城市再生水河道沉积物细菌群落空间变化分析:以京津冀北运河为例

Analysis of the Spatial Changes in Bacterial Communities in Urban Reclaimed Water Channel Sediments: A Case Study of the North Canal River

沉积物细菌因其在能量流动和污染物循环转化中发挥重要作用.关注沉积物细菌空间分布格局变化是深入了解其多样性产生和维持机制的前提.基于此,本文以流经京津冀地区以再生水为补给水源的北运河为研究区,对沉积物细菌群落界、门、纲、目、科、属、种和OTUs(operational taxonomic units)等不同分类水平空间变化模式及其形成机制进行分析.结果表明,较高的分类水平上、中、下游样点具有更均质化的分布格局,而较低分类水平样点具有更加清晰的分布界限和范围;不同地理空间尺度下的群落结构差异性随分类水平的降低呈组间差异逐渐增大和组内相似性逐渐减小的变化趋势.以弗兰克氏目(Frankiales)和红细菌目(Rhodobacterales)为代表的典型根际微生物呈现上游显著富集、中游次之、下游显著减少模式,以厌氧绳菌目(Anaerolineales)和脱硫杆菌目(Desulfobacterales)为代表的与碳、氮和硫循环相关的微生物集中呈现中游显著富集、下游次之、上游显著减少模式,以苯基杆菌属(Phenylobacterium)为代表的菌属在上游显著富集、中游次之、下游显著减少模式,以产气梭状芽孢杆菌(Clostridiumgasigenes)和奥斯陆莫拉菌(Moraxellaosloensis)为代表的致病菌呈现中游显著富集的模式.沉积物中Ca^(2+)、SO_(4)^(2-)和TOC表现为下游浓度高于上游和中游地区.下游未处理和经处理废水排放导致沉积物中盐分离子和TOC显著升高,而高度人工化的城市河道生态修复工程对水质和沉积物的净化作用是导致上、中游盐分离子和TOC显著降低的间接原因.环境选择为主、地理扩散为辅的共同作用模式决定了北运河沉积物细菌群落空间变化模式.

Sediment bacteria have attracted much attention because of their important roles in energy flow and pollutant cycle transformation. The changes in the spatial distribution pattern of bacteria are the basis for research on the biodiversity generation and maintenance mechanisms. However,there are few studies on the spatial variation in benthic microorganisms and its biogeographic models. The highly artificial North Canal River across the Beijing-Tianjin-Hebei area was chosen as the research area in this study. The spatial variation in the different classification levels of the Kingdom,Phylum,Class,Order,Family,Genus,Species,and operational taxonomic units and their diversity formation mechanisms were analyzed. The results showed that the samples at different classification levels had a more homogeneous distribution pattern. There were clearer distribution boundaries at the low classification levels than at the high classification levels. The significance of the bacterial community variation increased as the classification level of the bacterial community decreased. Furthermore,the difference between groups increased and the similarities within groups decreased as the classification level of the bacterial community decreased. The typical rhizosphere microorganisms represented by Frankiales and Rhodobacterales showed significant enrichment in the upstream samples,followed by the midstream samples and a significant decrease in the downstream samples. Microorganisms related to the carbon,nitrogen,and sulfur cycles represented by Anaerolineales and Desulfobacterales showed significant enrichment in the midstream,followed by the downstream and a significant reduction in the upstream. The genus Phenylobacterium was significantly enriched in the upstream followed by the midstream,and was significantly reduced in the downstream. The pathogenic bacteria represented by Clostridiumgasigenes and Moraxellaosloensis showed a significant enrichment pattern in the midstream. The contents of Ca^(2+),SO_(4)^(2-),and total organic carbon( TOC) in the downstream samples were significantly higher than those in the upstream and midstream samples. The discharge of untreated wastewater downstream increased the salt and TOC contents in the sediment. The ecological restoration project in the sediment of the riparian zone decreased the salt and TOC contents in the upstream and midstream samples. Environmental selection was the main driving factor of the pattern of spatial variation in the bacterial communities in the sediments of the North Canal River.