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Reconnaissance of Arsenic Concentrations in Ground Water From Bedrock and Unconsolidated Aquifers in Eight Northern-Tier Counties of Pennsylvania

Open-File Report 2006-1376

In cooperation with the Pennsylvania Department of Health and the Pennsylvania Department of Environmental Protection
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Abstract

Samples of ground water for analysis of total-arsenic concentrations were collected in eight counties--Potter, Tioga, Bradford, Susquehanna, Wayne, Pike, Sullivan, and Wyoming--and from eight bedrock formations (bedrock aquifers) and overlying glacial aquifers in the north-central and northeastern parts of Pennsylvania in July 2005 and from March through June 2006. The samples were collected from a total of 143 domestic wells, 2 stock wells, 4 non-community wells, 2 community water-system wells, and 3 domestic springs by well or spring owners using sampling kits provided by the U.S. Geological Survey (USGS). An additional 15 domestic wells were sampled by the USGS for analysis of total arsenic. These 15 samples were collected using the same methods and sampling kits provided to the homeowners. Samples were analyzed for total arsenic by the Pennsylvania Department of Environmental Protection Laboratory using a minimum reporting level of 4.0 ?g/L (micrograms per liter). Arsenic was detected in water from 18 domestic wells in four counties--Bradford (3 wells), Sullivan (1 well), Tioga (13 wells), and Wayne (1 well). The median concentration of total arsenic was less than 4.0 ?g/L, and the maximum concentration was 188 ?g/L. Water from 10 wells had concentrations of total arsenic greater than the U.S. Environmental Protection Agency Maximum Contaminant Level of 10 ?g/L. Detectable concentrations of total arsenic were measured in water from wells that ranged in depth from 29 to 400 feet, and that were completed in three aquifers--Lock Haven Formation, Catskill Formation, and unconsolidated glacial sediments; no springs had detectable concentrations of total arsenic. Water samples representing the Lock Haven Formation were collected from 60 wells; water from 12 of these wells had detectable concentrations of total arsenic. Water samples representing the Catskill Formation were collected from 57 wells; water from 4 wells had detectable concentrations of total arsenic. Water samples representing the unconsolidated glacial sediments were collected from 17 wells; 2 wells had water with detectable concentrations of total arsenic. Contingency tables tested for significant differences in total arsenic between aquifers, topographic settings, and well depths. Concentrations of total arsenic were significantly greater (95-percent confidence level) in the Lock Haven Formation than in the other bedrock units. Concentrations of total arsenic also varied significantly by topographic setting. Wells completed in the Lock Haven Formation and located in valleys had significantly greater concentrations of total arsenic than similar wells located on hilltops or slopes. Concentrations of total arsenic did not vary significantly by topographic setting in the Catskill Formation. Concentrations of total arsenic did not vary significantly by well depth for any aquifer. Iron staining, hydrogen-sulfide odor, or both were common complaints of well owners. Iron staining was a complaint of 44 well owners. Hydrogen-sulfide odor was a complaint of 35 well owners. Fourteen well owners complained of both iron staining and hydrogen sulfide. No correlation to the presence of arsenic in the wells sampled was found with iron staining, hydrogen-sulfide odor, or both. Water from 8 of the 10 wells that contained concentrations of total arsenic greater than 10 ?g/L were sampled by USGS personnel for the determination of concentrations of dissolved arsenic (minimum reporting level 0.3 ?g/L) and arsenic species {arsenite [As (III)], arsenate [As (V)], monomethylarsonate (MMA), and dimethylarsinate (DMA)} at the USGS National Water Quality Laboratory. Analytical results from these samples showed a median concentration of 38.7 ?g/L dissolved arsenic in water and a maximum of 178 ?g/L. As (III) was the most common arsenic species present in the water for seven of the eight wells and was found in water characteristic of reducing environments [pH 8.2

Study Area

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Reconnaissance of Arsenic Concentrations in Ground Water From Bedrock and Unconsolidated Aquifers in Eight Northern-Tier Counties of Pennsylvania
Series title:
Open-File Report
Series number:
2006-1376
Edition:
-
Year Published:
2007
Language:
ENGLISH
Contributing office(s):
Pennsylvania Water Science Center
Description:
iv, 35 p.
Time Range Start:
2005-07-01
Time Range End:
2006-06-30
Online Only (Y/N):
Y