WATER CHEMISTRY VARIATIONS IN A KARSTIC AQUIFER SYSTEM: SAN SOLOMON SPRINGS, FAR WEST TEXAS

In December 2019 personnel with the National Cave and Karst Research Institute initiated a five month campaign of water sample collection from four of the six springs of the San Solomon Spring Group, using ISCO automatic water samplers. The San Solomon spring group is a series of karstic springs that discharge groundwater from Cretaceous limestones along the northeast flank of the Davis Mountains in far west Texas. The water samples were analyzed for general chemistry, trace metals, stable isotopes, and organic contaminants. Most of the springs in the San Solomon Springs Group discharge slightly brackish water, with total dissolved solids ranging from ~2000 to 3000 mg/L. In general the dissolved solids content increases as groundwater moves downgradient. However, we observed significant and non-linear spatial and temporal variations in water chemistry, trace metals and response to precipitation events, reflecting the heterogeneous character of this karstic aquifer system. In addition, Saragosa Spring, one of the farthest downgradient springs, yields groundwater fresh enough for human consumption, suggesting that it is disconnected from the aquifer that provides water for the other springs in the system.