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1.
PLoS One ; 15(9): e0238469, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32877469

RESUMO

The spatial arrangement and pore size distribution play an important role in accumulation and protection of exogenous organic matter (EOM) in the soil, but how different organic materials contribute to modify pore structure is poorly understood. We aimed at exploring possible changes in the complexity of the soil phase during fertilization with different doses of digestate and sludges sourced from the agro-food industry. For this purpose, the short-term effects-one year, of soil fertilization, were investigated in several sampling periods and within two depths (0-25 cm and 25-40 cm). Changes in the specific surface area (SSA), total pore volume (VMIP), total pore area (SMIP), average pore radius (RMIP) and pore size distribution (PSD) were monitored using N2 adsorption/desorption (NAD) and mercury porosimetry (MIP) methods. Our results showed that the intensity of observed changes depended on the type and dose of organic material, soil depth and sampling date. Accumulation of EOM increased with soil depth, masking a large proportion of SSA. Deeper soil layer was more susceptible to changes in the pore size distributions due to the formation of new elongated pores. We concluded that this specific structural porosity was related to the decomposition of organic matter during the formation of soil aggregates.


Assuntos
Agricultura/métodos , Fertilizantes/análise , Solo/química , Adsorção , Indústria Alimentícia , Mercúrio/química , Nitrogênio/química , Porosidade , Esgotos/química
2.
Ecotoxicol Environ Saf ; 204: 111097, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32784016

RESUMO

Iron (hydr)oxide-natural organic matter (NOM) colloids, the dominant components of soil, usually occur in varied circumstances and may affect Hg transport and fate in soil. This study aims to reveal the Hg binding to preformed composites rather than only focusing on Hg retention by iron (hydr)oxides in the presence of NOM. Ferrihydrite-humic acid (FH-HA) is chosen as a representative composite, and the effect of the complexation method and FH morphology on Hg binding to various composites is evaluated. Three types of composites are developed: a dense coprecipitated composite (p-d-f), a gel-like adsorbed composite (a-g-f) and a dense adsorbed (a-d-f) composite. Batch sorption and stirred-flow kinetic tests together with surface property analysis and modern spectral analyses are carried out to explore the binding behavior of Hg to the three composites and clarify the interactions in the ternary systems of FH-HA-Hg. The results show that the Hg sorption isotherms all fit well with the Langmuir model, and the maximum sorption capacities follow the order a-g-f> a-d-f > p-d-f, implying that the adsorbed composite is more favorable than the coprecipitated composite for Hg binding and a gel morphology is more beneficial than a dense morphology. The stirred-flow experiments show that the adsorbed composite has a small advantage in Hg sorption compared to the coprecipitated composite and that the gel-like composite can adsorb more Hg at a faster rate than the dense composite. Both FH and HA participate in Hg sorption, and FH-HA-Hg complexes are speculated to form. These findings are helpful to better understand the mobility and fate of Hg in soils, as well as the associated dynamic model for predicting Hg behavior in the environment where the iron (hydr) oxide-NOM composites are pre-existed.


Assuntos
Mercúrio/química , Adsorção , Coloides , Compostos Férricos/química , Substâncias Húmicas/análise , Ferro/análise , Cinética , Mercúrio/análise , Compostos Orgânicos/química , Óxidos/química , Solo/química , Propriedades de Superfície
3.
Chemosphere ; 258: 127330, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32540538

RESUMO

A novel method to assess the uncertainty of measurement of mercury in precipitation for the UK's Heavy Metals Monitoring Network is presented. The method makes use of the fact that, because of the high risk of sample contamination, samples are taken in duplicate in order to ensure valid data is available for as many sampling periods as possible. Where both samples are valid a good opportunity is afforded to use the statistical differences in the rain volumes sampled and the mercury concentrations measured to assess the overall uncertainty of the measurement. This process has produced estimated uncertainties in good agreement with previous studies and well within the limits specified by European legislation. The work also highlighted an effective method to spot outliers in the paired samples at the data ratification stage.


Assuntos
Monitoramento Ambiental/métodos , Mercúrio/química , Mercúrio/análise , Metais Pesados/análise , Chuva , Incerteza , Reino Unido
4.
Appl Environ Microbiol ; 86(15)2020 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-32414793

RESUMO

Geothermal systems emit substantial amounts of aqueous, gaseous, and methylated mercury, but little is known about microbial influences on mercury speciation. Here, we report results from genome-resolved metagenomics and mercury speciation analysis of acidic warm springs in the Ngawha Geothermal Field (<55°C, pH <4.5), Northland Region, Aotearoa New Zealand. Our aim was to identify the microorganisms genetically equipped for mercury methylation, demethylation, or Hg(II) reduction to volatile Hg(0) in these springs. Dissolved total and methylated mercury concentrations in two adjacent springs with different mercury speciation ranked among the highest reported from natural sources (250 to 16,000 ng liter-1 and 0.5 to 13.9 ng liter-1, respectively). Total solid mercury concentrations in spring sediments ranged from 1,274 to 7,000 µg g-1 In the context of such ultrahigh mercury levels, the geothermal microbiome was unexpectedly diverse and dominated by acidophilic and mesophilic sulfur- and iron-cycling bacteria, mercury- and arsenic-resistant bacteria, and thermophilic and acidophilic archaea. By integrating microbiome structure and metagenomic potential with geochemical constraints, we constructed a conceptual model for biogeochemical mercury cycling in geothermal springs. The model includes abiotic and biotic controls on mercury speciation and illustrates how geothermal mercury cycling may couple to microbial community dynamics and sulfur and iron biogeochemistry.IMPORTANCE Little is currently known about biogeochemical mercury cycling in geothermal systems. The manuscript presents a new conceptual model, supported by genome-resolved metagenomic analysis and detailed geochemical measurements. The model illustrates environmental factors that influence mercury cycling in acidic springs, including transitions between solid (mineral) and aqueous phases of mercury, as well as the interconnections among mercury, sulfur, and iron cycles. This work provides a framework for studying natural geothermal mercury emissions globally. Specifically, our findings have implications for mercury speciation in wastewaters from geothermal power plants and the potential environmental impacts of microbially and abiotically formed mercury species, particularly where they are mobilized in spring waters that mix with surface or groundwaters. Furthermore, in the context of thermophilic origins for microbial mercury volatilization, this report yields new insights into how such processes may have evolved alongside microbial mercury methylation/demethylation and the environmental constraints imposed by the geochemistry and mineralogy of geothermal systems.


Assuntos
Archaea/metabolismo , Bactérias/metabolismo , Fontes Termais/microbiologia , Mercúrio/química , Metagenoma , Archaea/genética , Bactérias/genética , Mercúrio/metabolismo , Metagenômica , Nova Zelândia
5.
Acta Crystallogr C Struct Chem ; 76(Pt 5): 476-482, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32367829

RESUMO

Reaction of N,N'-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide), C20H18F2N4O2, (LF), with zinc chloride and mercury(II) chloride produced different types and shapes of neutral coordination complexes, namely, dichlorido[N,N'-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide)-κ2N,O]zinc(II), [ZnCl2(C20H18F2N4O2)], (1), and dichlorido[N,N'-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide)-κ4O,N,N',O']mercury(II), [HgCl2(C20H18F2N4O2)], (2). The organic ligand and its metal complexes are characterized using various techniques: IR, UV-Vis and nuclear magnetic resonance (NMR) spectroscopies, in addition to powder X-ray diffraction (PXRD), single-crystal X-ray crystallography and microelemental analysis. Depending upon the data from these analyses and measurements, a typical tetrahedral geometry was confirmed for zinc complex (1), in which the ZnII atom is located outside the bis(benzhydrazone) core. The HgII atom in (2) is found within the core and has a common octahedral structure. The in vitro antibacterial activities of the prepared compounds were evaluated against two different bacterial strains, i.e. gram positive Bacillus subtilis and gram negative Pseudomonas aeruginosa bacteria. The prepared compounds exhibited differentiated growth-inhibitory activities against these two bacterial strains based on the difference in their lipophilic nature and structural features.


Assuntos
Antibacterianos/síntese química , Antibacterianos/farmacologia , Cloretos/farmacologia , Mercúrio/química , Compostos de Zinco/farmacologia , Zinco/química , Antibacterianos/química , Cloretos/química , Complexos de Coordenação/química , Cristalografia por Raios X , Difração de Raios X , Compostos de Zinco/química
6.
Chemosphere ; 253: 126634, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32278908

RESUMO

Reduction of mercury (Hg) in natural waters, which releases a substantial amount of gaseous Hg(0) to the atmosphere, has a close relationship to Hg/DOC ratios. However, the role of Hg/DOC ratio on the Hg(II) reduction in natural waters remains poorly understood. In this study, natural water collected from Hongfeng Lake, SW China, was used to study the effects of Hg/DOC ratio on the Hg(II) reduction. The lake water was spiked with variable amounts of Hg to make different Hg/DOC solutions. Through a 72 h Hg(II) reduction process, we demonstrated that the maximum percentage reduction of Hg (29 ± 3%) occurred when Hg/DOC ratio was 1134 ng mg-1. Further increase or decrease of the Hg/DOC ratios would inhibit the reduction of Hg(II). This study clearly demonstrated that Hg/DOC ratio has a dual role in the reduction of Hg(II) from natural waters.


Assuntos
Monitoramento Ambiental , Mercúrio/química , Poluentes Químicos da Água/química , China , Gases , Lagos , Mercúrio/análise , Poluentes Químicos da Água/análise
7.
Chemosphere ; 250: 126606, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32234628

RESUMO

A cost-effective artificial humic substances (humic acid-modified biochar, HA-BCs) is fabricated by using conventional hydrothermal-assisted pyrolysis technique, and then is considered as a promising adsorbent material for removing mercury ions from aqueous solution. Artificial humic acid (A-HA), humic acid-modified biochar (HA-BCs) are analyzed by using SEM, EA, XRD, FTIR, XPS, and BET techniques. The removal efficiency of mercury ions was greater than 95% after reaching the adsorption equilibrium. Meanwhile, the adsorption kinetics coincided with the pseudo-second-order model and the isotherms for mercury ion sorption can be best interpreted using Freundlich isotherm model, with high regression coefficients (R2 = 0.967-0.990). Furthermore, the surface properties of HA-BCs before and after mercury adsorption are compared and evaluated, realizing that the mechanisms of removal of mercury ions on HA-BCs mainly include surface complexation with oxygen/nitrogen functional groups (-OH, -COOH and -NH2) and formation of precipitation with CO32- and OH-. Furthermore, the used HA-BCs can be regenerated via 0.05 mol/L KI solution and the adsorption capacity of mercury still reaches at 32.57 mg/g after four cyclic utilization.


Assuntos
Substâncias Húmicas/análise , Mercúrio/química , Poluentes Químicos da Água/química , Adsorção , Carvão Vegetal , Concentração de Íons de Hidrogênio , Íons , Cinética , Mercúrio/análise , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Água , Poluentes Químicos da Água/análise , Purificação da Água/métodos
8.
Food Chem ; 320: 126624, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32208181

RESUMO

A ratiometric fluorescence (FL) sensor was fabricated by coordinating 2, 6-pyridinedicarboxylic acid (DPA) sensitized Tb3+ (Tb-DPA) with NH2 and COOH on the surface of the N-doped carbon dots (N-CDs) for detecting Hg2+ in seafood. The sensor exhibited two FL emissions at 436 nm (N-CDs) as the response signal and at 543 nm (Tb-DPA) as the reference signal when excited at 290 nm. After adding Hg2+, the FL emission at 436 nm was significantly quenched and the FL emission at 543 nm was negligibly changed. The electron transfer (ET) between COO- of N-CDs and Hg2+ led to the FL quenching of N-CDs. The FL ratio (F436/F543) exhibited a good linear relationship in the Hg2+ concentrations of 1161.51 µM with a low limit of detection (LOD) of ~37 nM. The sensor presented high selectivity, satisfactory accuracy and precision toward Hg2+ in seafood with recoveries of 86.45-114.47% and RSDs of 0.20-1.92%.


Assuntos
Carbono/química , Análise de Alimentos , Mercúrio/análise , Alimentos Marinhos/análise , Térbio/química , Fluorescência , Limite de Detecção , Mercúrio/química , Pontos Quânticos , Espectrometria de Fluorescência
9.
Talanta ; 212: 120756, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32113534

RESUMO

The intensive use of pesticides in agricultural practices has promoted the appearance of environmental and public health problems. So, there has been a sharp increase in the development of simple, fast, sensitive, selective, and low-cost methods to analyse pesticides. Among them, electroanalytical methods have been frequently employed; however, the performance of these methods is strongly influenced by the working electrode material and so an adequate choice is critical to success of the analysis. Solid amalgam-based electrodes have been widely used; this review critically discusses the evolution of the preparation and use of these electrodes and their application in analysis of pesticides from different chemical classes, indicating challenges and trends in pesticide electroanalysis. The relationship between pesticides' chemical structures and electrochemical behaviour on a mercury-based electrode is explored in order to indicate the use of electroanalysis in pesticide determination.


Assuntos
Técnicas Eletroquímicas/métodos , Técnicas Eletroquímicas/tendências , Contaminação de Alimentos/análise , Água Doce/análise , Resíduos de Praguicidas/análise , Ligas/química , Técnicas Eletroquímicas/instrumentação , Eletrodos , Mercúrio/química
10.
Environ Res ; 182: 109092, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32069770

RESUMO

Four cruises were performed in the Bohai Sea (BS) and Yellow Sea (YS) to ascertain the levels and distributions of gaseous elemental mercury (GEM), dissolved gaseous mercury (DGM), methylmercury (MeHg), and total mercury (THg) during 2012 and 2014. Their concentrations and Hg0 flux exhibited clear spatial-temporal distributions. The GEM level over the BS in spring (2.71 ± 0.49 ng m-3) was significantly higher than that in fall (1.98 ± 0.91 ng m-3). Air masses with elevated GEM mainly originated from northern China. During the two cruises in 2012 over the BS, the mean DGM concentration in spring (35.7 ± 4.6 pg l-1) was comparable to that in fall (32.4 ± 4.6 pg l-1). During the spring cruise of 2014, the mean DGM concentration in the BS (52.8 ± 12.5 pg l-1) was comparable to that in the YS (52.4 ± 14.1 pg l-1), while during the fall cruise of 2014, it was significantly lower in the BS (26.7 ± 14.4 pg l-1) than in the YS (57.2 ± 17.9 pg l-1). DGM represents a small portion of unfiltered THg in the BS (3.95%) and YS (5.12%). The MeHg and MeHg% values were higher in nearshore areas than in open sea, indicating higher productivity in coastal regions. The Hg0 flux in the YS (4.56 ng m-2 h-1) was about twice that in the BS. The annual emission Hg0 fluxes from the BS and YS were 2.71 and 23.68 tons yr-1, respectively.


Assuntos
Mercúrio , Poluentes Químicos da Água , China , Monitoramento Ambiental , Gases , Mercúrio/química , Oceanos e Mares , Água do Mar , Poluentes Químicos da Água/química
11.
Chemosphere ; 249: 126164, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32065997

RESUMO

This study attempted to investigate the effect of impregnation sequence of the Pd/Ce/γ-Al2O3 sorbents on Hg0 removal. To this end, five kinds of sorbents were prepared and tested in simulated coal derived fuel gas (N2-H2-CO-H2S-Hg), including Pd/γ-Al2O3, Ce/γ-Al2O3 and three kinds of Pd-based sorbents with Ce impregnation on γ-Al2O3 substrate. The tests were conducted at 250 and 300 °C respectively. According to the results, bimetallic Ce-Pd/γ-Al2O3 sorbent prepared by simultaneously impregnating Pd and Ce showed much higher and more stable removal efficiency of Hg0 than the other three kinds of sorbents. The Hg0 removal efficiency of Ce-Pd/γ-Al2O3 sorbent reached above 98% within 480 min at 250 °C and 91% within 200 min at 300 °C. Characterization results indicated that the sorbent Ce-Pd/γ-Al2O3 prepared by the co-impregnation method had bigger specific surface area (216.6 m2/g) than the other three kinds of Pd-based sorbents. The content Pd and Ce on the sorbent Ce-Pd/γ-Al2O3 surface is 0.21% and 0.61%, which proved higher than that of the other three kinds of Pd-based sorbents, and observation from STEM-XEDS maps showed it demonstrated the highest dispersion. It is found that Ce is likely to promote the dispersion of Pd on the support surface during the preparation of the sorbent under the co-impregnation method. Meanwhile, Ce enhanced the H2S resistance of the sorbent. Thereby, Ce-Pd/γ-Al2O3 sorbent is found to have the optimal performance of mercury removal. In this study, the Hg0 removal mechanism of the Pd/Ce/γ-Al2O3 sorbents in the simulated coal derived fuel gas was also elaborated.


Assuntos
Poluentes Atmosféricos/química , Carvão Mineral/análise , Combustíveis Fósseis/análise , Mercúrio/química , Adsorção , Gases/química , Mercúrio/análise
12.
Mikrochim Acta ; 187(3): 185, 2020 02 22.
Artigo em Inglês | MEDLINE | ID: mdl-32088766

RESUMO

A highly stable copper nanoclusters (CuNC) carrying 4-chlorothiophenol as a protective ligand is described. They display self-assembly-induced emission with excitation/emission maxima at 330/605 nm even in neutral or alkaline aqueous environment. The fluorescence of these CuNC is quenched by Hg(II). Quenching is mainly ascribed to the formation of a complex formed via Hg-S bonding between the Hg(II) ions and the ligand. This destroys the ordered architectures of the assembled CuNC. The assay enables Hg(II) to be determined with good sensitivity and a linear response ranging from 1 to 500 nM Hg(II) with a 0.3 nM limit of detection. In addition, the method was implemented in a test strip (which undergoes a color change from red to blue) that can be used for visual determination of Hg(II) in complex environmental water samples. Graphical abstractNovel and highly selective fluorimetric and colorimetric methods have been designed for mercury(II) ions determination based on stable self-assembly-induced emission of copper nanoclusters.


Assuntos
Colorimetria/métodos , Cobre/química , Fluorometria/métodos , Mercúrio/química , Nanopartículas Metálicas/química , Humanos
13.
J Biol Chem ; 295(10): 3202-3212, 2020 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-31988242

RESUMO

In response to microbial invasion, the animal immune system generates hypochlorous acid (HOCl) that kills microorganisms in the oxidative burst. HOCl toxicity is amplified in the phagosome through import of the copper cation (Cu2+). In Escherichia coli and Salmonella, the transcriptional regulator RclR senses HOCl stress and induces expression of the RclA, -B, and -C proteins involved in bacterial defenses against oxidative stress. However, the structures and biochemical roles of the Rcl proteins remain to be elucidated. In this study, we first examined the role of the flavoprotein disulfide reductase (FDR) RclA in the survival of Salmonella in macrophage phagosomes, finding that RclA promotes Salmonella survival in macrophage vacuoles containing sublethal HOCl levels. To clarify the molecular mechanism, we determined the crystal structure of RclA from E. coli at 2.9 Å resolution. This analysis revealed that the structure of homodimeric RclA is similar to those of typical FDRs, exhibiting two conserved cysteine residues near the flavin ring of the cofactor flavin adenine dinucleotide (FAD). Of note, we observed that Cu2+ accelerated RclA-mediated oxidation of NADH, leading to a lowering of oxygen levels in vitro Compared with the RclA WT enzyme, substitution of the conserved cysteine residues lowered the specificity to Cu2+ or substantially increased the production of superoxide anion in the absence of Cu2+ We conclude that RclA-mediated lowering of oxygen levels could contribute to the inhibition of oxidative bursts in phagosomes. Our study sheds light on the molecular basis for how bacteria can survive HOCl stress in macrophages.


Assuntos
Proteínas de Escherichia coli/metabolismo , Escherichia coli/metabolismo , Flavoproteínas/metabolismo , Ácido Hipocloroso/farmacologia , Motivos de Aminoácidos , Sítios de Ligação , Domínio Catalítico , Cobre/química , Cristalografia por Raios X , Dimerização , Escherichia coli/efeitos dos fármacos , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Flavoproteínas/química , Flavoproteínas/genética , Cinética , Macrófagos/imunologia , Macrófagos/metabolismo , Macrófagos/microbiologia , Mercúrio/química , Mutagênese Sítio-Dirigida , NAD/química , Oxirredução , Estrutura Terciária de Proteína , Salmonella/efeitos dos fármacos , Salmonella/metabolismo , Alinhamento de Sequência , Superóxidos/metabolismo
14.
Environ Sci Pollut Res Int ; 27(8): 8596-8610, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31907806

RESUMO

Zooplankton play an important role in the transfer of mercury (Hg) from the lower to upper trophic positions in the food chain. In this study, total mercury (THg) and methylmercury (MeHg) levels were measured in three size fractions of zooplankton collected from three reservoirs (Hongfeng, Baihua, and Aha Reservoir) and one wetland in karst areas to understand mercury accumulation in zooplankton from alkaline environments. The results showed that the alkaline waters had lower zooplankton MeHg levels (0.1 to 66.8 ng g-1) than most of the acidic waters reported. However, the zooplankton THg levels (6.3 to 494.9 ng g-1) were comparable. The macro-zooplankton (> 500 µm) had significantly higher THg and MeHg levels than meso-zooplankton (116 to 500 µm) in the three reservoirs at all seasons, which showed biomagnification of mercury in the food chain. The correlation between Hg in water and zooplankton and Hg in zooplankton of different sizes indicated that THg bioaccumulation in zooplankton was related to the THg levels in water; however, MeHg bioaccumulation in zooplankton was controlled by many other factors, such as their feeding and living habits. In the three reservoirs, the THg and MeHg concentrations in zooplankton decreased with increasing eutrophication. However, compared with the three reservoirs, Caohai Wetland, with large amounts of aquatic plants, had a much lower trophic level and higher MeHg content in water but much lower zooplankton MeHg levels and bioaccumulation factors (BAFs). The large amounts of plant residue might dilute mercury in the food chain, revealing that high primary production could result in lower Hg bioaccumulation, rather than only being influenced by nutrient levels.


Assuntos
Mercúrio , Compostos de Metilmercúrio , Poluentes Químicos da Água , Zooplâncton/química , Animais , Bioacumulação , China , Monitoramento Ambiental , Eutrofização , Cadeia Alimentar , Mercúrio/análise , Mercúrio/química , Compostos de Metilmercúrio/química
15.
Food Chem ; 313: 126119, 2020 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31923869

RESUMO

This work establishes a hyphenated methodology coupling HPLC with ICP-MS for simultaneous speciation analysis of arsenic, mercury and lead for the first time. Four arsenicals (As(III), DMA, MMA and As(V)), four mercurials (Hg(II), MeHg, EtHg and PhHg) and three lead compounds (Pb(II), TML and TEL) were simultaneously analyzed within only 8 min with acceptable resolution (2.0-8.2 for As, 1.6-6.1 for Hg and 2.7-4.0 for Pb). The detection limits were 0.036-0.20 for As-species, 0.023-0.041 for Hg-species, and 0.0076-0.14 µg L-1 for Pb-species. The developed method was applied for the measurement of five lotus seed samples, indicating the presence of DMA (19.6-28.2 µg kg-1), TML (1.4-2.9 µg kg-1), MeHg (1.2-4.8 µg kg-1) and EtHg (0.8-2.2 µg kg-1). This method provides a promising tool for studying the toxic, metabolic and bioavailable behaviors of arsenic, mercury and lead.


Assuntos
Arsênico/análise , Chumbo/análise , Espectrometria de Massas , Mercúrio/análise , Arsênico/química , Cromatografia Líquida de Alta Pressão , Chumbo/química , Limite de Detecção , Mercúrio/química
16.
Environ Sci Pollut Res Int ; 27(8): 8492-8506, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31912389

RESUMO

Mercury (Hg) is deposited temporarily in soil and can be remobilised into rivers and seas. Given that rivers are a significant part of the mercury budget in the southern Baltic region (inland sea located in northern Europe) and meteorological changes (e.g. intense rain, drought) are observed more frequently, it is important to recognize the factors affecting the cycling of bioavailable Hg forms. The aim of this study was to identify the processes influencing the changes of labile and stabile mercury proportion in soil and the potential impact on the outflow of labile Hg into fluvial systems. For this purpose, soil samples, river sediments, and river water were collected from the Reda River (southern Baltic Sea catchment area) during the 2015 hydrologic year. The material was analysed for total and particulate mercury content and Hg forms, by a thermo-desorption method. The analysis showed that due to changes of meteorological and hydrological conditions Hg can enter rivers and then be introduced into the marine environment in various forms. On the one hand due to high precipitation events washing out of labile (i.e. bond with halogenides, MeHg, HgSO4), Hg forms into the river can be enhanced which affects increasing of availability of the most dangerous Hg form in the water systems. On the other hand the same event can cause the limitation of bioavailable mercury forms by a conversion of labile Hg into the most stable one (HgSO4 ➔ HgS) under anaerobic conditions.


Assuntos
Mercúrio , Poluentes Químicos da Água , Países Bálticos , Europa (Continente) , Mercúrio/análise , Mercúrio/química , Oceanos e Mares , Rios/química , Solo , Poluentes Químicos da Água/análise
17.
Chemosphere ; 246: 125688, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31896013

RESUMO

Marine mammals are more exposed to mercury (Hg) than any others animals in the world. As many trace elements, Hg it is able to impair the brain function, which could be a cause of population decline. Nevertheless, these issues have been scarcely studied because of the technical and ethical difficulties. We conducted a systematic review about marine mammals' brain exposition to Hg and other trace elements, and their neurotoxic effects. Information was scarce and the lack of standardization of nomenclature of brain structures, sample collecting and results presentation made it difficult to obtain conclusions. Hg was the most studied metal and toothed whales the most studied group. Despite being its target organ, brain accumulates lesser concentrations of Hg than other tissues as liver. We found a significant positive correlation between both organs' burden (rho = 0.956 for cetaceans; rho = 0.756 for pinnipeds). Reported Hg values in brain of cetaceans (median 3.00 ppm ww) surpassed by one or two orders of magnitude those values found in other species as pinnipeds (median 0.33 ppm ww) or polar bears (median 0.07 ppm ww). Such values exceeded neurotoxicity thresholds. Although marine mammals ingest mostly the organic and more toxic form MeHg, different fractions of inorganic mercury can appear in brain, which could suggest some detoxification mechanisms. Other suggested mechanisms include Se-Hg interaction and liver sequestration. Although other elements are subjected to a rigid homeostatic control, appear in low concentrations or do not exert an important neurotoxic effect, they should be more studied to elucidate their neurotoxicity potential.


Assuntos
Monitoramento Ambiental , Mercúrio/toxicidade , Oligoelementos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Caniformia , Inativação Metabólica , Fígado/metabolismo , Mercúrio/análise , Mercúrio/química , Oligoelementos/análise , Ursidae , Poluentes Químicos da Água/metabolismo
18.
Artigo em Inglês | MEDLINE | ID: mdl-31948052

RESUMO

To identify whether the iron (Fe) mining area in the Jiulongjiang River basin (JRB) has an influence on the mercury in the forest soil, the spatial distribution patterns of mercury's behavior on different controlling factors were analyzed, and a potential ecological risk assessment was done. A total of 107 soil samples were collected from two forest soil profiles, one profile near the Fe mining area and the other far from it. The soil near the mining area had a moderate potential ecological risk with high Fe content rich in the upper layer of soil (<70 cm), whereas soil collected far from the mining area had a low potential ecological risk. These results indicated that the rise of iron content in the soil near the mining area was beneficial to the enrichment of mercury, probably causing damage to the forest ecosystem. Both soil organic carbon (SOC) and Fe content have strong positive correlations with THg content, controlling the mercury behavior in the upper layer (<70 cm) and a lower layer (>70 cm) of soil, respectively. The high Fe content in the upper layer of soil will compete for the adsorption of mercury by SOC, leading to the poor correlation between SOC and THg.


Assuntos
Ferro/química , Mercúrio/química , Compostos Orgânicos/química , Poluentes do Solo/química , Solo/química , China , Ecologia , Ecossistema , Monitoramento Ambiental/métodos , Florestas , Mercúrio/análise , Mineração , Rios , Poluentes do Solo/análise
19.
Environ Geochem Health ; 42(2): 365-375, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31286341

RESUMO

The objectives of this study were to measure ambient air particles concentrations of different particulates sizes ranges (PM18, PM10, PM2.5, PM1, PM<1) at a complex (traffic, residential and commercial) site. Besides, particulates-bound mercury (Hg(p)) concentrations for various particulates sizes (PM18, PM10, PM2.5, PM1, PM<1) at mixed site were also studied. Finally, ambient air particulates and Hg(p) size distributions were also described at this complex sampling site. The results showed that the average PM18, PM10, PM2.5, PM1, PM<1 concentrations were 48.83, 41.78, 35.41, 19.89, and 11.86 µg/m3, respectively. And the average ambient air particulates-bound mercury (Hg(p)) which attached on PM18, PM10, PM2.5, PM1, PM<1 particles concentrations were 0.0838, 0.0867, 0.0790, 0.0546, and 0.0373 ng/m3, respectively, in the summer season. In addition, the average ambient air Hg(p) which attached on PM18, PM10, PM2.5, PM1, PM<1 particles concentrations were 0.0175, 0.0144, 0.0120, 0.0092, and 0.0057 ng/m3, respectively, in the autumn season. Finally, the average ambient air Hg(p) which attached on PM18, PM10, PM2.5, PM1, PM<1 particles concentrations were 0.0070, 0.0053, 0.0038, 0.0026, and 0.0014 ng/m3, respectively, in the winter season. And July has the average highest PM18 and PM10 concentrations. As for PM2.5, PM1 and PM<1 particulates, the average highest particulates concentrations all occurred in November. In addition, the highest average Hg(p) in PM18, PM10, PM2.5, PM1, and PM<1 concentrations all occurred in July. Moreover, the average particles and particulates-bound mercury m.m.d. values were ranged from 1.0 to 1.8 and 0.7 to 2.0 µm from July to December of 2018, respectively, at this mixed sampling site. As for monthly ambient air particles sizes distributions, the results further showed that the main peaks for July, September, and December all occurred in the sizes of 10-18 µm. The main peaks for October and November all occurred in the sizes of 2.5-10 µm. As for monthly Hg(p) sizes distributions, the results further showed that the main peaks for July occurred in the size of 0.3-1 µm. The main peak for September occurred in the size of 1-2.5 µm. The main peaks for October to December all occurred in the size of 10-18 µm. The above finding further concluded that the particulates-bound mercury (Hg(p)) was tended to be associated with the large particles sizes mode during the winter season. Finally, this study further shows that the Taichung Thermal Power Plant was responsible for the main emission source of Hg(p) especially in summer season of Central Taiwan.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Mercúrio/análise , Material Particulado/análise , Poluentes Atmosféricos/química , Atmosfera/química , Monitoramento Ambiental/métodos , Mercúrio/química , Tamanho da Partícula , Material Particulado/química , Centrais Elétricas , Estações do Ano , Taiwan
20.
Environ Sci Pollut Res Int ; 27(2): 2423-2431, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31786760

RESUMO

Heavy metals have a separate precaution in the air pollution components as they are not easily deteriorated in nature, they tend to bioaccumulate, they are carcinogenic or poisonous, and they can be toxic even at low concentrations. Therefore, monitoring of heavy metal pollution is of great importance. Plants are frequently used as biomonitors to monitor the heavy metal pollution. However, the heavy metal accumulation capacities of plants can vary considerably depending on the plant species, as well as on the organelle basis and the amount of particulate matter in the environment. It is also very important to determine how much of the heavy metal concentrations found in plants are derived from the plant species and how much from the particulate matter on the organ. In this study, it was aimed to determine the change of heavy metal accumulation in some landscape plants grown in the city center of Kastamonu depending on plant type, plant organism, washing status, and traffic density. For this purpose, leaf and branch samples were collected from individuals of Ligustrum vulgare L., Euonymus japonica Thunb., Biota orientalis L., Juniperus sabina L., Berberis thunbergii DC, Mahonia aquifolium (Pursh) Nutt., and Buxus sempervirens L., which are frequently used in urban landscape designs growing in areas with heavy, low dense, and no traffic. Some of the collected samples were washed, and heavy metal analyses were conducted to determine the amount of Pb and Mg concentrations. It was remarkable that Pb concentration was higher in branches than in the leaves for all the species. And the alteration depending on traffic density on the base of the factors studied was in different proportion depending on the metals.


Assuntos
Poluição do Ar/análise , Chumbo/análise , Mercúrio/análise , Metais Pesados/análise , Material Particulado/análise , Folhas de Planta/química , Monitoramento Ambiental , Poluição Ambiental/análise , Chumbo/química , Mercúrio/química , Metais Pesados/química , Material Particulado/química , Plantas , Urbanização
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