Denitrification in deep subsurface sediments

Francis, A.J.; Slater, Jennifer M.; Dodge, Cleveland J.

doi:10.1080/01490458909377853

Cited by 65 publications

(21 citation statements)

References 16 publications

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“…An understanding of subsurface microbial ecology is needed in order to effect in situ bioremediation of underground contaminant plumes, as well as to understand possible biodeterioration of contained nuclear waste stored in deep repositories. A number of studies have shown that significant bacterial populations exist hundreds of meters underground [1,4,5,9,12,14,16,19,20,21], and have attempted to describe and explain the distribution and abundance of these organisms. Microorganisms isolated in those studies were quite diverse and able to degrade a wide range of organic compounds, including relatively recalcitrant compounds such as aromatic hydrocarbons and chlorinated aliphatics.…”

Section: Introductionmentioning

confidence: 99%

Bacteria associated with deep, alkaline, anaerobic groundwaters in Southeast Washington

1993

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The microbial diversity in two deep, confined aquifers, the Grande Ronde (1270 m) and the Priest Rapids (316 m), Hanford Reservation, Washington, USA, was investigated by sampling from artesian wells. These basaltic aquifers were alkaline (pH 8.5 to 10.5) and anaerobic (Eh -200 to -450 mV). The wells were allowed to free-flow until pH and Eh stabilized, then the microflora was sampled with water filtration and flow-through sandtrap methods. Direct microscopic counts showed 7.6 × 10(5) and 3.6 × 10(3) bacteria ml(-1) in water from the Grande Ronde and Priest Rapids aquifers, respectively. The sand filter method yielded 5.7 × 10(8) and 1.1 × 10(5) cells g(-1) wet weight of sand. The numbers of bacteria did not decrease as increasing volumes of water were flushed out. The heterotrophic diversity of these bacterial populations was assessed using enrichments for 20 functional groups. These groups were defined by their ability to grow in a matrix of five different electron acceptors (O2, Fe(III), NO3 (-), SO4 (2-), HCO3 (-)) and four groups of electron donors (fermentation products, monomers, polymers, aromatics) in a mineral salts medium at pH 9.5. Growth was assessed by protein production. Culture media were subsequently analyzed to determine substrate utilization patterns. Substrate utilization patterns proved to be more reliable indicators of the presence of a particular physiological group than was protein production. The sand-trap method obtained a greater diversity of bacteria than did water filtration, presumably by enriching the proportion of normally sessile bacteria relative to planktonic bacteria. Substrate utilization patterns were different for microflora from the two aquifers and corresponded to their different geochemistries. Activities in the filtered water enrichments more closely matched those predicted by aquifer geochemistry than did the sand-trap enrichments. The greatest activities were found in Fe(III)-reducing enrichments from both wells, SO4-reducing enrichments from the Grande Ronde aquifer, and methanogenic enrichments from the Priest Rapids aquifer. Organisms from these aquifers may be useful for high-pH bioremediation applications as well as production of biotechnological products. These organisms may also be useful for modeling potential reactions near buried concrete, as might be found in subsurface waste depositories.

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Section: Introductionmentioning

confidence: 99%

Bacteria associated with deep, alkaline, anaerobic groundwaters in Southeast Washington

1993

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“…The limiting factor in these studies was the supply of available carbon ; Jarvis and Hatch (1994) observed a 2É5-fold increase in the denitriÐcation potential of grassland subsoils by the addition of a carbon source (glucose). In contrast, Francis et al (1989) found nitrate to be the limiting factor.…”

Section: Introductionmentioning

confidence: 68%

Effect of Poultry Manure on the Leaching of Carbon from a Sandy Soil as a Potential Substrate for Denitrification in the Subsoil

Shepherd

1997

J. Sci. Food Agric.

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“…However, very few studies have been conducted examining vadose zones at depth (>10 meters) in the subsurface. Both a study assessing denitrification activity to 289 meters in sand and clay and one determining denitrification in limestone and overlying units to 180-meter depth did show significant decreases in denitrification with sampling depth (8,9). The latter study showed a 100-fold lower denitrification rate (1.7 nM NO 3 /g/day) at depths of 40 meters or greater than in surface soils.…”

Section: Field Rates Of Denitrificationmentioning

confidence: 87%