某冶炼工厂周围农田土壤重金属污染状况及其对细菌群落影响

发布时间：2019-06-08 13:59

【摘要】：目的评价河南某冶炼工厂周围农田土壤重金属污染状况,并探讨重金属污染对该地土壤中细菌群落的影响。材料与方法于该工厂西侧(该地常年主导风向下风侧),依次选择距离工厂主烟囱741~2556m的7块农田观察区(G1~G7),分4个季度共采集28个混合土样,固体测汞仪法、原子荧光光谱法、电感耦合等离子体发射光谱法、电感耦合等离子体质谱法测定土壤中汞(Hg)、砷(As)、铅(Pb)、镉(Cd)、铜(Cu)、锌(Zn)、镍(Ni)、铬(Cr)8种重金属含量。单项累积指数法和内梅罗指数法进行重金属累积性评价,Hakanson潜在生态危害指数法进行土壤生态风险评价。采用美国国家环保局推荐的健康风险评估模型,评价8种重金属对成人和儿童健康产生的非致癌风险和致癌风险。运用基于16S rDNA的PCR-DGGE方法和Illumina MeSeq平台测序方法,对7块农田土壤细菌群落进行比较分析。结果1.重金属污染状况:(1)Cd、Pb、As、Hg、Cu和Zn等6种金属均在G1观察区出现超标,28份农田混合土样中超标最严重的是Cd和Pb,其最大超标倍数为42.33和6.43。(2)距离工厂最近的G1、G2观察区的6种重金属含量高于G4~G7观察区,差异均具有统计学意义(P值均小于0.05)。Cd、Pb、As、Hg、Cu和Zn等6种重金属含量与距工厂的距离呈负相关,P值均小于0.05。(3)6种重金属含量之间具有正相关性,相关具有统计学意义(P0.05)(4)土壤中As、Ni和Cr含量在不同季节分布差异有统计学意义(P值均小于0.05)。2.潜在生态风险评价:Cd、Pb、Hg的单项累积指数范围在9.25~342.69之间,达到重度累积。G1~G7观察区的综合累积指数为731.13~30588.88,均达到重度累积;G1~G7观察区的总潜在生态危害指数范围为1620.29~14059.37,均达到极强生态危害。3.健康风险评价:铅经手-口摄入暴露途径对儿童的最大非致癌风险指数为2.44,G1观察区农田土壤中8种重金属对儿童健康的最大总非致癌风险值为3.42,均大于非致癌风险限值1。在7块观察区农田,砷对成人和儿童健康的致癌风险分别为1.36×10-5~4.28×10-5和9.56×10-5~3.00×10-4,超过致癌风险控制值10-6约13.6~42.8和95.6~300倍。4.DGGE指纹图谱发现,第一季度的优势条带最多,共23条;第三季度最少,共有10条。四个季度共检出5种细菌门类,分别为变形菌门、放线菌门、厚壁菌门、拟杆菌门和酸杆菌门,其中变形菌门的检出率最高。主成分分析和聚类分析显示,重金属污染最重的G1和G2观察区的细菌群落结构差异性较小,但与其他观察区的差异性较大。冗余分析显示,重金属和理化因素对细菌群落分布均有影响,其中重金属对G1、G2、G6和G7观察区的影响程度最大。5.Illumina MeSeq测序方法共检出34个门、99个纲、138个目、152个科、166个属和50个种。变形菌门、放线菌门、酸杆菌门等优势菌门占总细菌微生物的相对丰度达95%以上。G1观察区的Chao指数、ACE指数、Simpson指数和Shannonz指数等细菌微生物多样性指数最低,分别为4009.14、4180.53、9.40和0.994,远低于细菌多样性最高的G7观察区。绿菌门、装甲菌门、迷踪菌门和拟杆菌门在7块观察区中的丰度分布差异有统计学意义(P0.05)。在污染最严重的G1观察区,绿菌门的相对丰度最高,与其他观察区相比差异均具有统计学意义(P值均小于0.001);其装甲菌门相对丰度最低,与污染最轻的G7观察区相比差异具有统计学意义(P值小于0.05)。G1观察区与G3~G7等5个观察区相比,节细菌属、贪铜菌属、芽球菌属等细菌的相对丰度增加,热单孢菌属、厌氧氨氧化菌属(Candidatus Solibacter)的相对丰度降低,差异均有统计学意义(P值均小于0.05)。冗余分析显示,重金属含量对不同观察区细菌群落分布的影响大于含水率等理化性质因素。结论1.Cd、Pb、Hg和As等金属是该地农田的主要重金属污染物;Cd、Pb、Hg的污染程度达到重度累积,存在极强生态危害;Pb含量对儿童健康具有非致癌风险;As含量对成人和儿童均具有致癌风险。2.重金属污染降低了该地农田土壤中细菌微生物多样性,是影响土壤细菌群落分布的主要因素,主要降低了装甲菌门、热单孢菌属、厌氧氨氧化菌属等细菌的丰度。
[Abstract]:Objective To evaluate the heavy metal pollution in the field of a smelting plant in Henan, and to explore the effect of heavy metal pollution on the bacterial community in the soil. The material and method are selected from 7 farmland observation areas (G1 to G7) of the main chimneys 741 to 2556m of the plant, and 28 mixed soil samples, solid mercury-measuring instrument method and atomic fluorescence spectrometry are collected in four quarters according to the 7 farmland observation area (G1-G7) of the main chimney 741-2556m of the plant in turn, The content of mercury (Hg), arsenic (As), lead (Pb), carbon (Cd), copper (Cu), zinc (Zn), nickel (Ni) and chromium (Cr) in the soil was determined by ICP-AES and ICP-MS. The evaluation of the accumulation of heavy metals was carried out by the single cumulative index method and the internal plum index method, and the ecological risk assessment of the soil was carried out by the Hakanson's potential ecological hazard index method. The non-carcinogenic and carcinogenic risks of 8 heavy metals to the health of adults and children were evaluated using a health risk assessment model recommended by the National Environmental Protection Agency. By using the 16S rDNA-based PCR-DGGE method and the Illumina MeSeq platform sequencing method, the bacterial community of 7 farmland soil was compared and analyzed. Results 1. The heavy metal pollution status: (1)6 kinds of metals such as Cd, Pb, As, Hg, Cu and Zn exceed the standard in the G1 observation area, and the most serious of the 28 farmland mixed soil samples is Cd and Pb, and the maximum superscalar is 42.33 and 6.43. (2) The content of six heavy metals in the G1 and G2 observation areas of the plant was higher than that of the G4-G7 observation area, and the difference was statistically significant (P <0.05). The content of 6 heavy metals, such as Cd, Pb, As, Hg, Cu and Zn, was negatively correlated with the distance from the plant, and the P value was less than 0.05. (3) There was a positive correlation between the contents of 6 kinds of heavy metals (P <0.05) (P <0.05) (4) The contents of As, Ni and Cr in the soil were different in different seasons (P <0.05). The potential ecological risk assessment: the single cumulative index of Cd, Pb and Hg is in the range of 9.25-342.69, reaching a severe accumulation. The comprehensive cumulative index of the G1-G7 observation region was 731.13-30588.88, and it had a severe accumulation; the total potential ecological hazard index in the G1-G7 observation region was 1620.29-14059.37, which reached a very strong ecological hazard. Health risk evaluation: The maximum non-carcinogenic risk index of the children was 2.44, and the maximum non-carcinogenic risk value of 8 heavy metals in the farmland soil of the G1 observation area was 3.42, which was greater than that of the non-carcinogenic risk limit 1. In the 7 observation area, the carcinogenic risk of arsenic to the health of adults and children is 1.36-10-5-4.28-10-5 and 9.56-10-5-3.00-10-4, exceeding the control value of carcinogenic risk 10-6, about 13.6-42.8 and 95.6-300-fold. In the four quarters, five species of bacteria were detected, namely, the strain, the actinomycete, the thick-walled fungus, the Bacteroides and the phylum, in which the positive rate of the strain was the highest. The principal component analysis and cluster analysis show that the difference of the bacterial community structure in the G1 and G2 observation regions with the heaviest heavy metal pollution is small, but the difference with other observation regions is relatively large. The results show that the heavy metal and the physical and chemical factors have an effect on the distribution of the bacterial community, and the influence of heavy metal on the observation areas of G1, G2, G6 and G7 is the greatest.5. The method of the Illumina MeSeq sequencing has 34 doors,99 classes,138 eyes,152 families,166 genera and 50 species. The relative abundance of the total bacterial micro-organisms is over 95%. The diversity index of the bacteria, such as the Chao index, the ACE index, the Simpson index, and the Shannonz index in the G1 observation area, is the lowest, which is 4009.14, 4180.53, 9.40 and 0.994, which is much lower than that of the G7 observation area with the highest bacterial diversity. There was a significant difference in the distribution of abundance in the 7 (P0.05). In the most polluted G1 observation area, the relative abundance of the green fungus was the highest, and the difference was statistically significant (P <0.001). The difference was statistically significant (P <0.05) compared to the most polluted G7 observation area. The relative abundance of the bacteria, such as the genus Arthrospira, the covetus, and the genus of the genus Bacillus, was increased, and the relative abundance of the genus Thermomonospora and the genus CANDIDatus Solibacter decreased, and the difference was statistically significant (P <0.05). The results of redundancy analysis show that the influence of heavy metal content on the bacterial community distribution in different observation areas is greater than that of water content. Conclusion 1. The metals such as Cd, Pb, Hg and As are the main heavy metal pollutants in the field. The degree of pollution of Cd, Pb and Hg has a severe accumulation, and there are very strong ecological hazards. The Pb content has non-carcinogenic risk to the children's health. As a result, the As content has a carcinogenic risk to both adults and children. The heavy metal pollution reduces the microbial diversity of the bacteria in the soil of the area, which is the main factor affecting the distribution of the bacterial community in the soil, which mainly reduces the abundance of the bacteria such as the Armored bacteria, the Thermomonospora, and the anaerobic ammoxidation bacteria.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X756;X53

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