Relation between road-salt application and increasing radium concentrations in a low-pH aquifer, southern New Jersey
The Kirkwood–Cohansey aquifer in southern New Jersey is an important source of drinking-water supplies, but the availability of the resource is limited in some areas by high concentrations of radium, a potential carcinogen at elevated concentrations. Radium (226Ra plus 228Ra) concentrations from a network of 25 drinking-water wells showed a statistically significant increase over a decadal time scale (p < 0.05), with a median increase of 0.35 picocuries per liter. Increases in Ra are correlated with road-salt application rates, and we hypothesize that the correlation is causal. Geochemical processes associated with road-salt applications that can mobilize Ra into solution include competition by excess sodium for sorption sites and formation of chloride complexes (RaCl+ and RaCl2). The largest increases in Ra were in groundwater with low pH (≤5), which is an indirect surrogate for low cation-sorption capacity. Correlations with other potential anthropogenic causes for the increase in Ra were not observed, further suggesting a road-salt effect. Given the significant increase in Ra concentrations in this drinking-water source, the known carcinogenic risks from Ra, the direct link to road-salt application, and the likelihood for continued increases, additional monitoring is necessary in areas with similar hydrogeologic and geochemical settings.
|Relation between road-salt application and increasing radium concentrations in a low-pH aquifer, southern New Jersey
|Bruce D. Lindsey, Charles A. Cravotta, Zoltan Szabo, Kenneth Belitz, Paul Stackelberg
|Environmental Science and Technology Water
|USGS Publications Warehouse
|National Water Quality Assessment Program; Pennsylvania Water Science Center; WMA - Earth System Processes Division