LeRoy L. Knobel

A hydrogen-based subsurface microbial community dominated by methanogens

The search for extraterrestrial life may be facilitated if ecosystems can be found on Earth that exist under conditions analogous to those present on other planets or moons. It has been proposed, on the basis of geochemical and thermodynamic considerations, that geologically derived hydrogen might support subsurface microbial communities on Mars and Europa in which methanogens form the base of the ecosystem. Here we describe a unique subsurface microbial community in which hydrogen-consuming, methane-producing Archaea far outnumber the Bacteria. More than 90% of the 16S ribosomal DNA sequences recovered from hydrothermal waters circulating through deeply buried igneous rocks in Idaho are related to hydrogen-using methanogenic microorganisms. Geochemical characterization indicates that geothermal hydrogen, not organic carbon, is the primary energy source for this methanogen-dominated microbial community. These results demonstrate that hydrogen-based methanogenic communities do occur in Earths subsurface, providing an analogue for possible subsurface microbial ecosystems on other planets.

Chemical Constituents in Ground Water from 39 Selected Sites with an Evaluation of Associated Quality Assurance Data, Idaho National Engineering and Environmental Laboratory and Vicinity, Idaho

This report presents a compilation of water-quality data along with an evaluation of associated quality assurance data collected during 1990-94 from the Snake River Plain aquifer and two springs located in areas that provide recharge to the Snake River Plain aquifer. The data were collected as part of the continuing hydrogeologic investigation at the Idaho National Engineering and Environmental Laboratory (INEEL). This report is the third in a series of four reports and presents data collected to quantitatively assess the natural geochemical system at the INEEL. Ground-water quality data - collected during 1990-94 from 39 locations in the eastern Snake River Plain - are presented.

Comparison of the effects of filtration and preservation methods on analyses for strontium-90 in ground water

From 1952 to 1988, about 140 curies of strontium-90 were discharged in liquid waste to disposal ponds and wells at the INEL (Idaho National Engineering Laboratory). Water from four wells was sampled as part of the U.S. Geological Surveys quality-assurance program to evaluate the effects of filtration and preservation methods on strontium-90 concentrations in ground water at the INEL. Water from each well was filtered through either a 0.45- or a 0.1-micrometer membrane filter; unfiltered samples also were collected. Two sets of filtered and two sets of unfiltered water samples were collected at each well. One of the two sets of water samples was field acidified.Strontium-90 concentrations ranged from below the reporting level to 52±4 picocuries per liter. Descriptive statistics were used to determine reproducibility of the analytical results for strontium-90 concentrations in water from each well. Comparisons were made with unfiltered, acidified samples at each well. Analytical results for strontium-90 concentrations in water from well 88 were not in statistical agreement between the unfiltered, acidified sample and the filtered (0.45 micrometer), acidified sample. The strontium-90 concentration for water from well 88 was less than the reporting level.For water from wells with strontium-90 concentrations at or above the reporting level, 94 percent or more of the strontium-90 is in true solution or in colloidal particles smaller than 0.1 micrometer. These results suggest that changes in filtration and preservation methods used for sample collection do not significantly affect reproducibility of strontium-90 analyses in ground water at the INEL.

Chemical and Radiochemical Constituents in Water from Wells in the Vicinity of the Naval Reactors Facility, Idaho National Engineering and Environmental Laboratory, Idaho, 1997-98

The US Geological Survey, in response to a request from the U.S Department of Energys Pittsburgh Naval Reactors Office, Idaho Branch Office, sampled water from 13 wells during 1997-98 as part of a long-term project to monitor water quality of the Snake River Plain aquifer in the vicinity of the Naval Reactors Facility, Idaho National Engineering and Environmental Laboratory, Idaho. Water samples were analyzed for naturally occurring constituents and man-made contaminants. A total of 91 samples were collected from the 13 monitoring wells. The routine samples contained detectable concentrations of total cations and dissolved anions, and nitrite plus nitrate as nitrogen. Most of the samples also had detectable concentrations of gross alpha- and gross beta-particle radioactivity and tritium. Fourteen quality-assurance samples were also collected and analyzed; seven were field-blank samples, and seven were replicate samples. Most of the field blank samples contained less than detectable concentrations of target constituents; however some blank samples did contain detectable concentrations of calcium, magnesium, barium, copper, manganese, nickel, zinc, nitrite plus nitrate, total organic halogens, tritium, and selected volatile organic compounds.

Chemical and Radiochemical Constituents in Water from Wells in the Vicinity of the Naval Reactors Facility, Idaho National Engineering and Environmental Laboratory, Idaho, 1996

The U.S. Geological Survey, in response to a request from the U.S. Department of Energys Pittsburgh Naval Reactors Office, Idaho Branch Office (IBO), samples water from 13 wells during 1996 as part of a long-term project to monitor water quality to the Snake River Plain aquifer in the vicinity of the Naval Reactors Facility (NRF), Idaho National Engineering and Environmental Laboratory, Idaho. The IBO requires information about the mobility of radionuclide- and chemical-waste constituents in the Snake River Plain aquifer. Waste-constituent mobility is determined principally by (1) the rate and direction of ground-water flow; (2) the locations, quantities, and methods of waste disposal; (3) waste-constituents chemistry; and (4) the geochemical processes taking place in the aquifer. The purpose of the data-collection program is to provide IBO with water-chemistry data to evaluate the effect of NRF activities on the water quality of the Snake River Plain aquifer. Water samples were analyzed for naturally occurring constituents and man-made contaminants.

Chemical and radiochemical constituents in water from wells in the vicinity of the Naval Reactors Facility, Idaho National Engineering Laboratory, Idaho, 1994--95

The US Geological Survey, in response to a request from the US Department of Energy`s Pittsburgh Naval Reactors Office, Idaho Branch Office, sampled water from 14 wells during 1994--95 as part of a long-term project to monitor water quality of the Snake River Plain aquifer in the vicinity of the Naval Reactors Facility, Idaho National Engineering Laboratory, Idaho. Water samples were analyzed for naturally occurring constituents and manmade contaminants. A total of 111 samples were collected from 10 monitoring wells and 4 production wells. Twelve quality-assurance samples also were collected and analyzed; 1 was a blank sample and 11 were replicate samples. The blank sample contained concentrations of one inorganic constituent, one organic constituent, and five radioactive constituents that were greater than the reporting levels. Concentrations of other constituents in the blank sample were less than their respective reporting levels. The 11 replicate samples and their respective primary samples generated 293 pairs of analytical results for a variety of chemical and radiochemical constituents. Of the 293 data pairs, 258 were statistically equivalent at the 95-percent confidence level; about 88 percent of the analytical results were in agreement.