Contaminative Characteristics Analysis Of Sediments And Plants In Estuary Of Tongyang River At Chaohu Lake

As one of the five major freshwater lakes,Chaohu Lake provides lots of freshwater resource for people,but is polluted by the surrounding cities.Recently, the water of Chaohu Lake is more and more deteriorating,and then eutrophication serious day and day. In order to improve the water quality of Chaohu Lake,the pollution of Sediment in Estuary is studed.And,it has important theoretical and practical significance for finding out the sources of pollution and exploring the measures to reduce pollution.In this paper, 3 controlling cross sections are designed,16 sampling points are chosen, 16 sediment samples and 80 plant samples are collected.While the samples are classifing treated,composition content of nutrient matter and heavy metals of samples are determined by using spectrophotometry, aromic absorption method,etc. according to surveys.Various pollutants accumulation of three typical plants (Phragmites communis,Typha,Alternanthera philoxeroides),composition and distribution of pollutants from estuarine wetland sediments in the Tongyang River are systematiccally studied. Triangular fuzzy theory is used to evaluate contamination risk of heavy metals in the sediments.(1) In the sediments,spatial distribution of pollutants are apparently different from each other.TN content has a higher level and Organic matter has a lower level lf contamination in dediment.(2) The heavy metals of sediments are determined by using aromic absorption method. Cu and Pb pollution are light but Zn and Pb are no pollution. The order of the pollution level is Cu>Pb>Cr>Zn.(3) Analysis of the nutrient elements and heavy metals content in plants shows that adsorptive ability of aerial parts of plant for nitrogen, phosphorus and organic matter is stronger than the underground parts of it.But adsorptive ability of the heavy metals of aerial part of plant is inferior.(4) Organic matter, total nitrogen and total phosphorus in sediments show no collection in samples extracted from other sediments.Correlation between Cu and Pb,Zn and Cr is obvious,but the correlation factor is low;The correlation analyses of the corresponging element in sediments and plants show:excpt that the correlation of Pb in the sediment and phragmites communis is obvious.No correlation can be found in other heavy metals.(5) Triangular fuzzy theory is more rationality and scientific than conventional methods applied in index of geo-accumulation for evaluating contamination of heavy metals in the sediments.And it provides a new reference methed for the risk assessment on heavy metals pollution in the sediments.