) counties for 12 months. Water samples from seven shallow wells near the springs were collected once. Basic water quality, nitrate, and PFAS of water samples were determined. To confirm any presence of PFAS, PFAS from spring sediments were also analyzed. The obtained Cl, Na, SO₄, and NO₃-N concentrations were separated into small, intermediate, and large. For nitrate, most of the springs had 2-4 mg/L NO₃-N. Urban springs of Greene County had higher Na, Cl, and SO₄, while most springs from Lawrence County had excellent water quality, except for two springs (Big Spring, Verona) that consistently had more nitrate than the others, and therefore monitoring these wells is recommended. Springs of Lawrence County were mainly affected by natural processes, evident by the correlation of water quality parameters with pH and precipitation. PFAS was not detected in any of the samples. Overall, the small concentration of contaminants in the shallow aquifer guarantees a small possibility of leakage of contaminants to the Ozark aquifer.