城市周边生活污水排放对绿地土壤环境质量的影响

Fuzzy analysis of the effect of city sewage water on environmental quality of greenspace soil

大城市郊区的小型居住区,将生活污水未经处理直接排入附近的绿地是比较常见的。这种直接排放虽然利用了有限水源,但对绿地土壤带来环境影响。为了研究这类排放对周边土壤环境的影响,选择了京郊一处接受附近生活污水直接排放的绿地,取其污水排放口附近的土壤样品为实验对象,以远离该点的土样为对照来研究生活污水排放对周边土壤环境质量的影响。模糊聚类分析结果表明:与对照点相比,生活污水排放提高了排放口附近土壤的养分含量,土壤pH值由8.9降低至7.32,有机质含量由1.7873%提高到5.9455%,钾含量由220 mg/kg提高到1230 mg/kg,磷含量由11.8 mg/kg提高到150.72mg/kg,全氮含量由0.1078%提高到0.5325%,重金属铅含量由52.87 mg/kg提高到129.53mg/kg、镉含量由0.7525mg/kg提高到2.5692mg/kg。铅含量达到了国家二级标准,而镉含量超过了国家三级标准,存在严重的土壤环境污染。

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.