长期再生水灌溉对干旱区山地土壤基本性质及重金属含量的影响

Effects of long-term reclaimed water irrigation on soil properties and heavy metal content in arid mountainous area

为合理评价长期再生水灌溉对干旱区山地土壤基本性质及重金属含量的影响,以乌鲁木齐市雅玛里克山(雅山)国家级绿化示范基地为研究区域,采集土壤样品61份,以5种土壤基本性质和6种重金属含量为因子,评价再生水灌溉17年后的土壤污染现状;通过对比分析再生水灌溉3年和17年各评价因子间的差异,探讨了长期再生水灌溉对土壤质量的影响。结果表明:61份土壤样品中6种重金属含量均低于国家标准(GB15618-2018)风险筛选值,但部分样品中Cd、Cu、Ni、Zn高于国家标准(GB 15618-1995)中的一级自然背景值,超标率分别为41.00%、37.70%、29.51%、16.39%。土壤重金属经单因子和内梅罗综合污染指数法评价为警戒线至轻度污染水平;长期再生水灌溉导致土壤的pH值和有机质含量显著增加,盐分含量显著减少;Cu、Ni、Cd和Zn含量显著降低,而Cr,Pb的含量显著增加,有污染增强趋势,应进行定期监测和污染评价。

In order to reasonably evaluate the effects of long-term reclaimed water irrigation on the basic properties and heavy metal content of mountainous soil in arid areas, 61 soil samples were collected from Yamalik Mountain(Yashan) National Greening Demonstration Base in Urumqi city. The status of soil pollution after 17 years of reclaimed water irrigation was evaluated by using 5 of soil properties and 6 of heavy metals as factors based on the difference of evaluation factors between 3 years and 17 years of reclaimed water irrigation, and the effect of long-term reclaimed water irrigation on soil quality was discussed. The results showed that the contents of six heavy metals in 61 soil samples were lower than the risk screening value of national standard(GB 15618-2018), but the contents of Cd, Cu, Ni and Zn in some samples were higher than the first level natural background value in national standard(GB 15618-1995), and the exceeding rates were 41.00%, 37.70%, 29.51% and 16.39%, respectively. The results showed that soil heavy metals were from warning line to slight pollution level by single factor and Nemerow comprehensive pollution index method. Long-term reclaimed water irrigation led to significant increase in soil pH and organic matter content, and a significant decrease in salt content. Cu, Ni, Cd and Zn contents decreased significantly, while Cr, Pb contents increased significantly, which showed a trend of pollution enhancement. Regular monitoring and pollution assessment should be carried out.