三峡水库蓄水前后洞庭湖区水环境演化过程研究进展

为揭示洞庭湖区水环境变化对三峡蓄水等因素的响应过程,总结各学者研究成果的基础上得出以下主要结论:三峡大坝建成运行后洞庭湖区主要污染物仍是总氮、总磷,湖区水质由贫-中营养过渡到轻度富营养,水质进一步恶化;三峡蓄水改变了原有湖区水文节律及底床冲淤状况,导致湖区水质指标变化;荆江河段与四水流域排污量增大,对湖区水质影响效应逐渐增强;湖区湿地出露时间提前,湿地生态系统受到一定程度破坏;目前各学者对水质评价指标各有不同、评价结果迥异,对水环境治理带来一定的影响。建立考虑三峡工程影响下合理的湖区水质预测预报机制已是当前亟需解决的重大科学问题,为预测湖区水质的变化趋势和水环境综合治理提供科学合理的理论依据。

Research on the water environment changes in the Dongting Lake before and after impoundment of the Three Gorges Reservoir

In order to reveal the response mechanism of water environment change in the Dongting Lake to the water impoundment of the Three Gorges Reservoir, the former research was summarized and analyzed. The main conclusions have been drawn as follows: The main pollutants in the Dongting Lake were still total nitrogen and total phosphorus after the Three Gorges Dam was put into operation. The water quality of the lake has changed from poor-medium to mild eutrophication, which implies that the water quality is further deteriorated; The Three Gorges Project changed the original hydrological rhythm and the bed erosion and deposition in the lake area, which resulted in some changes in water quality indexes; The increasing emissions from the tributaries and Jingjiang reach gradually deteriorated water quality in the Dongting Lake; Lake-bed exposure time was advanced, and the wetland ecosystem suffered some damage to some extent; In addition, there are some differences in the evaluation indexes and results among different scholars, which has a certain impact on the water environment governance. It has been an urgent scientific issue to be solved that the reasonable prediction mechanism of water quality should be established under the operation of the Three Gorges reservoir. The prediction mechanism could provide us with the scientific grounds and theoretical basis for the trend prediction and comprehensive management of water environment in the lake area.