Trace element concentrations were used as chemical indicators of the condition ground-water water quality across the Nation and in Urban/Suburban ecosystems.
Trace elements naturally occur in ground water in United States. The presence of natural geologic materials (rocks, sand, and soil) that contain trace elements varies across the Country. The presence of these trace-element containing minerals influences the concentrations of trace elements in ground water. Naturally occurring or background concentrations of trace elements has not been well documented and thus trace elements were not counted as a contaminant. However, data on the concentration of trace elements that have established human-health standards were used for calculation of exceedance of drinking-water standards.
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