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USGS1995

Radium and radon in ground water in the Chickies Quartzite, southeastern Pennsylvania

The Chickies Quartzite, a Lower Cambrian-age formation compromised of quartzite and slate overlying a basal conglomerate, forms a narrow ridges and crops out discontinuously over 112 square miles in the Piedmont physiographic province of southeastern Pennsylvania. The formation is a low-yielding, fractured- rock, water-table aquifer recharged primarily by local precipitation. It is the sole source of water supply for thousands of domestic users. Ground water in the Chickies Quartzite generally is soft and acidic. During 1986-88, the U.S. Geological Survey sampled water from 160 wells that penetrate the Chickies Quartzite to determine the magnitude and distribution of radium-226 (Ra-226), radium-228 (Ra-228), and radon-222 (Rn-222) activities in ground water in the formation and to characterize the geochemical environmental associated with elevated activities of radium (Ra). In addition, 28 wells penetrating adjacent geologic units and 1 well in the Hardyston Quartzite were sampled to determine relative background Ra and RN-222 activities in ground water. Analyses included determination of activities of dissolved Ra-226, Ra-228, and RN-222, and concentrations of dissolved uranium (U), dissolved organic carbon (DOC), and major and minor dissolved inorganic ions. Rock samples were analyzed for U and thorium (Th) and geophysical logs were run to determine sources of Ra and RN-222 in the Chickies Quartzite. Activities of up to 41 pCi/L (picocuries per liter) for Ra-226, 160 pCi/L for Ra-228, and 32,300 pCi/L for RN-222 were measured in ground water in the Chickies Quartzite. Forty-seven percent of the samples contained Ra-226 and Ra-228 activities greater than 5 pCi/L. Median activities measured were 1.2 pCi/L for Ra-226, 2.6 pCi/L for Ra-228, 4.2 pCi/L for combined Ra-226 and Ra-228, and 2,400 pCi/L for RN-222 Ra-228 activity exceeded Ra-226 activity in about 92 percent of 100 water samples; the median Ra-228/Ra226 activity ratio was 2.4. Ra-228/Ra-226 activity ratios commonly were greater in ground water than calculated Th/U ratios in rock samples, suggesting perferential leaching of Ra-228 from aquifer solids. Of ground water in the adjacent geologic units, the highest activities (up to 2.9 pCi/L for Ra-226, 12 pCi/L for Ra-228, and 25,300 pCi/L for RN-222) were measured in ground water in the Harpers Phyllite and Antietam Quartzite. Nonparametric (Spearman rho test) statistical correlations show that the activity of dissolved Ra is inversely related to pH and directly related to concentrations of total dissolved solids, DOC, barium, and sulfate. Low pH decreases absorption of Ra onto the aquifer matrix. The other factors may favor Ra mobility by enhancing complexation or increasing solubility. RN-222 activity does not correlate with and is not supported by the activity of its parent, Ra-226, in solution. Ra-226 activity correlates positively, but weakly, with U concentrations. Ra-226 does not appear to be supported by its parent, U-238, in solution. Observed distributions of Ra-228, Ra-226, and RN-222 activities in ground water in different lithologies of the Chickies Quartzite reflect different geochemical controls on absorption and distribution of parent thorium-232 (Th-232) and uranium-238 (U-238) in the formation. Radium activities were greatest in acidic ground water in the conglomerate and quartzite (median pH of 5.0 and 5.2, respectively) and least in the more neutral water in the slate (median pH of 6.4). For ground water in the conglomerate, quartzite, and slate, respectively, median activities measured were 1.3, 1.5, and .02 pCi/L for Ra-226; and 3.7, 2.5, and 1.0 pCi/L for Ra-228. Natural-gamma-ray geophysical logs and results of rock analyses indicate that the conglomerate may contain more Th and U than the quartzite and that the conglomerate may be more enriched in Th with respect to U than the quartzite; Th and U distribution in both lithogies is variable. Median RN-222 activities in gro

Water-Resources Investigations Report↗

USGS1987

Report of the River Master of the Delaware River for the period December 1, 1985, to November 30, 1986

A Decree of the Supreme Court of the United States in 1954 established the position of Delaware River Master. The Decree authorizes diversions of water from the Delaware River Basin (Figure 1) and requires compensating releases from certain reservoirs of the City of New York to be made under the supervision and direction of the River Master. Reports to the Court, not less frequently than annually, were stipulated. During the 1986 report year, December 1, 1985, to November 30, 1986, precipitation and runoff varied from below average to above average in the Delaware River Basin. For the year as a whole, precipitation was 4.3 inches above average. Runoff was near average. Operations were under a status of drought at the beginning of the report year. The drought emergency was terminated on December 18, 1985, by the Delaware River Basin Commission, and operations were returned to normal as prescribed by the Decree for the remainder of the report yr. Storage in the reservoirs increased to capacity during the winter months and all New York City Delaware River Basin reservoirs spilled throughout the year. Diversions from Delaware River Basin by New York City and New Jersey did not exceed those authorized by the terms of the Amended Decree. Releases were made as directed by the River Master at rates designed to meet the Montague flow objective on 69 days during the June to November period. Releases were made at conservation rates or at rates designed to relieve thermal stress in the streams downstream from the reservoirs at other times. The excess release quantity as defined by the Decree was not expended by end of the report year. New York City complied fully with the terms of the Decree and with the directives of the River Master during the year. (See also W89-04133) (USGS)

Open-File Report↗