Pollution Characteristics Analysis And Environmental Quality Assessment Of Sediments For Estuary Wetland Of Tangxihe River

In the present research, estuary wetland of Tangxihe River flowing into Chaohu Lake is taken as the subject investigated to conduct the pollution characteristics analysis and environmental quality assessment of sediments. In the research field, 88 sediment samples in 30 sampling points were acquired. Through the laboratory analysis, the content data of Cu, Zn , Pb, Cr, Cd, organic matter, total phosphorus and total nitrogen, et al. were obtained, respectively. On the basis, the pollution factors and pollution characteristics of sediments in the estuary wetland of Tangxihe River were analyzed, and the environmental quality and potential ecological risk of sediments were evaluated. The conclusions may be briefly summed up as follows:(1) On the whole, total phosphorus and organic matter content in the samples decline with the depth increase. That is, the contents in surface layer A were the highest while C layer lowest. As for total nitrogen, the content in surface layer A is the highest while B layer lowest. With respect to heavy metals Cu, Zn, Cd and Pb, the seriously polluted district is concentrated in the A layer whereas Cr concentrated in the B layer. Perpendicular to the lakeshore and along the lakeshore, there were no obvious similarities on the distribution characteristics for the sediment pollutants in all layers.(2) It was shown by the principal component factor analysis that organic matter degradation, industrial wastewater and domestic sewage discharge were the major source of pollutants in the A layer. In the B layer, organic matters which act as a combination of heavy metal recede in importance but it is still the main source of total phosphorus and total nitrogen pollutants. In the C layer, the importance of organic matter degradation as a source of pollution is further reduced. It may be just the main source of total nitrogen pollutants.(3) In the present study, a coupled model of unascertained cluster and correspondence factor analysis was proposed and applied to the analysis of pollution characteristics of sediments in the estuarine wetland of Tangxihe Stream. The results show that there are four kinds of obvious corresponding relationship between the samples and the pollution factors respectively for the high phosphorus pollution area, the combined pollution areas of Cd and organic matter, the compound pollution area of Cu-Zn-Pb-Cr, and the high nitrogen pollution area.(4) The environmental quality of sediments was evaluated according to the variable fuzzy recognition model of theory of engineering variable fuzzy set, and the evaluation results were compared with that of fuzzy comprehensive assessment. The results indicate that the environmental quality of sediment belongs to the level of alert, and is at clean level in general.(5) The potential ecological associated with the heavy metals pollution was evaluated by means of the potential ecological risk assessment model with blind numbers based on MATLAB. The results indicate that the degree of contamination was at the middle level, and the degree of the potential ecological risk was low. In general, the pollution degree of five heavy metals in the sediments can be arranged in the order, namely Cu>Cd>Zn>Pb>Cr, and as for the potential ecological risk, the arrangement can be expressed as Cd>Cu>Pb>Cr>Zn.