Lead and Manganese in Untreated Drinking Water from Aquifers in the Atlantic and Gulf Coastal Plain, Eastern USA
Monday, December 4, 2017: 11:30 a.m.
Concentrations of lead and manganese in 258 untreated drinking-water samples collected in 2013 from aquifers in the Coastal Plain were compared to select factors related to hydrologic position, mineral saturation, and geochemical conditions. Statistical comparisons between the concentrations and the explanatory factors were used to identify the factors most important to the occurrence of lead and manganese in groundwater. Lead and manganese were selected because: 1.) both trace metals and neurotoxins; 2.) both were detected at elevated concentrations in greater than 2 percent of samples collected within the study area. The lead and manganese concentrations were evaluated in terms of hydrologic position, well depth, and geochemical indicators including pH, dissolved oxygen, specific conductance, and select trace metals. Sample results from 258 wells completed in three principal aquifers in the Coastal Plain aquifer systems were included in the analysis. Elevated concentrations of lead were associated with relatively younger, high-oxygen, low-pH waters which occurred closer to recharge zones (relatively shorter flow paths). Elevated concentrations of manganese were associated with relatively older, low-oxygen, low-pH waters which occurred further away from recharge zones (relatively longer flow paths). Based on these associations, dissolved oxygen and pH, both relatively easy to measure in groundwater, can be used to identify locations within aquifers in the Coastal Plain systems that may be more susceptible to elevated manganese and lead concentrations.