摘要:

N2, Ar, O2, and CH4in sedimentary pore waters of the Tama Estuary, Tokyo, were determined. The distributions of N2and Ar reflected seasonal changes in these gases in the overlying water. N2/Ar ratios were always higher than in water in equilibrium with the atmosphere, providing direct evidence for denitrification in the sediment. N2production from nitrate by bacteria in the sediment was simultaneously determined using a15N tracer technique. The distribution of the excess N2so produced was calculated using a one‐dimensional diffusion model and compared with observations. Rapid loss of N2from sediment to overlying water is suggested.

ISSN:0149-0451    

DOI:10.1080/01490458109377763

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The downward transition from aerobic to anaerobic conditions in a harbor mud is not simply a function of the biological consumption of oxygen. It is also controlled by the amount of soluble iron (Fe2+) and microbially‐generated hydrogen sulfide available to coprecipitate as acid‐soluble sulfide (FeS). In this way both the chemistry and the microbiology of these sediments govern the iron and sulfur speciation as well as the depth of the aerobic zone.

ISSN:0149-0451    

DOI:10.1080/01490458109377764

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Gaseous nitrogen losses from15NH4+that was exogenously applied to desert surface soils which were then incubated under aerobic conditions for 35 days at constant 25% moisture reached 81% with plant material added and 75% without an exogenous carbon source. At a decreasing moisture regime, the respective values were 79% and 87%. The losses were attributed to denitrification and, partially, to dissimilatory N2O release during nitrification. Ammonia volatilization reached a plateau after 4 days, did not exceed 5% of the total15NH4+added, and was significantly higher in the plant interspace soils than in the canopy soils.

ISSN:0149-0451    

DOI:10.1080/01490458109377765

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Laguna Guerrero Negro and Ojo de Liebre are large, restricted embayments characterized by an arid climate and by a salinity ranging from that of normal seawater to the hypersalinity of sabkha environments. Intertidal microbial mats develop in some of the slightly hypersaline marshes and in many of the moderately hypersaline flats. Each major mat type corresponds to the lower, middle, or upper intertidal. In the lower intertidal mat, the photosynthetic horizon is a bilayer composed of: 1) a surface, blue‐green algal layer (about 3‐mm thick) dominated byMicrocoleus chthonoplastes;and 2) an underlying purple layer (about 2‐mm thick) of photosynthetic bacteria, predominantlyChromatiumsp. The mat may accrete to a thickness of 10 cm or more. It is characterized by fine laminations of alternating layers of blue‐green algae and of photosynthetic bacteria. The middle intertidal mat, dominated byLyngbya aestuarii,is relatively thin (usually 1 or 2 cm). Only a very thin, lower horizon of purple photosynthetic bacteria develops in this mat. One‐cm tall pinnacles that resemble the Precambrian stromatolite, “Conophyton,”; occur locally in theLyngbyamats. The upper intertidal is characterized by a crusty, wrinkled mat dominated byCalothrix crustacea;the total thickness of these mats is about 0.5 cm. None of the mats is lithified.

ISSN:0149-0451    

DOI:10.1080/01490458109377766

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The oxidation of uranous compounds by washed cell suspensions ofThiobacillus ferrooxidansandT. acidophiluswas monitored with a Clark oxygen electrode. The bacteria were able directly to oxidize U‐IV, which was supplied as uranous sulfate or as uranous oxide. The rates of oxygen uptake were dependent on: the cell concentration; the previous growth history of the organisms; the amounts of U‐IV and of inhibitors; pH and the presence of iron sulfates.

ISSN:0149-0451    

DOI:10.1080/01490458109377767

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Hypersaline Brines and Evaporitic Environments: Developments in Sedimentology 28, A.Nissenbaum (ed.). Elsevier Sci. Publ., Amsterdam, 1980. 270 p., $52.00

ISSN:0149-0451    

DOI:10.1080/01490458109377768

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/01490458109377762

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor