Geology topics

Research about Amargosa Desert Research Site

Source-linked reports with geographic coverage including Amargosa Desert Research Site.

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USGS1998

Tritium in unsaturated zone gases and air at the Amargosa Desert Research Site, and in spring and river water, near Beatty, Nevada, May 1997

Elevated tritium concentrations in the unsaturated zone at the Amargosa Desert Research Site (ADRS), immediately south and west of the low-level radioactive-waste burial site south of Beatty, Nevada, have stimulated research of processes that control the transport of tritium in arid unsaturated zones. In May 1997, 58 samples were collected from 1.5 m (meters) depth within a 250 m by 250 m grid at the ADRS. Measured concentrations ranged from 16 ± 9 to 36,900 ± 300 tritium units (TU), decreasing from northeast to southwest, possibly along an ancestral Amargosa River channel. The 10 air ports at test hole UZB-2 also were sampled, including ports at 57.6, 106.4, and 108.8 m depths that had not been sampled since 1994. Of the remaining seven ports, five were sampled in 1994, 1995, and 1996, and two were sampled in 1994 and 1996. Tritium concentrations at the four ports deeper than 50 m ranged from 791 ± 15 to 1765 ± 29 TU, having increased since they were last sampled. Tritium concentrations at the six ports shallower than 50 m ranged from 367 ± 11 to 1283 ± 20 TU, and appear to have stabilized since 1996. Tritium concentration in water vapor collected from air within the creosote bush canopy was 75 ± 9 TU near test hole UZB-2 and 9 ±6 TU near the uncontaminated Fischer test hole, 3.2 km to the south. Elevated tritium concentration in air near test hole UZB-2 was attributed to plant transpiration removing water from the unsaturated zone. Nearby surface water tritium concentrations were 6.3 ± 0.4 TU at Specie Spring, 0.0 ± 0.3 TU at Lower Indian Springs and at Upper Indian Springs, and 0.8 ± 0.6 TU in Amargosa River water.

Nevada↗

USGS1998

Hydrogeologic studies at the USGS Amargosa Desert Research Site

In 1976, the U.S. Geological Survey (USGS) began studies of unsaturated-zone hydrology in the Amargosa Desert in support of the USGS Low-Level Radioactive Waste Program. In 1983, agreements with the Bureau of Land Management and the State of Nevada established two field study areas: a 16-ha area adjacent to a waste-burial facility 17 km south of Beatty and a 0.1-ha area about 3 km farther south (fig. 1A). The study areas are collectively known as the Amargosa Desert Research Site (ADRS). Investigations at the ADRS have provided long-term benchmark information about hydraulic characteristics and soil-water movement for undisturbed conditions and for simulated waste-site conditions in arid environments. In 1995, as a result of unexpectedly finding high concentrations of tritium and carbon-14 in the unsaturated zone beneath the ADRS, the scope of research was broadened to include the study of processes affecting radionuclide transport. The ADRS was incorporated into the USGS Toxic Substances Hydrology Program in 1997. Research at the site is a multidisciplinary, collaborative effort that involves scientists from the USGS, universities, research institutes, and national laboratories. The overall objective for research at the site is to improve understanding of and methods for characterizing mechanisms that control subsurface migration and fate of contaminants in arid environments.

Nevada↗

USGS1995

Tritium and radioactive carbon (14C) analyses of gas collected from unsaturated sediments next to a low-level radioactive-waste burial site south of Beatty, Nevada, April 1994 and July 1995

Tritium activities in water vapor and radioactive carbon ( 14 C) activities in carbon dioxide were determined in gas samples pumped from small-diameter air ports installed in a test hole within the unsaturated sediments next to a commercial burial site for low-level radioactive waste south of Beatty, Nevada. In April 1994, gas samples were collected from test hole UZB-2, which was drilled about 350 feet south of the southwest corner of the fence enclosing the burial site. The test hole is part of a study to determine the depth to which atmospheric air circulates through the unsaturated sediments at the desert site. Laboratory results completed in May 1995 show activities of tritium and 14 C were greater than expected, with measured tritium in the water vapor as high as 762 tritium units at a depth of 79 feet and measured 14 C in carbon dioxide as high as 1,700 percent modern carbon at a depth of 18 feet. In July 1995, the uppermost five air ports in test hole UZB-2 were resampled. In addition, water vapor was collected for tritium analyses at a distant test hole, and water vapor for tritium analyses and carbon dioxide for 14 C analyses were collected from three depths at the research shaft about 200 feet north of test hole UZB-2, and at two shallow probes (depth of 5.5 feet) next to the fence enclosing the burial site. Analyses of samples collected in the upper 112 feet from test hole UZB-2 in July 1995 show the same distribution of tritium and 14 C as analyses of samples collected in April 1994, except that activities were somewhat greater in July. The greatest activities of tritium and 14 C were measured from a shallow probe next to the fence with activities of 29,400 tritium units and 517,000 percent modern carbon, respectively.

Nevada↗