Phytoplankton Uptake and Sediment Release of Nitrogen and Phosphorus in the Chowan River, North Carolina

摘要

The lower part of the Chowan River has suffered from blue-green algal blooms in recent years as a result of increased loading of nutrients. These nutrients (nitrate, ammonium, and phosphate) were reduced to lower concentrations during the warm seasons when algal growth was rapid and were more concentrated in winter and early spring when ammonium and phosphate were introduced by pulp-mill effluent. Uptake of ammonium by seston varied greatly; it was fastest during the blue-green bloom. Nitrate uptake averaged only a third as fast as the annual ammonium uptake rate. Phosphate uptake was predominantly biotic. Analysis suggests that nitrogen or phosphorus may limit algal growth at different times and places in the river. Elimination of the algal bloom problem in the Chowan River will be accomplished only by reducing nutrient loading from the watershed, especially phosphorus loading.