畜牧场土壤中重金属与抗生素抗性基因的分布规律研究

Distribution of Heavy Metals and Antibiotic Resistance Genes in the Soil of Livestock Farms

为研究畜牧场土壤中重金属和抗生素抗性基因(ARGs)的空间分布特点,揭示二者之间的相关性,为后续特色黑土的修复治理提供基础理论依据。结合GIS优化布点,在黑龙江省大庆市杜尔伯特蒙古族自治县某畜牧场园区分别采集内部10 cm和50 cm深度的土壤。采用原子吸收光谱仪和原子荧光分光光度计检测8种重金属含量,用单因子污染指数法和内梅罗综合污染指数法对重金属进行污染评价;通过实时荧光定量PCR技术检测土壤中的28种ARGs,运用Pearson分析重金属与ARGs的相关性,同时对二者之间的相似性进行聚类分析。10 cm和50 cm土壤的单因子污染指数分析显示,As均属于重度污染等级(P i>3),其他7种元素属于安全等级(P i≤1),内梅罗综合污染指数均属于重度污染等级(P综>3)。28种ARGs污染分布差异较大,除β-内酰胺类ARGs随土壤深度的增加污染程度呈增大的趋势,其余都呈减小的趋势;50 cm土层中blaTEM的相对丰度较高,约为0.65拷贝数/16S rRNA基因拷贝数。相关性分析表明,杜蒙园区土壤中sul2与tetX、tetR、tetW、tetC和tet34分别与重金属Cr、As、Pb和Cd存在一定程度的相关性(P<0.05);重金属污染程度较重的As和Cr对ARGs的选择压力相似。畜牧场中重金属污染严重,ARGs污染水平亟待推行评价标准,为后续恢复受污染的特色黑土的生态功能提供依据。

In order to study the spatial distribution characteristics of heavy metals and antibiotic resistance genes(ARGs)in the soil of livestock farms,reveal whether there is a correlation between the heavy metal and ARGs,and provide the basic theoretical basis for the subsequent restoration and treatment of characteristic black soil.GIS was used to optimize the sampling point design,soil samples both in 10 cm-depth and 50 cm-depth layer were collected in Daqing Duerbert Mongolian Autonomous County,Heilongjiang Province.The contents of eight heavy metals were detected by atomic absorption spectrometer and atomic fluorescence photometer,and the pollution of heavy metals was evaluated by single factor pollution index and Nemero comprehensive pollution index.Twenty-eight antibiotic resistance genes in soil were detected by real-time fluorescence quantitative PCR,Pearson index was used to analyze the correlation between heavy metals and ARGs,and the similarity between them was analyzed by clustering.In the single-factor pollution index of 10 cm-depth and 50 cm-depth soil,As elements all belong to the heavy pollution level(P i>3),the other 7 elements belong to the safety level(P i≤1),and the Nemerow comprehensive pollution index of 10 cm and 50 cm-depth soil all belonged to the heavy pollution level(P comprehensive>3).The distribution of 28 antibiotic resistance genes was significantly different,with the exception ofβ-lactams ARGs showing an increasing trend with the increase of soil depth,and all the others showed a decreasing trend with the increase of soil depth.The relative abundance of blaTEM in the 50 cm soil layer was high,approximately 0.65 copies of genes/copies of 16S rRNA genes.Correlation analysis showed that sul2 and tetX,tetR,tetW,tetC and tet34 were respectively correlated with heavy metals Cr,As,Pb and Cd to a certain extent in the soil of livestock farms(P<0.05).The selective pressure of As and Cr was similar to that of ARGs.Heavy metal pollution is serious in livestock farms,and the standard of ARGs pollution guidelines urgently need to be evaluated.This study can provide reference for restoring the ecological function of polluted black soil in the future.