Automated determination of total selenium in rocks, soils, and plants
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Geology topics
Publications and source records attributed to Paul H. Briggs.
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During 1984, 60 stream sites were sampled for the presence of Giardia sp. cysts. The sampling sites ranged in elevation from 6 ,000 to 12,000 feet, and were distributed over a distance of more than 200 miles, from the Lake Tahoe basin in the north to Mt. Whitney in the south. Cysts of Giardia were detected in 27 of 78 samples. The number of cysts detected ranged from 1 to 41. Of the 27 samples positive for Giardia, only 1 cyst was detected in each of 10 samples, 2 cysts were detected in each of 8 samples, 3 cysts were detected in each of 3 samples, 4 cysts were detected in each of 2 samples, and 5, 6, 14, and 41 cysts were detected in 1 sample each. (USGS)
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The North Fork Smith River Roadless Areas are located primarily in Del Norte County, northern California, include small parts of Curry and Josephine Counties, Oreg., and cover parts of the Gasquet, Crescent City, and Chetco Peak 15-minute quadrangles. The areas encompass aproximately 39,400 acres of Six rivers National Forest and 950 acres of Siskiyou National Forest and extend from just north of the California-Oregon border southward about 6 mi to the town of Gasquet, Calif. (fig. 1).
Introduction: The favorable response to the reports on the geochemistry of unconsolidated surficial materials of the conterminous United States (informally called the '50-mile geochemical survey,' Shacklette and others, 1971a, 1971b, 1973, and 1974) led us, in 1975, to initiate a somewhat similar survey of Alaska. The principal objective of studies of this type is to establish estimates of the abundance of elements in soils and other surficial materials. Such information is useful in the evaluation of geochemical data for (1) mineral resources, (2) environmental appraisals, and (3) the definition of broad-scale geochemical patterns. For about six years this effort progressed slowly on a non-funded, time-available basis. During fiscal years 1982 and 1983, however, some funds were made available through the USGS Energy Lands and Alaska Mineral Surveys programs which allowed for the completion of the field-work phase of the project. The sampling plan was kept simple because, as with the 50-mile study, the acquisition of samples depended on the voluntary cooperation of field personnel (only about 40 percent of the total number of samples was obtained by the authors).
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This Upper Devonian shale is of interest because of its unusual enrichment in trace elements, especially U; a new chemical analysis for major, minor and trace elements is presented. Stable isotopes of carbon (organic) show delta 13C approx -29per mille and for total sulphur show -21 to -27per mille delta 34S. The organic matter was found to range from dominantly marine (Dowelltown member) to dominantly terrestrial (Gassaway member) by extraction-column chromatography-GS and also by pyrolysis-GS of kerogen. Trace elements U, Mo, Co, Zn, Cu, Ni, V, As and Hg are enriched in the organic- and sulphide-rich units. This enrichment can be related to a euxinic depositional environment, to a very slow sedimentation rate (approx 2 mm/1000 years), to the type of organic matter that varied from mainly marine to terrestrial, and to the source of the metals, which shows abundance variations that originated, at least in part, from volcanic ash layers.-R.S.M.
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Using several analytical techniques, results of analysis of U. S. Geological Survey new standard SDO-1 are given for selected elements. The Devonian black shale shows an organic carbon content of approximately 10.3 percent, a sulfur content of approximately 5.6 percent, and a uranium content of approximately 56 ppm. Some elements show higher than average values for black shales: Mn, 389 ppm; Co, 57 ppm; Ni, 128 ppm; As, 104 ppm; and Hg, 0.19 ppm.