施用有机肥对土壤重金属累积的影响及风险评价

Effect of organic fertilizer application on heavy metals accumulation in soil and risk assessment

为探讨施用不同量有机肥对土壤重金属含量和污染程度影响,采用玉米大区定位试验,设置不施肥(CK)、高量有机肥(T150)、中量有机肥(T45)、低量有机肥(T30)、化肥(T0)5个处理,连续3年研究有机肥用量对土壤中Cd、Cr、Ni、As、Hg、Pb、Cu、Zn 8种重金属含量影响,并评价土壤中重金属污染程度,为合理应用有机肥控制农田土壤重金属污染提供科学依据。结果表明,随有机肥用量和施用时间延长,8种重金属均表现逐渐增加趋势,T150>T45>T30>T0>CK,T150处理含量显著高于其他4个处理(P<0.05)。T150处理2017、2018年Cd、Ni、Pb、Cu单因素污染指数大于1,内梅罗综合污染指数大于1,处于轻度污染。2018年T45处理仅Cu单因子污染指数大于1,内梅罗综合污染指数为1.08,达到轻度污染。与T0相比,T30处理各重金属含量增幅最小,Cd、 Cr、 As、 Hg、 Cu、 Zn 3年增幅分别为8.59%~27.59%、 14.79%~16.23%、 0.95%~5.58%、 8.79%~19.18%、7.41%~10.20%、0.30%~6.04%。T30处理连续3年内梅罗污染综合指数小于1,均处于清洁水平,重金属含量皆未超过国家标准,潜在生态危害指数均未超标。结果表明,随时间累积和有机肥施用量添加,土壤中重金属含量增加,适宜有机肥比例对环境综合污染风险评价影响较小,较长时间内对土壤重金属潜在生态危害不严重。

In order to study the effect of different amounts of organic fertilizer on the content and pollution degree of heavy metals in soil,a large-scale experiment of maize was conducted and five treatments were set up,i.e.no fertilizer(CK),high organic fertilizer(T150),medium organic fertilizer(T45),low organic fertilizer(T30)and chemical fertilizer(T0),to study the effect of organic fertilizer application on eight kinds of heavy metals,Cd,Cr,Ni,As,Hg,Pb,Cu and Zn contents in three consecutive years,and to evaluate the pollution degree in soil,which would provide scientific basis for the reasonable application of organic fertilizer to control the heavy metal pollution of farmland soil.The results showed that with the increase of time and amount of organic fertilizer,the contents of eight heavy metals increased gradually.The increasing trend was T150>T45>T30>T0>CK.The contents of T150 treatment were significantly higher than those of other four treatments(P<0.05).For the T150 treatment in 2017 and 2018,Cd,Ni,Pb and Cu the single factor pollution index was greater than 1,and the Nemero comprehensive pollution index was greater than 1,which was in mild pollution degree.Only Cu single factor pollution index was greater than 1 for T45 treatment in 2018,and the Nemero comprehensive pollution index was 1.08 to achieve mild pollution degree.The increase content of each heavy metal in the T30 treatment was the smallest compared with that in the T0,by the increase of8.59%-27.59%,14.79%-16.23%,0.95%-5.58%,8.79%-19.18%,7.41%-10.20%,0.30%-6.04%of Cd,Cr,As,Hg,Cu and Zn in three years,respectively.For the three consecutive years,the Nemero pollution index of T30 treatment was less than 1,which was clean,neither the metal content nor the potential ecological hazard index in the three consecutive years exceeded the national standard.It was concluded that with the accumulation of years and the addition of organic fertilizer,the contents of heavy metals in soil were increased,proper amount of organic fertilizer should have little impact on the risk assessment index of environmental comprehensive pollution,and the potential ecological harm of heavy metals in soil should not be serious over a long period of time.