Overview
Senior and colleagues sampled 89 domestic wells in Wayne County, Pennsylvania, to establish a baseline for shallow groundwater quality in bedrock aquifers before potential extensive shale-gas development. This is in-scope as groundwater exposure and source-attribution context, not bottled-water or salt occurrence evidence.
Key numbers
The sampled wells ranged from 85 to 1,300 ft deep, with a median depth of 291 ft. The report states that all groundwater samples were analyzed for bacteria, major ions, nutrients, selected inorganic trace constituents, radon-222, gross alpha and beta activity, selected man-made organic compounds, dissolved gases, and methane isotopes where enough methane was present.
The abstract reports that arsenic concentrations exceeded the 10 µg/L MCL in 4 of 89 samples (4.5%), with concentrations as high as 20 µg/L. Arsenic concentrations exceeded the 2 µg/L Health Advisory level in 27 of 89 samples (30%). Table 4 reports dissolved arsenic above the reporting level in 82 of 89 samples (92%), with minimum <0.010 µg/L, median 0.38 µg/L, and maximum 20.1 µg/L.
Table 4 trace-element summary values include:
| Constituent | Fraction above reporting level | Minimum | Median | Maximum | Standard exceedance |
|---|---|---|---|---|---|
| Aluminum, dissolved | 21 of 89 (24%) | <2.2 µg/L | <2.2 µg/L | 52.3 µg/L | 0 of 89 |
| Antimony, dissolved | 28 of 89 (31%) | <0.027 µg/L | <0.027 µg/L | 0.227 µg/L | 0 of 89 |
| Arsenic, dissolved | 82 of 89 (92%) | <0.010 µg/L | 0.38 µg/L | 20.1 µg/L | 4 of 89 over MCL |
| Cadmium, dissolved | 2 of 89 (2%) | <0.030 µg/L | <0.030 µg/L | 0.132 µg/L | 0 of 89 |
| Copper, dissolved | 80 of 89 (90%) | <0.80 µg/L | 5.8 µg/L | 121 µg/L | 0 of 89 |
| Lead, dissolved | 79 of 89 (89%) | <0.040 µg/L | 0.20 µg/L | 3.06 µg/L | 0 of 89 |
| Nickel, dissolved | 70 of 89 (79%) | <0.20 µg/L | 0.37 µg/L | 1.7 µg/L | 0 of 89 |
| Zinc, dissolved | 69 of 89 (78%) | <2.0 µg/L | 6.6 µg/L | 81.9 µg/L | 0 of 89 |
| Barium, dissolved | 89 of 89 (100%) | 1.26 µg/L | 52.8 µg/L | 803 µg/L | 0 of 89 |
| Iron, total | 70 of 89 (80%) | <1.0 µg/L | 10.6 µg/L | 8,800 µg/L | 9 of 89 over SMCL |
| Manganese, dissolved | 38 of 89 (43%) | <0.40 µg/L | <0.40 µg/L | 246 µg/L | 2 of 89 over SMCL |
| Manganese, total | 33 of 89 (37%) | <0.50 µg/L | 0.8 µg/L | 262 µg/L | 2 of 89 over SMCL |
| Strontium, dissolved | 89 of 89 (100%) | 7.17 µg/L | 144 µg/L | 3,040 µg/L | 0 of 89 |
The report links elevated arsenic to higher-pH groundwater. It states that arsenic concentrations in 2014 and 2013 were generally higher than the 10 µg/L MCL only when pH was greater than 7.8, and higher than the 2 µg/L Health Advisory when pH was greater than 7.2.
Table 3 reports pH from 5.4 to 9.3, median 7.3. Twenty-seven of 89 samples (30%) were outside the EPA SMCL range of 6.5 to 8.5: 20 samples had pH less than 6.5 and 7 samples had pH greater than 8.5. Total dissolved solids ranged from 24 to 370 mg/L, median 120 mg/L, with 0 of 89 above the 500 mg/L SMCL.
Table 5 reports radon-222 in all 89 samples, from 25 to 7,400 pCi/L, median 2,120 pCi/L. Eighty-six of 89 samples (97%) exceeded the proposed 300 pCi/L MCL, and 12 of 89 samples (13%) exceeded the proposed alternative MCL of 4,000 pCi/L.
Methods (brief)
The study sampled domestic wells during July-September 2014. Field parameters included temperature, pH, dissolved oxygen, specific conductance, and alkalinity. Dissolved trace elements were analyzed in filtered samples by the USGS National Water Quality Laboratory; selected total trace constituents were analyzed in unfiltered samples by contract laboratories using drinking-water methods. The page reports total and dissolved forms separately where the source does.
Implications
Certification: Do not use these values as bottled-water, mineral-water, salt, or product occurrence data. They are domestic-well groundwater context values for an aquifer system and are useful for water-source due diligence, source attribution, and exposure context.
Courses: Strong example of why baseline groundwater characterization matters before industrial development: the report captures natural/geochemical arsenic patterns, pH-linked mobilization, methane context, and drinking-water-standard exceedances.
App: Context only. The source can support local groundwater risk flags and water-source questions, not finished-product scoring.
Wiki pages this source may touch
- Irrigation water and soil amendments as anthropogenic inputs to cropland
- Source attribution and environmental burden apportionment
- Arsenic
- Lead
- Cadmium
- Iron
- Manganese
- Uranium
Verification notes
Recovered from skip:not-food-occurrence under the 2026-06-10 inclusion-by-default rule. The old skip treated the report as out of scope because it was not a food matrix. On reading, it is in-scope a3/a4 groundwater and exposure-context evidence because it measures routeable drinking-water aquifer values, including arsenic exceedances.
Numbers were checked against the extracted PDF text, especially the abstract, Table 3, Table 4, Table 5, and the arsenic and iron/manganese discussion sections. Units and dissolved/total labels are copied as printed. Products and ingredients are intentionally empty.
Update history
This page has no substantive edit history yet. Future revisions will be recorded here once the change lands in git.