摘要:

Coliform bacteria have been considered as a model for studies on the deposition and survival of microorganisms in estuaries. These bacteria were deposited in bottom muds of an estuarine system once the salinity exceeded a specific conductivity of 2.5 mS cm‐1. Survival of the bacteria appeared to be enhanced in the sediments. Studies of bacterial survival in specially constructed chambers immersed in an estuary indicated that sediment particulates have a protective effect, prolonging the survival of the bacteria compared with that in seawater. A similar protection of the bacteria was observed in the presence of a montmorillonitic clay. The interaction of microorganisms with both colloidal and larger particulates is considered in relation to such protective effects. The role of salinity in microbial sorption‐desorption phenomena, as well as the role of particulates in inhibiting biological control of alien bacteria, must be of general significance in the geomicrobiology of sediments in estuaries.

ISSN:0149-0451    

DOI:10.1080/01490457909377727

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

In vitro incubation of Santa Barbara Basin sediments indicated that methane production occurs at all depths sampled, including those in which sulfate reduction occurs. Methane production in the sulfate zone decreases with depth. U‐14C‐lactate is readily metabolized in the sulfate‐reducing zone, with14CO2production being greater than14CH4production. However, if sulfate is added to incubated sediments that have become depleted in sulfate, the14CH4production increases dramatically at the expense of14CO2production. Contrary to what has been observed in other ecosystems, sulfate stimulated methane production, especially from lactate. Experiments using 2‐14C‐acetate or H14CO3‐have indicated that bicarbonate is the principal source of methane and acetate is oxidized to CO2in sediments from the methane‐producing zone.

ISSN:0149-0451    

DOI:10.1080/01490457909377728

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Beachrock formation and degradation along the shores of the Gulf of Aqaba (Sinai) were studied in the field and at the laboratory. Different types of beachrock were found, including laminated rocks. Rates of photosynthesis and respiration were studied under high‐and low‐tide conditions. Epilithic, chasmolithic, and endolithic bacteria, cyanobacteria, and algae were studied quantitatively. Bacterial contribution to carbonate precipitation and cementation was estimated in thin sections and by laboratory experiments. Precipitation of aragonite and monohydrocalcite was observed at salinities between28‰and 45‰. Concentrations of dissolved organic matter (DOM) and particulate organic matter (POM) were high at initial stages of beachrock formation and extremely low in final rock. Anaerobic and later aerobic decay processes initiate carbonate precipitation. A model is suggested that places beachrock as an intermediate between cyanobacterial influenced subtidal and su‐pratidal rocks. Formation, cementation, and terminal concentration of organic matter in beachrocks, depend largely on microbial activity, sedimentation rates, energy, oxygen supply, evaporation rates, and water movement in the intertidal zone. Fossil remains of the biological origin of beachrock are extremely rare and difficult to interpret.

ISSN:0149-0451    

DOI:10.1080/01490457909377729

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/01490457909377726

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor