Kinetics of Phosphorus Uptake in the Chowan River, North Carolina

摘要

Gross biotic uptake rates of filterable reactive phosphorus by plankton were measured in surface waters of the Chowan River from May 1980 to October 1981. Uptake rates varied widely, ranging from 0 to 6.15 micrometers/h, and were greater in the warmer months in the middle and lower reaches of the river. Abiotic phosphate uptake rates were usually much less than biotic uptake rates and ranged from 0.001 to 0.63 micrometers/h. Rapid biotic uptake coincided with low filterable reactive phosphorus concentrations and high levels of chlorphyll-a. Size fractionation of the uptake indicated that most of the uptake occurred in particles with dimensions less than 8.0 micrometers. Phosphorus uptake rates and turnover times were good indicators of the phosphorus nutritional status of phytoplankton in the Chowan River. The plankton were often phosphorus limited during the summer months in the middle and lower river. Phosphorus uptake kinetics were discussed in relation to the occurrence of surface blooms of blue-green algae and the relative abundance of nitrogen and phosphorus.