摘要
为探究连续施用生活污泥对苹果和果园土壤重金属污染风险的影响,通过田间试验,设置常规施肥(T1)、中量施用污泥(T2)、高量施用污泥(T3)和低量施用污泥(T4)4个处理,分析污泥不同用量、不同施用年限苹果和土壤的重金属污染风险.结果表明,苹果中的Cd、Cr、Pb、Hg和As含量均未超过限量标准.施用污泥3 a,土壤重金属的单因子污染指数分别低于警戒线71.98％～75.98％、66.57％～69.90％、92.32％～94.01％、78.59％～90.40％、17.22％～23.29％;内梅罗综合污染指数和潜在生态风险指数分别低于警戒线9.51％～16.08％、82.50％～86.75％.施用污泥3 a,Hg和As含量的单因子污染指数分别比背景值增长29.52倍、83.14％.T2—T4处理的潜在生态风险指数与背景值相比升高78.38％、95.69％、48.18％,Hg的潜在生态风险贡献率从11.00％～17.02％增长至19.32％～33.70％,As从21.55％～24.61％增长至31.54％～39.17％.基于Cd和Hg计算的污泥安全施用年限较短,为32.30～116.31、36.07～129.91 a.综上,连续施用生活污泥3 a,苹果果实和土壤均处于无污染状态;随施污泥年限增加,土壤单因子污染指数(Hg和As)、综合污染指数和潜在生态风险均升高,其中Hg和As是主要贡献因子.基于施肥量计算的污泥安全施用年限,Cd和Hg是最主要的限制性元素.污泥合理利用不会引起土壤重金属污染.
Abstract
To investigate the impact of continuous application of municipal sludge on the risk of heavy metal contamination in apples and orchard soil,a field experiment was conducted with four treatments:conventional fertilization(T1),moderate sludge application(T2),high sludge application(T3)and low sludge application(T4).The study analyzed the risk of heavy metal contamination in apples and soil under different sludge application rates and durations.The results indicated that the concentrations of Cd,Cr,Pb,Hg,and As in apples did not exceed the regulatory limits.After three years of sludge application,the single-factor pollution indexes for heavy metals in the soil were below the warning thresholds by 71.98％to 75.98％,66.57％to 69.90％,92.32％to 94.01％,78.59％to 90.40％,and 17.22％to 23.29％,respectively.The Nemerow comprehensive pollution index and potential ecological risk index were also below the warming thresholds by 9.51％to 16.08％and 82.50％to 86.75％,respectively.Following three years of sludge application,the single-factor pollution index for Hg and As increased by 29.52 times and 83.14％compared to background levels.The potential ecological risk index for treatments T2 to T4 increased by 78.38％,95.69％and 48.18％respectively,compared to background values.The potential ecological risk contribution rate of Hg increased from 11.00％—17.02％to 19.32％—33.70％,while As increased from 21.55％—24.61％to 31.54％—39.17％.Based on the calculations for Cd and Hg,the safe application duration for sludge was relatively shorter,ranging from 32.30 to 116.31 years and from 36.07 to 129.91 years,respectively.In summary,after the continuous application of sewage sludge for three years,both apple fruit and soil remained in an uncontaminated state.However,with the increasing of sludge application duration,the single-factor pollution index for Hg and As,comprehensive pollution index and potential ecological risks all increased,with Hg and As being the primary contributing factors.Based on the safe application duration of sludge,Cd and Hg emerged as the most significant limiting elements.The rational utilization of sludge does not lead to heavy metal contamination in the soil.
维普
万方数据