| Sediment is an important component of freshwater ecosystems,which not only accumulates nutrient, organic compounds and heavy metals in water environment, but also is the main habitat of benthic animals and microorganisms. The sediment exchanges matter and energy with overlying water frequently. Due to rapid development of urbanization and the interference of human activities, pollutants enter into water and subsequently accumulated in sediment by atmospheric sedimentation, wastewater discharge, loss of water including soil, rain eluviation. The pollutants in sediment would change the microenvironment in sediment, and further affect the structure and function of microbial community. On the contrary, microorganisms, degrading migrating and transforming of pollutants, could be potentially used as indicators for water quality and recovery status of contaminated sediment. Index of biological integrity（IBI） has been widely used in river ecosystem health evaluation. However, the existing IBI lack of integrated evaluation system including microbe, which is regarded as represent for decomposers. Therefore, thisstudy focused on the community structure, diversity and functional gene abundance of microbe in the sediment of typical mining polluted lakes, rivers along with different function districts and different gradient pollution river, to explore the response of microbial community towards different human disturbance on the sediment, and to propose representative microbial indicators and microbial biological integrity index to evaluate health of the aquatic ecosystem comprehensively.The main content and results of the paper are as follows:（1） To study to the response of microbial community to heavy metal pollution in the lake sediments, which are located near the copper mine and nickel mine in Finland. The most dominant phylums in the six lake sediments is Proteobacteria（> 20%） and the other dominant phylums（1-10%） include Acidobacteria, Actinomycetes, Bacteroides, cyanobacterium, Firmicutes, Nitrospirae, Planctomycetes, Verrucomicrobia. Generally, microbial community composition of PJ samples（control lake） is similar to H sample（control lake）, while the JS and KS,near the copper mining area, and the SJ and LS, samples‘ microbial community composition are similar respectively. In particular, the abundance of functional gene for copper resistence（cop A gene） ranges from 1.33×106 to 5.34×106 copies/ng, and the cop A gene copy numbers in the two lake（KS and JS） sediment near copper mining area are significantly higher than that in the other four lake sediment. The ratio between eight groups of functional microbe and total number of bacteria is accounting for 28.83%, including the methane oxidizing bacteria（8.60%） and nitrogen-fixing bacteria（18.17%）, small proportion of sulfate reducing bacteria（0.18%）, sulfur oxidizing bacteria（0.24%）, and denitrifying bacteria（< 0.01%）. In the control lakes H, there are a few kinds functional bacteria accounting for 1.30% of the total number of bacteria in the sediment and functional bacteria accounted for 0.99% of the total number of bacteria in the sediment at JS point. Functional groups in lake sediment are less than 0.1% of the total number of bacteria at the others. Heavy metal pollution significantly affect the growth of microbial communities in sediments. Canonical correspondence analysis（CCA） found the key environmental factors significantly affect microbial community structure included p H, ammonia（NH4+-N）, nitrate(NO3-), chromium（Cr）, arsenic（As） and sulphur（S）.（2）To study the impact of unbanization on water quality, the microbial community structures in different watershed sediments at functional areas（agriculture district, industrial estate, residential） in Haining were investigated by Illumina sequencing and quantity PCR Illumina sequencing of 16 S r RNA amplicons revealed that the sediments at all of the tested sites were dominated by Proteobacteria（41.4–54.4 %）, with notable differences among the communities from different functional zones. The abundances of the nif H（5.57×105–8.27×105 copies ng-1DNA）, nir K（4.79×104–6.22×104 copies ng-1 DNA） and pmo A（7.02×104–9.29×104 copies ng-1DNA） genes in the industrial zone were significantly higher than in the residential and agricultural zones. The gene copy numbers from both ammonia-oxidising Archaea（AOA） and Bacteria（AOB） from the agricultural zone were significantly higher than in the residential and industrial zones. Functional microorganisms for methanogenesis, nitrification and denitrification and sulphate reduction showed significant correlations with petroleum, nitrogen and sulphide, respectively. The ratio of AOA/AOB amo A gene copy numbers in the agricultural zone was <1.0, indicating that the river basin in the agricultural zone was at a higher eutrophic level. The ratios of Bacteroidetes, Gammaproteobacteria and Nitrospira/Betaproteobacteria（BGN/β） for the industrial zone（2.03–3.51） were significantly higher than those for the other two zones, indicating lower water quality in the industrial zone.（3） To study microbial community characteristics in the sediments along pollution gradient within Fenghuajiang valley in Ningbo, We compared the community structure and abundance of C, N and S transformation-related functional microorganisms along Fenghuajiang rivers in south-eastern China.The results found that dominant species included Proteobacteria（11.5%-44.3%）, Acidobacteria（2.17%- 19.9%）, Actinobacteria（0.34%-17.1%）, Planctomycetes（2.48%- 21.2%） and Verrucomicrobia（2.54%- 10.9%）. Total copy numbers for archaea and bacteria changed accordantly, the abundance of which sediment in tributary was less than that in confluence. The total copy numbers of bacteria ranged in 5.37 x 103-8.91 x 106 copies/ng DNA, which were more than archaea copy numbers, ranging from 4.6×101 to 2.70×104 copies/ng DNA. CCA indicated 7 key environmental factors, including ammonia nitrogen（NH4+）, total nitrogen（TN）, p H, total carbon（TC）, total organic carbon（TOC）, nitrate(NO3-) and ferric iron(Fe3+), have significant impact on the bacteria distribution. Through establishing microbial biological integrity index（M-IBI） a, we found the M-IBI at six relatively clean control point were at Ⅰ health level（XN was Ⅱ sub-health） so that water quality of the control point were relatively good, while the M-IBI score of 16 damaged sampling sites at middle and lower reaches had certain differences, illustrate the damaged points were suffered from different levels of interference, the worst was at SSN with flowing through the quarry and highways, because industrialization has large influence and damage on water quality. |
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