Temporal and Spatial Distribution of Chlorophyll-a in Caotang River of Three Gorges Reservoir

Abstract

To study the formation of algae blooms in Caotang River, a tributary of the Three Gorges Reservoir, the authors set up six monitoring sites in Caotang River and Yangtze River to continuously monitor the concentration of chlorophyll-a for one year from July 2017 to June 2018 and analyzed the distribution of algae blooms. It is found that in the vertical direction, chlorophyll-a had a maximum concentration at 2.41 mg/m3 at the surface and a minimum concentration of 0.69 mg/m3 at the bottom. The algae blooms broke out in Caotang River from July to September 2017, and there was no significant difference in the concentration of chlorophyll-a during other periods. During algae blooms, the concentration of chlorophyll-a increased from downstream to upstream except for the source section. There was no significant difference in the concentration of chlorophyll in the middle and bottom water bodies. The Yangtze River has a lower concentration of algal toxin than that in the Caotang River. Excluding the source where algal toxin was not observed, this study found that the concentrations of algal toxin in the other three sections (CT01, CT02 and CT03) were at 0.42 ug/L, 0.56 ug/L and 0.83 ug/L, respectively.