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RESUMO As microcistinas (MC), que estão entre as cianotoxinas mais encontradas em florações de cianobactérias, não são eficientemente removidas pelas tecnologias do ciclo completo de tratamento de água. Como barreira adicional para sua remoção, destaca-se o processo de adsorção com carvão ativado granular (CAG). Esta pesquisa comparou a eficiência de remoção de MC-LR por sete CAG produzidos a partir de diferentes matérias-primas, analisando as propriedades das amostras: umidade, teor de cinzas, pH e características texturais. Inicialmente, os resultados indicaram que as propriedades dos CAG foram influenciadas pelo material de origem, assim como pelo método de produção. Nos ensaios de adsorção, o modelo de Langmuir indicou que, em quatro horas, com dosagem de 100 mg.L-1, o CAG de linhito (CGLIN) apresentou a maior capacidade de remoção (97,2%) de MC-LR (Co: 115,1 µg.L-1), com qe,máx de 10,6 mg.g-1. O volume de mesoporos influenciou significativamente a capacidade adsortiva de MC dos carvões avaliados (r=0,98, Pearson). Esses resultados podem oferecer subsídios para a aplicação do processo de adsorção de MC-LR em estações de tratamento de água (ETA) para a minimização de intoxicações por água contaminada.
ABSTRACT Microcystins (MC), which are among the cyanotoxins more commonly found in cyanobacterial blooms, are not efficiently removed by full-cycle water treatment technologies. As an additional barrier, there is the adsorption process with granular activated carbon (GAC). This research compared the efficiency of MC-LR removal by seven GACs produced from different raw materials, analyzing these samples' properties: moisture, ash content, pH and textural characteristics. Initially, the results indicated that the GAC properties were influenced by the source material, as well as by the production method. In the adsorption assays, the Langmuir model indicated that in 4h, with 100 mg.L-1 dosage, the granular activated carbon of lignite (CGLIN) had the highest MC-LR (Co: 115.1 µg.L-1) removal capacity (97.2%), with qe,max of 10.6 mg.g-1. The volume of mesopores significantly influenced the adsorption capacity of microcystin by the evaluated GACs (r=0.98, Pearson). These results can support the application of the MC-LR adsorption process in water treatment plants to minimize intoxication with contaminated water.
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A competitive electrochemical immunosensor based on the nano-composite material immobilization and enzymatic amplification was designed for detection of microcystin-LR. Gold nanoparticles/carboxylated multi-walled carbon nanotubes (AuNPs/c-MWCNTs) composite film, which formed by electrodepositing of AuNPs on the C-MWCNTs modified glassy carbon electrode,was used for the immobilization of the antibody of microcystin-LR (anti-MCLR). Horseradish peroxidase (HRP) was introduced onto the nanocomposite interface by HRP blocked sensing interface and specific capture of antibody with target. It could be employed to catalyze the reduction of H2O2, and to block the possible remaining active sites as well. A competitive immunoreaction between antigen and MCLR-HRP was used for target analysis. In the presence of H2O2and hydroquinone (HQ),MCLR could be indirectly detected with differential pulse voltammetry (DPV) method by determining the reduction current of HQ. Under the optimal conditions, the proposed immunosensor exhibited wide linear ranges in the concentration ranges of 0.1-100.0 μg/L, with a detection limit of 0.038 μg/L (S/N = 3,n=8). The immunosensor showed good specificity, stability and sensitivity. It was used to determine MCLR in real water samples with the recoveries of 72.9%-117.3%.
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Objective To study the protection of glutathione (GSH) on renal oxidative damage to mice which caused by mi‐crocystin‐LR(MC‐LR) .Methods Forty healthy KM mice were divided into five groups by randomly sampling ,which were saline control group ,GSH control group ,MC‐LR group ,low dose GSH +MC‐LR group and high dose GSH +MC‐LR group ,and the ex‐periment was lasting 15 days by intraperitoneal injection .Then we took out the kidney for pathological observation and detected the activity of CAT ,SOD ,GSH‐Px and the content of GSH ,MDA .Results Compared with control group ,the MC‐LR increased the content of MDA[(2 .31 ± 0 .22)nmol/mg prot ,P=0 .000] and decreased the content of GSH[(0 .68 ± 0 .02)mg/g prot] .The activi‐ty of CAT[(320 .54 ± 38 .99)nmol/mg prot] ,SOD[(180 .93 ± 15 .30)U/mg prot] ,GSH‐Px[(295 .11 ± 42 .40)U/mg prot](P<0 .05) .However ,after GSH was given ,compared with MC‐LR group ,MDA content[(1 .94 ± 0 .12)nmol/mg prot]of high dose GSH+MC‐LR group significantly decreased (P<0 .05) ,GSH content[(1 .01 ± 0 .08)mg/g prot ,(1 .08 ± 0 .16)mg/g prot]and CAT activity[(383 .46 ± 21 .98)nmol/mg prot ,(428 .50 ± 28 .61)nmol/mg prot] of both GSH groups significantly increased (P<0 .05) ,the activity of SOD[(222 .01 ± 11 .51)U/mg prot] and GSH‐Px[(358 .37 ± 20 .29)U/mg prot] of high dose GSH +MC‐LR group significantly increased (P<0 .05) .Conclusion MC‐LR may cause renal oxidative damage through promoting the lipid perox‐idation on renal cells .The GSH may reach a certain protective effect on kidney by reducing the lipid peroxidation ,improving the an‐tioxidant activity ,and removing oxygen free radicals .
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RESUMO Usualmente, o tratamento convencional de águas com altas densidades de cianobactérias e concentração de cianotoxinas não garante efluente consoante o padrão de potabilidade vigente (1,0 µg.L-1 de microcistina). Etapas adicionais fazem-se necessárias, destacando-se a adsorção por carvão ativado granular ou pulverizado. Neste contexto, o objetivo geral deste trabalho foi avaliar em escala de bancada a remoção de microcistina em água natural por adsorção em colunas de carvão ativado granular de casca de coco, após as etapas de clarificação e filtração em areia. Os resultados mostraram que o transpasse no carvão de maior granulometria ocorreu em menor tempo de contato (2 h), quando comparado ao de menor granulometria. Tais resultados abrem perspectiva de emprego em escala real por garantir efluente com concentração inferior ao que estabelece a Portaria 2914 por mais tempo e utilizando menor massa de carvão.
ABSTRACT Conventional treatment process of natural waters with high densities of cyanobacteria and cyanotoxins usually presents low efficiency according to the present drinking water standard (maximum permissible value of 1.0 µg.L-1 of microcystin). Additional steps, such as activated carbon, commonly become necessary to achieve the maximum permissible value of microcystin (1.0 µg.L-1) set up by Brazilian Drinking Water Regulation 2914. In this context, the main objective of this work was to evaluate microcystin removal from natural waters by means of two granular activated carbons after clarification and sand filtration in bench scale. The results pointed out that the breakthrough happened in activated carbon with highest grain sizes in lower contact time (2 h) , when compared with that with smaller grain sizes. These results open the perspective of an application of the activated carbon in actual scale, assuring the treated water quality in compliance with the Brazilian Drinking Water Standards Regulation 2914.
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OBJECTIVE Apolyclonalantibody-basedhomogeneouschemiluminescenceimmunoas-say was developed and optimized using AlphaLISA technology for the quantitative detection of microcys-tin-LR(MC-LR)inwatersamples.METHODS Thismethodwasbasedonacompetitivemodelin which an immune complex was formed from the ingegral binding of artificial MC-LR antigen-coated lumi-nescene beads,free MC-LR standards or sa mples,antibody and biotinylated second antibody.Next sensor bead were added that approached the i mmune co mplex through biotin-streptavidin interaction. With the exciting light,the energy was passed from the sensor luminescer before a special emission light could be observed.To opti mize the reaction conditions,working dilutions of polyclonal antibody and bioti-nylated second antibody were assayed while the effect of buffer syste ms and ti me of each reaction were evaluated.RESULTS Maininfluencingfactorsoftheassaywerediscussedasworkingdilutionsofpoly-clonal antibody and biotinylated goat anti rabbit IgG,assay buffer and reacting ti me.After opti mization of reaction conditions,MC-LR AlphaLISA could be finished in 40 min,with a sensitivity of 0.006 μg·L-1 and a dynamic range of 0.006 -5 μg·L-1 .The coefficient of variation was below 10% and average recovery was 1 07.7%.Moreover,the cross reactivity rates of MC-RR and MC-RY to MC-LR were 13.2%and0.91%,respectively.CONCLUSION Thismethodishighlysensitiveandspecific,time-saving and quite suitable for high throughput determination of MC-LR water samples.
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ObjectiveTo observe the potential effects of microcystin-LR (MC-LR) to open field behaviors and cognitive functions of rats after low-dose and 60 days exposure.Methods20 SD male rats (4 weeks old) were grouped into control ( double distilled water),0.2,1.0 and 5.0 μg/kg groups by random number table.Rats were exposed to microcystin-LR intragastrically every two days for 60 d.Open fields and Morris water maze were employed to observe the spontaneous behavior and spatial learning and memory capacity of rats.ResultsFor each group,the duration in the central area of open field were ( 8.86 ± 3.38 ) s,( 3.09 ± 1.22 ) s,( 1.68 ± 0.24) s,(1.22 ±0.93) s,frequencies in central area were (4.80 ± 1.16) times,(4.40 ± 1.91 )times,( 1.40 ±0.23)times,(3.80 ± 1.02 ) times,movement duration were ( 137.30 ± 5.25 ) s,( 122.97 ± 9.50) s,( 108.86 ± 6.38 ) s,( 129.35 ± 9.40) s,the escape latency were ( 23.17 ± 4.28 ) s,(77.00 ± 8.31 ) s,(59.00 ± 11.89) s,( 63.80 ±16.09) s,respectively.Compared to control,the duration in the central area of open field decreased and escape latency increased significantly (P ＜ 0.05 ) in all the MC-LR treated groups; and frequencies in central area and movement duration of 1.0 μg/kg treated rats decreased significantly.No significant differences were observed between expsoured group and control group in spacial probe tests(P＞0.05).ConclusionMC-LR exerts effects on the spontaneous behavior and spatial cognitive ability of rats.The further study on neurobehavior effects of MC-LR is necessary.
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Objective To know the microcystins pollution caused by cyanobactcria bloom in two drinking water sources in Ningbo city.Methods Water samples were collected at four sampling sites in Yaojiang River and three sampling sites in Miehu reservoir from 20 July,2007 to 31 August,2007.The algae in these water samples were classified and counted,and Microcystin-LR (MC-LR),MC-RR were determined by UPLC-MS-MS.Results The Cyanobacteria cell concentration in Yaojiang River and Meihu reservoir ranged from 0.8?10~6 to 6.7?10~7,and from 1.21?10~7 to 9.928?10~8 cells/L respectively.The MC-LR and MC-RR in Yaojiang River weren't detected,and neither was the MC-RR in MeiHu reservoir.However,the MC-LR was detected at sometimes,and the maximum concentration of MC-LR was 0.84?g/L.Conclusion There is no microcystins pollution in Yaojiang River,but there existed MC-LR pollution in MeiHu Reservoir,and the MC-LR concentration in it was below national standard limit of 1.0?g/L after the treatment of controlling alage and microsystins.
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Objective The aim of this paper is to know about the pollution of microcystin-LR(MC-LR)in Fenhe First reservoir and Fenhe Second reservoir in Taiyuan and provide reference for making the policy of prevention microcystin-LR pollution.Methods During the low water period(May,2005)and common period(Oct,2005),5 liter water was sampled in the entrance,the center and the exit in Fenhe First reservoir and Fenhe Second reservoir respectively.The concentrations of MC-LR in two reservoirs were determined by the high-performance liquid chromatography(HPLC).Results The average concentration (0.875 ?g/L)of MC-LR in low water period was 3 time of that(0.283 ?g/L)in common period in Fenhe First reservoir.The average concentration(0.815 ?g/L)of MC-LR in low water period was 17 time of that(0.048 ?g/L)in common period in Fenhe Second reservoir.The level of MC-LR in the entrance was the highest,that in the exit was the lowest,that in the center was middle. The concentration of MC-LR of the entrance in low water period was more than the MC-LR limit(1 ?g/L)in Life drinking water hygienic guide(2001).Conclusion MC-LR pollution has been found in Fenhe First reservoir and Fenhe Second reservoir and the pollution is serious in low water period.
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Objective To study the impact of temperature, light, nitrogen and phosphorus on growth and microcystin-LR production of Microcystis aeraginosa strain under laboratory conditions. Methods M.aeraginosa strain was cultivated in BG-11 medium. Growth was determined by counting cell, while microcystin-LR was analyzed by high-performance liquid chromatography. Results M.aeraginosa strain had a biggest growth rate at temperature of 25 ℃ and light intensity of 3 000 lx, while microcystin-LR production contents reached maximum at 20 ℃ and 5 000 lx respectively. Under the phosphorus-fixed condition, M. aeraginosa amount and mircrocystin-LR content increased by nitrogen concentration and reached the peak when the nitrogen concentration was 650.0 ?mol/L. But higher concentration of nitrogen could probably restrain the cell growth and toxin production. Under the nitrogen-fixed condition, M. aeraginosa strain grew slowly at phosphorus concentration of 1.43 ?mol/L, but had a higher growth rate when phosphorus concentration was 6.50 ?mol/L. No significant change was found with the increase of phosphorus concentration. And almost similar contents of microcystin-LR produced by M. aeraginosa were observed at different phosphorus concentrations. Positive correlations between total microcystin-LR concentrations and chlorophyll-a contents and M. aeraginosa cell densities were found. Conclusion The optimum conditions for growth and toxin production of M. aeraginosa are not the same. Phosphorus is a probable limitation nutrient factor, and a low concentration will satisfy the growth and toxin production of M. aeraginos. The N∶P atomic ratio at 100∶1 was determined as the optimum for growth and toxin production. The total microcystin-LR concentration can be forecasted by M. aeraginosa cell density or chlorophyll-a content.