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1.
Ecotoxicol Environ Saf ; 169: 516-522, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30472476

RESUMO

Mercury is one of the most harmful pollutant that threat marine biota. This study assessed the Hg impact on the fatty acid (FA) composition and the antioxidant statues in Holothuria forskali body wall tissue. Specimens were exposed to HgCl2 graded doses (40, 80 and 160 µg L-1) for 96 h. A decrease in linoleic, arachidonic and eicosapentaenoic acid levels and an increase of docosahexaenoic acid were mainly observed at the nominal tested dose. The exposure to the upper dose promoted oxidative stress with an increase of malondialdehyde, hydrogen peroxide, advanced oxidation protein product, glutathione and non-protein thiols levels. Moreover, a decrease in catalase and an increase in superoxide dismutase and glutathione peroxidase activities were observed. Yet, an increase of the metallothionein level was registered in all treated groups. This study confirmed the Hg toxicity on the redox statue of H. forskali and highlighted the usefulness of the FA composition as an early sensitive bioindicators.


Assuntos
Antioxidantes/metabolismo , Ácidos Graxos/metabolismo , Holothuria/efeitos dos fármacos , Cloreto de Mercúrio/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Biomarcadores/metabolismo , Holothuria/metabolismo , Mar Mediterrâneo , Cloreto de Mercúrio/análise , Oxirredução , Água do Mar/química , Tunísia , Poluentes Químicos da Água/análise
2.
Sci Total Environ ; 636: 580-587, 2018 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-29723830

RESUMO

Gas-to-particle phase partitioning controls the pathways for oxidized mercury deposition from the atmosphere to the Earth's surface. The propensity of oxidized mercury species to transition between these two phases is described by the partitioning coefficient (Kp). Experimental measurements of Kp values for HgCl2 in the presence of atmospheric aerosols are difficult and time-consuming. Quantum chemical calculations, therefore, offer a promising opportunity to efficiently estimate partitioning coefficients for HgCl2 on relevant aerosols. In this study, density functional theory (DFT) calculations are used to predict Kp values for HgCl2 on relevant iron-oxide surfaces. The model is first verified using a NaCl(100) surface, showing good agreement between the calculated (2.8) and experimental (29-43) dimensionless partitioning coefficients at room temperature. Then, the methodology is applied to six atmospherically relevant terminations of α-Fe2O3(0001): OH-Fe-R, (OH)3-Fe-R, (OH)3-R, O-Fe-R, Fe-O3-R, and O3-R (where R denotes bulk ordering). The OH-Fe-R termination is predicted to be the most stable under typical atmospheric conditions, and on this surface termination, a dimensionless HgCl2Kp value of 5.2 × 103 at 295 K indicates a strong preference for the particle phase. This work demonstrates DFT as a promising approach to obtain partitioning coefficients, which can lead to improved models for the transport of mercury, as well as for other atmospheric pollutant species, through and between the anthroposphere and troposphere.


Assuntos
Aerossóis/análise , Cloreto de Mercúrio/análise , Modelos Químicos , Compostos Férricos , Ferro , Óxidos
3.
J Trace Elem Med Biol ; 45: 104-113, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29173465

RESUMO

Zuotai, a famous Tibetan medicinal mixture containing ß-HgS, has been used to combine with herbal remedies for treating diseases for more than 1 300 years. The target organ for inorganic mercury toxicity is generally considered to be the kidney. Therefore, it is crucial to reveal the chemical speciation, spatial distribution and potential nephrotoxicity of mercury from Zuotai in kidney. To date, this remains poorly understood. We used X-ray absorption spectroscopy (XAS) and micro X-ray fluorescence (µ-XRF) imaging based on synchrotron radiation to study mercury chemical forms and mercury special distribution in kidney after mice were treated orally with Zuotai, ß-HgS or HgCl2. Meanwhile, the histopathology of kidney was observed. Mice exposed with Zuotai showed kidney with significant proportion of mercury ions bound to sulfydryl biomolecules (e.g. Cys-S-Hg-S-Cys) plus some of unknown species, but without methylmercury cysteine, which is the same as ß-HgS and HgCl2. The mercury is mainly deposited in renal cortex in mouse treated with Zuotai, ß-HgS or HgCl2, but with a low level of mercury in medulla. The total mercury in kidney of mice treated with HgCl2 was much higher than that of ß-HgS, and the later was higher than that of Zuotai. And, HgCl2 cause severe impairments in mouse kidney, but that was not observed in the Zuotai and ß-HgS groups. Meanwhile, the bio-metals (Ca, Zn, Fe and Cu) micro-distributions in kidney were also revealed. These findings elucidated the chemical nature, spatial distribution and toxicity difference of mercury from Zuotai, ß-HgS and HgCl2 in mouse kidney, and provide new insights into the appropriate methods for biological monitoring.


Assuntos
Rim/efeitos dos fármacos , Cloreto de Mercúrio/efeitos adversos , Compostos de Mercúrio/efeitos adversos , Animais , Cloreto de Mercúrio/análise , Compostos de Mercúrio/análise , Camundongos
4.
Aquat Toxicol ; 187: 124-131, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28411467

RESUMO

Mercury (Hg) pollution is a ubiquitous and serious concern in marine environments, but the response mechanisms of marine animals to Hg pollution (i.e., toxicity/tolerance) are poorly understood. To compare the global responses of two marine copepods (Tigriopus japonicus and Pseudodiaptomus annandalei), we analyzed whole transcriptomes using RNA-seq technology in response to Hg treatment (a nominal 10µg/L HgCl2 in seawater) for 5h. Hg was strikingly accumulated in both copepods under treatment. The Hg concentration in P. annandalei was higher under metal exposure by approximately 1.4-fold compared with treated T. japonicus. Among transcriptomic data, 101 genes in T. japonicus and 18 genes in P. annandalei were differentially regulated in response to Hg exposure. The up-regulated genes in T. japonicus were concerned with stress, growth, and development, while the down-regulated ones were mainly related to immune response. In P. annandalei, most of the differentially expressed genes were up-regulated, and all were involved in stress response. Our work indicated that Hg exhibits endocrine-disrupting potential at the transcriptomic level in marine copepods. Overall, our study demonstrates the species-specific molecular responses of these two copepods to Hg pollution.


Assuntos
Copépodes/efeitos dos fármacos , Disruptores Endócrinos/toxicidade , Cloreto de Mercúrio/toxicidade , Transcriptoma/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Copépodes/genética , Copépodes/metabolismo , Relação Dose-Resposta a Droga , Disruptores Endócrinos/análise , Disruptores Endócrinos/metabolismo , Cloreto de Mercúrio/análise , Cloreto de Mercúrio/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/genética , Água do Mar/química , Especificidade da Espécie , Regulação para Cima , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo
5.
Environ Sci Pollut Res Int ; 22(21): 16830-42, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26099598

RESUMO

We present a sensitivity analysis of a reactive transport model of mercury (Hg) fate in contaminated soil systems. The one-dimensional model, presented in Leterme et al. (2014), couples water flow in variably saturated conditions with Hg physico-chemical reactions. The sensitivity of Hg leaching and volatilisation to parameter uncertainty is examined using the elementary effect method. A test case is built using a hypothetical 1-m depth sandy soil and a 50-year time series of daily precipitation and evapotranspiration. Hg anthropogenic contamination is simulated in the topsoil by separately considering three different sources: cinnabar, non-aqueous phase liquid and aqueous mercuric chloride. The model sensitivity to a set of 13 input parameters is assessed, using three different model outputs (volatilized Hg, leached Hg, Hg still present in the contaminated soil horizon). Results show that dissolved organic matter (DOM) concentration in soil solution and the binding constant to DOM thiol groups are critical parameters, as well as parameters related to Hg sorption to humic and fulvic acids in solid organic matter. Initial Hg concentration is also identified as a sensitive parameter. The sensitivity analysis also brings out non-monotonic model behaviour for certain parameters.


Assuntos
Poluentes Atmosféricos/análise , Mercúrio/análise , Modelos Químicos , Poluentes do Solo/análise , Solo/química , Poluentes Químicos da Água/análise , Adsorção , Cloreto de Mercúrio/análise , Compostos de Mercúrio/análise , Volatilização
6.
Environ Sci Technol ; 48(18): 10681-9, 2014 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-25180562

RESUMO

Mercury (Hg) is a toxicant of global concern that accumulates in organisms as methyl Hg. The production of methyl Hg by anaerobic bacteria may be limited in anoxic sediments by the sequestration of divalent Hg [Hg(II)] into a solid phase or by the formation of elemental Hg [Hg(0)]. We tested the hypothesis that nanocrystalline mackinawite (tetragonal FeS), which is abundant in sediments where Hg is methylated, both sorbs and reduces Hg(II). Mackinawite suspensions were equilibrated with dissolved Hg(II) in batch reactors. Examination of the solid phase using Hg LIII-edge extended X-ray absorption fine structure (EXAFS) spectroscopy showed that Hg(II) was indeed reduced in FeS suspensions. Measurement of purgeable Hg using cold vapor atomic fluorescence spectrometry (CVAFS) from FeS suspensions and control solutions corroborated the production of Hg(0) that was observed spectroscopically. However, a fraction of the Hg(II) initially added to the suspensions remained in the divalent state, likely in the form of ß-HgS-like clusters associated with the FeS surface or as a mixture of ß-HgS and surface-associated species. Complexation by dissolved S(-II) in anoxic sediments hinders Hg(0) formation, but, by contrast, Hg(II)-S(-II) species are reduced in the presence of mackinawite, producing Hg(0) after only 1 h of reaction time. The results of our work support the idea that Hg(0) accounts for a significant fraction of the total Hg in wetland and estuarine sediments.


Assuntos
Poluentes Ambientais/química , Compostos Ferrosos/química , Sedimentos Geológicos/química , Cloreto de Mercúrio/química , Mercúrio/química , Nanopartículas/química , Anaerobiose , Poluentes Ambientais/análise , Cloreto de Mercúrio/análise , Mercúrio/análise , Oxirredução , Solubilidade , Soluções , Espectrometria de Fluorescência , Propriedades de Superfície , Espectroscopia por Absorção de Raios X
7.
Huan Jing Ke Xue ; 35(6): 2287-93, 2014 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-25158508

RESUMO

Luminescent bacteria have attracted more and more attention in recent years as an effective mean for biological toxicity of water environment monitoring. First of all, fluorescent protein Frex was correctly expressed in Escherichia coli, and then the effect of toxic substances on microbial metabolism in the water was monitored through the determination of the changes in the fluorescence intensity in bacteria caused by the change of NADH level in the bacteria. Then the effects of culture temperature, inducing time and the final concentration of inductor isopropyl beta-D-thiogalactopyranoside (IPTG) on the expression level and fluorescent activity of the fusion protein Frex were studied. The recombinant fluorescent bacteria was then applied in the initial detection of toxic substances in water environment. Four international standard substances of biological toxicity test including HgCl2, 3,5-dichlorophenol, potassium dichromate, and zinc sulfate heptahydrate were chosen to conduct experimental assay. The results suggested that all of these substances can cause a rapid decrease in the fluorescence of the bacteria. This test method has advantages of rapid reaction and high sensitivity. Meanwhile, the optimization of the conditions for the biological toxicity test lays foundation for subsequent application, and expands the application scope of luminescent bacteria in other aspects.


Assuntos
Escherichia coli , Proteínas Luminescentes/química , Proteínas Recombinantes de Fusão/química , Testes de Toxicidade/métodos , Poluentes Químicos da Água/análise , Bioensaio , Clorofenóis/análise , Fluorescência , Isopropiltiogalactosídeo/química , Cloreto de Mercúrio/análise , Dicromato de Potássio/análise , Temperatura , Sulfato de Zinco/análise
8.
Anal Bioanal Chem ; 406(7): 1909-16, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24442014

RESUMO

In order to reveal the time-depending mercury species uptake by human astrocytes, a novel approach for total mercury analysis is presented, which uses an accelerated sample introduction system combined on-line with an inductively coupled plasma mass spectrometer equipped with a collision/reaction cell. Human astrocyte samples were incubated with inorganic mercury (HgCl2), methylmercury chloride (MeHgCl), and thimerosal. After 1-h incubation with Hg(2+), cellular concentrations of 3 µM were obtained, whereas for organic species, concentrations of 14-18 µM could be found. After 24 h, a cellular accumulation factor of 0.3 was observed for the cells incubated with Hg(2+), whereas the organic species both showed values of about 5. Due to the obtained steady-state signals, reliable results with relative standard deviations of well below 5 % and limits of detection in the concentration range of 1 ng L(-1) were obtained using external calibration and species-unspecific isotope dilution analysis approaches. The results were further validated using atomic fluorescence spectrometry.


Assuntos
Astrócitos/metabolismo , Cloreto de Mercúrio/análise , Compostos de Metilmercúrio/análise , Espectrofotometria Atômica/métodos , Timerosal/análise , Calibragem , Técnicas de Cultura de Células , Células Cultivadas , Desenho de Equipamento , Humanos , Limite de Detecção , Cloreto de Mercúrio/metabolismo , Isótopos de Mercúrio/análise , Compostos de Metilmercúrio/metabolismo , Padrões de Referência , Reprodutibilidade dos Testes , Soluções , Espectrometria de Fluorescência , Espectrofotometria Atômica/instrumentação , Relação Estrutura-Atividade , Timerosal/metabolismo , Fatores de Tempo
9.
J Am Soc Mass Spectrom ; 25(1): 149-53, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24146306

RESUMO

Solid HgCl2 is readily detected at ambient conditions by electron capture in a HePI-MS source. The captured electron occupies the empty 6 s orbital of the Hg atom. The resulting radical-anion HgCl2 (-•) can exist as three "flexomers" of different Cl-Hg-Cl angle. The facile in-source formation of HgCl2 (-•) and the adduct [HgCl3](--) is exploited to detect other solid Hg compounds by exposing them to an external chloride source, such as HCl, NaCl, or vapors emanating from solid TiCl3. In situ oxidation of Hg2Cl2 with H2O2 generated signals for HgCl2 (-•) and [HgCl3] (-), suggesting that oxidation makes Hg 6 s orbital available for electron capture.


Assuntos
Espectrometria de Massas/métodos , Cloreto de Mercúrio/análise , Isomerismo , Cloreto de Mercúrio/química , Termodinâmica
10.
J Proteomics ; 94: 37-53, 2013 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-24012530

RESUMO

UNLABELLED: Hg discharged into the environmental waters can generally be bioaccumulated, transformed and transmited by living organisms, thus resulting in the formation of Hg-toxicity food chains. The pathway and toxicology of food chain contaminated with environmental Hg are rarely revealed by proteomics. Here, we showed that differential proteomics had the potential to understand reproduction toxicity mechanism in marine molluscs through the Hg-contaminated food chain. Hg bioaccumulation was found in every link of the HgCl2-Chlorella vulgaris-oyster-mice food chain. Morphological observations identified the lesions in both the oyster gonad and the mice ovary. Differential proteomics was used to study the mechanisms of Hg toxicity in the oyster gonad and to find some biomarkers of Hg contamination in food chain. Using 2-DE and MALDI-TOF/TOF MS, we identified 13 differential protein spots, of which six were up-regulated, six were down-regulated, while one was undecided. A portion of these differential proteins was further confirmed using real-time PCR and western blotting methods. Their major functions involved binding, protein translocation, catalysis, regulation of energy metabolism, reproductive functioning and structural molecular activity. Among these proteins, 14-3-3 protein, GTP binding protein, arginine kinase (AK) and 71kDa heat shock connate protein (HSCP 71) are considered to be suitable biomarkers of environmental Hg contamination. Furthermore, we established the gene correspondence, responding to Hg reproductive toxicity, between mouse and oyster, and then used real-time PCR to analyze mRNA differential expression of the corresponding genes in mice. The results indicated that the mechanism of Hg reproductive toxicity in mouse was similar to that in oyster. We suggest that the proteomics would be further developed in application research of food safety including toxicological mechanism. BIOLOGICAL SIGNIFICANCE: It is well known that mercury (Hg) is one of the best toxic metal elements in nature. The research reports as previously described indicated that multiple mercury compounds can directly contaminate the aquatic animals by flowing of water body and through the diffusion of air. The pollution sources of the mercury compounds in marine water were mainly found from the pathways such as steam power plant and mineral exploitation which are located on the inshore. Of note, after being released into environmental waters, mercury compounds undergo the processes of bioaccumulation, transformation and transmission in living organisms, thus resulting in the multiple forms of Hg found in Hg-toxicity food chains, and among them, methyl mercury (MeHg) showing the high toxic characteristics is the main form of Hg. The abundant reports indicated that the metal salts were easily found within the various organs of the animals, but it is difficult to judge the level of its perniciousness according to its content only in vivo. Here, the algae to have been contaminated by the mercury compounds have the ability for contaminating both the fish and shellfish as food pathway quickly. If these fish and shellfish edible as food will be taken by human, they will further affect the human health badly. However, studies about their perniciousness are rarely reported, especially in using proteomics. The oysters as normal food are largely consumed in Southern China, especially in Xiamen City. Similarly, a pathway question that the contaminated oysters can effect on the human health such as cancer is unclear or poorly understood. Here, we showed that an analytical technology such as differential proteomics has potential to understand toxicity mechanism induced by Hg-contamination through the food pathway. It is for reason that the oyster proteomics including relative analytical methods have been used to reveal the contaminant level and to determine its perniciousness using toxic algae as food. Here, we also indicated that the research here shows great significance for both analysis of food safety and toxicology of the metal compounds. In addition, a few biomarkers have shown their strong potential for monitoring the level of Hg pollution in sea in the manuscript and gene correspondence between mouse and oyster, the two contiguous links of the Hg-contaminated food chain, was further investigated to better illustrate our finding in the analysis of food chain proteomics. Moreover, similar research work is rarely reported compared to the current proteomic development, showing that a lot of novel results by proteomic methods in the manuscript have strong potential for developing the new area of food chain proteomics.


Assuntos
Crassostrea/metabolismo , Cadeia Alimentar , Gônadas/metabolismo , Cloreto de Mercúrio/análise , Proteoma/metabolismo , Proteômica , Poluentes Químicos da Água/análise , Animais , Chlorella vulgaris/química , Chlorella vulgaris/metabolismo , Crassostrea/química , Análise de Alimentos/métodos , Gônadas/química , Humanos , Cloreto de Mercúrio/metabolismo , Camundongos , Frutos do Mar/análise , Poluentes Químicos da Água/metabolismo
11.
Inorg Chem ; 52(19): 11136-45, 2013 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-24066721

RESUMO

A multisignaling Hg(II) sensor based on a benzimidazole substituted BODIPY framework was designed, which displays excellent selectively toward Hg(II) in vitro and in vivo. Optical and fluorogenic measurements in solution reveal that the sensor can detect mercury ions at submicromolar concentrations, with high specificity. The detection of Hg(II) is associated with a blue-shift in optical spectra and a simultaneous increase in the fluorescence quantum yield of the sensor, which is attributed to a decrease in charge delocalization and inhibition of photoinduced electron transfer upon binding to Hg(II). Using several spectroscopic measurements, it is shown that the binding mechanism involves two sensor molecules, where lone pairs of the benzimidazole nitrogen coordinate to a single mercury ion. The utility of this BODIPY sensor to detect Hg(II) in vivo was demonstrated by fluorescence imaging and spectroscopy of labeled human breast adenocarcinoma cells. While average emission intensity of the sensor over a large number of cells increases with incubated mercury concentrations, spatially resolved fluorescence spectroscopy performed on individual cells reveals clear spectral blue-shifts from a subensemble of sensors, corroborating the detection of Hg(II). Interestingly, the emission spectra at various submicrometer locations within cells exhibited considerable inhomogeneity in the extent of blue-shift, which demonstrates the potential of this sensor to monitor the local (effective) concentration of mercury ions within various subcellular environments.


Assuntos
Benzimidazóis/química , Compostos de Boro/química , Neoplasias da Mama/química , Cloreto de Mercúrio/análise , Compostos de Boro/síntese química , Linhagem Celular Tumoral , Feminino , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/química , Humanos , Espectroscopia de Ressonância Magnética , Imagem Óptica
12.
Anal Biochem ; 440(1): 49-55, 2013 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-23727561

RESUMO

The use of ovalbumin (OVA)-immobilized layer-by-layer-assembled chitosan/polystyrene sulfonate membranes for the detection of hydrogen peroxide (H2O2) at subpicomolar levels is reported. The detection of mercuric chloride (HgCl2) and potassium iodide (KI) was also investigated. While the detection limits of HgCl2 and KI remained in the micromolar concentration range, H2O2 could be sensed to a remarkably lower range (subpicomolar). Analysis of fluorescence quenching data of OVA by H2O2 using Stern-Volmer plots revealed a static quenching mechanism with high Stern-Volmer quenching constant (9.10×10(12) L mol(-1)) and k (5.82×10(21) L mol(-1) s(-1)). The possibility of the conformational transition of OVA in the immobilized state is discussed using steady-state and time-resolved spectroscopic techniques. The resulting increased accessibility of tryptophan residues together with the reversibility of the bilayer for the sensing of H2O2 is also illustrated.


Assuntos
Quitosana/análise , Peróxido de Hidrogênio/análise , Cloreto de Mercúrio/análise , Ovalbumina/análise , Poliestirenos/análise , Iodeto de Potássio/análise , Espectrometria de Fluorescência/métodos , Triptofano/análise , Fluorescência , Conformação Molecular
13.
Environ Sci Technol ; 47(13): 7307-16, 2013 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-23651121

RESUMO

The chemical compounds that make up gaseous oxidized mercury (GOM) in the atmosphere, and the reactions responsible for their formation, are not well understood. The limitations and uncertainties associated with the current method applied to measure these compounds, the KCl-coated denuder, are not known due to lack of calibration and testing. This study systematically compared the uptake of specific GOM compounds by KCl-coated denuders with that collected using nylon and cation exchange membranes in the laboratory and field. In addition, a new method for identifying different GOM compounds using thermal desorption is presented. Different GOM compounds (HgCl2, HgBr2, and HgO) were found to have different affinities for the denuder surface and the denuder underestimated each of these compounds. Membranes measured 1.3 to 3.7 times higher GOM than denuders in laboratory and field experiments. Cation exchange membranes had the highest collection efficiency. Thermodesorption profiles for the release of GOM compounds from the nylon membrane were different for HgO versus HgBr2 and HgCl2. Application of the new field method for collection and identification of GOM compounds demonstrated these vary as a function of location and time of year. Understanding the chemistry of GOM across space and time has important implications for those developing policy regarding this environmental contaminant.


Assuntos
Poluentes Atmosféricos/análise , Brometos/análise , Monitoramento Ambiental/instrumentação , Cloreto de Mercúrio/análise , Compostos de Mercúrio/análise , Óxidos/análise , Adsorção , Resinas de Troca de Cátion/química , Monitoramento Ambiental/métodos , Membranas Artificiais , Nylons/química , Oxirredução , Cloreto de Potássio/química
14.
Environ Toxicol Pharmacol ; 33(3): 459-64, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22407169

RESUMO

This study evaluates the toxic effects of five substances (atropine, fenitrothion, potassium cyanide, mercuric chloride and lead nitrate) on the yeast Saccharomyces cerevisiae. It describes a new biological toxicity test based on inhibition of S. cerevisiae viability and compares it with two standard toxicity tests based on Daphnia magna mobility inhibition (EN ISO 6341) and Vibrio fischeri bioluminiscence inhibition (EN ISO 11348-2). The new biological test -S. cerevisiae lethal test - is cheaper and 24 times faster than the D. magna test. The test speed is comparable with the V. fischeri test but the new test is more sensitive for some substances. The test indicates reliably the presence of all used toxicants in water in concentrations which are significantly lower than the concentration in toxic or lethal doses for man. Therefore, this new toxicity test could be proposed for rapid detection of toxic substances in water.


Assuntos
Monitoramento Ambiental/métodos , Saccharomyces cerevisiae/efeitos dos fármacos , Testes de Toxicidade/métodos , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Atropina/análise , Atropina/toxicidade , Fenitrotion/análise , Fenitrotion/toxicidade , Substâncias Perigosas/análise , Substâncias Perigosas/toxicidade , Chumbo/análise , Chumbo/toxicidade , Cloreto de Mercúrio/análise , Cloreto de Mercúrio/toxicidade , Azul de Metileno/metabolismo , Nitratos/análise , Nitratos/toxicidade , Cianeto de Potássio/análise , Cianeto de Potássio/toxicidade , Saccharomyces cerevisiae/metabolismo
15.
Inorg Chem ; 49(24): 11485-92, 2010 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-21077658

RESUMO

A newly synthesized 1,4,8,11-tetraazacyclotetradecane derivative (L), functionalized with a diazo moiety as the reporter functionality, is found to bind specifically to Hg(2+) with an associated change in color that could be visually detected. With biologically benign ß-CD, it forms an inclusion complex (L·2ß-CD), which shows a much higher solubility in water, and this helps in developing a more intense color on binding to Hg(2+) in a CH(3)CN-HEPES buffer medium. The nontoxic nature of L was checked with the living cells of a Gram negative bacterium, Pseudomonas putida . Further, experiments revealed that these two reagents could be used as staining agents for the detection of Hg(2+) present in this microorganism.


Assuntos
Compostos Heterocíclicos/química , Cloreto de Mercúrio/análise , Compostos Azo/química , Compostos Heterocíclicos/farmacologia , Espectroscopia de Ressonância Magnética , Pseudomonas putida/efeitos dos fármacos , Espectrometria de Massas por Ionização por Electrospray , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , beta-Ciclodextrinas/química
16.
Sci Total Environ ; 408(2): 286-93, 2009 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-19846208

RESUMO

Two detoxification mechanisms working in the marine diatom Thalassiosira weissflogii to cope with mercury toxicity were investigated. Initially, the effect of mercury on the intracellular pool of non-protein thiols was studied in exponentially growing cultures exposed to sub-toxic HgCl(2) concentrations. T. weissflogii cells responded by synthesizing metal-binding peptides, named phytochelatins (PCs), besides increasing the intracellular pool of glutathione and gamma-glutamylcysteine (gamma-EC). Intracellular Hg and PC concentrations increased with the Hg concentration in the culture medium, exhibiting a distinct dose-response relationship. However, considerations of the PCs-SH:Hg molar ratio suggest that glutathione could also be involved in the intracellular mercury sequestration. The time course of the non-protein thiol pool and Hg intracellular concentration shows that PCs, glutathione and gamma-EC represent a rapid cellular response to mercury, although their role in Hg detoxification seems to lose importance at longer incubation times. The occurrence of a process of reduction of Hg(II) to Hg degrees and subsequent production of dissolved gaseous mercury (DGM) was also investigated at lower Hg concentrations, at which the PC synthesis doesn't seem to be involved. The significant (P<0.01) correlation between the cellular density in solution and the production of DGM suggests that this diatom is capable of directly producing DGM, both in light and dark conditions. This finding has been confirmed by the absence of DGM production in the culture media containing formaldehyde-killed cells. Finally, the relationship between these two different pathways of Hg detoxification is discussed.


Assuntos
Diatomáceas/metabolismo , Cloreto de Mercúrio/farmacocinética , Compostos de Sulfidrila/metabolismo , Poluentes Químicos da Água/farmacocinética , Animais , Dipeptídeos/metabolismo , Relação Dose-Resposta a Droga , Glutationa/metabolismo , Cloreto de Mercúrio/análise , Cloreto de Mercúrio/toxicidade , Oxirredução , Fitoquelatinas/metabolismo , Água do Mar , Espectrofotometria Atômica , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
17.
Int J Dev Neurosci ; 27(5): 459-68, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19446626

RESUMO

This study examined the effects of inorganic mercury exposure on behavioral and biochemical parameters and investigated the possible preventive effects of zinc on the alterations induced by mercury. Pups were exposed from 3rd to 7th postnatal day to ZnCl2 (27 mg/kg/day, s.c.) and subsequently to HgCl2 (5 doses of 5 mg/kg/day, s.c.). Each litter contained two rats for each treatment. The rats were submitted to behavioral task and litters were killed at 13 or 33 days old for acetylcholinesterase activity assays and for the determination of metal levels. Based on the results obtained from 13-day-old rats, they were divided in two groups of litters that were defined at the end of the experimental period (33 days) as less sensitive rats to mercury and more sensitive rats to mercury in accordance with the recovery of body weight until day 33. The mercury exposure caused accumulation of this metal in cerebrum and cerebellum in all mercury treated rats, and inhibited the cerebellum acetylcholinesterase activity from 13-day-old rats. Besides, the mercury-animals of the most sensitive litters to mercury presented impairment in motor function and muscular strength verified in the beaker test, as well as a reduction of the locomotor and exploratory activities in the open field task. Zinc partially prevented all the alterations induced by mercury exposure and reduced the mercury level accumulated in cerebrum and cerebellum. This study confirms the preventive effect of zinc on behavioral alterations induced by mercury in young rats and demonstrates that the mercury behavioral effects are present even for a long time after the end of the exposure.


Assuntos
Acetilcolinesterase/metabolismo , Cloretos/uso terapêutico , Cloreto de Mercúrio/envenenamento , Intoxicação do Sistema Nervoso por Mercúrio/prevenção & controle , Atividade Motora/efeitos dos fármacos , Compostos de Zinco/uso terapêutico , Animais , Animais Recém-Nascidos , Peso Corporal/efeitos dos fármacos , Cerebelo/química , Cerebelo/efeitos dos fármacos , Cerebelo/enzimologia , Cérebro/química , Cérebro/efeitos dos fármacos , Cérebro/enzimologia , Cloreto de Mercúrio/análise , Intoxicação do Sistema Nervoso por Mercúrio/patologia , Intoxicação do Sistema Nervoso por Mercúrio/fisiopatologia , Ratos , Ratos Wistar
18.
Sci Total Environ ; 407(3): 1211-7, 2009 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-18817946

RESUMO

Mercury [Hg] emissions from old plant collections treated with mercuric chloride (HgCl(2)) may present a high health risk for staff working in certain herbaria. The present study evaluated Hg concentrations in ambient air, plant specimens and biological samples from staff working in the Pretoria National Herbarium (PRE) and the H.G.W.J. Schweickerdt Herbarium (PRU), University of Pretoria. Biological samples from a group of 15 people exposed to HgCl(2) in herbaria and a non-exposed control group of five people were studied. Additionally, plant samples from herbarium specimens treated and non-treated with HgCl(2) were analysed. Plant materials treated with HgCl(2) had persistent high concentrations of Hg in the range of 114-432 microg g(-1), whereas untreated materials were in the range of 0.20-0.45 microg g(-1). The HgCl(2)-treated plant specimens induced elevated concentrations of Hg into the herbarium rooms near storage cabinets, where up to 1 microg m(-3) of Hg was measured in the air of both herbaria. However, no significant difference in mean Hg concentrations in hair was found between herbarium workers and members of the control group, 0.46 and 0.64 microg g(-1) respectively (p0.05, Student's t-test). For both groups, Hg concentrations were lower than that indicated by the World Health Organization [WHO] for non-exposed adults, namely 2 microg g(-1). The mean concentration of total Hg in urine from the mercury-exposed herbarium group, 2.28 microg g(-1) creatinine, was significantly higher than in the control group, 1.05 microg g(-1) of creatinine. For both populations, the concentrations of Hg in their urine were below the threshold Hg values set by the WHO, i.e., 5 microg g(-1) creatinine. We concluded that there was no strong response by individual herbarium staff from long-term exposure to Hg concentrations in the range of 0.28-1.1 microg m(-3).


Assuntos
Poluentes Ocupacionais do Ar/análise , Cloreto de Mercúrio/análise , Mercúrio/análise , Desenvolvimento Vegetal , Monitoramento Ambiental/métodos , Humanos , Monitorização Fisiológica , Museus , Exposição Ocupacional/análise , Segurança , África do Sul
19.
J Hazard Mater ; 157(1): 146-53, 2008 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-18289781

RESUMO

This paper investigated the effectiveness of (ground granulated blast furnace slag) GGBFS-added chemically bonded phosphate ceramic (CBPC) matrix on the stabilization/solidification (S/S) of mercury chloride and simulated mercury-bearing light bulbs (SMLB). The results showed that the maximal compressive strength was achieved when 15% and 10% ground GGBFS was added for HgCl(2)-doped and SMLB-doped CBPC matrices, respectively. The S/S performances of GGBFS-added matrices were significantly better than non-additive matrices. As pore size was reduced, the leaching concentration of Hg(2+) from GGBFS-added CBPC matrix could be reduced from 697 microg/L to about 3 microg/L when treating HgCl(2). Meanwhile, the main hydrating product of GGBFS-added matrices was still MgKPO(4).6H(2)O. The improvement of S/S effectiveness was mainly due to physical filling of fine GGBFS particles and microencapsulation of chemical cementing gel.


Assuntos
Cerâmica/química , Resíduos Perigosos/análise , Cloreto de Mercúrio/análise , Modelos Químicos , Fosfatos/química , Eliminação de Resíduos/métodos , Tamanho da Partícula , Propriedades de Superfície , Difração de Raios X
20.
Water Res ; 42(1-2): 91-100, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17675134

RESUMO

Since the 19th century, mercury(II)chloride (HgCl(2)) has been used on wood impregnation sites to prevent wooden poles from decay, leaving behind a legacy of highly contaminated soil/aquifer systems. Little is known about species transformation and mobility of HgCl(2) in contaminated soils and groundwater. At such a site the behaviour of HgCl(2) in soils and groundwater was investigated to assist in risk assessment and remediation. The soil is low in organic carbon and contains up to 11,000 mg Hg/kg. Mercury (Hg) concentrations in groundwater decrease from 230 to 0.5 microg/l within a distance of 1.3 km. Hg species transformations in soil and aqueous samples were analysed by means of solid-phase Hg pyrolysis and CV-AAS. In aqueous samples, Hg species were distinguished between ionic/reactive Hg and complex-bound Hg. Potential mobility of Hg in soils was studied through batch experiments. Most Hg in the soil is matrix-bound HgCl(2), whereas in the aquifer secondary formation to Hg(0) could be observed. Aqueous Hg speciation in groundwater and soil solutions shows that an average of 84% of soluble Hg exists as easily reducible, inorganic Hg species (mostly HgCl(2)). The proportion of complex-bound Hg increases with distance due to the transformation of inorganic HgCl(2). The frequent occurrence of Hg(0) in the aquifer suggests the formation and degassing of Hg(0), which is, in addition to dilution, an important process, lowering Hg concentrations in the groundwater. High percentage of mobile Hg (3-26%) and low seepage fluxes will result in continuous Hg release over centuries requiring long-term groundwater remediation. Results of soluble Hg speciation suggest that filtering materials should be adapted to ionic Hg species, e.g. specific resins or amalgamating metal alloys.


Assuntos
Cloreto de Mercúrio/análise , Mercúrio/análise , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Abastecimento de Água/análise , Monitoramento Ambiental , Alemanha , Cloreto de Mercúrio/química , Mercúrio/química , Medição de Risco , Poluentes do Solo/química , Gerenciamento de Resíduos , Poluentes Químicos da Água/química
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