滇池污染底泥环保疏浚一期工程实施后环境效益评估

Study on Environmental Benefits of Environmental Dredging the First Phase Project in Lake Dianchi

通过对滇池草海污染底泥环保疏浚一期工程实施前后水质、底质及水生生物的监测和分析,评价工程实施后对改善草海水质,减轻内源负荷及对水生态恢复的环境效益。结果表明,疏浚工程直接去除了草海污染底泥层,随污染层分别去除TN、TP20 538 t和1 716 t。疏浚后草海水体透明度由0.37 m提高到0.80 m,水体中的TN和TP由疏挖前的8.91 mg/L和1.07 mg/L降低到疏挖后的8.15 mg/L和0.69 mg/L。疏浚后新生界面层促使形成新的水—沉积物的平衡,水质与底质条件改善以及水下光照条件超过沉水植物恢复的需求,是疏浚后水生态呈现恢复趋势的机理。

Based on monitoring and analysis of data of water quality, sediment and aquatic organism before and after the project, the environmental benefits of the Lake Dianehi Dredging the First Pahse Project were evaluated. The results showed that dredging directly removed the contaminated sediment layer of Caohai with simultaneously removal of pollutant TN and TP 20 538 t and 1 716 t respectively. After dredging, main water quality indexes such as TN and TP decreased fi＇om 8.91 mg/L to 8.15 mg/L and 1.07 mg/L to 0.69 mg/L respectively, which led to increase of water transparency from 0.37 m to 0.80 m. Formation of new interfacial layer after dredging forced starting new balance between water and sediment, which contributed to improvement of water quality. And the improvement of aquatic and sediment quality after dredging, especially increase of underwater light conditions, was the mechanism of restoration trend of aquatic ecosystems of Caobai.