油松育苗地施用污泥厌氧消化产品重金属污染风险评价

Risk Assessment of Heavy Metal Pollution by Applying Sludge Anaerobic Digestion Products in the Nursery Field of Pinus tabulaeformis

[目的]探究城镇排水污泥厌氧消化产品在油松育苗地施用后的重金属累积情况及其污染风险,为判定其应用的可行性及确定其施用量提供依据。[方法]在现有18年生油松大苗育苗地,采取随机区组试验设计,按0、1、2、3、4、5 kg/m^(2)设置6个施用量水平定株施入污泥产品,通过测定土壤中铜(Cu)、镍(Ni)、铬(Cr)、锌(Zn)、镉(Cd)、汞(Hg)、砷(As)、铅(Pb)8种重金属的含量,利用潜在生态危害指数法对不同处理下的土壤环境质量进行评价。[结果]铜、镍、铬、锌、铅5种重金属随着污泥产品施用量的增加呈现先减少后增加的趋势,且在污泥产品中含量较高的铜、锌在0~20和20~40 cm土层中对照组皆显著高于4 kg/m^(2)的处理(P<0.05),砷和汞含量变化幅度不大。不同土层重金属总量随施肥量增加的变化趋势类似,并在0~20 cm土层4 kg/m^(2)处理下出现最小值。重金属镉具有产生污染的潜在风险,且在4 kg/m^(2)处理下潜在生态危害指数最低。其他重金属单独作用或8种重金属共同作用均为低生态风险。[结论]综合考虑镉的生态风险及重金属含量的变化情况,在油松大规格苗木移植培育育苗地施用污泥产品可将用量控制在4 kg/m^(2)较为适宜。

[Objective]To explore the accumulation of heavy metals and pollution risks of the anaerobic digestion products of urban sewage sludge after application in the seedling nursery of Pinus tabulaeformis Carr.,so as to provide a basis for judging the feasibility of its application and determining its application rate.[Method]In the existing 18-year-old Pinus tabulaeformis seedling nursery,a randomized block experiment design was adopted,and 6 application levels were set at 0,1,2,3,4,and 5 kg/m^(2)to apply the sludge products.The contents of eight heavy metals such as copper(Cu),nickel(Ni),chromium(Cr),zinc(Zn),cadmium(Cd),mercury(Hg),arsenic(As)and lead(Pb)in the soil were determined.The potential ecological risk index method was used to evaluate the soil environmental quality under different treatments.[Result]The five heavy metals of copper,nickel,chromium,zinc,and lead showed a trend of first decreasing and then increasing with the increase in the application amount of sludge products,and the contents of copper and zinc in sludge products were significant higher in the control group than those in the treatment of 4 kg/m^(2)in the soil layer between 0-20 and 20-40 cm(P<0.05);variation in the content of arsenic and mercury was not significantly.The change trend of the total amount of heavy metals in different soil layers with increasing fertilization is similar,and the minimum value appeared at the treatment of 4 kg/m^(2)in the 0-20 cm soil layer.The heavy metal cadmium has the potential risk of pollution,and the potential ecological risk index is the lowest under the treatment of 4 kg/m^(2).Other heavy metals acting alone or 8 kinds of heavy metals acting together are all at low risk level.[Conclusion]Considering the ecological risk of cadmium and the change of heavy metal content,it is more appropriate to control the dosage of sludge products at 4 kg/m^(2)in the nursery land of large-scale seedling transplantation and cultivation of Pinus tabulaeformis.