Distribution and Sources of Phosphorus of Surface Water in Dezhou Irrigated District, China

The phosphorus contamination of surface water is closely associated with human health and change of water ecological environment.In this study,33 surface water samples were collected in the Dezhou Irrigated District located in the lower reaches of the Yellow River.pH,water temperature,and electrical conductivity were analyzed in situ.The concentrations of total phosphorus(TP),orthophosphate(P-ortho),dissolved total phosphorus(TDP) and dissolved orthophosphate(P-D-ortho) were determined by the method of phosphorus determination using Semi-Automated Colorimetry(Environmental Protection Agency,EPA).This study provided a scientific basis for the management of the surface water in the Yellow River Irrigated district.Results indicated that the concentrations of TP,P-ortho,TDP,and P-D-ortho were in range of 0.03~5.39 mg·L-1,0~5.10 mg·L-1,0~1.73 mg·L-1 and 0.01~2.19 mg·L-1,respectively.EC,TP,P-ortho,TDP and P-D-ortho had obviously spatial variations.Spatial variations of EC were found within each river.The spatial distributions of the four forms of phosphorus concentrations had significantly differences.The concentrations of phosphorus in the Zhangweixin River were the highest,followed by Tuhai River,and lowest in Dehuixin River.Moreover,the spatial distributions of phosphorus in suspended matter were affected by suspended matter concentration as well as industrial and agricultural productions.TP was affected by human activities extremely,and water bodies had different levels of contamination in the Dezhou Irrigated District.According to the Surface Water Environment Quality Standard of China(GB 3838—2002),about 84.9% of the samples have reached Class Ⅲ(0.1TDP≤0.2 mg·L-1) or exceeded water quality standards in the whole irrigated area.The concentrations of phosphorus was the highest in the Zhangweixin River,about 77.8% of the samples have reached Class V(0.3TDP≤0.4 mg·L-1) or exceeded class V(TDP0.4 mg·L-1).