Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 18 de 18
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Environ Pollut ; 305: 119310, 2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35430312

RESUMO

Bacterial and fungal communities have been widely applied as bio-indicators for ecological evaluation of copper (Cu) mine pollution in river sediments. However, the response pattern of their abundant and rare sub-communities is still unknown, limiting the further development of biological diagnostics. Here, the alpha-diversity, community composition, environmental contribution and co-occurrence network of total, abundant and rare taxa for bacteria and fungi in the Jiaopingdu Cu Mine wastewater treatment plant (WWTP) were investigated through high-throughput sequencing. The results revealed different responses of microbial alpha-diversity for abundant and rare sub-communities. The abundant taxa were ubiquitous in all sediments, while rare taxa exhibited increases of species richness in polluted areas because of heterochthonous inputs of WWTP drainage. Nevertheless, the variations of community composition were consistent for bacterial and fungal abundant and rare taxa, all of which showed significant dissimilarity between control and polluted areas. Distance-decay relationship and canonical correlation analysis indicated that abundant taxa assemblies (rbacteria = -0.924, rfungi = -0.684) were more strongly driven by environmental changes than rare ones (rbacteria = -0.626, rfungi = -0.349), because abundant microbes had higher proportions of significant variations in abundance. Co-occurrence networks revealed more keystone species with high node degree and centrality among abundant taxa compared with rare ones. Moreover, bacterial abundant and rare taxa were more sensitive to Cu mine pollution than relevant fungal taxa owing to different Cu tolerance. In conclusion, among all microbial sub-communities, abundant bacteria had the highest environmental sensitivity, suggesting their important application in biological diagnosis of Cu mine pollution. Accordingly, the abundant taxa could act as "key reservoir" for future selection of specific indicator species, for example Thiobacillus, while rare taxa no longer need excessive in-depth analysis, which would greatly improve microbial diagnosis efficiency.

2.
Environ Res ; 207: 112236, 2022 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-34678255

RESUMO

Dam construction causes phosphorus (P) accumulation in reservoir sediments and significantly affects the generation of available P. However, the effect of dam construction on the activity of sediment alkaline phosphatase (ALP), which is encoded by the bacterial phoD gene and participates in P mineralization, in river sediments remains unclear. Here, we investigated the ALP activities in 78 sediment samples collected from the cascade reservoir regions located in the Lancang River and the Jinsha River, two highly regulated rivers in southwestern China. The abundance and community composition of phoD-harboring bacteria were determined based on the phoD gene using quantitative real-time PCR and MiSeq sequencing, respectively. Comparison of control and affected sites indicated that dam construction significantly increased sediment ALP activity in both rivers. The abundances of phoD-harboring bacteria increased and their community compositions varied in response to dam construction; the relative abundances of the dominant genera Methylobacterium and Bradyrhizobium were particularly higher in affected site than control site. Co-occurrence network analyses revealed much higher network connectivity and relative abundances of keystone species in affected sites. Some microbial factors including phoD-harboring bacterial abundances, network clustering coefficients, and relative abundance of keystone species were positively correlated with ALP activity. The relative abundance of keystone species was identified as the most important microbial factor contributing to variation in ALP activity based on structural equation modeling analysis. These findings enhance our understanding of how dam construction affects the functions of phoD-harboring bacteria and their role in the P biogeochemical cycle in highly regulated rivers.


Assuntos
Fosfatase Alcalina , Rios , Fosfatase Alcalina/genética , Bactérias , China , Genes Bacterianos , Sedimentos Geológicos , Fósforo/análise
3.
Chemosphere ; 286(Pt 1): 131648, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34315079

RESUMO

Aquatic macrophytes have been widely employed for in-situ phytoremediation of cadmium (Cd) polluted sediments. But, little is known about the responses of rhizosphere bacteria and their interspecific interactions to phytoremediation. In this study, the α-diversity, community composition, co-occurrence network and keystone species of sediment bacteria in rhizosphere zones of two typical macrophytes, Hydrilla verticillata and Elodea canadensis, were investigated using 16S rRNA gene high-throughput sequencing. The results showed that after fifty days of phytoremediation, a group of specialized sediment bacteria were assembled in the rhizosphere zones closely associated with different host macrophytes. Rhizosphere micro-environments, i.e., the increases of redox potential and organic matter and the decreases of pH, nitrogen and phosphorus, reduced bacterial α-diversity through niche-based species-sorting process, which in turn reduced interspecific mutualistic relationships. But meanwhile, benefiting from the nutrients supplied from macrophyte roots, more bacterial species survived in the highly Cd-contaminated sediments (50 mg kg-1). In addition, the co-occurrence network revealed that both macrophytes harbored two same keystone bacteria with the high betweenness centrality values, including the family Pedosphaeraceae (genus_unclassified) and genus Parasegetibacter. Their relative abundances were up to 28-fold and 25-fold higher than other keystone species, respectively. Furthermore, these two keystone bacteria were metabolic generalists with vital ecological functions, which posed significant potentials for promoting plant growth and tolerating Cd bio-toxicity. Therefore, the identified keystone rhizobacteria, Pedosphaeraceae and Parasegetibacter, would be potential microbial modulations applied for the future optimization of phytoremediation in Cd-contaminated sediment.


Assuntos
Hydrocharitaceae , Biodegradação Ambiental , Cádmio/análise , RNA Ribossômico 16S/genética , Rizosfera
4.
Huan Jing Ke Xue ; 42(9): 4311-4318, 2021 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-34414729

RESUMO

In this study, four typical submerged macrophytes, namely Hydrilla verticillata, Elodea canadensis, Potamogeton crispus, and Ceratophyllum demersum, were tested for their chlorophyll content and antioxidant enzyme activity, to analyze their cadmium tolerance. The biota-sediment accumulation factor (BSAF) and plant transport factor (TF) were utilized to understand the accumulation capacity of the plants. Finally, the distribution of cadmium in submerged macrophytes was revealed through phytohistochemical methods, to provide theoretical support for the practical application of submerged macrophytes. The results showed that three of the plants, excluding C. demersum, exhibited varying tolerances to cadmium pollution in sediments, among which the tolerance of H. verticillata and E. canadensis were the strongest. P. crispus had the strongest accumulation capacity (BSAF was 2.32) at relatively low pollution levels (≤20 mg·kg-1). In this study, because of its weak root system, the BSAF of C. demersum was less than 1.0, indicating that macrophyte roots play an important role in phytoremediation of Cd-contaminated sediments. Comparing the TF of different plants, it can be found that the roots of H. verticillata had the strongest above-ground cadmium transport capacity, while P. crispus mainly accumulated cadmium in its roots. At the same time, when the cadmium concentration was 50 mg·kg-1, cadmium was found to be evenly distributed in the stem organelles of P. crispus, in contrast to the other plants. Based on the cadmium tolerance and accumulation mechanism of the plants, and in consideration of real-world factors, H. verticillata and P. crispus were selected as ideal plants for repairing cadmium-containing sediments. Meanwhile, based on the different transport capabilities of plants, it is recommended that only the above-ground part of H. verticillate should be removed, while P. crispus should be uprooted regularly.


Assuntos
Hydrocharitaceae , Potamogetonaceae , Biodegradação Ambiental , Cádmio , Clorofila
5.
Sci Total Environ ; 796: 148973, 2021 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-34274679

RESUMO

Emerging organic pollutants (EOPs) in urban rivers have raised concerns regarding their eco-toxicological effects. However, the bacterioplankton community disturbances caused by EOPs in urban rivers and the associated ecological mechanisms remain unclear. This study provided profiles of the spatial distribution of a bacterioplankton community disturbed by human activity along an urban river. The results showed that EOP concentration and composition were differently distributed in residential and industrial areas, which significantly influenced bacterioplankton community structure. Based on redundancy analysis, parabens (methylparaben and propylparaben) were the major factors driving bacterioplankton community changes. Parabens inhibited gram-positive bacteria and promoted oxidative stress-tolerant bacteria in the river ecosystem. Parabens also disturbed ecological processes of bacterioplankton community assembly, shifting from a homogeneous selection (consistent selection pressure under similar environmental condition) to stochastic processes (random changes due to birth, death, immigration, and emigration) with changing in paraben concentrations. Heterogeneous selection was predicted to dominate microbial community assembly with paraben concentration changes exceeding 61.6 ng/L, which could deteriorate the river ecosystem. Furthermore, specific bacterial genera were identified as potential bioindicators to assess the condition of EOP contaminants in the river. Overall, this study highlights significant disturbances in bacterioplankton communities by EOPs at environmental concentrations, and our results could facilitate generation of appropriate management strategies aimed at EOPs in urban rivers.


Assuntos
Poluentes Ambientais , Microbiota , Organismos Aquáticos , Bactérias , China , Ecossistema , Humanos , Rios
6.
Environ Res ; 199: 111418, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34052244

RESUMO

Riverine bacterioplankton are highly responsive to river alterations and their abundant and rare sub-communities may have different roles in biogeochemical cycling. However, with the rapid development of dam constructions, our knowledge on adaptation mechanism of these sub-communities in regulated river ecosystem was still limited, especially with regard to their functional traits. Here, our study was conducted in the 2800 km Yarlung Tsangpo River on the Tibetan Plateau to address the question of how abundant and rare bacterioplankton would respond taxonomically and functionally to river damming using 16S rRNA gene sequencing combined with Geochip microarray technique. Our results showed that abundant sub-community dominated taxonomic composition while rare sub-community largely determined functional composition. It is also observed that taxonomic diversity of abundant sub-community was significantly stimulated in the reservoir while that of rare sub-community was markedly inhibited. Moreover, abundant sub-community exhibited functional redundancy under damming disturbances since altered taxonomic composition and unaltered functional composition co-occurred simultaneously. Meanwhile, due to portfolio effect, rare sub-community maintained a greater stability under damming disturbances with little variation in taxonomic and functional compositions. In addition, the Stegen null model analysis revealed that stochastic process governed community assembly in both abundant and rare sub-communities. However, according to source tracking analysis, the taxonomic dispersion of abundant sub-community was less significantly impeded by the dam while the functional dispersion of rare sub-community was less strongly interrupted, indicating that the dispersal process in the dominated sub-community was less susceptible to damming. Therefore, by considering bacterioplankton functional traits, our study provided comprehensive evidences for the distinct strategies of abundant and rare sub-communities in response to damming.


Assuntos
Ecossistema , Rios , Organismos Aquáticos , China , RNA Ribossômico 16S/genética
7.
Environ Sci Pollut Res Int ; 28(31): 42300-42312, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33811632

RESUMO

Bacterial communities play critical roles in biogeochemical cycles and serve as sensitive indicators of environmental fluctuation. However, the influence of mineral resource exploitation on shaping the bacterial communities in the urban river is still ambiguous. In this study, high-throughput sequencing was used to determine the spatial distribution of the sediment bacterial communities along an urban river in the famous mining city Panzhihua of China. The results showed that mineral resource exploitation had a significant impact on the urban river bacterial community structure but not on the bacterial ecological functions. Distinct families of bacteria often associated with nutrients (i.e., Comamonadaceae and Sphingomonadaceae) and metal contaminants (i.e., Rhodobacteraceae) were more predominant in the residential and mining area, respectively. Relative to dispersal dynamics, environmentally induced species sorting may primarily influence bacterial community structure. Heavy metals and sediment physicochemical properties had both similar and significant influence on shaping bacterial community structure. Among heavy metals, essential metal elements explained more rates of bacterial variation than toxic metals at moderate contaminant levels. Moreover, the bacteria with multiple metal resistances identified in culture-dependent experiments were probably not suitable for indicating heavy metal contamination in field research. Thus, several sensitive bacterial genera such as Rhodobacter, Hylemonella, and Dechloromonas were identified as potential bioindicators to monitor metals (iron and titanium) and nutrients (phosphorus and organic carbon) in the river ecosystem of the Panzhihua region. Together, these results profiled the coupling effect of urbanization and mineral resource utilization on shaping sediment bacterial communities in urban rivers.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Bactérias , China , Ecossistema , Monitoramento Ambiental , Sedimentos Geológicos , Metais Pesados/análise , Rios , Poluentes Químicos da Água/análise
8.
Environ Res ; 198: 110449, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33217435

RESUMO

Pharmaceuticals and personal care products (PPCPs) are recognized as a group of emerging contaminants closely related to anthropogenic activities, which capture increasing attention worldwide. To evaluate the anthropogenic disturbances on PPCP distribution and sources, this study investigated the distribution and sources of 50 PPCPs along the 2300 km long Jinsha River and revealed different anthropogenic disturbances on PPCPs. Results showed that 40 out of the 50 PPCPs were ubiquitously detected among these river water samples, with the concentrations varied from less than 1 ng/L to more than 500 ng/L. Although most PPCPs concentrations were much lower in the Jinsha River than in highly developed rivers, the prevalence of PPCPs suggested the widespread use and improper disposal of PPCPs in the Jinsha River. The risk assessment also revealed that some PPCPs posed risks to aquatic organisms in the Jinsha River. Anthropogenic activities including human habitation and dam construction had different influence on PPCPs. PPCP distribution varied significantly across the "Hu Huanyong line", indicating human habitation significantly influenced PPCP distribution. Dam construction was insignificant in altering PPCP distribution throughout the Jinsha River. Moreover, the land use index indicated degradation level of multiple lands related to anthropogenic activities and represented the major sources of PPCPs in the Jinsha River. Most PPCPs were correlated with anthropogenic lands, for example, antibiotics, analgesics, and endocrine disrupting chemicals mainly originated from artificial surfaces, whereas other PPCPs mainly originated from cultivated lands. Together, this study indicates the disturbances of multiple anthropogenic activities on PPCP distribution and sources along the Jinsha River, which contributes to PPCP management in rural areas.


Assuntos
Cosméticos , Preparações Farmacêuticas , Poluentes Químicos da Água , China , Cosméticos/análise , Monitoramento Ambiental , Humanos , Rios , Poluentes Químicos da Água/análise
9.
Huan Jing Ke Xue ; 41(12): 5458-5469, 2020 Dec 08.
Artigo em Chinês | MEDLINE | ID: mdl-33374062

RESUMO

As an important primary producer, diatoms play a key role in aquatic ecosystems. However, little is known about the geographical distribution characteristics and driving factors of diatoms in large rivers. In this study, based on a high-throughput sequencing dataset of microeukaryotes, we analyzed the diversities and community compositions of planktonic and sedimentary diatoms in the 1200 km mainstream of Lancang River, a typical large river in southwestern China. The results showed that the diversities of planktonic and sedimentary diatoms in Lancang River were higher in the upstream natural section, and the community compositions of both groups were significantly different among different river sections. Dam construction had a significant effect on the dominant genera. Variance partitioning analysis showed that dispersal limitation was a major driving factor for the distribution pattern of planktonic and sedimentary diatoms, with explanation proportions of 16.7% and 29.8%. Co-occurrence network analyses showed that the interspecific competition relationship and network connectivity of the planktonic diatom network were stronger than the sedimentary ones. The network connectivity of planktonic and sedimentary diatoms in the cascade reservoir section was higher than that of the upstream natural section. This study will help to better understand the biogeographical distribution of diatoms in large rivers and provide useful information for ecological responses of diatoms to dam construction in rivers.


Assuntos
Diatomáceas , Rios , China , Ecossistema , Monitoramento Ambiental , Plâncton
10.
Environ Res ; 191: 110194, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32919971

RESUMO

River damming has raised controversial concerns as it simultaneously contributes to socioeconomic development but may jeopardize aquatic ecology. Since bacterioplankton catalyze vital biogeochemical reactions and play important roles in aquatic ecosystems, more attention has been paid to their responses in dammed rivers. Here, a comparative study was conducted between single-dammed (the Yarlung Tsangpo River) and cascade-dammed (the Lancang River) rivers in Southwest China to investigate whether bacterioplankton respond equally to different river regulations. Our results showed that the decreased bacterioplankton abundance and the increased α-diversity always co-occurred in reservoirs of the Yarlung Tsangpo River and the Lancang River. However, the impact of damming on bacterioplankton abundance and α-diversity were resilient in the Lancang River, which can be attributed to the repeated alterations of environmental heterogeneity in cascade damming reaches. Meanwhile, a generalized additive model (GAM) was applied to identify the important drivers affecting bacterioplankton variation. The abundance was influenced by trophic conditions, such as dissolved silicon, while α-diversity was closely related to the microbial dispersal process, such as elevation and distance-from source. And it is also noted that the bacterioplankton dispersal process was interrupted in cascade damming reaches. In addition, based on their important drivers, variations in abundance and α-diversity were also predicted by GAM. As revealed by the quantitative mutual validation between the two rivers, abundance and α-diversity in the cascade-dammed river can be predicted by their response to single-dammed river, suggesting that the impact of cascade damming on bacterioplankton can be pre-assessed by referring to the single stage damming effect. Therefore, our study provides the first trial of quantitative evidence that bacterioplankton do not respond equally to different river regulations, and the impact of cascade damming on bacterioplankton can be predicted based on single stage damming effect, which can contribute to the protection of aquatic ecology in the cascade hydropower development.


Assuntos
Ecossistema , Rios , Organismos Aquáticos , China
11.
Front Microbiol ; 11: 158, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32117173

RESUMO

Bacterioplankton communities commonly consist of few highly abundant species and a large number of rare species that play key roles in biogeochemical cycles of aquatic ecosystems. However, little is known about the biogeographic assemblies of these communities, especially in large rivers suffering from cascade dam regulation. Here, we used a 16S rRNA gene amplicon sequencing approach to investigate the biogeographic patterns and underlying assembly mechanisms of abundant and rare bacterioplankton taxa in cascade reservoirs of the Jinsha River in China. The results revealed species loss of bacterioplankton due to dam construction, which was more significant for rare taxa than for abundant ones. The distributions of abundant and rare taxa exhibited similar spatial and temporal patterns, which were significantly distinct between winter and summer and between upstream and downstream reservoirs. Both spatial (dispersal-related process) and environmental (selection process) factors seemed to together govern the assembly and biogeography of abundant and rare taxa, although both factors explained only a small fraction of variation in the rare taxa. More importantly, environmental factors explained more community variation in abundant sub-community than that in rare sub-community. Co-occurrence network analysis revealed that abundant species with closer interactions were more often located in a central position of the network compared with rare species. Nevertheless, half of the keystone species were rare species and may play important roles in maintaining the network stability. Overall, these findings indicate that distinct assembly mechanisms underlie the similar biogeography of rare and abundant bacteria in cascade reservoirs of a large river.

12.
Environ Microbiol ; 22(3): 832-849, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31469494

RESUMO

Despite the essential functions of sedimentary bacterial and fungal communities in biogeochemical cycling, little is known about their biogeographic patterns and driving processes in large rivers. Here we investigated the biogeographic assemblies and co-occurrence patterns of sedimentary bacterial and fungal communities in the Jinsha River, one of the largest rivers in southwestern China. The mainstream of river was divided into upstream, midstream and downstream. The results showed that both bacterial and fungal communities differed significantly among three sections. For both communities, their composition variations in all sites or each river section were controlled by the combination of dispersal limitation and environmental selection, and dispersal limitation was the dominant factor. Compared with bacteria, fungi had stronger dispersal limitation. Co-occurrence network analyses revealed higher network connectivity but a lower proportion of positive interaction in the bacterial than fungal network at all sites. In particular, the keystone species belonging to bacterial phyla Proteobacteria and Firmicutes and fungal phyla Ascomycota and Chytridiomycota may play critical roles in maintaining community function. Together, these observations indicate that fungi have a stronger dispersal limitation influence and less network connectivity than bacteria, implying different community assembly mechanisms and ecological functions between bacteria and fungi in large rivers.


Assuntos
Microbiologia Ambiental , Fungos/fisiologia , Sedimentos Geológicos/microbiologia , Micobioma/fisiologia , Rios/microbiologia , Fenômenos Fisiológicos Bacterianos , China
13.
Huan Jing Ke Xue ; 40(11): 4914-4923, 2019 Nov 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854557

RESUMO

To study the pollution characteristics and ecological risks of heavy metals in the western area of the Wangyu River, water and surface sediment samples of five rivers were investigated. The concentration and chemical fractions of eight heavy metals (Ni, Cu, Cr, Zn, As, Cd, Pb, and Hg) were analyzed, the pollution sources of heavy metals were studied using multivariate statistical analysis, and various ecological risk assessments were applied to identify the level of heavy metal contaminants. The results showed that the concentration of heavy metals in water was low, except for Hg, which was lower than the Class I standard of Surface Water Environmental Quality Standard. The content of heavy metals in surface sediments was high, except for Hg, which was significantly higher than the environmental background values. The partition coefficient of heavy metals in water-sediments showed that Cd, As, and Hg had strong re-emission potential. The Igeo indicated that Cu, Zn, and Cd were in a high pollution state as a whole. The RI showed that Cd was the main ecological risk factor in the study area. The RRSP indicated that the degree of pollution by Ni, Zn, and As was low because of its high residual fraction ratio, which was difficult to release under natural conditions. However, the degree of pollution by Cd was high because it had the highest content of weak acid extractable fraction among all the heavy metals. Therefore, it is necessary to pay more attention to Cd contamination. The source analysis of heavy metals showed that the western area of the Wangyu River was mainly affected by the pollution emissions from the surrounding machinery factories.


Assuntos
Metais Pesados , Poluentes Químicos da Água , China , Monitoramento Ambiental , Sedimentos Geológicos , Medição de Risco , Rios
14.
Mol Ecol ; 27(22): 4444-4458, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30225945

RESUMO

Rivers make vital contributions to the transport of water, sediment and nutrients from terrestrial to marine ecosystems. However, many large rivers worldwide are suffering from dam regulation. Increasing attention has been paid to bacterioplankton communities since they are highly responsive to river alterations and may influence biogeochemical processes. Here, a comprehensive study was conducted in the highly regulated Lancang-Mekong River Basin to address the question of how bacterioplankton communities respond to cascade damming. The results showed that dam constructions increased nutrient concentrations and threatened water quality in cascade reservoirs. Bacterioplankton cell abundance was reduced by damming, and α-diversity was inhibited in cascade reservoirs. Fortunately, however, river ecosystems were resilient after the remarkable disturbance caused by damming. Moreover, bacterioplankton community composition was significantly altered by cascade dams, including a shift in the dominant phylum from r-strategists to k-strategists. Meanwhile, according to GeoChip analysis, the functional composition of bacterioplankton was less affected than taxonomic composition. In addition, geographic and environmental features both followed a distance-decay relationship with community and functional composition, but the local environment condition was the dominant driver in the Lancang River. Therefore, the impoundments of cascade dams had significant impacts on bacterioplankton communities and more attention should be paid to the potential ecological consequences of river regulation.


Assuntos
Bactérias/classificação , Ecossistema , Plâncton/classificação , Rios , Movimentos da Água , China , Consórcios Microbianos , RNA Ribossômico 16S/genética , Rios/química , Rios/microbiologia , Qualidade da Água
15.
Ecotoxicol Environ Saf ; 165: 573-581, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30236919

RESUMO

Bacterioplankton communities play a critical role in ecological processes in river systems, and shifts of their composition may impact microbial levels and raise public health concerns. The aim of this study was to comprehensively analyze the essential factors influencing bacterioplankton community, along with pathogen, and to estimate the health risk caused by the pathogens downstream of the Liushahe River, which is located in the famous touristic city Xishuangbanna. Results showed that wastewater treatment plants (WWTPs) and a subtropical recreational park impacted the bacterioplankton community and pathogen population, and potential pathogen identification demonstrated that 76 of 145 reference genera were present in the river. Moreover, the bacterioplankton community and pathogen were differently impacted by environmental gradients, and SRP, NO2 and pH were main factors influencing bacterioplankton community while pathogen population was highly correlated with temperature and turbidity. In addition, it is noted that the pathogen population was dominated by bacterioplankton community and this might because the capacity of resistance invasion pathogen was determined by of bacterioplankton community diversity. Therefore, bacterioplankton community diversity can be used to control and predict the amount of pathogens. Quantitative microbial risk assessment (QMRA) also revealed that the infection risks of Escherichia coli (E. coli), Mycobacterium avium (M. avium), and Pseudomonas aeruginosa (P. aeruginosa) during five recreational activities, especially water-based activities in the touristic city, were greater than that in natural areas and mostly exceeded the U.S. EPA risk limit for recreational activities. Our study offered the first insight into the potential relationship between the bacterioplankton community and bacterial pathogens within a touristic river.


Assuntos
Rios/microbiologia , Organismos Aquáticos , Bactérias/classificação , Bactérias/isolamento & purificação , Biodiversidade , Escherichia coli/classificação , Escherichia coli/isolamento & purificação , Concentração de Íons de Hidrogênio , Mycobacterium avium/classificação , Mycobacterium avium/isolamento & purificação , Pseudomonas aeruginosa/classificação , Pseudomonas aeruginosa/isolamento & purificação , Medição de Risco , Qualidade da Água
16.
Front Microbiol ; 9: 999, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29867892

RESUMO

Sediment microbes play major roles in riparian ecosystems; however, little is known about their longitudinal distribution pattern and their responses to dam construction, the most severe human disturbance in river basins. Here, we investigated the variability of sediment bacterial communities along a large-scale longitudinal gradient and between dam-controlled and dam-affected sites in riparian zone of the Lancang River, China. The abundance, activity and diversity of sediment bacteria gradually increased in a downstream direction, but were significantly lower in the dam-affected sites than in the dam-controlled sites. The bacterial community compositions differed significantly between the upper-middle-reach and downstream sites at all control sites, and also between the dam-affected and dam-controlled sites. In the cascade dam area, the relative importance of spatial distance and environmental heterogeneity for bacterial distribution differed between the dam-controlled and dam-affected sites. Spatial distance was the primary cause of variations in bacterial community in dam-controlled site. By contrast, the environmental heterogeneity had more control over the bacterial communities than did the spatial distance in dam-affected site. Network analysis showed that the bacterial community in the dam-affected sites had lower connectivity and stability when compared with that in dam-controlled sites. These results suggest the distinct variations in sediment bacterial community in dam-affected sites, which could enhance our understanding of potential ecological effects caused by dam construction.

17.
Sci Rep ; 7(1): 12529, 2017 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-28970506

RESUMO

River systems have critical roles in the natural water environment and the transportation of nutrients. Anthropogenic activities, including wastewater discharge and river damming, raise adverse impacts on ecosystem and continuum of rivers. An increasing amount of attention has been paid to riverine bacterioplankton as they make vital contributions to biogeochemical nutrient cycle. A comprehensive study was conducted on the bacterioplankton community along the Yarlung Tsangpo River, which is the longest plateau river in China and is suffering from various anthropogenic impacts. The results indicated that nutrient variations corresponded to anthropogenic activities, and silica, nitrogen and phosphorus were retained by the dam. River damming influenced the biomass and diversity of the bacterioplankton, but significant alterations in the community structure were not observed between upstream and downstream of the dam. Moreover, the spatial distribution of the bacterioplankton community changed gradually along the river, and the dominant bacterioplankton in the upstream, midstream and downstream portions of the river were Firmicutes, Bacteroidetes and Proteobacteria, respectively. Soluble reactive phosphorus, elevation, ammonium nitrogen, velocity and turbidity were the main environmental factors that shape the bacterioplankton community. Our study offers the first insights into the variation of a bacterioplankton community of a large river in plateau region.


Assuntos
Organismos Aquáticos/fisiologia , Biodiversidade , Ecossistema , Plâncton/fisiologia , Organismos Aquáticos/efeitos dos fármacos , Organismos Aquáticos/metabolismo , Bacteroidetes/efeitos dos fármacos , Bacteroidetes/metabolismo , Bacteroidetes/fisiologia , China , Monitoramento Ambiental , Atividades Humanas , Humanos , Fósforo/toxicidade , Plâncton/metabolismo , Rios , Tibet , Águas Residuárias/toxicidade , Poluentes Químicos da Água/efeitos adversos
18.
Environ Pollut ; 229: 19-28, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28575712

RESUMO

Widely used titanium dioxide (TiO2) nanoparticles are likely to accumulate ultimately in sediments and potentially pose a risk to water ecosystems. This study evaluated the effect of TiO2 nanoparticles on the photodissolution of particulate organic matter (POM) through fluorescence spectroscopy. Excitation-emission matrices and parallel factor analyses revealed that the fluorescent characteristics of produced dissolved organic matter (DOM) during photodissolution of suspended sediment and synthetic particulate organic matter (SPOM) were primarily humic-like. SPOM particles appeared to simulate well the photodissolution of suspended sediment. Quasi-complete increases in fluorescence intensity and chromophoric DOM (CDOM) abundance were reached after 90, 60, and 50 min irradiation for TiO2 concentrations of 0, 2, and 5 mg L-1, respectively. The faster increment of fluorescence intensity and CDOM abundance indicated the photocatalytic dissolution of SPOM, as opposite charges between TiO2 and SPOM at pH = 4 favored the adsorption of TiO2 onto SPOM. For sediments, the CDOM abundance and fluorescence intensity decreased with increasing TiO2 concentration, resulting from the photocatalytic degradation of photoproduced DOM from sediments. These results demonstrated that pH plays an important role in the photocatalytic dissolution of POM by TiO2. Therefore, appropriate pH controls should be implemented when TiO2 are used to treat sediments contaminated with organic pollutants. Finally, with increasing use of TiO2, its accumulation in sediments may affect the fate of carbon, nutrients, and heavy metals in shallow-water ecosystems.


Assuntos
Substâncias Húmicas , Nanopartículas/química , Processos Fotoquímicos , Titânio/química , Adsorção , Carbono , Meio Ambiente , Modelos Químicos , Material Particulado/química , Espectrometria de Fluorescência , Raios Ultravioleta
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...