铁矿区内重金属对土壤氨氧化微生物群落组成的影响

以密云水库上游某铁矿区为研究对象,采用荧光定量PCR和变性梯度凝胶电泳(DGGE)分析了矿区内不同采样点的土壤中氨氧化微生物的数量和群落结构的变化,结果表明,土样中氨氧化细菌(AOB)和氨氧化古菌(AOA)的数量变化范围分别为3.01×107~1.08×109copies/g干土和8.65×107~2.69×109copies/g干土.重金属含量与氨氧化微生物数量的相关性分析以及氨氧化微生物群落结构的冗余分析结果表明,该矿区内重金属污染改变了土壤中的氨氧化微生物的数量和结构.Cu污染对AOA的数量起到了显著抑制作用(r= -0.653*, P<0.05),但是对AOB则没有明显作用;Zn污染对尾矿库区域土壤的AOA/AOB比值影响显著(r= -0.606*, P<0.05);Cd污染改变了AOB的种群分布,降低了AOB的多样性水平.土壤中Cr长期干扰并没有改变氨氧化微生物的数量和结构,但是明显得抑制了氨氧化速率,表明重金属污染在一定程度上也影响了土壤生态系统的氮循环.

Impact of long-term heavy metals pollution on ammonia oxidizing microbial community in an iron mine soil

To examine the changes of ammonia-oxidizing microorganisms community in an iron mine of the upstream area of Miyun Reservoir, soil samples were collected from fourteen sites. Quantification of ammonia-oxidizing bacteria (AOB) and archaea (AOA) were performed by real-time PCR, and the microbial community structures were studied by denaturing gradient gel electrophoresis (DGGE). The results showed that the copy numbers per gram of dry soil of AOB changed from 3.01×107to 1.08×109and the copy numbers per gram of dry soil of AOA varied from 8.65×107to 2.69×109. Pearson correlation and the redundancy analysis results showed that heavy metal pollution had changed the abundance and community structure of soil ammonia-oxidizing microorganisms in this iron area. The Cu pollution had a significant inhibitory effect on abundance of AOA (r = -0.653*, P < 0.05), but had no effect on AOB; The Zn pollution had a remarkable effect on AOA/AOB ratio of tailing area (r= -0.606*, P<0.05); Cd pollution changed the AOB community structure and reduced its diversity; The long-term interference of Cr did not change the abundance and community structure of soil ammonia oxidizing microorganisms, but inhibited the ammonia oxidation rate obviously. The results showed that heavy metal pollution affect the circulation of nitrogen in soil ecosystem to a certain extent.