RESUMEN
Reclaimed water plays an important role in alleviating the shortage of urban water resources; however, the trace pollutants and pathogens in reclaimed water have an effect on the plankton community in the receiving water. This study investigated the spatial variation mechanism of microbial community diversity in the Beijing-Tianjin-Hebei reach of the Nordkanal River based on the OTUs and phylum level fragment number and fragment abundance data matrix. The results showed that the physical and chemical disturbance caused by the frequent inflow of reclaimed water changed the hydrology and water quality of the water body, and the plankton community could be divided into two different groups along the geographical scale:the medium and upstream clustering (MUC) and the downstream clustering (DC). The analysis of diversity index based on the OTUs data matrix showed that the species diversity of the DC group was significantly higher than that of the MUC group, and the abundance distribution and evenness showed the opposite trend. The species richness was mainly determined by the fragment diversity of the occasional microflora; the evenness was mainly determined by the variation of the abundance of the dominant microflora; the sensitivity of the subcommunity structure with different abundance levels to spatial change was in the order of non-dominant microflora > occasional microflora > dominant microflora. The diversity analysis of the data matrix based on phylum level also showed that the species diversity of the DC group was significantly higher than that of the MUC group, and the change trend of abundance was the opposite; the most sensitive microflora group was the non-dominant phyla, followed by the occasional phyla, and the dominant phyla group was the least sensitive. The data matrix based on the number of level segments of the gate was more sensitive to environmental changes than the multi-degree data matrix based on the level of the gate. The environmental factors significantly related to microbial community were turbidity; permanganate index; oxidation-reduction potential (ORP); macrolide (MLs); tetracycline antibiotic (TCs); and regional response factors of salt ions, carbon, and inorganic nitrogen. In the aspect of abundance and diversity, these phylas that the DC group was significantly more than the MUC group were more significantly negatively correlated with MLs, whereas they were positively correlated with TCs, and these phylas that the MUC group was significantly more than the DC group was more significantly positively correlated with MLs. The research results can provide a theoretical basis and technical guidance for the ecological rehabilitation of urban river courses with reclaimed water as their main water supply source.
Asunto(s)
Microbiota , Plancton , Beijing , Microbiota/genética , Plancton/genética , Ríos , Calidad del AguaRESUMEN
Due to the limitations of the treatment process of urban sewage treatment plants and the complexity of water sources, the rich inorganic nitrogen and trace persistent organic matter in the reclaimed water cause potential human health risks through lateral leakage or bioaccumulation during the replenishment process of rivers and lakes. Exploring the distribution law of different types of reclaimed water characteristic water quality factors and their formation in reclaimed water replenishment river channels is of great significance to river and lake management. This study takes the Beijing-Tianjin-Hebei section of the North Canal as the research area and explores the spatial variation characteristics of conventional physical parameters, full index, inorganic nitrogen, and salinity hydronium antibiotics in river water quality with the help of clustering, discrimination, principal components, and variance decomposition. The results showed that, although the spatial distribution patterns of different types of water quality factors were consistent, they all showed significant mid-upstream and downstream distribution; however, there were big differences in the degree of variation and the mechanism of variation. The spatial variation of inorganic nitrogen and antibiotics was the most obvious, whereas the variation in conventional physical parameters and the full index was the weakest, and the salinity hydronium showed moderate variation. The spatial variation mechanism of conventional physical parameters was mainly reflected in microbial degradation. The full index was the result of the combined effect of microorganisms, diffusion, the synergy of the two, and a certain degree of source-sink homogeneity. Diffusion was the main mechanism affecting the spatial variation in salinity hydronium. The spatial variation mechanism of inorganic nitrogen was mainly reflected in the source-sink homogenization and microbial degradation; as a secondary mechanism of the spatial variation of inorganic nitrogen, diffusion had a synergistic mode with microbial degradation. Antibiotics, which have great differences in chemical structural stability and biodegradability, showed high spatial variability and had the highest diffusion and microbial synergy mechanism. This research provides a quantitative analysis of the spatial variability mechanism of water quality based on variance decomposition, which has practical guiding significance for the causes of the spatial variability of river pollutants and river management.
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Contaminantes Químicos del Agua , Calidad del Agua , China , Monitoreo del Ambiente , Humanos , Lagos , Nitrógeno/análisis , Ríos , Contaminantes Químicos del Agua/análisisRESUMEN
As the bridge of pollutant exchange between sediments and aquatic ecosystems, microorganisms play an important role in material circulation. However, there are few comparative studies of microorganisms in water and sediment of urban rivers with unconventional water supply, sluice dam, and lining closure. The highly artificial area of Beijing-Tianjin-Hebei section of the North Canal was chosen for this study. We analyze the differences of microbial community composition in water and sediment using high-throughput sequencing. The results show that the microbial communities in the sediments of the North Canal have higher α-diversity than those in the water. With regards to ß-diversity, the similarity of microbial communities in the water is higher than that in the sediment. There is no significant difference in the abundance of Proteobacteria between water and sediments. The abundance of α-Proteobacteria, Actinobacteria, Cyanobacteria, and Verrucomicrobia was higher in water than that of sediment, while the abundance of γ-Proteobacteria, δ-Proteobacteria, Chloroflexi, Firmicutes, and Acidobacteria was higher in sediments than that of water. Aerobic or facultative anaerobes dominated the microbial aquatic system, while anaerobes dominated the sediments. The risk of bacteria releasing pathogens from the sediment into the water habitat is high. The research results provide a scientific basis for revealing the mechanism of microbial community change under river pollution risk in highly artificial reclaimed water.
Asunto(s)
Cianobacterias , Microbiota , Sedimentos Geológicos , Secuenciación de Nucleótidos de Alto Rendimiento , Microbiota/genética , ARN Ribosómico 16S/genética , AguaRESUMEN
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 Clostridium_gasigenes and Moraxella_osloensis showed a significant enrichment pattern in the midstream. The contents of Ca2+, SO42-, 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.
Asunto(s)
Acuaporinas , Ríos , Bacterias/genética , Beijing , Biodiversidad , China , Monitoreo del Ambiente , Sedimentos GeológicosRESUMEN
In order to study the effect of reclaimed water on bacterial community composition and function in urban river sediment, the changes of bacteria community diversity, composition and function in Mayu wetland upon the supply of reclaimed water were investigated by a range of sophisticated procedures, including Terminal Restriction Fragment Length Polymorphism(T-RFLP), 16S rRNA clone library technology, and Real-time Quantitative PCR Detecting System(qPCR).The results showed that carbon, nitrogen and phosphorus were major factors driving the variation of bacterial diversity and community structure in river sediment, and the bacteria were gradually recovered after purification in downstream under the effect of artificial wetland. In addition, the bacterial community in reclaimed water outfall was mainly constituted by ß-Proteobacteria, δ-Proteobacteria, Bacteroidales and Cyanobacteriain, and ε-Proteobacteria, Chloroflexi and Spirochaetes were unique groups. Besides, the major biological geochemical cycle was nitrogen, carbon and phosphorus cycle in river sediment, which was closely related to functional genes. There were about 45.9% of the clones related to nitrogen cycle in reclaimed water outfall, such as Comamonas sp., higher than those of upstream and downstream (27.7% and 23.4%), 17.9% of the clones were closely related to the carbon cycle, such as Lysobacter sp., higher than those of upstream and downstream (14.4% and 12.9%). Furthermore, the trace of pathogenic bacteria and antibiotics in reclaimed water also changed the transformation pattern participating in carbon and nitrogen cycle, for example, Rhodocyclus sp. conducted nitrogen fixation by photosynthesis in reclaimed water outfall, whereas Burkholderia sp. fixes nitrogen by ways of plants symbiotic nitrogen fixation in upstream and downstream. This research provides theoretical reference for studies on remediation of reclaimed water supplying river by artificial wetland.