潜流人工湿地基质结构与微生物群落特征的相关性

为查明造成不同基质结构人工湿地净化性能差异的微生物因素,利用高通量测序技术,研究水平潜流人工湿地基质结构与微生物群落结构的相关性.结果表明,3个对比人工湿地系统中,从床体表层到底层渗透系数逐渐升高的六层结构人工湿地(CW6)净化性能最高,其出水中COD、TN、NO-3-N及NH_4~+-N平均浓度分别为39、11、0.35及4 mg·L~(-1),其后为三层结构人工湿地(CW3),而单层结构人工湿地(CW1)的净化效果最差,平均出水浓度分别为95、21、0.60及12 mg·L~(-1).高通量测序结果显示,多层结构人工湿地中微生物OTUs略低于单层结构湿地,但其优势菌门变形菌门(Proteobacteria)和其属水平上的硝化与反硝化细菌的相对丰度却显著高于单层湿地.PCA和丰度热图分析结果显示,CW3和CW6床体中变形菌门(Proteobacteria)属水平上的微生物存在显著的空间分布差异,从而有利于污染物的分区降解,而CW1各样点间的微生物群落结构无显著性差异.

Correlations Between Substrate Structure and Microbial Community in Subsurface Flow Constructed Wetlands

To identify the microbial factors that cause the differences in the purification performance of constructed wetlands with different substrate structures, the relationship between the substrate structure and the microbial community composition in horizontal subsurface flow constructed wetlands (HSSFCWs) was studied by high throughput sequencing. The results revealed that the purification performance of a six-layer constructed wetland (CW6), of which the permeability coefficient gradually increased from the surface layer to the bottom layer, was the highest among the three constructed wetland systems. The average concentrations of COD, TN, NO₃^--N, and NH₄⁺-N in the effluent were 39, 11, 0.35, and 4 mg·L^-1, respectively. The monolayer structure constructed wetland (CW1) had the worst purifying efficiency, with average effluent concentrations of 95, 21, 0.60 and 12 mg·L^-1 for COD, TN, NO₃^--N, and NH₄⁺-N, respectively. The results of the high-throughput sequencing showed that the number of microbial OTUs in multilayer structure wetlands was slightly lower than that in the monolayer structure wetland, but the relative abundance of the dominant phylum Proteobacteria and the nitrifying and denitrifying bacteria in the genus was significantly higher than the monolayer structure wetland. The results of PCA and heatmap indicated that there were significant differences in the spatial distribution of microbes in the genus of Proteobacteria in CW3 and CW6, which facilitated the degradation of pollutants. No significant differences were found in the community structure of CW1.