An analysis of the relationship between land use and arsenic, vanadium, nitrate and boron contamination in the Gulf Coast aquifer of Texas

Data for arsenic, vanadium, nitrate, and boron contamination were obtained from groundwater monitoring samples of the Gulf Coast aquifer of Texas. Using water samples from 1990 to 2006 from 1270 wells, results were spatially and statistically analyzed. The aquifer was divided into two regions based on annual precipitation, high precipitation in the north and lower to the south. All constituents were found to exceed the established maximum contaminant levels (MCL) or Health Risk Limits (HRL) in some samples from the study area. High boron and arsenic values were found to be significantly more common in the southern region, with 60% of boron samples over the HRL and 40% of arsenic samples over the MCL. Statistically significant negative correlation between nitrate and well depth suggests a surface source for the constituent. Statistically significant correlations between vanadium and arsenic suggest a geologic source. Analysis of oil/gas wells in the region suggests that oilfield discharge is not a source for boron.