Photochemically produced carboxylic acids as substrates for freshwater bacterioplankton

Article Abstract:

Evidence suggests that carboxylic acids which are produced photochemically in a humic lake may act as bacterial substrates. Four carboxylic acids, including oxalic, malonic, formic and acetic acid, were produced in substantial amounts by photochemical processes. The carbon from these acids was assimilated and oxidized to CO2 at rate exceeding that of bacterial carbon production. The microbial utilization of carboxylic acids was much lower than the photochemical production under natural sunlight at the surface of the lake, but the acids may accumulate and serve as a substrate for bacteria at night as well or after mixing into deeper layers.

Bacteria, Carboxylic acids, Photochemistry

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Relaxation of phosphorus limitation due to typhoon-induced mixing in two morphologically distinct basins of Lake Biwa, Japan

Article Abstract:

A typhoon led to increased phosphorus (P) concentrations in a shallow eutrophic basin of Lake Biwa (the south basin), Japan, but not in a deep oligo-mesotrophic basin (the north basin). Plankton in both basins was P-deficient before the typhoon. A day after the typhoon, the plankton in the south basin was P-sufficient, but by a week after the typhoon, P concentrations had nearly returned to the pre-typhoon levels. Entrainment of nutrient-rich pore water by wave-induced shear stresses caused the increase in P in the south basin.

Economic aspects, Japan, Phosphorus, Phosphorus (Chemical element), Typhoons, Lake Biwa

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Groundwater flow influences the biomass and nutrient ratios of epibenthic algae in a north temperate seepage lake

Article Abstract:

Biomass of epibenthic algae and nitrogen:phosphorus (N:P) ratios were affected by groundwater flow in a north temperate seepage lake, Sparkling Lake, Wisconsin. Sites with high groundwater discharge have significantly higher algal biomass, pore-water soluble reactive phosphorus (SRP) concentrations and SRP fluxes, as well as significantly lower concentrations of pore-water ammonia. In situ experimental chambers were used to investigate the relationship between groundwater flow patterns, N:P ratios and epibenthic algal biomass.

Wisconsin, Algae, Groundwater flow, Seepage, Seepage (Hydrology)

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