Evaluation of Water Eutrophication on Taihu Lake-Connected Channels in Yixing City

Abstract

Taihu Lake is one of the five largest freshwater lakes in China. The gross economy of the basin has an important contribution to the whole country. Meanwhile, it is the main source of drinking water for 40 million residents of the region. Hence, it is significant to take up research on water pollution prevention. In order to approach deeply the countermeasures for controlling eutrophication of the lake, 10 channels connected to Taihu Lake in Yixing were chosen to test the degree of eutrophication based on the Carlson trophic state index (TSI). By employing techniques to measure chlorophyll “a” and other chemical indicators such as nitrogen and phosphorus in water body of the channels, TSI was computed using formula, TSI = 10 (2.46 + ln Chla/ln 2.5). The results indicated that TSI, between 53.77 and 70.03, and chlorophyll “a” were suitable parameters to indicate the degree of eutrophication, as well as the content of TP. Through the measurement and evaluation, it was found that all the 10 channels were eutrophic, and the major cause was possibly the higher quantity of P in the channels. The location and land use type of these channels indicated that eutrophication, although a natural process over time, was often accelerated by human activities. Human beings influence the lake by increasing the concentration of plant nutrients, primarily phosphorous. These nutrients can enter the waterway through agricultural land, sewage, or wastewater and cause over enrichment.