Bacterial biomass and viability in a turbid Alabama reservoir and adsorption to clay particles of dissolved enzymes and organic matter.

摘要

Elledge Lake (reservoir) was studied from November 1999 through November 2000 to document the distribution bacterial biomass and the percentage of live bacterial cells. Bacterial biomass generally increased through the stratified period, to over 30 μg L−1. Horizontal patterns of bacterial biomass increased from the inflowing river towards the dam, with no indication of the anticipated peak in the transitional zone. The most striking pattern in the percentage of live bacterial cells was a sharp decline following a turbid April storm. Generally there was a higher percentage of live bacterial cells later in the stratified period and in areas with high chlorophyll concentrations.; Enzymes released by microorganisms are important in nutrient and organic matter processing. Clay minerals form aggregates with organic molecules that could alter enzyme activity. Montmorillonite and Elledge Lake Basin clay were combined with alkaline phosphatase, glucosidase, protease, and xylosidase to assess adsorption and the effect of this adsorption on enzyme activity. Elledge basin clay adsorbed alkaline phosphatase, and montmorillonite adsorbed all four enzymes. Enzyme activity was influenced by the adsorption of substrate onto the clays. The activity of adsorbed enzymes was not significantly decreased when these enzyme-clay complexes were exposed to natural sunlight. These enzyme-clay complexes may serve to protect the enzymes from photodegradation.; Studies of dissolved organic matter transport from terrestrial to aquatic ecosystems have focused on lakes with little inorganic turbidity. It is unclear what effect clay turbidity would have on these processes. In controlled experiments the adsorption of leaf leachates onto montmorillonite, kaolinite, and soil clay ranged between 0 and 31 mg C g clay−1. Experiments demonstrated that increased clay turbidity neither limited nor enhanced photodegradative processes, though significant amounts of dissolved organic matter were released from the aggregates. Montmorillonite clay addition produced a significant decrease in bacterial production. The addition of clay - organic matter aggregates significantly increased bacterial production. This increase suggests that these aggregates may play an important role in the transport and utilization of terrestrial organic matter.