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1.
Rev Environ Contam Toxicol ; 248: 111-189, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-30671689

RESUMO

Metal-rich sediments have the potential to impair life in freshwater streams and rivers and, thereby, to inhibit recovery of ecological conditions after any remediation of mine water discharges. Sediments remain metal-rich over long time periods and have long-term potential ecotoxicological interactions with local biota, unless the sediments themselves are physically removed or replaced by less metal-rich sediment. Laboratory-derived environmental quality standards are difficult to apply to the field situation, as many complicating factors exist in the real world. Therefore, there is a strong case to consider other, field-relevant, measures of toxic effects as alternatives to laboratory-derived standards and to seek better biological tools to detect, diagnose and ideally predict community-level ecotoxicological impairment. Hence, this review concentrated on field measures of toxic effects of metal-rich sediment in freshwater streams, with less emphasis on laboratory-based toxicity testing approaches. To this end, this review provides an overview of the impact of metal-rich sediments on freshwater stream life, focusing on biological impacts linked to metal contamination.


Assuntos
Monitoramento Ambiental , Metais/análise , Mineração , Rios , Poluentes Químicos da Água/análise , Água Doce , Sedimentos Geológicos/química
2.
J Environ Sci (China) ; 85: 156-167, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31471022

RESUMO

This study evaluated uranium sequestration performance in iron-rich (30 g/kg) sediment via bioreduction followed by reoxidation. Field tests (1383 days) at Oak Ridge, Tennessee demonstrated that uranium contents in sediments increased after bioreduced sediments were re-exposed to nitrate and oxygen in contaminated groundwater. Bioreduction of contaminated sediments (1200 mg/kg U) with ethanol in microcosm reduced aqueous U from 0.37 to 0.023 mg/L. Aliquots of the bioreduced sediment were reoxidized with O2, H2O2, and NaNO3, respectively, over 285 days, resulting in aqueous U of 0.024, 1.58 and 14.4 mg/L at pH 6.30, 6.63 and 7.62, respectively. The source- and the three reoxidized sediments showed different desorption and adsorption behaviors of U, but all fit a Freundlich model. The adsorption capacities increased sharply at pH 4.5 to 5.5, plateaued at pH 5.5 to 7.0, then decreased sharply as pH increased from 7.0 to 8.0. The O2-reoxidized sediment retained a lower desorption efficiency at pH over 6.0. The NO3--reoxidized sediment exhibited higher adsorption capacity at pH 5.5 to 6.0. The pH-dependent adsorption onto Fe(III) oxides and formation of U coated particles and precipitates resulted in U sequestration, and bioreduction followed by reoxidation can enhance the U sequestration in sediment.


Assuntos
Biodegradação Ambiental , Poluentes Radioativos do Solo/metabolismo , Urânio/metabolismo , Sedimentos Geológicos/química , Poluentes Radioativos do Solo/química , Tennessee , Urânio/química
3.
An Acad Bras Cienc ; 91(3): e20180414, 2019 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-31411255

RESUMO

The deep sea remains the least known biome. Despite this fact, anthropic activities have affected these regions in various ways. The objective of this study was to outline the scientific production scenario based on deep sea research and to analyze trends present in the literature. For this, the bibliographical resources available from the Web of Science (WoS) were surveyed. Between 1987 and 2016, 11,079 articles on the deep sea were published. Growth was over 100% from the first to second decade and 75% from the second to third. The most productive countries were the USA, Germany, France, England and Japan. Of the 404 journals that published articles on the deep sea, 10% accounted for approximately 60% of the total published articles. The keyword with the highest occurrence was "diversity". In the first two decades, the keywords with the greatest "strength" were related to research on mining, especially for hydrocarbons. The description of new species and the analysis of the effects of climate change appear to be emerging trends in deep sea research. Mining continues to be primarily responsible for driving the development of deep sea research.


Assuntos
Bibliometria , Pesquisa Biomédica/estatística & dados numéricos , Oceanos e Mares , Publicações Periódicas como Assunto/estatística & dados numéricos , Biodiversidade , Pesquisa Biomédica/tendências , Mudança Climática , Bases de Dados Factuais/estatística & dados numéricos , Sedimentos Geológicos , Alemanha , Publicações Periódicas como Assunto/tendências , Estudos Retrospectivos , Água do Mar , Estados Unidos
4.
Ying Yong Sheng Tai Xue Bao ; 30(7): 2393-2403, 2019 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-31418243

RESUMO

Polyphosphate accummulating organisms (PAOs) play an important role in the phosphorus metabolic cycling in the sediment of reservoir. We assessed the diversity and community structure of PAOs in the sediments by T-RFLP and clone sequencing which targeted ppk1 gene at the hearts of three reservoirs (Jiulongjiangxipi reservoir, Sanshiliujiao lake reservoir and Dongyaxi reservoir) in Fujian Province. The results showed that the diversity of PAOs varied among different reservoirs, though not statistically significant. The diversity of PAOs in the Sanshiliujiao lake reservoir was highest (Shannon index H=2.89±0.03, Simpson index D=0.06±0.01). The community structure of the PAOs in the Sanshiliujiao lake reservoir was most complicated, consistent with the results of the T-RFLP. The differences of dominant PAOs genera in three reservoirs were distinct, mainly concentrated in the Proteobacteria, Actinobacteria and Acidobacteria. The percentage of those three phylum accounted for 74.5%, 85.0% and 75.0%, respectively, of the total PAOs. The dominant groups in each reservoir sediment were Anaeromyxobacter and Solibacter. Various forms of phosphorus had certain influence on the diversity of PAOs. There were significantly correlation between Fe/Al-P and PAOs diversity and community structure. The dominant genus in the three reservoirs, Anaeromyxobacter, was positively correlated with all forms of phosphorus and significantly correlated with insoluble phosphorus such as OP and Ca-P, while Solibacter was negatively correlated with all forms of phosphorus. The results suggested that PAOs had important impacts on the phosphorus cycle of sediment in eutrophicatied reservoirs.


Assuntos
Sedimentos Geológicos/microbiologia , Lagos , Polifosfatos/metabolismo , China , Fósforo
5.
Water Sci Technol ; 79(12): 2318-2327, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31411586

RESUMO

Deposition of sediment is a vital economical and technical problem for design of sewers, urban drainage, irrigation channels and, in general, rigid boundary channels. In order to confine continuous sediment deposition, rigid boundary channels are designed based on self-cleansing criteria. Recently, instead of using a single velocity value for design of the self-cleansing channels, more hydraulic parameters such as sediment, fluid, flow and channel characteristics are being utilized. In this study, two techniques of neuro-fuzzy (NF) and gene expression programming (GEP) are implemented for particle Froude number (Frp) estimation of the non-deposition condition of sediment transport in rigid boundary channels. The models are established based on laboratory experimental data with wide ranges of sediment and pipe sizes. The developed models' performances have been compared with empirical equations based on two statistical factors comprising the root mean square error (RMSE) and the concordance coefficient (CC). Besides, Taylor diagrams are used to test the resemblance between measured and calculated values. The outcomes disclose that NF4, as the precise NF model, performs better than the best GEP model (GEP1) and regression equations. As a conclusion, the obtained results proved the suitable accuracy and applicability of the NF method in Frp estimation.


Assuntos
Sedimentos Geológicos , Modelos Químicos , Lógica Fuzzy , Expressão Gênica
6.
Water Sci Technol ; 79(12): 2395-2406, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31411594

RESUMO

Untreated combined sewer overflows (CSOs) cause serious water pollution problems. In this study, the effects of CSO-induced heavy metals and the remediation practice of installation of a long-term water diversion (LTWD) on the microbial environment in river sediments were analyzed in an inland river. The Zn, Cd, Cr, and Cu contents in sediments and water were analyzed. DNA extraction and polymerase chain reaction analysis were conducted based on the Illumina MiSeq platform. The results showed that CSOs have a significant adverse impact on the diversity of microbial populations in river sediments. The LTWD is helpful in improving the richness of microorganisms and the proportion of Gram -ves, but it is challenging to reduce the accumulation of heavy metals in the sediment. The correlation analysis shows a strong relationship between some metabolic pathways and Zn and Cd accumulation in river sediments. Some detoxification compound metabolisms are also promoted at these sites. Thus, chronic exposure to environmental heavy metals from CSOs decreases the river microbial community, and further affects the ecological environment of the river. Therefore, without eliminating CSOs or reducing overflow frequency, it is difficult to alleviate the accumulation of heavy metals in river sediments and improve river ecology via water diversion alone.


Assuntos
Sedimentos Geológicos/microbiologia , Metais Pesados , Microbiota , Poluentes Químicos da Água , China , Monitoramento Ambiental , Recuperação e Remediação Ambiental , Medição de Risco , Rios , Água , Microbiologia da Água
7.
Water Sci Technol ; 80(1): 11-24, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31461418

RESUMO

This paper aims to assess the performance of a distributed hydrological model for simulating the transport of various heavy metals in rivers, to enhance and support environmental monitoring strategies for rivers in developing countries. In this context, we evaluated the performance of the Geophysical flow Circulation (GeoCIRC) model based on Object-Oriented Design (OOD) for the simulation of contamination from multiple heavy metals (Pb, Hg, Cr, and Zn) in Harrach River in Algeria. The results of the case study were in good agreement with the observations. Methodology for the assessment of data quality control and the improvement of monitoring procedures was proposed by using the hydrological model to simulate different scenarios. The GeoCIRC-model-based OOD allowed the prediction of the concentrations of heavy metals with minimal input data. Also, various heavy metals could be numerically treated simultaneously because the OOD increases the model's flexibility to allow the handling of many transportable materials. Therefore, the GeoCIRC model is a powerful tool for the monitoring of environmental contamination in rivers by various heavy metals.


Assuntos
Monitoramento Ambiental , Metais Pesados/análise , Poluentes Químicos da Água/análise , Argélia , China , Sedimentos Geológicos , Modelos Químicos , Medição de Risco , Rios
8.
J Environ Manage ; 248: 109293, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31386990

RESUMO

Studying the composition and structure of bacterial communities in sediments helps to understand the contribution of bacteria to environmental changes and the role of feedback in response to disturbances. However, seasonal changes in bacterial communities of river sediments with different pollution levels and sources have not been clear yet. In this study, we collected sediment samples during the dry season, wet season and level season from 40 sites with various pollution sources in three inflow rivers (Fengle-Hangbu River, Nanfei River and Zhegao River) of Chaohu Lake. Bacterial community compositions were determined based on high-throughput sequencing. The 'Bioenv' in the R package 'Vegan' and redundancy analysis was used to explore the influence of environmental factors on the bacterial community in the river sediments. Results showed that a significant deviation in bacterial communities was found among seasons and rivers. In addition, seasonal dynamics had a greater impact on shaping bacterial communities than rivers with different pollution sources. A higher diversity was found in the wet season as compared to the other seasons. The bacterial diversity was negatively correlated with nutrients (OM, TN, NH4+, IP, OP and TP) and metals (Cu and Zn). Bacterial communities were more sensitive to heavy metals pressure than nutrients. We also concluded that heavy metals (Cu and Cd) were the key contributing factors in explaining variations in bacterial communities. This study provided a valuable reference for assessing ecological stress.


Assuntos
Metais Pesados , Poluentes Químicos da Água , China , Monitoramento Ambiental , Sedimentos Geológicos , Rios , Estações do Ano
9.
J Environ Manage ; 248: 109332, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31394473

RESUMO

The presence of anthropic activity in the coastal or riverine environment modifies the wave as well as the water and sediment current regime. In particular, the body of water around ports is an area where intense currents and sediment transport rates are usually present and can be affected by low water velocities that take place close to the entrance and inside the port basin. Consequently, sediment can be entrained and accumulated in such areas, creating problems to navigation. Ports and moorings are filled with fine sediments due to deposition resulting from solid transport. In particular, silt particles settle because of the weak vertical and lateral shearing of the velocity field. The result is that harbours frequently require ordinary maintenance dredging. The dredging process involves the removal of sediment in its natural deposited condition by using either mechanical or hydraulic equipment. Dredging is a consolidated and proven technology, but involves considerable drawbacks. In particular, dredging has a notable environmental impact on marine flora and fauna, contributes to the mobility and diffusion of contaminants and pollutants already present in the silted sediments, obstructs navigation and is characterized by relatively high and low predictable costs. This paper aims to provide an original structured overview of technologies alternative to dredging that have been tested in the past 50 years. More than 150 articles have been analysed to compare standard dredging technologies with market-ready competitors from techno-economic and environmental perspectives. In particular, the paper focuses on anti-sedimentation infrastructures and on innovative plant solutions characterized by low maintenance costs and by a very limited environmental impact. The final aim of the paper is to describe the currently available technologies that prevent port inlet and channel siltation and to classify them through a techno-economic and environmental impact assessment. The comparison shows that dredging has both the higher costs and environmental impact, while fixed sand by-passing plants are characterized by the lowest environmental impact and operation costs that are competitive with dredging.


Assuntos
Poluentes Ambientais , Sedimentos Geológicos , Baías , Meio Ambiente , Monitoramento Ambiental
11.
Environ Monit Assess ; 191(7): 476, 2019 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-31256265

RESUMO

Concentrations of arsenic, nickel and chromium in sediments of the nearshore Pilbara Region of Western Australia's mid -north coast have caused concerns to regulators issuing ocean disposal permits for many years. A meta-analysis of data from a large number of surveys, conducted in support of permit applications over many years and across hundreds of kilometres of coastline, shows that, when assessed as total metal concentrations, chromium and nickel occur routinely at concentrations above those recommended as screening triggers by national guidelines and arsenic more rarely. Arsenic was concentrated in surface sediments, consistent with an organic origin. Concentrations of nickel and chromium were higher in deeper sediment layers, consistent with a natural geological origin. However, sediment particle sizing was a major determinant of total metal concentrations of all three metals, and bioavailability was always much lower and within recommended guidelines. Past dredging activity for channels and berths in the large ports of the Pilbara has most likely led to an elevation of fine fractions of surface sediments within operating port areas, when compared to the undisturbed surrounding areas, and may also have increased the proportion of sediment from deeper substrates at the surface. Whilst total concentrations of chromium and nickel commonly exceed screening guidelines throughout the nearshore Pilbara Region, their bioavailability was low and these metals present a little threat to biota.


Assuntos
Sedimentos Geológicos/análise , Metais/análise , Poluentes Químicos da Água/análise , Arsênico/análise , Disponibilidade Biológica , Cromo/análise , Monitoramento Ambiental , Níquel/análise , Oceanos e Mares , Austrália Ocidental
12.
Sci Total Environ ; 691: 969-980, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31326819

RESUMO

A good understanding of lead (Pb) mobilization in eutrophic lakes is a key to the accurate assessment of Pb pollution. In this work, dissolved and labile Pb was determined by both high resolution dialysis (HR-Peeper) and diffusive gradients in thin films (DGT) in sediment-water profiles of the hyper-eutrophic Meiliang Bay of Lake Taihu on a monthly basis during one year. The drinking water standards for dissolved Pb of the World Health Organization (10µg/L) and those of China were exceeded in the overlying water (20.79-118.5µg/L). Out of which, a total of five months even exceeded the fisheries water quality limitation (50µg/L) in China. The algal blooms created an anaerobic environment in the surface sediments in July. The reductive conditions led to the dissolution of Fe/Mn and this caused the release of Pb, followed by organic matter complexation. This was supported by the coincident changes of dissolved Pb with dissolved organic matter (DOM) in sediments under anaerobic incubation. Algae residue decomposition in October caused another distinct release of Pb, but this process should be considerably suppressed by increased sulfide precipitation and pyrite adsorption of Pb ion. These results indicated that Pb mobilization in sediments can be significantly enhanced by algal blooms in eutrophic lakes, indicating that further attention should be paid to Pb pollution in waters with harmful algal blooms.


Assuntos
Sedimentos Geológicos/química , Proliferação Nociva de Algas , Chumbo/análise , Poluentes Químicos da Água/análise , China , Monitoramento Ambiental
13.
Environ Monit Assess ; 191(8): 485, 2019 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-31280379

RESUMO

The limited carrying capacities of shallow tropical lakes render them more vulnerable to ecological problems like eutrophication. Unregulated human activities such as unsustainable aquaculture and urbanization can alter ecosystem dynamics rapidly, and this warrants more comprehensive researches than what has been previously conducted. Here, we presented an integrated assessment of the nutrient dynamics, phytoplankton diversity, and sediment geochemistry in Lake Palakpakin, a shallow tropical lake of volcanic origin, to understand its deteriorating ecological state. Water, phytoplankton, and sediment samples were collected, and in situ water quality measurements were done during wet and dry seasons in four critical areas in the lake, namely, the inlet, center, sanctuary, and outlet. Results revealed that high light extinction coefficient (1.13 m-1), high turbidity (28 NTU), high phosphate concentration (> 2.0.5 mg/L), and the abundance of Microcystis aeruginosa, Anabaena helicoidea, and Lyngbya sp. indicate that from a relatively healthy lake in 2008, Lake Palakpakin has become a eutrophic to hypereutrophic freshwater body. High concentrations of available nutrients such as N and P were detected in the center and sanctuary sediments, which drive the internal nutrient loading in the lake. We recommend that management efforts be directed towards a whole-ecosystem approach in addressing the problem of eutrophication, especially in shallow tropical lakes.


Assuntos
Monitoramento Ambiental , Lagos/química , Fitoplâncton/crescimento & desenvolvimento , Biodiversidade , Conservação dos Recursos Naturais , Cianobactérias , Ecossistema , Eutrofização , Sedimentos Geológicos/química , Microcystis , Filipinas , Fósforo/análise , Estações do Ano , Poluentes da Água/análise , Qualidade da Água
14.
Int J Syst Evol Microbiol ; 69(9): 2854-2861, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31274408

RESUMO

A Gram-stain-negative, non-motile, mesophilic, short rod-shaped, aerobic bacterium designated as 318-1T was isolated from a marine sediment collected from Masan Bay, South Korea. Strain 318-1T grew optimally at pH 6-7, at 30 °C and in the presence of 2-3 % (w/v) NaCl, tolerant of up to 8 % (w/v) NaCl, and accumulated poly-ß-hydroxybutyrate (PHB). A comparative analysis of 16S rRNA gene sequences revealed that strain 318-1T formed a distinct phyletic lineage in the genus Ruegeria (family Rhodobacteraceae, class Alphaproteobacteria) and showed high sequence similarity to Ruegeria halocynthiae DSM 27839T (96.5 %) and Shimia haliotis DSM 28453T (96.3 %). Comparing the genome sequence of 318-1T with those of the type strains of seven species of the genus Rugeria and two species of the genus Shimia, the values obtained were below the thresholds with analysis of average nucleotide identities (ANI, 71.6-76.8 %) and in silico DNA-DNA hybridisation, Genome-to-Genome Distance Calculator (GGDC, 18.5-20.6 %). The DNA G+C content was 65.75 mol%. Chemotaxonomic data [predominant quinone ubiquinone Q10; polar lipid profile consisting of major compounds phosphatidylcholine (PC), phosphatidylglycerol (PG), an unidentified aminolipid and an unidentified lipid; major fatty acids summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c)] supported the affiliation of strain 318-1T to the genus Ruegeria. Genomic, chemotaxonomic, and phenotypic differentiation of strain 318-1T from the members of the genus Ruegeria support it as a novel species. On the basis of the results in this study, a novel species, Ruegeria lutea sp. nov., is proposed. The type strain is 318-1T (=JCM 30927T=KEMB 7306-525T=KCTC 72105T).


Assuntos
Sedimentos Geológicos/microbiologia , Filogenia , Rhodobacteraceae/classificação , Água do Mar/microbiologia , Técnicas de Tipagem Bacteriana , Composição de Bases , Baías , DNA Bacteriano/genética , Ácidos Graxos/química , Hibridização de Ácido Nucleico , Fosfolipídeos/química , RNA Ribossômico 16S/genética , República da Coreia , Rhodobacteraceae/isolamento & purificação , Análise de Sequência de DNA , Ubiquinona/análogos & derivados , Ubiquinona/química
15.
Water Sci Technol ; 79(10): 1868-1877, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31294703

RESUMO

Microplastics are considered to be a widespread environmental contaminant, posing a serious threat to the aquatic environment. We addressed this issue based on field observations and laboratory analysis of samples from Poyang Lake. We collected sediment samples from 10 sites across Poyang Lake during 2017. Data were analyzed by one-way analysis of variance (ANOVA). Results showed that the abundance of microplastics ranged from 11 to 3,153 items/kg dw in the sediment samples. Except at Nanjishan, the amount of microplastics in different periods decreased in the order: December > April > July. Microplastics with a size <1 mm were the most abundant fraction in sediments, reaching over 50%. Observations under microscope revealed four types of microplastics in Poyang Lake: fragments, films, foams and fibers. Fragments were more common in sediments. Microplastics have complex surface topography, typically including rough surfaces, porous structures, cracks and extensive damage. Energy dispersive X-ray analysis indicated that most microplastics contained Si, Na, Ca, Cl and Al. Overall, the results provided strong evidence of high levels of microplastics in Poyang Lake, suggested that the microplastics pollution status in Poyang Lake should continue to be monitored.


Assuntos
Monitoramento Ambiental , Lagos , Plásticos/análise , Poluentes Químicos da Água/análise , China , Sedimentos Geológicos
16.
Water Sci Technol ; 79(11): 2056-2067, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31318343

RESUMO

The purpose of this study was to describe the dynamics of anaerobic oxidation of methane (AOM) coupled with sulfate reduction (SR) using experimental data from a continuous incubation experiments published earlier in order to show that formation of consortia of anaerobic archaea (ANME) and Desulfosarcina-like bacteria (DSS) may have a significant effect on sulfur isotope fractionation. The dynamic simulation of reversible AOM by ANME coupled with SR by DSS was performed. This simulation took into account biomass growth and fractionation of stable isotopes of sulfur. Two kinetic schemes with and without ANME + DSS consortium formation were tested. The respective models were applied at five influent methane concentrations. A good fit to experimental data was obtained only when assuming active ANME and DSS biomass accumulation. The assumption about incorporation of reversibility of anaerobic methane oxidation and sulfate reduction did not improve the model's fit to experimental data. In accordance with both the models, sulfur isotope fractionation was smallest for the highest influent methane concentration. The model considering the formation of consortia of ANME + DSS is proved to be more appropriate.


Assuntos
Biodegradação Ambiental , Metano/metabolismo , Consórcios Microbianos , Anaerobiose , Archaea , Sedimentos Geológicos , Isótopos , Oxirredução , Sulfatos/metabolismo
17.
J Agric Food Chem ; 67(27): 7609-7615, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31257874

RESUMO

Shallow water systems are uniquely susceptible to environmental processes such as photolysis and hydrolysis that can influence the dissipation of pesticides into sediments. The fungicide dicloran has previously been shown to undergo photolysis and is reported to dissipate in soils and sediments. The photodegradation and dissipation of dicloran in freshwater and seawater was monitored in a laboratory-simulated shallow water system. While no difference was observed between freshwater and seawater systems in the presence of simulated sunlight, the dissipation of dicloran in dark trial systems differed between salinities; 30% of the applied mass dissipated into the sediment in freshwater vs 22% in seawater, and the photodegradation rate and half-life were also impacted by the presence of sediment. The potential for dicloran to dissipate and photodegrade affects the overall behavior of dicloran between waters. Differences in chemical behavior with sediment presence and potential for photodegradation have the capacity to impact organisms within the ecosystem and suggest that these factors may need to be implemented into chemical exposure assessments dependent upon location.


Assuntos
Compostos de Anilina/química , Água Doce/química , Sedimentos Geológicos/química , Fotólise , Água do Mar/química , Luz Solar , Ecossistema , Fungicidas Industriais/química , Solo/química , Poluentes Químicos da Água/química
18.
Microbiol Res ; 226: 65-73, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31284946

RESUMO

Bacterial communities are resilient to the environmental changes, yet the effect of long term ecological changes on bacterial communities remain poorly explored. To study the effect of prolonged environmental changes, a 25 m long sediment core was excavated from a paleo beach ridge located on the Cauvery delta, south east coast of India. Geological evidences suggested that the site has experienced multiple marine transgressions and regressions. The three paleosols from Vettaikaraniruppu (VKI) beach ridge, VKI-2 (2.8 m bgl; 3 kybp), VKI-5 (7.2 m bgl; 6 kybp) and VKI-14 (24.5 m bgl; 146 kybp) was chosen for bacterial community analysis based on their formation period. Bacterial community structure of paleosols was reconstructed using V3 hypervariable region of bacterial 16S rDNA targeted Illumina sequencing. The VKI-5 sediment layer which formed under marine environment contained highest bacterial diversity, and the community was a mix up of terrestrial and marine bacterial population. The final community VKI-2 exhibited an approximate structural pattern witnessed in the native bacterial community VKI-14 which formed during marine regression. Furthermore, marine transgression and regression experienced in VKI resulted in the formation of distinct biogeographic patterns.


Assuntos
Bactérias/classificação , Biodiversidade , Ecossistema , Microbiota , Água do Mar/microbiologia , Bactérias/genética , DNA Bacteriano/genética , DNA Ribossômico/genética , Ecologia , Sedimentos Geológicos/microbiologia , Índia , Biologia Marinha , Microbiota/genética , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência
19.
J Environ Radioact ; 208-209: 106016, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31325733

RESUMO

Theoretical and experimental studies have shown that activity concentrations of fallout radionuclides (such as 137Cs and excess 210Pb) decrease with particles size in aqueous suspensions. This paper is aimed at reviewing the theoretical fundamentals for granulometric speciation of radionuclides, and at exploring its practical use in the analytical context of gamma spectrometry for the radiometric dating of recent sediments, with view to: i) improving the detection of 137Cs (since its use as independent chronostratigraphic mark is challenging in the southern hemisphere because its low fallout rate), ii) supporting refined CIC models and normalization techniques in 210Pb-based radiogeochronologies. The work uses surface sediments sampled from the Tinto Estuary (SW Spain), affected by mining and phosphate-fertilizer industries, and from the Ankobra Estuary (Ghana), affected by intensive artisanal gold-mining. Granulometric classes have been separated by a sieving column with decreasing mesh sizes and the obtained cumulative percentage of mass mathematically described by a Rosin-Rammler particle-size distribution. The target radionuclides for gamma spectrometry were 210Pb, 226Ra and137Cs, complemented with 40K, 234Th and 228Ra. Results revealed that, far from ideal experiments, under actual environmental conditions the increase in activity concentrations with decreasing particle sizes is too moderate, and in general they are affected by larger counting uncertainties due to the small available amount of mass. Indeed, there was no correlation between grain-size and 137Cs concentrations (p = 0.25), and similarly for excess 210Pb (p = 0.53). No effect of the organic matter content was observed in 137Cs (p = 0.58) and excess 210Pb (p = 0.85) concentrations. Present results pose some concerns to the general use of granulometric speciation in the context of gamma spectrometry for supporting the radiometric dating of recent sediments. A detailed discussion on the use of normalization methods is also presented.


Assuntos
Sedimentos Geológicos/química , Monitoramento de Radiação , Datação Radiométrica/métodos , Poluentes Radioativos da Água/análise , Gana , Mineração , Espanha , Espectrometria gama
20.
Int J Syst Evol Microbiol ; 69(9): 2717-2722, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31361214

RESUMO

A Gram-reaction-negative, aerobic, flagellated and coccoid-shaped bacterial strain, designated SM1702T, was isolated from Antarctic intertidal sediment collected off Ardely Island, West Antarctica. The strain grew at 0-30 °C and with 0.5-5.0 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences and single-copy orthologous clusters both showed that strain SM1702T, together with Poseidonibacter lekithochrous, occupied an independent phylogenetic branch, sharing the highest 16S rRNA gene sequence similarity with type strain of the latter (95.6 %). The major fatty acids were summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c), C16 : 0, and summed feature 2 (C14 : 0 3-OH and/or iso-C16 : 1 I). Polar lipids were phosphatidylethanolamine and phosphatidylglycerol. The genomic DNA G+C content of strain SM1702T was 27.1 mol%. Based on the results of the polyphasic characterisation for strain SM1702T, it is identified as the representative of a novel species of Poseidonibacter, for which the name Poseidonibacter antarcticus sp. nov. is proposed. The type strain of Poseidonibacter antarcticus is SM1702T (=MCCC 1K03471T=KCTC 62796T).


Assuntos
Campylobacteraceae/classificação , Sedimentos Geológicos/microbiologia , Filogenia , Água do Mar/microbiologia , Regiões Antárticas , Técnicas de Tipagem Bacteriana , Composição de Bases , Campylobacteraceae/isolamento & purificação , DNA Bacteriano/genética , Ácidos Graxos/química , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
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