The occurrence and geochemistry of arsenic in groundwaters of the Newark basin of Pennsylvania

摘要: Abstract Elevated As concentrations in groundwater the eastern United States have been recognized predominantly accretionary geologic terranes of northern New England. A retrospective examination more than 18,000 existing samples from Pennsylvania Department Environmental Protection (PA DEP) Drinking Water and Sampling Information System database indicates that elevated occur throughout half Piedmont Province Pennsylvania. Chemical analyses 53 collected 2005 drinking water wells this area all had detectable As, 23% these contained (>133 nmol/L or >10 μg/L) As. were most common Mesozoic sedimentary strata composed sandstone red mudstone with interbedded gray shale, to black siltstone shale. Arsenic was typically not diabase intrusions Newark Basin crystalline calcareous aquifers north Basin. Geochemical parameters such as pH oxidation–reduction potential can indicate mobility mechanisms some regions. In area, measured conditions oxidizing (Eh > +50 mV), 85% arsenate dominant species. Variations strongly correlated concentration, highest observed at values greater 6.4. The original source is likely shales contain arsenian pyrite be controlled by adsorption/desorption reactions Fe oxides aquifer materials.