Detectable Levels of Bacterial Pathogens in the Rivers of the Lake Chaohu Basin, China.
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ABSTRACT:
SUBMITTER: Shao K
PROVIDER: S-EPMC6926985 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundBacterial community play a key role in environmental and ecological processes in river ecosystems. Rivers are used as receiving body for treated and untreated urban wastewaters that brings high loads of sewage and excrement bacteria. However, little is known about the bacterial community structure and functional files in the rivers around the eutrophic Chaohu Lake, the fifth largest freshwater lake in China, has been subjected to severe eutrophication and cyanobacterial blooms over the past few decades. Therefore, understanding the taxonomic and functional compositions of bacterial communities in the river will contribute to understanding aquatic microbial ecology. The main aims were to (1) examine the structure of bacterial communities and functional profiles in this system; (2) find the environmental factors of bacterial community variations.ResultsWe studied 88 sites at rivers in the Chaohu Lake basin, and determined bacterial communities using Illumina Miseq sequencing of the 16 S rRNA gene, and predicted functional profiles using PICRUSt2. A total of 3,390,497 bacterial 16 S rRNA gene sequences were obtained, representing 17 phyla, and 424 genera; The dominant phyla present in all samples were Bacteroidetes (1.4-82.50 %), followed by Proteobacteria (12.6-97.30 %), Actinobacteria (0.1-17.20 %). Flavobacterium was the most numerous genera, and accounted for 0.12-80.34 % of assigned 16 S reads, followed by Acinetobacter (0.33-49.28 %). Other dominant bacterial genera including Massilia (0.06-25.40 %), Psychrobacter (0-36.23 %), Chryseobacterium (0.01-22.86 %), Brevundimonas (0.01-12.82 %), Pseudomonas (0-59.73 %), Duganella (0.08-23.37 %), Unidentified Micrococcaceae (0-8.49 %). The functional profiles of the bacterial populations indicated an relation with many human diseases, including infectious diseases. Overall results, using the β diversity measures, coupled with heatmap and RDA showed that there were spatial variations in the bacterial community composition at river sites, and Chemical oxygen demand (CODMn) and (NH4+ )were the dominant environmental drivers affecting the bacterial community variance.ConclusionsThe high proportion of the opportunistic pathogens (Acinetobacter, Massilia, Brevundimonas) indicated that the discharge of sewage without adequate treatment into the rivers around Chaohu Lake. We propose that these bacteria could be more effective bioindicators for long-term sewage monitoring in eutrophic lakes.
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Project description:Sediment bacterial communities are critical for the circulation of nutrients in lake ecosystems. However, the bacterial community function and co-occurrence models of lakes have not been studied in depth. In this study, we observed significant seasonal changes and non-significant spatial changes in the beta diversity and community structure of sediment bacteria in Lake Chaohu. Through linear discriminant analysis effect size (LEfSe), we observed that certain taxa (from phylum to genus) have consistent enrichment between seasons. The sudden appearance of a Firmicutes population in spring samples from the Zhaohe River, an estuary of Lake Chaohu, and the dominance of Firmicutes populations in other regions suggested that exogenous pollution and environmental induction strongly impacted the assembly of bacterial communities in the sediments. Several taxa that serve as intermediate centers in Co-occurrence network analysis (i.e., Pedosphaeraceae, Phycisphaeraceae, Anaerolineaceae, and Geobacteraceae) may play an important role in sediments. Furthermore, compared with previous studies of plants and animals, the results of our study suggest that various organisms, including microorganisms, are resistant to environmental changes and/or exogenous invasions, allowing them to maintain their community structure.
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Project description:The perfluoroalkyl substances (PFAAs) have received growing attention in recent years as emerging contaminants in the aquatic environment. The occurrence, removal and bioaccumulation of fourteen PFAAs (C4-C14 carboxylate; C4, C6, C8 sulfonates) were investigated in Lake Chaohu, China. The concentrations of the selected PFAAs in inflowing river, lake water and sewage treatment plant (STP) samples were analyzed by ultra performance liquid chromatograph (UPLC-MS/MS). The results showed that perfluorohexanesulfonic acid (PFHxS), perfluorobutane sulfonate (PFBS), perfluorobutyric acid (PFBA) and perfluoropentanoic acid (PFPeA), instead of perfluorooctanoic acid (PFOA), were predominant PFAAs in the inflowing river and lake water with maximum concentrations in the ranges of 52.2-1866 and 27-236 ng L-1, respectively. The highest concentrations of total PFAAs were detected in the western rivers. The effluents from seven STPs were likely important sources of PFAAs in surface water, and the amount of the daily fluxes in the effluent were 132 g for short-chain PFAAs and 109 g for long-chain PFAAs. PFAAs were widely detected in Chinese icefish (Neosalanx tangkahkeii taihuensis) collected from Lake Chaohu, with maximal concentrations ranging from 1.79 ng g-1 to 50.9 ng g-1. The logarithmic bioaccumulation factors of perfluorodecanoic acid (PFDA, 3.5), perfluorooctane sulfonate (PFOS, 3.35) and perfluorononanoic acid (PFNA, 3.31) indicated the bioaccumulation of these long-chain PFAAs. This study is useful for enhancing our understanding of the pollution profiles of PFAAs and their environmental health risk in the freshwater lake.
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Project description:Urbanisation is known to result in 'urban stream syndrome', which poses a huge threat to the river health. Birds, which are an important part of the river ecosystem, are sensitive to environmental changes in the basin. The ratio of the impervious surface area is a macroscopic indicator of urbanisation intensity in river basins. In this study, we combined the results of a year-round field survey of seven river wetlands around Chaohu Lake (China) with satellite remote sensing image data from the same period. The species richness at sections of the lake entrance was higher than in the middle sections of the river, and the Shannon-Wiener index during autumn was higher than that during winter. The waterbird diversity index declined exponentially with increases in the intensity of urbanisation. The changes in the land use patterns around river wetlands associated with urbanisation resulted in the loss of food resources and habitats. Therefore, the intensity of urbanisation was an important driving factor that leads to changes in the bird community structure of river wetlands, so it had a significant impact on the diversity of river wetland birds in all four seasons combined with a variety of influencing factors. Our research could be a guide for urban landscape planning and bird diversity protection. For example, the results suggested that it is necessary to identify river wetlands as an important part of the urban ecosystem, reduced building area, increased vegetation coverage, and retained slope protection and river beach land.
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Project description:Administrative division adjustments, such as agglomerations, upgrading, and revocation, introduce a series of uncertain impacts on the social and economic development in administrative regions. Previous studies have focused more on the economic effects of administrative division adjustments, but in this paper, we also consider the environmental effects of such adjustments. In 2011, with the approval of the State Council, the prefecture-level Chaohu city was officially revoked, resulting in a county-level Chaohu city. One district and four counties under the jurisdiction of the original Chaohu city were placed under the jurisdiction of Hefei, Wuhu, and Ma'anshan. This adjustment made Chaohu Lake an inner lake of Hefei city. The administrative division adjustment of Chaohu Lake, China, is used as a quasi-natural experiment to explore the influence of such an adjustment on pollution control. The synthetic control method (SCM) is used in this study to evaluate the effect of the administrative division adjustment on the water quality indicators of Chaohu Lake. The following conclusions are drawn. First, after the administrative division adjustment, some water quality indicators, such as ammonia nitrogen, improved; however, other major pollution indicators, such as chemical oxygen demand (COD) and dissolved oxygen (DO), worsened to varying degrees. Second, the results reveal that improper development ideas, excessive industrial expansion, and the shift in economic growth and environmental goals were problems after the adjustment. Returning to the original intention of the administrative division adjustment, rationalizing the Chaohu Lake management system and designing a sound and feasible accountability mechanism are fundamental measures for reducing pollution.
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Project description:Phthalate esters (PAEs) are frequently tracked in water environments worldwide. As a typical class of endocrine disruptor chemicals (EDCs), PAEs posed adverse effects on aquatic organisms at low concentration. Thus, they have attracted wide attention in recent years. In the present study, the concentrations of seven typical PAEs from 30 sampling sites in Baiyangdian Lake were measured, and the environmental exposure data of PAEs were gathered in typical rivers in China. Then, based on the aquatic life criteria (ALCs) derived from the reproductive toxicity data of aquatic organisms, two risk assessment methods, including hazard quotient (HQ) and probabilistic ecological risk assessment (PERA), were adopted to evaluate the ecological risks of PAEs in water. The sediment quality criteria (SQCs) of DEHP, DBP, BBP, DIBP and DEP were deduced based on the equilibrium partitioning method. Combined with the gathered environmental exposure data of seven PAEs in sediments from typical rivers in China, the ecological risk assessments of five PAEs in sediment were conducted only by the HQ method. The results of ecological risk assessment showed that in terms of water, DBP and DIBP posed low risk, while the risk of DEHP in Baiyangdian Lake cannot be ignored and should receive attention. In typical rivers in China, BBP and DEP posed no risk, while DIBP and DBP posed potential risk. Meanwhile, DEHP posed a high ecological risk. As far as sediment is concerned, DBP posed a high risk in some typical rivers in China, and the other rivers had medium risk. DEHP posed a high risk only in a few rivers and low to medium risk in others. This study provides an important reference for the protection of aquatic organisms and the risk management of PAEs in China.
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