[Analysis of Spatial Variability of Water Quality and Pollution Sources in Lihe River Watershed, Taihu Lake Basin].

The source of pollutants in the Tai Lake basin and the characteristics of spatiotemporal variations were studied by conducting water quality monitoring in the Lihe River watershed to the west of Tai Lake in 2014. The dynamic changes in total phosphorus (TP), ammonia nitrogen (NH-N), and chemical oxygen demand (COD) were studied in flood and non-flood seasons at five monitoring points from upstream to downstream. The average concentrations of TP, NH-N, and COD were 0.176 mg·L, 1.075 mg·L, and 10.626 mg·L respectively, and the water quality was lower than the grade Ⅳ standard. From upstream to downstream, the concentrations of TP and NH-N gradually increased. The water quality downstream was poor, worse than the gradeⅤstandard; however, COD was low and met the grade Ⅳ standard. During the non-flood season, the pollutant concentrations gradually increased from upstream to downstream. There was no obvious trend in flood season. Concentrations of pollutants gradually increased with the increase in the area of inhabited land and decrease in the area of forest land. The population density, livestock, and poultry production were significantly correlated with the concentrations of pollutants in the river. The pollutants in the Lihe River watershed mainly originated from human activities, and livestock and poultry breeding activities.