松原灌区建设对查干湖生态风险分析及对策

松原灌区将对国家自然保护区查干湖周围的盐碱地实施大面积围垦,若大量高浓度碱性尾水直排入湖,将导致查干湖生态系统严重污染.对这一风险合理评估并防范,关系到湖区生态安全与灌区的可行.本文在对湖区生态环境及灌区尾水排放模式与含盐特性系统分析基础上,提出利用退化沼泽湿地(盐沼)构建湿地处理系统(生态缓冲区),而非直接入湖的构想.当灌区运行一定时期,尾水水质得到改善,再入湖发挥补水效应.同时在设计上采取盐碱地分批滚动开发,以控制年排盐总量,降低排盐强度;以及充分利用碱湖泡随机承泄,减轻对查干湖的压力,既可防止湖水污染,又可保证灌区建设可行.

Risk analysis and mitigation on the impact of the development of Songyuan Irrigation area on the ecology of Lake Chagan

In order to increase food supply and suppress the ecological degradation, the saline-alkaline land surrounded the Lake Chagan will be developed into the largest irrigated area-Songyuan Irrigation area, in the Songhuajiang-Nenjiang(Songnen) Plain. The area will be 2.84×10⁷ km². The proposed irrigated area is located in the center of saline-alkaline region of the plain. The important objectives include new rice fields, improving the existing dry land of low yields, and recovering grassland and wetland. The drained water from the irrigation area is saline-alkaline water, while the Lake Chagan is a light alkaline lake, the largest lake in the Songnen Plain, and a national natural protection zone. The plants under protection include Phragmites and Suaeda glauca (Bunge), and the animals under protection include Ciconia, Grus leucogeranus, Gruiformes, Aquila chrysaetos, etc. Most birds in the region belong to the first class national protected animals or endangered species. Therefore, the lake is an important base for the biological species and plays an important environmental function in accommodating local climate. In this area, the ecological systems have been seriously degraded, so that some of the land has become the alkaline deserts. Since the Lake Chagan is a conflux center for the ground and surface water, if the tailing water of the irrigation engineering is pumped into the lake directly, the lake biological system would be in serious aftermath. Thus the key issue is how to avoid the ecological risk that the development the irrigation area might bring to the Lake Chagan. For getting both the benefits of protecting the lake biological system and developing the saline-alkaline land, this paper, based on analyses of the risks, has designed five wetland disposal systems as the transition area to deal with the alkaline tailing water. First of all, through degrading and precipitating of the pollutants, the pH of the tailing water was decreased when it enters into the modeling water processing systems. If the salt contents need to be decreased, the tailing water should be mixed with the water deriving from the Songhua River. Only when the tailing water quality meets the standard, the water will be allowed to discharge into the lake. The hazard evaluation indicates that this utilization model would not only not damage the lake ecosystem, but also be conducive to the stabilization of the lake ecosystem. Furthermore, the utilization model could develop saline-alkaline region and promote social economic development in the area.