Characteristics and Evaluation for Nitrogen Pollution in Water and Surface Sediments of Xixi Wetland

In this paper, it was investigated and evaluated about characteristics of nitrogen pollution for 11 sampling water or surface sediments (0~10cm) in Hang Zhou Xixi Wetland, and correlation analysis was conducted amongst nitrogen indexes for water and that for surface sediments. The results revealed that nitrogen nutrient loading was generally serious in water of Xixi Wetland, total nitrogen(TN) and NH₄⁺-N concentration exceeded the standard in most sampling water. Organic nitrogen(ON) was the mainly existing nitrogen forms in surface sediments of Xixi Wetland, according to evaluation criteria for organic nitrogen (ON, %) in sediments, the content of organic nitrogen (ON, %) in all the sampling sediments exceeded the pollution level IV, and TN contents showed serious biological toxicity in most sampling site based on Ontario environmental quality standards. Significantly positive correlation was found between concentration of TN or NH₄⁺-N in water and NO₃^--N content in surface sediments, moreover, content of NO₃^--N in surface sediments may be attributed to the decomposition of organic matter in sediments since significantly negative correlation was found between total organic carbon (TOC) content and NO₃^--N in sediments. Therefore, It is of great significance for controlling and reduction of organic matter and TN content existed in surface sediment of Xixi Wetland.