Title: The Significance of Regenerated Nitrogenous Compounds as a Nitrogen Source for Phytoplankton in the Whitewater of the Pre-Amazonian Floodplain in Brazil
Abstract: compound. Turbidity in the waters was very high, indicating that both aquatic systems were of the Whitewater type. Salinity in the Pindare waters was high, whereas those in the Turiacu were fairly low. Concentrations of ammonia, nitrate and urea nitrogen were relatively low in the two aquatic systems, indicating that in both systems the supply of nitrogenous compounds from their watersheds was at a low level, and/or microorganisms were rapidly consuming the compounds as a nitrogen source. The uptake rates of ammonia nitrogen were 19 to 30 mg N m -1 in the Turiacu. The chlorophyll-a-specific nitrogen uptake rates were somewhat similar to the photosynthetic carbon assimilation rates. Correlation coefficients were obtained at a statistically significant level between the nitrogen uptake rate and the chlorophyll a amount or photosynthetic rate. The nitrogen uptake rate may be primarily modified by the standing crop of phytoplankton and their photosynthetic activity. Much shorter turnover times of ammonia and urea were calculated. The present results suggest that the regenerated form of nitrogenous compounds was a significant factor in sustaining phytoplankton growth.
Publication Year: 2013
Publication Date: 2013-08-01
Language: en
Type: article
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