生活垃圾焚烧厂周边土壤硝化和反硝化功能基因分布特征及影响因子

摘要

以上海某垃圾焚烧厂为研究对象,采用电感耦合等离子体发射光谱(ICP-OES)和荧光定量 PCR 定量分析了其周边土壤中重金属(Cd、Pb、Cu、Ni、Cr、Zn和As)含量水平,及不同硝化和反硝化功能基因丰度(AOB-amoA、nxrB、narG、nirS、norB 和 nosZ),并通过空间插值法分析了目标重金属与硝化和反硝化功能基因的空间分布特征,同时通过相关性分析和冗余分析探讨了土壤重金属及其理化性质对硝化和反硝化功能基因丰度变化的作用影响.结果表明,研究区域土壤中Cd、Pb、Cu、Ni、Cr、Zn和As的含量分别为0.083~1.065、15.54~43.17、18.30~65.52、24.58~41.65、65.04~201.0、58.96~153.5和0.098~5.115 mg·kg-1,而土壤中AOB-amoA、nxrB、narG、nirS、norB和nosZ基因丰度分别为4.89×102~1.34×105copies·g-1、5.43×106~5.41×107copies·g-1、1.21×106~7.91×106copies·g-1、3.79×106~7.39×107copies·g-1、1.61×105~ 1.33×107copies·g-1和1.44×104~2.18×105copies·g-1.由空间插值分析结果可知,土壤中重金属主要来源于焚烧烟气排放沉降,硝化和反硝化功能基因的空间分布特征与土壤总氮及重金属均具有相似性.相关性分析和冗余分析结果显示,除Cd和Zn外,其余重金属含量对硝化和反硝化功能基因丰度影响不显著,表明垃圾焚烧厂周边土壤中重金属污染对氮循环过程影响较小.相比之下,土壤理化性质如总有机碳、总氮等对硝化和反硝化功能基因丰度影响更显著.该研究可为相关地区垃圾焚烧厂周边土壤重金属污染控制及微生物生态风险评价提供参考.%The contents of heavy metals (i.e., Cd, Pb, Cu, Ni, Cr, Zn and As) and quantities of nitrification and denitrification functional genes(i.e.,AOB-amoA,nxrB,narG,nirS,norB and nosZ)were determined in the surface soils surrounding a municipal solid waste incineration (MSWI) plant in Shanghai by using an inductively coupled plasma optical emission spectrometer (ICP-OES) and quantitative PCR (qPCR), respectively. The spatial distribution characteristics of these heavy metals and functional genes were analyzed by a spatial interpolation method, and the effects of heavy metals and soil physicochemical properties on the quantities of nitrification and denitrification functional genes were also studied by correlation analysis and redundancy analysis. The results showed that the contents of Cd, Pb, Cu, Ni, Cr, Zn, and As were 0.083~1.065, 15.54~43.17, 18.30~65.52, 24.58~41.65, 65.04~201.0, 58.96~153.5,and 0.098~5.115 mg·kg-1,respectively, while the quantities of AOB-amoA, nxrB,narG, nirS, norB,and nosZ genes were 4.89×102~1.34×105copies·g-1(dry soil), 5.43×106~5.41×107copies·g-1, 1.21×106~7.91×106copies·g-1, 3.79×106~7.39×107 copies·g-1, 1.61×105~1.33×107copies·g-1and 1.44×104~2.18×105copies·g-1, respectively. The results of spatial interpolation suggested that the detected heavy metals in soils mainly originated from the precipitation of incineration flue gas, and the spatial distribution characteristics of functional genes were similar to those of total nitrogen (TN) and heavy metals. Besides, the results of correlation analysis and redundancy analysis indicated that the effect of heavy metal contents on the quantities of nitrification and denitrification functional genes was not significant, except Cd and Zn, suggesting that the soil heavy metal pollution surrounding the MSWI plant had little influence on the nitrogen cycles. By contrast, a positive significant correlation was found between soil physicochemical properties such as pH, TOC and TN and the quantities of nitrification and denitrification functional genes. This study provides references for control of heavy metal pollution and microbial ecological risk assessment in soils surrounding MSWI plants.