太湖底泥的生态疏浚工程

指出:①太湖底泥是湖体水生态系统的基本要素,也是重要的内污染源.②在湖泊外源污染得到一定控制后,以减少内源污染负荷为目的的生态疏浚是控制内源污染效果较为明显的工程措施.③太湖底泥疏浚属水生态整治工程,以最大可能取走污染物、改善水生态环境为控制目标,生态疏浚是局部的薄层精确疏浚.经采用生态调查方法,查明太湖底泥总蓄积量为19亿m3.主要疏浚范围是底泥厚且污染重的重点功能湖区,如梅梁湖、贡湖等.依据太湖底泥的污染特性,疏浚深度以40～50cm为宜,并应为后续生物修复技术介入创造必要的生态环境条件.密闭无扰动抽吸式头部掘进是关键,冬初至春末为最佳施工期.排泥场防渗、尾水处理达标后排放、淤泥安全处置和资源化利用是生态疏浚的环保要求.

Eco-dredging project of sediment in Taihu Lake

The sediment in Taihu Lake is an essential element of the water ecosystem and an important inner pollution source. After the control of outer-source pollution to a certain extent, the eco-dredging, aiming at the reduction of inner-source pollution, becomes an effective measure to control inner source pollution. The sediment dredging in Taihu Lake is a water ecosystem control project with the removal of pollutants as much as possible and improvement of water eco-environment as the objectives, and the ecological dredging is a local thin-stratum fine dredging. Ecological investigation shows that the total amount of sediment in Taihu Lake is 1.9 billion m 3, and that the dredging regions mainly concentrate in the key areas with thick sediment and serious pollution, such as Meiliang Lake and Gonghu Lake. According to the characteristics of sediment pollution in Taihu Lake, the appropriate depth of dredging is 40—50?cm, and the dredging should create necessary environmental condition for the following ecosystem restoration. The study also shows that the sealed and non-turbulent head-digging is the key technique for sediment dredging, and that the beginning of winter and the end of spring are the optimal construction periods. Moreover, the seepage control for the area of sediment dredging, up-standard discharge of tailwater after treatment, and appropriate treatment of sediment and its reuse as resources are the targets of ecological dredging for environment protection.