Study On Sediments Characteristics And Evalution System For A Drinking Water Reservoir

Nowadays, the endogenous pollution of lakes and reservoirs has increasingly drawn people's concerns. As for the water source reservoir, the diffused pollution from the drainage basin has been generally well controlled, but the researches and the controlling problem on the (?) pollution need to be further explored. This paper takes one water source reservoir in Zhejiang province as the research objective to wholly study the distribution status of the peservoir sediment, the pollution status of the sediments and the creature conditions. This paper is to explore the release mechanism of the endogenous pollutants of the reservoirs and to (?) the endogenous pollution load of the sediments so as to establish a evaluation system of the sediments quality to estimate the current status of the reservoirs sediments, to put it (?), there are:(1) The actual measurement and simulation methods were used to study the distribution of the reservoir sediments. The sediments is relatively more distributed in the middle while at the two ends of the reservoir there is relatively less sediments and the total accumulation is about 130,000 to 140,000 cubic meters. There is relatively less sediments in the backwater area and some places are washed by the water; in the middle part of the reservoir, namely the upper (?) of the backwater area, is the major area of the sediments and the largest sediment (?) is about 30 cm; there is relatively less sediments in front of the dam and the thickness (?) about 12cm. in the front edge of the sediments is located in the middle of the reservoir, and the sediments are in the triangle or ribbon form.(2) According to the analysis results, the sediments have released chemical elements such (?) and phosphorus, and the results show that the various kinds of chemical pollutants (?) vertically located, and most of them are 0-20 cm below the sediments surface. The (?) content of nitrogen, phosphorus and organic carbon in the sediments respectively is (?) 0.49 g/kg. and 12.23 g/kg, and moreover some salt is also accumulated there. Except iron and manganese,the chemical elements content of copper,zinc,chromium and chromium in the sediments are fairly equal to that in Ningshao plain and the soil in Zhcjiang province,implying that the accumulation of the heavy metal in the sediment is not very obvious.The average content of iron and manganese is higher than other soils in Zhejiang and other places in china,implying that the sediments which take the reducing condition as the main method is beneficial for the accumulation of iron and manganese and the result is consistent with other research conclusions.(3)The biology-feature of sediment is one of the important properties of sediments.According to research,there lives large sum of microorganism,the benthic animal and plant in Tangpu reservoir sediments,and to a certain extent,they affect the physical and chemical properties of sediments play a very important role in decomposing,migrating and transforming the sediments.The microbial communities,in the sediments differ largely from each other and only four of the known ten ones,the Mycetozoan,Acidobacteria,Chloroflexi and Verrucomicrobia,coexist in the four sediment samples,in which the mycetozoan is the most.The main benthonic animal in the sediment is the aquatic insects.In reservoir,the common species are Cryptochionomus and Limnodrilus and in streams the common ones are Elmidae and Hydropsyche etc.the benthic animals are declining from the reservoir to the dam.The Shannon-wiener species divcrsily index and margalcf specices richness index show that from the upstream to the reservoir the se dim ents pollution status is becoming serious.The sediment benthic algae are identified to have 25 genres and 129 kinds,of which the Navicula is the most with 33 kinds and the Nitzschia is the second with 17 kinds.The diatom eutrophication index and biotic index show the basin ecology is in good condition but the cutrophication degree and the pollution status of the rivers are higher than the reservoir.(4)There are many factors hat affect the release of pollutants such as the nitrogen and phosphorus.This paper focuses on the influences of the sediment's temperature,dissolved oxygen and particle size on the release of nitrogen and phosphorus.This paper adopts the particle swarm optimization to calculate the formula of the nitrogen and phosphorus's release speed under the various influential factors.Then this formula is used to calculate the release volume of nitrogen and phosphorus of the sediments under some certain conditions.According to the calculation,the yearly nitrogen release volume of the reservoir sediments is about 87600kg of which the river takes up 15%,the transition area takes up 27%and the lake area takes up 58%;the phosphorus release volume is about 12944kg of which the river takes up 7%,the transition area takes up 33%and the lake area takes up 60%.(5)In order to wholly master the quality status of the Tangpu reservoir sediment,based on the sediments features,water features and biology features of Tangpu reservoir this paper has cstablishcd a quality cvaluation system with 3 element layers and 10 indicators to evaluate the current status of the reservoir sediments.The results show that the reservoir s,ediments are overall clean and lightly polluted.The sediment pollution and the ecology quality are relatively good and the water condition is relatively bad.