Fuzzy analysis of the effect of city sewage water on environmental quality of greenspace soil
城市周边生活污水排放对绿地土壤环境质量的影响

It is a common phenomenon that untreated sewage water is delivered to the greenspace in suburban residential areas of large cities. Though this is an attempt to maximize the usage of a finite supply of water, it dose have an impact on greenspace in these regions. In order to investigate the effects of sewage water on the soil quality of greenspace, we analyzed the soil quality of a section of greenspace in a suburb of Beijing, which was irrigated with sewage water. Soil samples from different depths of soil near the drainage outlet of the sewage water were analyzed and compared with the soil samples collected away from the drainage outlet. Fuzzy clustering analysis was applied to the evaluation of soil quality. The results showed that compared with other soil samples the pH value near the drainage outlet of the sewage water was quite low, from 8.9to7.32, but the sewage water can increase the soil contents of organic matter content froml. 7873% to5. 9455%, potassium content from 220 mg/kg to 1230 mg/kg,phosphorous content froml 1.8 mg/kg to 150.72mg/kg, nitrogen content from 0. 1078% to 0. 5325% ,heavy metal Pb from 52.87 mg/kg to 129.53mg/kg, Cd from 0. 7525 mg/kg to 2. 5692mg/ kg. Pb content of the soil had reached the second level of the national standard. While Cd content exceeded the third level of the national standard, which has an adverse impact on the soil environment.