再生水灌水水平对土壤重金属及致病菌分布的影响

Effects of different irrigation levels of reclaimed water on the distribution of soil heavy metals and typical pathogenic bacteria

为了探讨再生水不同灌水水平对土壤重金属、活性微生物和典型环境致病菌分布的影响,采用室内土柱灌水实验,研究再生水、自来水不同灌水水平对土壤重金属Cd、Pb、Cu、Zn和土壤细菌、真菌、大肠菌群、大肠埃希氏菌分布的影响.结果表明:相同灌水水平下,与自来水灌溉处理相比,再生水灌溉处理下土壤重金属含量略有提高,但仍远低于《土壤环境质量标准》[GB15618-1995]限值,因此短期再生水灌溉不会造成土壤重金属污染;再生水不同灌水水平对比分析表明,充分灌溉相比非充分灌溉提高了表层土壤Cd、Pb含量,Cu、Zn含量无明显差异.此外,相同灌水水平下,再生水灌溉相比自来水显著提高了表层土壤细菌总数和大肠菌群、大肠埃希氏菌数量,对土壤真菌总数影响不大;再生水不同灌水水平对比分析表明,充分灌溉相比非充分灌溉显著提高了表层土壤细菌和真菌总数及大肠菌群、大肠埃希氏菌数量.土壤重金属与土壤活性微生物及典型环境致病菌之间的相关性分析表明,土壤Cd、Pb、Zn含量与土壤细菌、真菌总数及大肠菌群、大肠埃希氏菌数量之间呈正相关性,推断较低含量重金属对土壤活性微生物及典型致病菌的生长繁殖存在一定程度上的刺激作用.因此,再生水灌溉促进了土壤活性微生物的繁衍,并且在一定程度上增加了土壤重金属和环境致病菌的污染风险;合理控制再生水灌水水平可以有效阻控土壤重金属和致病菌含量.

This study aimed to discern the effect of different levels of irrigation with reclaimed water on soil heavy metals and the distribution of soil active microorganisms and typical environmental pathogenic bacteria.The effects of two irrigation water qualities(reclaimed water and tap water)and two irrigation levels(full irrigation and insufficient irrigation)on soil heavy metals and the distribution of soil active microorganisms and typical environmental pathogenic bacteria were studied through indoor soil column irrigation.Results indicated that reclaimed water irrigation increased the content of heavy metals in soil,but according to the soil environmental quality standard,soil after irrigated by reclaimed water did not exceed the standard.Therefore,reclaimed water irrigation could not cause soil heavy metals pollution.Compared with insufficient irrigation with reclaimed water,full irrigation with reclaimed water significantly increased the content of Cd and Pb in surface soil,there was no significant difference in the content of Cu and Zn.At the same irrigation level,the number of bacteria,coliform group and Escherichia coli in surface soil significantly increased with reclaimed water irrigation,there was no significant difference in the number of soil fungi at two irrigation water quality.The number of bacteria,fungi,coliform group and Escherichia coli in surface soil under full irrigation with reclaimed water was significantly higher than with insufficient irrigation using reclaimed water.There was a positive correlation between the content of heavy metals(Cd,Pb,Zn)and the quantity of bacteria and fungi,and between the content of heavy metals and the quantity of coliform group and Escherichia coli.Reclaimed water therefore promoted the reproduction of active microorganisms in surface soil,and increased the risk of soil heavy metals and environmental pathogens pollution.Reasonable irrigation with reclaimed water can therefore effectively control the content of heavy metals and the quantity of soil pathogens in soil.