摘要:

Microbial methanogenesis was proved geochemically, based on the abundance of methanogenic bacteria and methane production rates in experiments with radioactive carbon. The results are compared with direct measurements of methane concentrations in mud samples taken with a hermetic sampler. The migration of methane formed in sediments occurs during filtration of porewater rather than at the expense of gas diffusion.

ISSN:0149-0451    

DOI:10.1080/01490458109377770

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Rapakivi granite samples were incubated withPseudomonas aeruginosaculture solutions in order to elucidate the possible role of bacteria in rapakivi (crumbling stone) disintegration. SEM micrographs showed micromorphological alterations on the incubated rapakivi surface at 21 to 23°C for 20 days. Elevated concentrations of Na, Ca, K, Fe, and Mg were detected in the culture solutions after incubation. Elemental oxide ratios [K2O : (Na2O + CaO)] in culture solutions were similar to those in rapakivi ovoids, suggesting a proportional dissolution pattern of these elements.

ISSN:0149-0451    

DOI:10.1080/01490458109377771

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Thermophilic sulfate‐reducing and methanogenic bacteria were detected in deep (1200 to 1800 m) ground waters from geologic units that make up the Madison Formation, which underlies a large portion of the northern Great Plains. Some sulfate‐reducing bacteria were isolated and tentatively identified asDesulfotomaculum nigrificans.These organisms probably produce the hydrogen sulfide that is in the ground water. Direct microscopic counting methods demonstrated the presence of about 1000 bacteria/ml in the ground waters. Attempts to detect aerobic and other anaerobic bacteria were unsuccessful.

ISSN:0149-0451    

DOI:10.1080/01490458109377772

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The vertical distribution of porewater chemistry, and the numbers and activities of methane‐producing bacteria (MPB) and sulfate‐re‐ducing bacteria (SRB) were examined in shallow subtidal marine sediment cores. Sulfate concentrations decreased sharply below 5 cm in three of the four cores collected, and methane levels were highest (2500 to 3500 nmol/ml) immediately below the depth where sulfate was depleted. The fourth core (BM‐2) showed little sulfate depletion with depth and contained low levels of methane (less than 15 nmol/ml). Upon extended incubation at 20°C, rates of methano‐genesis were highest immediately below the high sulfate zone and decreased with depth. Sulfate reduction rates were highest in surface layers and decreased sharply with depth. The respiratory index [Rl =14CO2/(14CO2=14CH4)] for [2‐14C] acetate metabolism was high in the presence of high levels of sulfate and decreased sharply in the core sections low in sulfate. In the high sulfate BM‐2 core, meth‐anogenesis was not detected and an Rl of 1.0 was calculated at all depths where radioactivity was detected. Bacterial counts revealed that populations of MPB were 1 to 2 orders of magnitude less than SRB at all depths. Numbers did not decrease sharply below surface sediments, but the activities of these groups did decrease. These results demonstrated that sulfate reduction dominated over methane production in regions of high sulfate, while the relative importance of methanogenesis increased in low sulfate regions. The magnitude of the rates of either process, however, was more related to depth in the sediment core than to sulfate concentration.

ISSN:0149-0451    

DOI:10.1080/01490458109377773

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Massive pyrite was shown to produce soluble iron, hydrogen, and sulfate ions on exposure to air and water. The rate of this process was directly proportional to the surface area of the mineral; it was unaffected by a drop in the pH and the presence of the ferrous and sulfate ions formed. Cupic ion had no effect but ferric ion accelerated pyrite degradation until all the ferric ion was consumed, in accordance with FeS2+ 2Fe3+—>‐3Fe2++ 2S°.Thiobacillus ferrooxidansincreased pyrite degradation considerably; the presence ofThiobacillus thiooxidanshad no influence on pyrite degradation.

ISSN:0149-0451    

DOI:10.1080/01490458109377774

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Calcium carbonate precipitation by bacterial activity was noted in seawater collected from offshore Bermuda as well as from Halifax Harbor, provided that a minimum of 70 mg/liter of organic matter was added in addition to trimethylamine‐N‐oxide (TMAO) or sodium nitrate (final minimum concentrations, 1.33 and 0.17 g/liter, respectively). Observations made during these investigations indicated that the pH was the most important factor in the initiation of carbonate precipitation; the addition of calcium acetate, sodium carbonate, calcium sulfate, or ammonium carbonate did not result in carbonate precipitation. Precipitation was noted in cultures only when the pH exceeded 8.3. Precipitation occurred in the absence of bacteria when the culture was filtered after the pH increased to above 8.3 (2 days after nutrient amendment). Filter‐sterilized seawater, adjusted to pH 8.4 or above with NH4OH, also precipitated carbonates. A study of 53 random isolates from Bermuda waters and sediments revealed that only 20% of the isolates were able to precipitate carbonates. In most cases, the calcium carbonate precipitating isolates raised the pH above 9.0. No isolates from Bermuda or Halifax Harbor have yet been discovered that are able to precipitate calcium carbonates at in situ pH values.

ISSN:0149-0451    

DOI:10.1080/01490458109377775

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/01490458109377776

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Geomicrobiology,H. L. Ehrlich. Marcel Dekker, Inc., New York, Basel, 1981. With 99 figures, 30 tables, xi + 393 p. $29.75 (Price 20% higher outside U.S. and Canada)

ISSN:0149-0451    

DOI:10.1080/01490458109377777

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/01490458109377769

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor