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1.
Chemosphere ; 261: 127888, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33113669

RESUMO

Besides anthropogenic contamination, freshwater environments can also be affected by the presence of natural toxins. Mycotoxins, plant toxins and cyanotoxins are the most relevant groups that can be found in the aquatic system. However, until now, only cyanotoxins have been more carefully studied. In the present work, single workflow for the assessment of natural toxins in waters, based on suspect screening and target screening of a selected group of toxins is presented. The approach is based on a triple-stage solid-phase extraction (SPE) able to isolate a wide range of natural toxins of different polarities, followed by liquid chromatography coupled to high-resolution mass spectrometry (HPLC-ddHRMS2) using a Q-Exactive Orbitrap analyser. The acquisition was performed in full-scan (FS) and data-dependant acquisition (ddMS2) mode, working under positive and negative mode. For the tentative identification, different on-line databases such as ChemSpider and MzCloud and an in-house natural toxins list with 2384 structures, that includes cyanotoxins, plant toxins and mycotoxins, were used. Also, thanks to the MS2 data, it was possible to achieve a high level of tentative identification confidence, but confirmation was only possible comparing the standards of the suspected compounds. For those, the analytical parameters of the developed method were also validated, and the quantification was possible by external calibration. Validation showed recoveries in the range between 53 and 95%, and method limits of detection (MDL) between 0.02 and 1.22 µg/L. This approach was applied to study natural toxins in 4 sampling sites along the Ter River in Catalonia (NE Spain). In this preliminary study 23 natural toxins were tentatively identified, and 9 of them confirmed (aflatoxin B1, anatoxin-a, nodularin, microcystin-LR, baicalein, kojic acid, cinchonine, B-asarone and atropine). The results of the quantification of these compounds showed concentrations below 1 µg/L in all cases, that is considered safe according to the actual legislation. This suspect screening approach allows a more comprehensive assessment of natural toxins in natural waters.


Assuntos
Toxinas Bacterianas/análise , Água Potável/química , Água Doce/química , Micotoxinas/análise , Poluentes Químicos da Água/análise , Cromatografia Líquida de Alta Pressão/métodos , Água Potável/normas , Limite de Detecção , Espectrometria de Massas/métodos , Microcistinas/análise , Peptídeos Cíclicos/análise , Extração em Fase Sólida/métodos , Espanha , Tropanos/análise
2.
Sci Total Environ ; 747: 141135, 2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-32795791

RESUMO

Scale-up feasibility of the graphitized sand filter (GS1) for Microcystin-LR (MC-LR) removal and its impact on other water pollutants (WPs) was assessed through a mass-balance study, using a laboratory-based drinking water treatment plant (DWTP) micromodel named: SAP-1©. The treatment system comprised: raw water tank, pre-oxidation tank (oxidant: potassium permanganate), followed by a coagulation/flocculation tank (alum supplemented), sedimentation tank, filtration module and finally disinfection tank (dosed with hypochlorite solution). Two filter modules (FMs) were studied: a) FM1: graphitized-sand media + sand media = ½ GS1 + ½ sand and b) FM2: ½ sand + ½ sand. The MC-LR removal study (initial concentration: 50 µg/L) was performed for two varieties of MC-LR source: a) commercial MC-LR, and b) algal-biomass released MC-LR. Along with MC-LR, other WPs were also evaluated including metal ions (Fe2+ and Cu2+), total coliform, turbidity, ammonia-N and dissolved organic carbon. The removal efficiency of these WPs was determined for each treatment unit (as it passed). FM1 was able to reduce the inflow residual of MC-LR (coming from the preceding unit: sedimentation unit) from 12.1 µg/L and 25.4 µg/L (for commercial and algal-cell MC-LR source, respectively) to <0.61 µg/L and hence successfully complying the WHO guidelines (<1 µg/L). The protein phosphatase 1A (PP1A) toxicity assay confirmed a much safer and more toxic-free filtrate (by 40%-50%) for FM1 as compared to the filtrate obtained from FM2. The techno-economic evaluation showed that for an annual household filter application, 160 CAD needs to be spent on one GS1-based filter unit as compared to over 6000 CAD (equivalent price) for the conventional sand-based filter to provide MC-LR-free water. The present study demonstrates the feasibility of the utilization of these units in household filtration systems.


Assuntos
Água Potável , Poluentes Químicos da Água , Purificação da Água , Água Potável/análise , Microcistinas/análise , Areia , Poluentes Químicos da Água/análise
3.
Environ Monit Assess ; 192(8): 513, 2020 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-32666330

RESUMO

Cyanobacterial harmful algal blooms and the toxins they produce are a global water-quality problem. Monitoring and prediction tools are needed to quickly predict cyanotoxin action-level exceedances in recreational and drinking waters used by the public. To address this need, data were collected at eight locations in Ohio, USA, to identify factors significantly related to observed concentrations of microcystins (a freshwater cyanotoxin) that could be used in two types of site-specific regression models. Real-time models include easily or continuously-measured factors that do not require that a sample be collected; comprehensive models use a combination of discrete sample-based measurements and real-time factors. The study sites included two recreational sites and six water treatment plant sites. Real-time models commonly included variables such as phycocyanin, pH, specific conductance, and streamflow or gage height. Many real-time factors were averages over time periods antecedent to the time the microcystin sample was collected, including water-quality data compiled from continuous monitors. Comprehensive models were useful at some sites with lagged variables for cyanobacterial toxin genes, dissolved nutrients, and (or) nitrogen to phosphorus ratios. Because models can be used for management decisions, important measures of model performance were sensitivity, specificity, and accuracy of estimates above or below the microcystin concentration threshold standard or action level. Sensitivity is how well the predictive tool correctly predicts exceedance of a threshold, an important measure for water-resource managers. Sensitivities > 90% at four Lake Erie water treatment plants indicated that models with continuous monitor data were especially promising. The planned next steps are to collect more data to build larger site-specific datasets and validate models before they can be used for management decisions.


Assuntos
Lagos , Microcistinas/análise , Monitoramento Ambiental , Ohio
4.
Environ Sci Pollut Res Int ; 27(28): 35284-35293, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32592053

RESUMO

Microcystins (MCs) are the most studied toxins of cyanobacteria in freshwater bodies worldwide. However, they are poorly documented in coastal waters in several parts of the world. In this study, we investigated the composition of cyanobacteria and the presence of microcystins (MCs) in several coastal aquatic ecosystems of Nigeria. Direct morphological analysis revealed that members of the genus Oscillatoria were dominant with five species, followed by Trichodesmium with two species in Nigerian coastal waters. Oso Ibanilo had the highest cyanobacterial biomass (998 × 103 cells/L), followed by Rivers Ocean (156 × 103 cells/L). Except for the Cross River Ocean, cyanobacteria were present in all the investigated aquatic ecosystems. Ten (10) out of twenty water bodies examined had detectable levels of MCs. Furthermore, genomic DNA analysis for the mcyE gene of microcystin synthetase (mcy) cluster showed identities higher than 86% (query coverage > 96%) with toxic strains of cyanobacteria in all the samples analyzed. Also, the sequences of samples matched those of uncultured cyanobacteria from recreational lakes in Southern Germany. Our findings indicate that the presence of toxic cyanobacteria in coastal waters of Nigeria is of public and environmental health concern.


Assuntos
Ecossistema , Microcistinas/análise , Monitoramento Ambiental , Alemanha , Guiné , Nigéria
5.
J Chromatogr A ; 1623: 461198, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32505287

RESUMO

Microcystins (MCs) and nodularin (NOD) are tumor promoters produced by cyanobacteria and present in surface water. In this work, a novel mesoporous metal-organic framework-5@chitosan (MOF-5@CS) material was synthesized and applied for the enrichment of MCs and NOD in water and fish samples. The mesoporous MOF-5@CS material was firstly synthesized via a one-step hydrothermal method, and the chitosan was combined with MOF-5 via chemical bonding assembly. As a new adsorbent, the as-synthesized material was found having a large specific surface area and good thermal stability. Under the optimized conditions, MCs and NOD were enriched by the MOF-5@CS material and detected by ultra-performance liquid chromatography-tandem mass spectrometry. The limit of detection of the new method for MCs and NOD were in the range of 0.0018-0.077 ng/mL. The value of relative standard deviation for repeatability were 2.69-6.30%, and the recovery of the analytes ranged from 84.36% to 118.51%. Compared with other reported method for MCs and NOD detection in complex matrices, better adsorption performance for MCs and NOD were obtained by our new method, and the sensitivity of MCs-RR and NOD were improved nearly 20 times and 30 times, respectively.


Assuntos
Quitosana/química , Cromatografia Líquida de Alta Pressão/métodos , Estruturas Metalorgânicas/química , Microcistinas/análise , Peptídeos Cíclicos/análise , Espectrometria de Massas em Tandem/métodos , Adsorção , Microcistinas/química , Peptídeos Cíclicos/química , Padrões de Referência , Reprodutibilidade dos Testes , Extração em Fase Sólida , Espectroscopia de Infravermelho com Transformada de Fourier , Poluentes Químicos da Água/análise
6.
Biosensors (Basel) ; 10(3)2020 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-32235710

RESUMO

This paper presents a capacitive differential bridge structure with both AC and DC excitation and balancing capability for low cost electrode-solution interfacial capacitance biosensing applications. The proposed series RC balancing structure offers higher sensitivity, lower susceptibility to common-mode interferences, and drift control. To evaluate the bridge performance in practice, possible effects of initial bridge imbalance due to component mismatches are investigated considering the required resolution of the balancing networks, sensitivity, and linearity. This evaluation is also a guideline to designing the balancing networks, balancing algorithm and the proceeding readout interface circuitry. The proposed series RC bridge structure is implemented along with a custom single frequency real-time amplification/filtering readout board with real-time data acquisition and sine fitting. The main specifications for the implemented structure are 8-bit detection resolution if the total expected fractional capacitance change at the interface is roughly 1%. The characterization and measurement results show the effectiveness of the proposed structure in achieving the design target. The implemented structure successfully achieves distinct detection levels for tiny total capacitance change at the electrode-solution interface, utilizing Microcystin-(Leucine-Arginine) toxin dilutions as a proof of concept.


Assuntos
Técnicas Biossensoriais/métodos , Microcistinas/análise , Capacitância Elétrica , Eletrodos , Desenho de Equipamento
7.
Sci Total Environ ; 728: 138775, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32339839

RESUMO

It is essential to have tools that can be used to diagnose water resources. For this reason, this study sets out on the one hand to assess water quality in three reservoirs in Spain (Salas, A Baxe and Conchas) with Cyano-Habs problems through the application of water quality indexes: The National Sanitation Foundation Water Quality Index (NFSWQI), the General Quality Index (GQI), the Trophic State Index (TSI), and the Trophic Contamination Index (ICOTRO). On the other hand, it seeks to learn how parameters such as nitrogen and phosphorus influence the presence of cyanotoxin, specifically Microcystis aeruginosa. To that end, samples from the three reservoirs are cultured and physical-chemical parameters and the toxicity of the water are measured. The results show that Salas reservoir has the worst water quality rating (GQI is bad and NFSWQI medium), while As Conchas and A Baxe obtain very good figures for NFSWQI. This contrasts with the data obtained via the TSI of moderately eutrophic conditions for all three reservoirs, and hypereutrophic levels for As Conchas and A Baxe downstream. On the other hand, the toxicity analysis shows levels of 1.12 ±â€¯0.06 µg/l microcystin-LR (MC-LR) for As Conchas, 0.64 ±â€¯0.04 µg/l MC-LR for Salas, and 1.24 ±â€¯0.05 µg/l MC-LR for A Baxe, of which 20% corresponds to free MC-LR. This study finds that nitrogen is the parameter that most favors the production of MC-LR. We conclude that the eutrophication indexes are more reliable when studying the presence of cyanobacteria. Furthermore, nitrogen and phosphorous are the most significant parameters in this regard. They are taken into account in the quality indices (GQI, NFSWI), but they are not sufficiently representative. It is recommended as a future line of research that water quality indices be adapted or designed to incorporate eutrophication levels and even water toxicity.


Assuntos
Cianobactérias , Microcystis , Eutrofização , Microcistinas/análise , Espanha , Qualidade da Água
8.
Microbiol Res ; 236: 126452, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32200249

RESUMO

Harmful cyanobacterial blooms are increasingly common in aquatic environments. This can lead to higher concentrations of cyanotoxins, such as microcystins (MCs), posing a great risk to diverse organisms, including humans. MCs are among the most commonly reported cyanotoxins in freshwater environments worldwide, where they may have different fates. MCs can adsorb to suspended particles into the water column and deposit onto the sediment where they can be affected by physical factors (e.g. winds in shallow lakes causing sediment resuspension) or biological factors (e.g. biodegradation). Here we focused on the conditions of a coastal shallow lagoon contaminated by MCs aiming to estimate the return of pre-existing MCs from the sediment to the water column, to evaluate the adsorption of dissolved MC-LR to the sediment and to verify the occurrence of biodegradation. In experiments with sediment, desorption and adsorption were tested under the influence of temperature, pH and aeration, reproducing conditions observed in the lagoon. MC-desorption was not detected under the tested conditions. Spiking MC-LR into lagoon water samples in the presence of sediment resulted in a 50 % reduction of soluble MC-LR concentration in control conditions (25 °C, pH 8.0, no aeration). Increasing temperature (45 °C) or introducing aeration further stimulated MC-LR removal from the water. Biodegradation was observed in sediment samples and interstitial water (even with tetracycline). The composition of the bacterial community differed in sediment and interstitial water: major phyla were Chloroflexi, Proteobacteria, Firmicutes, and OP3. From the assigned OTUs, we identified genera already described as MC degrading bacteria. Thus, the sediment is a key factor influencing the fate of MC-LR in this shallow coastal lake contributing to stable adsorption and biodegradation.


Assuntos
Cianobactérias/metabolismo , Sedimentos Geológicos/microbiologia , Proliferação Nociva de Algas , Microbiota/genética , Microcistinas , Poluentes Químicos da Água/análise , Biodegradação Ambiental , Genes Bacterianos , Sedimentos Geológicos/análise , Humanos , Concentração de Íons de Hidrogênio , Lagos/microbiologia , Metagenômica , Microcistinas/análise , RNA Ribossômico 16S/genética , Temperatura , Água/análise
9.
PLoS Negl Trop Dis ; 14(3): e0008060, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32163415

RESUMO

The northeast (NE) region of Brazil commonly goes through drought periods, which favor cyanobacterial blooms, capable of producing neurotoxins with implications for human and animal health. The most severe dry spell in the history of Brazil occurred between 2012 and 2016. Coincidently, the highest incidence of microcephaly associated with the Zika virus (ZIKV) outbreak took place in the NE region of Brazil during the same years. In this work, we tested the hypothesis that saxitoxin (STX), a neurotoxin produced in South America by the freshwater cyanobacteria Raphidiopsis raciborskii, could have contributed to the most severe Congenital Zika Syndrome (CZS) profile described worldwide. Quality surveillance showed higher cyanobacteria amounts and STX occurrence in human drinking water supplies of NE compared to other regions of Brazil. Experimentally, we described that STX doubled the quantity of ZIKV-induced neural cell death in progenitor areas of human brain organoids, while the chronic ingestion of water contaminated with STX before and during gestation caused brain abnormalities in offspring of ZIKV-infected immunocompetent C57BL/6J mice. Our data indicate that saxitoxin-producing cyanobacteria is overspread in water reservoirs of the NE and might have acted as a co-insult to ZIKV infection in Brazil. These results raise a public health concern regarding the consequences of arbovirus outbreaks happening in areas with droughts and/or frequent freshwater cyanobacterial blooms.


Assuntos
Morte Celular/efeitos dos fármacos , Microcefalia/patologia , Envenenamento/complicações , Envenenamento/patologia , Saxitoxina/toxicidade , Infecção por Zika virus/complicações , Infecção por Zika virus/patologia , Animais , Toxinas Bacterianas/análise , Toxinas Bacterianas/toxicidade , Encéfalo/patologia , Brasil/epidemiologia , Células Cultivadas , Modelos Animais de Doenças , Surtos de Doenças , Feminino , Humanos , Incidência , Toxinas Marinhas/análise , Toxinas Marinhas/toxicidade , Camundongos Endogâmicos C57BL , Microcistinas/análise , Microcistinas/toxicidade , Modelos Teóricos , Neurotoxinas/análise , Neurotoxinas/toxicidade , Saxitoxina/análise , Água/química
10.
Environ Int ; 138: 105648, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32187572

RESUMO

Microcystins (MCs) produced by cyanobacteria pose serious threats to human health. However, the contribution of long-term exposure to MCs to the development of nonalcoholic fatty liver disease (NAFLD) remains poorly documented. In this study, we estimated the environmental uptake of MCs by a small population of fishers who have lived for many years on Meiliang Bay of Lake Taihu, where cyanobacterial blooms occur frequently. Serum biochemical indices of liver function and their relationships with MC contamination in these people were also investigated. Moreover, to mimic the long-term effects of MC on the livers of fishers, an animal model was established in which mice were exposed to MC-LR at an environmentally relevant level, a reference level (the no-observed adverse effect level, NOAEL), and three times the NOAEL through drinking water for 12 months. We estimated the total daily intake of MCs by fishers through contaminated lake water and food to be 5.95 µg MC-LReq, far exceeding the tolerable daily intake (2.40 µg MC-LReq) proposed by the World Health Organization (WHO). More than 80% of participants had at least one abnormal serum marker. The indices of aspartate aminotransferase (AST)/alanine aminotransferase (ALT), triglyceride (TG), globulin (GLB), and lactate dehydrogenase (LDH) had close positive associations with MC contamination, indicating that both liver damage and lipid metabolism dysfunction were induced by chronic MC exposure. Furthermore, the animal experimental results showed that long-term exposure to MC-LR at the environmentally relevant level led to hepatic steatosis with molecular alterations in circadian rhythm regulation, lipid metabolic processes, and the cell cycle pathway. Exposure to MC-LR at or above the NOAEL worsened the pathological phenotype towards nonalcoholic steatohepatitis disease (NASH) or fibrosis. These results suggest that prolonged exposure to the reference level (NOAEL) of MC-LR could cause severe liver injury to mammals. People with long-term environmental exposure to MCs might be at high risk for developing NAFLD.


Assuntos
Cianobactérias , Hepatopatia Gordurosa não Alcoólica , Animais , Modelos Animais de Doenças , Exposição Ambiental/efeitos adversos , Humanos , Fígado/química , Camundongos , Microcistinas/análise , Microcistinas/toxicidade , Hepatopatia Gordurosa não Alcoólica/induzido quimicamente
11.
Talanta ; 211: 120738, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32070620

RESUMO

The presence of cyanobacteria and their toxins in water used as drinking water or for recreational purposes may represent a risk for human health. This work describes the development of an advanced analytical method for simultaneous determination of 21 cyanotoxins (including Microcystins, Cyanopeptolins, Anabaenopeptins and Microginins) in drinking water based on Ultra Performance Liquid Chromatography coupled with a Q-TOF mass spectrometer. Water samples, spiked with Nodularin as internal standard at 1 µg/L, were extracted using Carbograph 4 SPE cartridge and 10 µL of the extracted sample were injected into the UPLC-HRMS/MS system. Analytes separation was obtained using a UPLC C18 column, acetonitrile and water as mobile phases, both containing 10 mM formic acid, and operating in positive ionization mode and sensitivity mode. The method has been proven to be robust, precise and accurate with recovery percentages above 85% and with relative standard deviations ≤16% and LODs between 0.002 and 0.047 µg/L, fitting for the intended purposes at the concentrations of interest. This method was applied during a monitoring activity in an Italian volcanic lake in Viterbo (Lazio Region, Italy), due to a severe algal proliferation in January 2018-March 2019 period and for the assessment of cyanobacteria proliferation risk and of cyanotoxin production in drinking water chain.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Água Potável/análise , Monitoramento Ambiental/métodos , Microcistinas/análise , Espectrometria de Massas em Tandem/métodos , Poluentes Químicos da Água/análise , Humanos , Limite de Detecção
12.
Environ Pollut ; 259: 113884, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31918143

RESUMO

High concentrations of microcystins (MCs) in sediment pose a serious hazard to aquatic and terrestrial organisms. Hence, we investigated the seasonal variation of dominant MCs (MC-LR, MC-RR and MC-YR) in sediments of Lake Taihu over four seasons for the first time. Sediment MCs varied seasonally (p < 0.01) with concentrations highest in August and lowest in February. The MCs were dominated by MC-LR (61.47%) with the content ranging from 0.02 to 2.37 µg/g dry weight in sediment. The three MC congeners and their proportions were significantly correlated with latitude and longitude. Meiliang Bay in the north had the highest MCs of all sites, while the eastern part of the lake had a high level especially in August. Variation of MC-LR and MC-RR concentrations was significantly correlated (p < 0.05) with water temperature, dissolved total organic carbon, cyanobacteria density, total suspended solid particles, and total organic carbon and total nitrogen in sediment, while MC-YR was negatively correlated (p < 0.01) with nutrients in the water column and heavy metals in sediments. An ecological risk assessment suggested the MCs already pose significant adverse effects on Potamopyrgus antipodarum; although the adverse effects on humans were weak, children were at greater risk than adults.


Assuntos
Monitoramento Ambiental , Sedimentos Geológicos , Lagos , Microcistinas , Criança , China , Sedimentos Geológicos/química , Humanos , Lagos/química , Microcistinas/análise , Microcistinas/toxicidade , Medição de Risco , Estações do Ano
13.
Environ Toxicol Chem ; 39(4): 787-798, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31900949

RESUMO

Blooms of the cyanobacterium Microcystis spp. could affect fish health through the ingestion of colonies as well as exposure to dissolved microcystins in the water column. The goal of the present study was to evaluate the dietary exposure pathway through which Microcystis spp. blooms may affect liver function and nutritional status using a novel approach involving multiple analytical methods to assess the potential risk. Our study was conducted using threadfin shad, Dorosoma petenense, which is a pelagic fish commonly exposed to Microcystis spp. blooms in the upper San Francisco Estuary. The approach incorporated published and optimized methods that offer multiple lines of evidence including in situ hybridization, immunohistochemistry, histopathology, condition factor indices, and nutritional profiles. Measurements of threadfin shad health and tissue condition were conducted at sites where Microcystis was present or absent during the 2007 bloom season. The results showed that dietary exposure to fish from Microcystis blooms resulted in the accumulation of microcystin in the gut and liver tissues of threadfin shad collected from the sites with blooms. Although toxicity endpoints were likely confounded by antecedent conditions, our findings demonstrate dietary exposure of Microcystis toxins to fish using a novel approach with multiple lines of evidence. Environ Toxicol Chem 2020;39:787-798. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.


Assuntos
Estuários , Peixes/metabolismo , Fígado/efeitos dos fármacos , Microcistinas/toxicidade , Microcystis/crescimento & desenvolvimento , Poluentes Químicos da Água/toxicidade , Animais , California , Proliferação Nociva de Algas , Fígado/metabolismo , Fígado/patologia , Microcistinas/análise , Microcystis/metabolismo , Poluentes Químicos da Água/análise
14.
Talanta ; 210: 120650, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31987168

RESUMO

The portable and automated fluorescence microarray biosensing platform (FMB) that employed a compact hybrid optical structure, microfluidics, and microarray biosensors was constructed for on-site parallel detection of multiple analytes. In the FMB, a hybrid optical structure that composed of a 1 × 4 single mode fiber optic coupler, four fiber optic switches, a single-multi mode fiber optic bundle coupler was at the first time developed for the transmission of the excitation light and the collection and transmission of multi-channel fluorescence signals. Through the control of fiber optic switches, the parallel fluorescence assay of four channels could be achieved using only one excitation light and one photodiode detector on the basis of the time-resolved effect. This optical design not only greatly increased the efficiency of light transmission and fluorescence collection and detection sensitivity of the FMB, but also allows the miniaturization and portability of the whole system because of few optical separation elements used and no requirement of rigorous optical alignment. Taking Microcystin-LR (MC-LR), 2,4-D, atrazine (ATZ), and bisphenol A (BPA) for example, the application potential of the FMB to rapidly and parallelly detect four typical pollutants in real water with high sensitivity and specificity was demonstrated. The limits of detection of MC-LR, 2,4-D, ATZ, and BPA were 0.04 µg/L, 0.09 µg/L, 0.02 µg/L, and 0.03 µg/L, respectively. The FMB could also achieve early-warning of pollutants thanks to its ability of rapidity, high-frequency, and multiple-analyte detection. The FMB has significant implications as a multiplexable, portable, rapid, and quantitative detection platform for pollution accidents and water quality management to satisfy the increasing demands of alerting and protecting civilians.


Assuntos
Automação , Técnicas Biossensoriais , Poluentes Químicos da Água/análise , Ácido 2,4-Diclorofenoxiacético/análise , Atrazina/análise , Compostos Benzidrílicos/análise , Técnicas Biossensoriais/instrumentação , Microcistinas/análise , Microscopia de Fluorescência/instrumentação , Fenóis/análise
15.
Sci Total Environ ; 703: 135052, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-31733495

RESUMO

Sand as a filter media is often challenged by the presence of organics in the form of natural organic matter, metal ions, and various micropollutants in the source water. It is mainly due to the presence of limited active adsorption sites and low surface area that governs an ineffective adsorption potential of the sand material. Herein, graphitized sand was synthesized to tackle the above limitations using two sugar solution sources: a) brewery effluent (as a low-cost solution) (GS1) and; b) sucrose solution (GS2). GS1 showed 68%, 60%, and 99% higher maximum adsorption constant (qmax) for divalent metal ions: iron, copper, and manganese, respectively as compared to raw sand (RS). Coating of MnO2 over the graphitized sand (GSMs: GS1M and GS2M) further helped in Microcystin-LR (MC-LR) removal (3%-9%) when inoculated with MC-LR-degraders, but was not as effective in removing metals, organic carbon and nitrogen when compared to just graphitized sand (GS1 or GS2). Inoculating GS and GSMs (for both sugar sources) not only helped in higher MC-LR removal (10%-15% more) but also enhanced the removal of other water contaminants including metals, organic nitrogen, and carbon. GS1 showed 20% and 50% more MC-LR removal than the sand material when tested at a low and high initial concentration of MC-LR (5 µg/L and 50 µg/L). The highest breakthrough period was obtained for GS1 filter using 1 mg/L Rhodamine-B dye, which was 12 times (48 min) more than the raw sand filter and almost 2.5 times (second best, 21 min) than GS1M. After three cycles of regeneration and reuse of GS1 filter, a decrease of just 14% in saturation adsorption capacity indicated its high reusability aspects.


Assuntos
Grafite/química , Compostos de Manganês/química , Microcistinas/química , Óxidos/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Microcistinas/análise , Poluentes Químicos da Água/análise
16.
Environ Pollut ; 258: 113718, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31838385

RESUMO

Problems with antibiotic resistance genes (ARGs) and secondary pollution from microcystins (MCs), caused by cyanobacterial blooms have become significant global issues. These two pollutants co-occur in drinking water treatment plants (DWTPs), but the exact relationships between them requires further clarification. Here, a high-throughput quantitative real-time PCR and enzyme-linked immunosorbent assay were used to investigate the behavior of ARGs and MCs in a practical DWTP in the first place. After the on-site investigation, the effect of MCs on the horizontal transfer of ARGs was studied under laboratory conditions, and mechanisms explored at both cellular and molecular levels. MCs could promote the spread of ARGs, especially in relatively stationary and stable environments such as biofilms. MC-LR was the most efficient microcystin subtype promoting conjugative transfer, which was 25.13 times higher than for the control group. MCs affected the horizontal transfer of ARGs by regulating a series of gene systems involved in conjugative transfer, stimulating the formation of reactive oxygen species (ROS), and increasing cell membrane permeability. This study can provide a theoretical basis for the control of ARGs and MCs in DWTPs, which is of great significance for the scientific assessment of drinking water safety.


Assuntos
Água Potável/análise , Genes Bacterianos , Microcistinas/análise , Purificação da Água , Antibacterianos , Resistência Microbiana a Medicamentos/genética , Transferência Genética Horizontal
17.
J Chromatogr A ; 1609: 460432, 2020 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-31431355

RESUMO

Microcystins (MCs) are cyclic heptapeptide toxins produced by various cyanobacterial genera that are toxic to both animals and humans. In this study, a novel strategy was proposed for the quantitation of nine MCs and Nodularin-R (NOD) in lake water using UHPLC-MS/MS under negative ionization mode, in which only centrifugation was employed during sample preparation. As a result, limits of quantification (LOQ) ranging from 0.05 to 0.1 µg/L for all studied compounds were obtained in water samples, which were lower than the results obtained using positive ionization mode. Additionally, validation was performed by spiking three different levels of MCs at 0.05 or 0.1, 0.5, 1.0 µg/L (n = 6). Recoveries ranged from 88.6% to 101.8%, and intraday and interday variability were lower than 12% and 14%, respectively, for all targeted compounds. Furthermore, the proposed method was applied to investigate microcystins contamination in fifty lake water samples collected in different regions in China. As a result, MC-LR, MC-RR, MC-YR, MC-WR, MC-LW, MC-LA, MC-LY, and MC-HilR were detected in lake water samples at trace level ranging from 0.06 to 0.37 µg/L. The obtained results indicated that it was necessary to monitor the presence of MCs in lake water, especially during regular cyanobacterial blooms during warmer months.


Assuntos
Cromatografia Líquida/métodos , Lagos/química , Microcistinas/análise , Peptídeos Cíclicos/análise , Espectrometria de Massas por Ionização por Electrospray/métodos , Espectrometria de Massas em Tandem/métodos , Poluentes Químicos da Água/análise , Animais , China , Limite de Detecção
18.
Chemosphere ; 245: 125575, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31846787

RESUMO

Photocatalysis has been shown to successfully remove microcystins (MC) in laboratory experiments. Most research to date has been performed under ideal conditions in pure or ultrapure water. In this investigation the efficiency of photocatalysis using titanium dioxide was examined in a complex matrix (waste stabilisation lagoon water). A flow-through photocatalytic reactor was used for the photocatalytic removal of four commonly occurring microcystin analogues (MC-YR, MC-RR, MC-LR, and MC-LA). Up to 51% removal for single MC analogues in waste lagoon water was observed. Similar removal rates were observed when a mixture of all four MC analogues was treated. Although treatment of MC-containing cyanobacterial cells of Microcystis aeruginosa resulted in no decline in cell numbers or viability with the current reactor design and treatment regime, the photocatalytic treatment did improve the overall quality of waste lagoon water. This study demonstrates that despite the presence of natural organic matter the microcystins could be successfully degraded in a complex environmental matrix.


Assuntos
Microcistinas/análise , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/microbiologia , Poluentes Químicos da Água/análise , Cianobactérias/metabolismo , Microcistinas/metabolismo , Microcystis/metabolismo , Titânio
19.
Artigo em Inglês | MEDLINE | ID: mdl-31766304

RESUMO

The study investigated the effects of cyanobacteria toxins such as microcystins in water sources and water stored in containers during its blooming and decaying seasons. Samples from water sources and containers near the Hartbeespoort Dam in South Africa were analysed using a microcystin ELIZA test kit. Microcystins were present in water sources used by the community, with an average of 4.3 µg/L in communal tap water and 4.8 µg/L in the water stored in tanks. The concentration of microcystins was lower in groundwater in the decaying season (0.38 µg/L) than in the blooming season (1.4 µg/L). Although microcystins were present in the storage containers, the average levels in all water samples were below the acceptable limit of 1 µg/L. The present study confirmed the presence of microcystins in the water storage containers. Therefore, it is suggested that water used for drinking from community water sources should be treated before storage to eliminate microcystins.


Assuntos
Água Potável/análise , Microcistinas/análise , Poluentes da Água/análise , Abastecimento de Água , Cianobactérias , Água Potável/microbiologia , Monitoramento Ambiental , Estações do Ano , África do Sul
20.
Environ Int ; 133(Pt B): 105194, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31675558

RESUMO

To determine distributions, bioaccumulation, and trophic transfer of freshwater cyanobacterial toxins such as microcystins (MCs), surface water, suspended solids, sediments, and coastal organisms were collected from seven stations in inner and outer regions of the estuary dam in the Geum River Estuary in June and July 2017. Concentrations of MC variants (MC-LR, -RR, and -YR) in the multimedia samples were analyzed using a HPLC-MS/MS. Trophic position (TP) of organisms (fish, bivalve, gastropod, decapod, and polychaete) was determined by nitrogen stable isotope analyses of both bulk tissues and amino acids. From July to August 2017, great concentrations of MCs were detected in discharged freshwater ranging from 0.4 to 75 µg L-1. Considerable amounts of MCs are delivered to the Geum River Estuary in summer season. MCs spread far away as dissolved phases (18.7-49.5 ng L-1) in July when large amount of freshwater was discharged during the rainy season. Concentrations of MCs in marine organisms varied among species, ranging from 40 to 870 ng g-1 dw. Bioaccumulated MCs tend to decrease with increasing TP of organisms, suggesting that MCs are biodiluted through the marine food web. Compound-specific isotope analysis (nitrogen of amino acids) provides more reliable TPs compared with those by bulk isotope analysis in a closed estuary (such as the Geum River Estuary) with large fluctuations in the isotope ratio of primary producers.


Assuntos
Geum/química , Rios/química , Aminoácidos/química , Animais , Bioacumulação , Monitoramento Ambiental , Estuários , Peixes , Cadeia Alimentar , Isótopos/análise , Microcistinas/análise , Multimídia , Chuva , República da Coreia , Alimentos Marinhos , Estações do Ano , Espectrometria de Massas em Tandem
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