ABSTRACT
The U.S. Geological Survey, in cooperation with the New Jersey Department of Environmental Protection, Division of Water Resources, is conducting a study to determine the occurrence and distribution of naturally occurring radionuclides in ground water in the Newark Basin, New Jersey, and to identify other aqueous chemical constituents that may be associated with these radionuclides. Water samples were collected by the U.S. Geological Survey in 1985 and 1986 from 260 ground-water sites areally distributed throughout the Newark Basin. Specific conductance, pH, alkalinity, dissolved oxygen, Eh (oxidation-reduction potential), and water temperature were measured on site. Subsequently, these samples were analyzed in the laboratory for gross alpha- and gross beta-particle activity. If gross alpha radiation exceeded 5 pCi/L (picocuries per liter), uranium, radium-226, major ion, and trace metal concentrations were also determined. In addition, sampling density was increased in these areas, and selected wells were sampled for dissolved radon-222.
Gross alpha-particle radiation activities ranged from less than 0.1 to 124 pCi/L; uranium activities ranged from 0.1 to 40 pCi/L; radium-226 activities 284ranged from less than 0.01 to 22.5 pCi/L; and radon-222 activities ranged from 71 to 15,900 pCi/L. Where gross-alpha radiation in reducing waters was high, radium-226 activities were elevated; however, where gross-alpha radiation in oxidizing waters was high, uranium activities were elevated. These results suggest that oxidation-reduction potential is an important control on radium-226 and uranium concentrations in the ground water. Elevated activities of radium-226 or uranium were not found exclusively in any one chemical class of ground water; however, elevated levels of radium-226 are absent from sulfate-dominated waters. In several instances, radium-226 activities in excess of 1 pCi/L were associated with anomalously high levels of iron (11,000 µg/L [micrograms per liter]), manganese (1,600 µg/L) , and barium (1,300 µg/L) . Uranium activities in excess of 4 pCi/L were locally associated with strontium concentrations as high as 5,100 /µg/L. No definitive relation could be determined between concentrations of radon-222 and radium-226 in the ground water.
