Siegel et al. 2022 — Groundwater quality in the northwestern Appalachian Basin
Siegel et al. collected and analyzed 216 water samples from domestic wells and springs in eastern Ohio and northwestern West Virginia — a region of co-occurring unconventional oil and gas (UOG) development, coal mining, and conventional oil and gas activity. Using ICP-MS and ICP-AES, supplemented by noble gas geochemistry and hierarchical cluster analysis, they characterize contaminant distributions and attribute sources. Arsenic exceeded the EPA MCL (10 µg/L) in 6.8% of samples, with concentrations highest in valley wells in Doddridge and Tyler counties (West Virginia) and strongly associated with naturally geochemical conditions (alkaline, ion-exchange-driven groundwater) rather than with proximity to UOG operations. Manganese exceeded the EPA health advisory level of 0.3 mg/L in 7.3% of samples, and iron exceeded aesthetic SMCLs in many more. The study provides concentration data for arsenic and manganese in a rural drinking water system serving 2.4 million residents.
Key numbers
All concentrations are in groundwater samples from domestic wells and springs (n=216), analyzed dissolved fraction (0.45 µm filtered, preserved with HNO3):
- Arsenic above EPA MCL (10 µg/L): 6.8% of samples (n=15); exceedances concentrated in West Virginia (Doddridge, Ritchie, Tyler counties)
- West Virginia As: mean 7.29 µg/L (SD 8.71 µg/L)
- Ohio As: mean 1.26 µg/L (SD 3.58 µg/L)
- As detection rate (above LOD of 0.998 µg/L): 42% of samples
- Manganese above EPA health advisory (0.3 mg/L): 7.3% of samples (n=16); range to >3 mg/L
- Iron above SMCL (0.3 mg/L): 10%+ samples; range to 38 mg/L
- Nitrate above MCL (10 mg/L as N): 1.3% of samples (3 wells in Ohio agricultural areas)
- Source attribution for As exceedances: geochemical (alkaline, Na-HCO3 groundwaters with ion exchange) rather than UOG or coal mining
Manganese concentrations consistent with WHO guideline exceedance at 7.3% of tested domestic wells serving rural households.
Methods (brief)
ICP-MS (trace metals, including As and Mn) following 0.45 µm filtration and HNO3 preservation. ICP-AES for major cations and dissolved iron. LOD for arsenic: 0.998 µg/L. Noble gas isotope analysis (n=28 Ohio samples) for residence time and source attribution. Hierarchical cluster analysis (HCA) using isometric log-ratio transformation for multivariate source attribution. Geochemical forward modeling (PHREEQC) to identify dominant controls.
Limitations: Single sampling campaign (2019–2020); no longitudinal trend data. Domestic wells are not federally regulated and testing is homeowner responsibility.
Implications
Certification: Not directly applicable to food products. Relevant for arsenic-in-drinking-water exposure baseline and for framing groundwater as a background exposure contributor for populations in resource-extraction regions.
Courses: Documents that naturally occurring arsenic from geological sources (alkaline ion-exchange groundwaters) can exceed the US MCL in rural domestic wells, unrelated to industrial activity. Illustrates the importance of well water testing in agricultural and resource-extraction regions. Mn health advisory exceedance in 7.3% of samples documents neurological risk from drinking water.
App: Background exposure context; domestic well water quality in rural regions is a meaningful source of arsenic exposure for agricultural populations.