Spatial Pattern of Groundwater Arsenic Occurrence and Association with Bedrock Geology in Greater Augusta, Maine, USA
| Autor: | Robert G. Marvinney, Yan Zheng, Daniel B Locke, Charles W. Culbertson, Marc C. Loiselle, Heidi Cheek, Hilary Thibodeau, Hun Bok Jung, Qiang Yang |
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| Jazyk: | angličtina |
| Rok vydání: | 2009 |
| Předmět: |
Hydrology
geography geography.geographical_feature_category Bedrock chemistry.chemical_element Aquifer General Chemistry Geostatistics Article Arsenic Arsenic contamination of groundwater chemistry Groundwater pollution Environmental Chemistry Spatial variability Maine Geology Groundwater Water Pollutants Chemical |
| Popis: | In New England, groundwater arsenic occurrence has been linked to bedrock geology on regional scales. To ascertain and quantify this linkage at intermediate (10(0)-10(1) km) scales, 790 groundwater samples from fractured bedrock aquifers in the greater Augusta, Maine area are analyzed, and 31% of the sampled wells have arsenic concentrations10 microg/L. The probability of [As] exceeding 10 microg/L mapped by indicator kriging is highest in Silurian pelite-sandstone and pelite-limestone units (approximately 40%). This probability differs significantly (p0.001) from those in the Silurian-Ordovician sandstone (24%),the Devonian granite (15%), and the Ordovician-Cambrian volcanic rocks (9%). The spatial pattern of groundwater arsenic distribution resembles the bedrock map. Thus, bedrock geology is associated with arsenic occurrence in fractured bedrock aquifers of the study area at intermediate scales relevant to water resources planning. The arsenic exceedance rate for each rock unit is considered robust because low, medium, and high arsenic occurrences in four cluster areas (3-20 km2) with a low sampling density of 1-6 wells per km2 are comparable to those with a greater density of 5-42 wells per km2. About 12,000 people (21% of the population) in the greater Augusta area (approximately 1135 km2) are at risk of exposure to10 microg/L arsenic in groundwater. |
| Databáze: | OpenAIRE |
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