Identification Of Water Pollution Factors And Their Responses To LULC Along The Upper Stream Of Wuxi Port

With the rapid development of population growth and industrial, agricultural, stockbreeding, water pollutions have become increasingly prominent. Sediment, nitrogen and phosphorus and other pollutant emissions leading to the river system, due to human activity that alters the land use structure increased, causing deterioration of water quality. The non-point source pollution caused by runoff of farmland, villages and intensive livestock farming, rural and small town sewage, soil erosion and other pollutants by rainfall runoff into the water. Control capacity of point source pollution continues to increase, due to the easy way of identification and control, which bold the emergence of the non-point source pollution problem.China is now facing the period of rapid change in pollution; the proportion of non-point source pollution load is also gradually increased.Non-point source pollution sources and land use have a segnificant relationship. Land use patterns affect the great differences of the different land uses such as input and output of chemical substances, runoff, soil,vegetation type, topography, farming methods and other factors, arising from non-point source pollution is an important parameter of the non-point source pollution.In the lake watershed, streams are important landscape corridors.The ecosystem health of streams is usually used to indicate the aquatic biodiversity of the lake ecosystem, as well as being affected by water pollution factors in response to changes in land use cover of the terrestrial ecosystem due to natural geographic characteristics of the watershed with the closure of ridge lines.Therefore, identification of the water pollution factors with aquatic-bio indicators has a good effect on the restoration of aquatic ecosystem health and the control of water pollution in the lake watershed.The data of the research came from eight sampling sites along the Wuxi Port and its upstream, including water quality, aquatic, land-use conditions and spatial and temporal distribution, which were collected in the dry season (January) and rainy season (June) of2010.(1)LULC of Wuxi Port and its upper stream with significant spatial heterogeneity were divided into five types according to the main land use types. Two periods of water quality spatial heterogeneity make little different. And the river is divided into the light polluted and heavily polluted area in sampling site4and5,the paddy field area coincide with the heavily polluted area.(2) Phytoplankton distribution in Wuxi Port and its upper stream is divided into the low number of species and density of the upper reaches of light pollution, and the most sensitive species for water quality upstream and downstream the majority for the characterization of the eutrophication of algae.Water quality pollutants were divided into three components by using factor analysis.Phytoplankton distribution was used to further identify the main pollution factors; it comes up to nitrogen and phosphorus nutrition.(3)The land use structure was divided into several contributing zones. In order to tell how water quality responses to the land use along the river within different kind of contributing zones, seasons.And, establish the optimal regression prediction equation. The rice paddies are an important source of nitrogen and phosphorus and other pollutants, nitrogen nutrient pollution is the main form of NH3-N,the most significant range from the dry season, when added to the wet period and300m1500m;rural settlements in the dry season is PO4the-P, the main source of the TP rainy season and dry land, PO4-P, the TP to the water input significantly reduce, most significantly with the range300m～500m; woodland plays a role of somehow, purification on water pollution, in the300m range most significantly with; waters,cities and towns on Wuxi Port water quality impact is not significant.(4) Combined with the results of the study, to distinguish the major pollution factor and the response of land use, non-point source pollution control process to improve the scientific basis and reference.Plain river network region with intensive agricultural activities to deal with the middle and lower reaches of the Wuxi Port to focus on prevention and control, collection and treatment of rural sewage and garbage, to promote environment-friendly agricultural production technologies for nitrogen and phosphorus in the farmland zone ecological ditch to intercept, with the estuary Lake with wetland restoration project to reduce the number of pollutants import Taihu can contribute to the protection of the water environment of Taihu Lake.