Environmental path of arsenic in groundwater: Completion report

Abstract

This is the final completion report for a project begun in July, 1974, for the purpose of determining the concentration of arsenic in the Pedro Dome-Cleary Summit area of the Fairbanks Mining District, Alaska. Because arsenic contamination of the waters of the area was detected during the first year, the study was extended for another year to examine for arsenic the waters of the Ester Dome area, a more populated part of the district. This study was undertaken because it was known that arsenic as arsenopyrite and arseniferous pyrite accompanies the gold mineralization in the Fairbanks District. It was not known if such arsenic was liberated to the waters of the area by weathering processes. The Pedro Dome-Cleary Summit area was chosen for the initial study because arsenopyrite- bearing rocks are abundant and mining activities which might accelerate release of arsenic had long been carried out in the region. The area also had a few wells thus permitting a limited number of groundwater samples to be taken. The subsequently studied Ester Dome area permitted extensive sampling of the groundwater there. From a health standpoint, 70 mg arsenic has proven to be toxic to humans, while arsenic in low concentrations appears to be a carcinogen. In view of these facts, the United States Public Health Service (USPHS) recommended guide limit for arsenic in potable waters is 10 parts per billion (ppb) with 50 ppb a level which, if exceeded, constitutes grounds for rejection of the water as a public water supply. Because of the rapid population growth in the Fairbanks area and the growing reliance upon domestic wells as a source of water by much of the population, it is important that the arsenic content of the surface and ground water be determined.