Blue-Green Algae Bloom in Dianchi Lake, The Sixth Largest Freshwater Lake in China (除滇池蓝藻, 要优先降磷)

A massive algae bloom has spread out over another of China’s big lakes.

"The bloom comes after algae choked Taihu and Chaohu lakes, China’s third and fifth largest freshwater lakes respectively, in late May and early June, underscoring the state of China’s degraded water system. More than 70 percent of China’s waterways and 90 percent of its underground water are contaminated by pollution, according to the State Environmental Protection Administration" (from Gulf Times).

"The clean-up measures to date have failed to stem the pollution because they have focussed almost exclusively on (industrial) point sources around the lake periphery. They have not addressed agricultural runoff or pollution of the lake tributaries. According to a recent press report, 80 percent of domestic sewage entering the 16 rivers that flow into the Dianchi is untreated. Meanwhile, heavy use of chemical fertilizers and pesticides on farm fields lying east of the lake leads to extremely high runoff of nitrates and phosphates" (from US Embassy-Beijing Report).

My proposed engineering solution: Reduce the phosphorus input first if not enough money to reduce both phosphorus and nitrogen inputs to a very low level. The scientific justification is that the blue-green algae is prevalent in the low nitrogen-phosphorus ratio environment. Therefore, the priority now should be placed on controlling phosphorus-rich sources such as the domestic sewage.

Photo Credit: Dongfang (East) IC