Linyi Water Source (Andi Reservoir) Investigation And Assessment On The Water Quality

Also known as Yunmeng lake, Andi Reservoir is located in Mengyin County. In1996it was designated as Linyi urban drinking water sources in Linyi City, and is currently the only source of drinking water. After examining the water quality, sediment heavy metal content and the plankton community of Andi Reservoir, and the estuary of the lower reaches of its two major tributaries, Dongwen River and Zi River, it is found water quality of the reservoir is Ⅲ-Ⅳ, among which drinking water is of class Ⅲ, a far cry from the target of the second grade water quality for the source of drinking water in a protected area. COD and TP significantly exceed the standard of the current quality target, that is water of class Ⅲ. Moreover, Hg is also a potential pollution index for the long term target of the second water quality. From the earlier studies, the water quality of the downstream, Dongwen river and Zi river, which are the main tributary river of the Andi reservoir meets the standard of class Ⅲ. But due to the pollution from the sewage treatment plant of Mengyin, the water quality of the Dongwen Estuary is relatively poor. Investigation finds that, the content of Cd and Pb in the bottom surface sediments which lies in the inshore of Andi reservoir and estuary of Zi river is beyond the first class according to the "soil quality standards "(GB15618-1995). Meanwhile the content of Cr, Pb and As also shows risk for the Benthic organisms. But in the same period water, except the content of Hg is the class Ⅲ standard, others contents of heavy metal are consistent with class Ⅰ standard. The flow biological community diversity in Andi reservoir is average, the species composition and biomass density spatial distribution is uneven, larger seasonal changes, community structure is unstable. The result of evaluation also shows that the Andi reservoir is still in mild to moderate pollution status. Overall, Andi reservoir watershed ecological environment condition, soil erosion is severe. The measures of industrial water pollution management and control are not full implemented. The pollution source from rural area cannot be efficiently controlled. The inflowing rivers coast lacks effective and protective barrier, the ability of interception and purifying is poor, thus results a large number of pollutants through surface runoff into the reservoir. Moreover, Andi reservoir lacks the wetland ecological system which is carried by higher water plants. The structure of food chain is simple. These led to the self-clean ability of water rather poor, and the environmental capacity is seriously insufficient. That is the direct cause for the water quality from the reservoir exceeding the standard in long-term. In the same time, the unsmooth for the mechanism of the management in the reserve, and the contradiction between the social development of the river basin and environmental protection in the water source, that is the important reason why the water environmental problems can not be cured fundamentally.