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1.
Environ Pollut ; 292(Pt A): 118241, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34582918

RESUMO

Arsenic (As) pollution remains a major threat to the quality of global soils and drinking water. The health effects of As pollution are often severe and have been largely reported across Asia and South America. This study investigated the possibility of using unmodified biochar derived from rice husk (RB) and aspen wood (WB) at 400 °C and 700 °C to enhance the precipitation of calcium/arsenic compounds for the removal of As(III) from solution. The approach was based on utilizing calcium to precipitate arsenic in solution and adding unmodified biochar to enhance the process. Using this approach, As(III) concentration in aqueous solution decreased by 58.1% when biochar was added, compared to 25.4% in the absence of biochar. Varying the pH from acidic to alkaline enabled an investigation into the pH dependent dynamics of the approach. Results indicated that significant precipitation was only possible at near neutral pH (i.e. pH = 6.5) where calcium arsenites (i.e. Ca(AsO2)2, and CaAsO2OH•½H2O) and arsenates (i.e. Ca5(AsO4)3OH) were precipitated and deposited as aggregates in the pores of biochars. Arsenite was only slightly precipitated under acidic conditions (pH = 4.5) while no arsenite was precipitated under alkaline conditions (pH = 9.5). Arsenite desorption from wood biochar was lowest at pH 6.5 indicating that wood biochar was able to retain a large quantity of the precipitates formed at pH 6.5 compared to pH 4.5 and pH 9.5. Given that the removal of As(III) from solution is often challenging and that biochar modification invites additional cost, the study demonstrated that low cost unmodified biochar can be effective in enhancing the removal of As(III) from the environment through Ca-As precipitation.


Assuntos
Arsênio , Adsorção , Arseniatos , Cálcio , Carvão Vegetal
2.
Environ Pollut ; 292(Pt A): 118268, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34610411

RESUMO

There is little information available to decipher the interaction between molybdenum (Mo) and nitric oxide (NO) in mitigating arsenic (AsV) stress in plants. The present work highlights the associative role of exogenous Mo and endogenous NO signaling in regulating AsV tolerance in wheat seedlings. Application of Mo (1 µM) on 25-day-old wheat seedlings grown in the presence (5 µM) or absence of AsV stress caused improvement of photosynthetic pigment metabolism, reduction of electrolytic leakage and reactive oxygen species (ROS), and higher accumulation of osmolytes (proline and total soluble sugars). The molybdenum treatment upregulated antioxidative enzymes, such as superoxide dismutase, ascorbate peroxidase and glutathione reductase. In addition, the accumulation of nonenzymatic antioxidants (ascorbate and glutathione) was correlated with an increase in ascorbate peroxidase and glutathione reductase activity. The application of cPTIO (endogenous NO scavenger; 100 µM) reversed the Mo-mediated effects, thus indicating that endogenous NO may accompany Mo-induced mitigation of AsV stress. Mo treatment stimulated the accumulation of endogenous NO in the presence of AsV stress. Thus, it is evident that Mo and NO-mediated AsV stress tolerance in wheat seedlings are primarily operative through chlorophyll restoration, osmolytes accumulation, reduced electrolytic leakage, and ROS homeostasis.


Assuntos
Antioxidantes , Plântula , Arseniatos , Clorofila , Molibdênio , Óxido Nítrico , Estresse Oxidativo , Triticum
3.
Sci Total Environ ; 802: 149796, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34464787

RESUMO

Elevated arsenic (As) in soil is of public concern due to the carcinogenicity. Phosphorus (P) strongly influences the adsorption, absorption, transport, and transformation of As in the soil and in organisms due to the similarity of the chemical properties of P and As. In soil, P, particularly inorganic P, can release soil-retained As (mostly arsenate) by competing for adsorption sites. In plant and microbial systems, P usually reduces As (mainly arsenate) uptake and affects As biotransformation by competing for As transporters. The intensity and pattern of PAs interaction are highly dependent on the forms of As and P, and strongly influenced by various biotic and abiotic factors. An understanding of the PAs interaction in 'soil-plant-microbe' systems is of great value to prevent soil As from entering the human food chain. Here, we review PAs interactions and the main influential factors in soil, plant, and microbial subsystems and their effects on the As release, absorption, transformation, and transport in the 'soil-plant-microbe' system. We also analyze the application potential of P fertilization as a control for As pollution and suggest the research directions that need to be followed in the future.


Assuntos
Arsênio , Poluentes do Solo , Arseniatos/análise , Arsênio/análise , Poluição Ambiental , Humanos , Fósforo , Plantas , Solo , Poluentes do Solo/análise
4.
Chemosphere ; 286(Pt 1): 131629, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34375193

RESUMO

The aim of this study was to evaluate the efficacy of biological and chemical remediation of chromated copper arsenate (CCA) treated Corymbia citriodora poles, removed from service after 30 years. The presence of arsenic (As), chromium (Cr) and copper (Cu) was quantified by inductively coupled plasma optical emission spectrometry (ICP-OES). Twelve species of decay fungi were used for the biological remediation assay. For chemical remediation oxalic, citric, maleic and ethylenediamine tetraacetic (EDTA) acids were used for 24 and 48 h. In biological remediation, copper-tolerant brown-rot fungi, Wolfiporia cocos, Antrodia xantha and Fibroporia radiculosa, performed the best results, with the highest removals for As (59-85 %) and Cr (38-61 %). Cu was the most easily extracted, with removals above 60 % among the tested fungi, with the best results (90-98 %) for F. radiculosa, Coniophora puteana, Antrodia vaillantii and Postia placenta. In chemical remediation, the extraction time of 48 h was the most effective, and oxalic acid generally reached the highest removals. The EDTA + oxalic acid combination reached the highest value for Cu extraction (98 %).


Assuntos
Arseniatos , Madeira , Basidiomycota , Cobre , Polyporales
5.
Ecotoxicol Environ Saf ; 227: 112883, 2021 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-34653941

RESUMO

Arsenic (As) in the aquatic environment is a considerable environmental issue, previous studies have reported the toxic effects of low concentrations (≤ 150 µg/L) of As on fish. However, limited information is available regarding the impact of low levels of As on apoptosis. To evaluate this, zebrafish embryos were exposed to different concentrations (0, 25, 50, 75, and 150 µg/L) of As (arsenite [AsIII] and arsenate [AsV]) for 120 h. Our results indicated that low concentrations of AsIII exposure significantly inhibited the survival of zebrafish larvae, and significantly increased the transcription of Caspase-9 and Caspase-3, the ratio of Bax/Bcl-2 transcription, and protein levels of Caspase-3. In contrast, AsV decreased the ratios of Bax/Bcl-2 transcription and protein levels, as well as protein levels of Caspase-3. Our data demonstrated that AsIII and AsV exert different toxic effects, AsIII induced apoptosis via the mitochondrial pathway and the extrinsic pathway, while AsV induced apoptosis only via the mitochondrial pathway.


Assuntos
Arsênio , Animais , Apoptose , Arseniatos/toxicidade , Arsênio/toxicidade , Larva , Peixe-Zebra
6.
Aquat Toxicol ; 240: 105991, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34673466

RESUMO

Arsenobetaine (AsB) is the major form of arsenic in marine fish; however, its biodynamics within the fish tissues is not well understood. This study simulated the biodynamics and biotransportation (absorption, distribution, and elimination) of dietary AsB and arsenate [As(V)] in the marine grouper Epinephelus fuscoguttatus, by constructing a physiologically based pharmacokinetic (PBPK) model. The transfer rates between different compartments (gill, intestine, liver, heart, kidney, and muscle) and blood were modeled during exposure (14 d) and depuration (20 d). The model showed that AsB had a weak ability to cross the intestinal membranes and circulated slowly in the blood. The newly AsB absorbed from the blood did not enter the hepatointestinal circulation for elimination, but was effectively distributed in liver. Thereafter, it was slowly absorbed and finally stored in the muscle, the most important organ for AsB deposition, at a constant rate of 63.5 d-1. In contrast, As(V) displayed a dynamic behavior, including rapid crossing through the intestinal membranes, quick circulation in the blood and transportation to other tissues, and elimination. Biodynamics coupled with biotransformation illustrated, for the first time, the unique strategies of dietary AsB that passed slowly through the fish intestine with the highest deposition rate in the muscle, thereby contributing to the high AsB bioaccumulation in the muscle tissue of marine fish. CAPSULE: AsB displayed a weaker ability to cross the intestine membranes, slowly absorbed and finally stored in muscle, whereas As(V) displayed rapid crossing the intestine membranes, quick transportation, and elimination.


Assuntos
Arsênio , Arsenicais , Bass , Poluentes Químicos da Água , Animais , Arseniatos , Poluentes Químicos da Água/toxicidade
7.
Braz J Biol ; 83: e248022, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34468531

RESUMO

Previous studies have suggested that arsenic crosses the placenta and affects the fetus development. The study under consideration aims to show comparative ameliorative effect of Moringa oleifera leaf and flower extracts against sodium arsenate induced fetus toxicity of mice. Pregnant mice (N=44) were kept in lab and divided into eleven group from (A to K) and were orally administered the doses 6 mg/kg, 12 mg/kg for sodium arsenate, 150 mg/kg and 300 mg/kg for Moringa oleifera leaf extracts (MOLE) and 150 mg/kg and 300 mg/kg for Moringa oleifera flower extracts (MOFE) comparing with control. The investigation revealed evident reduction in the fetuses weight, hind limb, fore limb, tail and snout length, crown rump and head circumferences well as malformations in tail, feet, arms, legs, skin and eyes in the negative control group (only administered with sodium arsenate). Co-administration of sodium arsenate with MOLE and MOFE ameliorate the reversed effect of sodium arsenate on the shape, length, body weight and DNA damage of fetus significantly at 95% confidence interval. However, Moringa oleifera leaf extract showed more significant results in comparison to Moringa oleifera flower extract. Hence concluded that Moringa oleifera leaf extract ameliorated the embryo toxic effects of sodium arsenate and can be used against environmental teratogens.


Assuntos
Moringa oleifera , Animais , Arseniatos , Dano ao DNA , Camundongos , Extratos Vegetais/farmacologia , Folhas de Planta
8.
Environ Pollut ; 291: 117958, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34547656

RESUMO

Nitric oxide (NO) and hydrogen sulfide (H2S) since their discovery have proven to be game changing molecules in alleviating abiotic stress. They individually play role in plant stress management while the pathways of stress regulation through their crosstalk remain elusive. The current study focuses on investigating the interplay of NO and H2S signalling in the amelioration of arsenate As(V) toxicity in rice seedlings and managing its growth, photosynthesis, sucrose and proline metabolism. Results show that As(V) exposure declined fresh weight (biomass) due to induced cell death in root tips. Moreover, a diminished RuBisCO activity, decline in starch content with high proline dehydrogenase activity and increased total soluble sugars content was observed which further intensified in the presence of Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME, an inhibitor of nitric oxide synthase-like activity), and DL-propargylglycine (PAG, an inhibitor of cysteine desulfhydrase activity). These results correlate with lower endogenous level of NO and H2S. Addition of L-NAME increased As(V) toxicity. Interestingly, addition of SNP reverses effect of L-NAME suggesting that endogenous NO has a role in mitigating As(V) toxicity. Similarly, exogenous H2S also significantly alleviated As(V) stress, while PAG further stimulated As(V) toxicity. Furthermore, application of H2S in the presence of L - NAME and NO in the presence of PAG could still mitigate As(V) toxicity, suggesting that endogenous NO and H2S could independently mitigate As(V) stress.


Assuntos
Sulfeto de Hidrogênio , Oryza , Arseniatos , Sulfeto de Hidrogênio/toxicidade , Óxido Nítrico , Plântula
9.
Sci Total Environ ; 800: 149479, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34399332

RESUMO

Arsenate (As-V) is a ubiquitous contaminant in soil as a result of excessive use of veterinary drugs and pesticides, causing enormous environmental risks. Multiple biomarkers have been used to assess the ecotoxicity of arsenic, however, the mechanisms of toxicity remain unclear. This paper describes the exposure of the earthworm (Eisenia fetida) to natural soil with different As-V concentrations for 28 days, then biomarkers from oxidative stress and burrowing behavior were quantified to evaluate As-V stress. Dynamic changes in reactive oxygen species (ROS), lipid peroxidation (MDA), adenosine triphosphate (ATP) content and antioxidant enzymes activity (Gpx, SOD, CAT) implied two stages of intensified stress responses and physiological adaptability. The transcriptional expression and regulation of antioxidant enzymes showed different responses. The mRNA expression of sod1 was up-regulated, while that of cat showed no significant change. The related regulators, nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), showed dose-dependent activation, suggesting antioxidant defense induced by Nrf2 signaling. The burrowing behavior after 14-day exposure indicated that As-V inhibited burrowing activity, especially the burrow length and maximum burrow depth. These multiple biomarkers were integrated using a biomarker response index (BRI) model, which showed significant dose-effect relationship especially on day 28, and suggested that ATP was a sensitive and representative biomarker. This study provided evidence that burrowing activity, Nrf2 and HO-1 were useful biomarkers warranting inclusion into the BRI model. Arsenic toxicity was comprehensively understood through redox homeostasis regulation, biochemical and behavioral changes, and these results suggested new strategies for soil pollutants diagnosis.


Assuntos
Oligoquetos , Poluentes do Solo , Animais , Arseniatos/toxicidade , Biomarcadores/metabolismo , Catalase/metabolismo , Oligoquetos/metabolismo , Estresse Oxidativo , Poluentes do Solo/toxicidade , Superóxido Dismutase/metabolismo
10.
Sci Total Environ ; 794: 148691, 2021 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-34214812

RESUMO

Biochar-loaded Ce3+-enriched ultra-fine ceria nanoparticles (Ce-BC) were used as a novel nanostructured adsorbent for the removal of arsenate (As(V)) from aqueous solutions. The effect of cerium valence on As(V) adsorption and the mechanism of As(V) adsorption onto Ce-BC were investigated using batch experiments and a series of spectroscopy detection technologies. The adsorption isotherm data fitted with the Langmuir model, with maximum As(V) sorption capacity of 219.8 mg g-1 at pH 5.0 and 25 °C. The adsorption kinetics fitted well with the pseudo-second-order model. Ce3+ on the surface of Ce-BC plays an important role in the adsorption of As(V). The decrease in Ce3+ concentration from 60.1% to 48.9% on the Ce-BC surface, significantly decreased the adsorption of As(V) on Ce-BC. Furthermore, a strong affinity between As(V) and Ce3+-enriched Ce-BC was revealed, resulting in irreversible adsorption. Most importantly, the adsorbed As(V) could further react with Ce3+ of the ultra-fine cerium oxide nanoparticles in Ce-BC to form rod-like CeAsO4 precipitates. Through the novel adsorption-precipitation process, Ce-BC can be used to remove trace As(V).


Assuntos
Nanopartículas , Poluentes Químicos da Água , Purificação da Água , Adsorção , Arseniatos , Carvão Vegetal , Concentração de Íons de Hidrogênio , Cinética , Água , Poluentes Químicos da Água/análise
11.
Ecotoxicol Environ Saf ; 222: 112522, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34304132

RESUMO

Arsenic (As) contamination of freshwater resources constitutes a major environmental issue affecting over 200 million people worldwide. Although the use of microorganisms for the bioremediation of As has been well studied, only very few candidates have been identified to date. Here, we investigated bacteria associated with the Red Sea sponge Theonella swinhoei and their potential to reduce As in a low-salinity liquid medium. This Indo-Pacific common sponge has been shown to hyper-accumulate As, at an average concentration of 8600 mg/g-1 in an environment uncontaminated by arsenic or barium. Four isolated strains of bacteria exhibited arsenic reduction potential by transforming inorganic As in the form of arsenate (iAsV) to arsenite (iAsIII). Two of these isolates were identified as Alteromonas macleodii and Pseudovibrio ascidisceicola, and the other two isolates, both belonging to the same species, were identified as Pseudovibrio denitrificans. The four isolates were then cultured in a low-salinity iAsV-rich medium (5 mM) and As concentration was measured over time using a specifically designed high-performance liquid chromatograph coupled to a mass spectrometer (HPLC-MS). Out of the four isolates, A. macleodii and P. ascidisceicola grew successfully in a low-salinity liquid medium and reduced AsV to AsIII at an average rate of 0.094 and 0.083 mM/h, respectively, thereby demonstrating great potential for the bioremediation of As-contaminated groundwater.


Assuntos
Arsênio , Rhodobacteraceae , Theonella , Alteromonas , Animais , Arseniatos , Biodegradação Ambiental , Humanos , Filogenia , RNA Ribossômico 16S
12.
Chemosphere ; 285: 131525, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34265703

RESUMO

Arsenic (As) is a problematic pollutant that can cause cancer and other chronic diseases due to its potential toxicity. Iron (oxyhydr)oxides can readily sorb As and play important roles in the geochemical cycle of As. Attention has mainly been given to the affinity and mechanism of As sorption by synthetic pure iron (oxyhydr)oxides, and little is known about the relationship between As behavior and multicomponent secondary iron minerals (SIMs) naturally formed in acid mine drainage (AMD). To investigate this relationship, we performed sorption kinetics, isotherm and competitive sorption experiments to investigate As(V) sorption behaviors on naturally formed SIMs harvested from different runoff zones of an abandoned coal mine. Several spectroscopic analyses were used to evaluate the structural and component changes and phase transformation. Three environmental SIMs formed at nascent (n-SIM), transient (t-SIM) and mature (m-SIM) stages were determined to be similar in the element components of Fe, S and O but different in structure. As(V) sorption behaviors on these environmental SIMs followed a pseudo-second-order kinetic model, and the sorption extent followed the sequence of n-SIM > t-SIM > m-SIM. As(V) sorption is not significantly influenced by Na+/Ca2+ concentration or ionic strength except for that of PO43-, and it slightly decreases as the Cr(Ⅲ) concentration increases but increases with increasing Sb(Ⅲ)/(V) concentration. The results of spectral analyses indicate that As(V) immobilization mainly depends on exchange with SO42- and surface complexation, along with the phase transformation of schwertmannite/jarosite to goethite and other phases. These findings are helpful for better understanding the geochemical behaviors of As(V) associated with environmental SIMs.


Assuntos
Arsênio , Compostos de Ferro , Adsorção , Arseniatos , Compostos Férricos , Ferro , Minerais
13.
Antonie Van Leeuwenhoek ; 114(8): 1285-1292, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34117562

RESUMO

A novel arsenate-reducing bacterium, LY-1T, was isolated from freshwater sediment in Huangshi, China. Morphological analysis indicated that the cells were shaped like rods and were gram-negative. The major fatty acids (> 10%) were C16:0, summed feature 3 (C16:1 ω7c, C16:1 ω6c) and summed feature 8 (C18:1 ω7c, C18:1 ω6c). An assessment of the phylogeny based on 16S rRNA gene sequences indicated that the strain LY-1T belonged to the genus Citrobacter, while further analysis based on the recN gene indicated that LY-1T occupies a distinct phylogenetic niche within the Citrobacter genus. Moreover, average nucleotide identity and digital DNA-DNA hybridization between the strain LY-1T and the type strains of closely related species of the genus Citrobacter (C. europaeus, C. brakii, C. portucalensis, C. freundii, C. werkmanii, C. cronae, C. youngae, C. pasteurii, C. tructae, C. gillenii, and C. murliniae) were 85.8-93.8% and 31.2-56.9%, respectively. In addition, the LY-1T strain's capacity to metabolize various compounds and its characteristic G + C content of 51.9% were also distinct from other species of the Citrobacter genus. These discriminatory features cumulatively indicate the LY-1T strain as a new species within the Citrobacter genus. We propose the species name Citrobacter arsenatis for this new species, with LY-1T (= CCTCC AB 2019169T = KCTC 72440T) as the type strain.


Assuntos
Arseniatos , Citrobacter , Técnicas de Tipagem Bacteriana , Composição de Bases , Citrobacter/genética , DNA Bacteriano/genética , Ácidos Graxos/análise , Água Doce , Hibridização de Ácido Nucleico , Fosfolipídeos , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
14.
Artigo em Inglês | MEDLINE | ID: mdl-34063914

RESUMO

Copper chrome arsenate (CCA) water-borne solution used to be widely used to make timber highly resistant to pests and fungi, in particular, wood products designed for outdoor use. Nowadays, CCA is a restricted chemical product in most countries, since potential environmental and health risks were reported due to dermal contact with CCA residues from treated structures and the surrounding soil, as well as the contamination of soils. However, large quantities of CCA-treated timber are still in use in framings, outdoor playground equipment, landscaping, building poles, jetty piles, and fencing structures around the world, thus CCA remains a source of pollutants to the environment and of increasing toxic metal/metalloid exposure (mainly in children). International efforts have been dedicated to the treatment of materials impregnated with CCA, however not only does some reuse of CCA-treated timber still occur, but also existing structures are leaking the toxic compounds into the environment, with impacts on the environment and animal and human health. This study highlights CCA mechanisms and the documented consequences in vivo of its exposure, as well as the adverse environmental and health impacts.


Assuntos
Arseniatos , Arsênio , Animais , Arseniatos/toxicidade , Arsênio/toxicidade , Criança , Cromo , Cobre/toxicidade , Humanos , Madeira
15.
J Hazard Mater ; 415: 125589, 2021 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-34088170

RESUMO

We explored genetic evidence for strigolactones' role in rice tolerance to arsenate-stress. Comparative analyses of roots of wild-type (WT) and strigolactone-deficient mutants d10 and d17 in response to sodium arsenate (Na2AsO4) revealed differential growth inhibition [WT (11.28%) vs. d10 (19.76%) and d17 (18.03%)], biomass reduction [(WT (33.65%) vs. d10 (74.86%) and d17 (60.65%)] and membrane damage (WT < d10 and d17) at 250 µM Na2AsO4. Microscopic and biochemical analyses showed that roots of WT accumulated lower levels of arsenic and oxidative stress indicators like reactive oxygen species and malondialdehyde than those of strigolactone-deficient mutants. qRT-PCR data indicated lower expression levels of genes (OsPT1, OsPT2, OsPT4 and OsPT8) encoding phosphate-transporters in WT roots than mutant roots, explaining the decreased arsenate and phosphate uptake by WT roots. Increased levels of glutathione and OsPCS1 and OsABCC1 transcripts indicated an efficient vacuolar-sequestration of arsenic in WT roots. Furthermore, higher activities (transcript levels) of SOD (OsCuZnSOD1 and OsCuZnSOD2), APX (OsAPX1 and OsAPX2) and CAT (OsCATA) corresponded to lower oxidative damage in WT roots compared with strigolactone-mutant roots. Collectively, these results highlight that strigolactones are involved in arsenic-stress mitigation by regulating arsenate-uptake, glutathione-biosynthesis, vacuolar-sequestration of arsenic and antioxidant defense responses in rice roots.


Assuntos
Arsênio , Oryza , Antioxidantes , Arseniatos/toxicidade , Arsênio/toxicidade , Compostos Heterocíclicos com 3 Anéis , Lactonas , Oryza/genética , Raízes de Plantas
16.
J Environ Manage ; 293: 112898, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34082345

RESUMO

The co-occurrence of arsenic and fluoride in the water environment has led to many health concerns for living beings. Simultaneous removal of such ions is crucial to the safety of water resources, and biochar has been extensively engaged to address this issue. Here four magnetic biochars (mBCs) including pristine magnetic biochar and three aluminum (Al) and/or magnesium (Mg) oxides-anchored magnetic biochar (i.e., Al-mBC, Mg-mBC, and MgAl-mBC) were prepared via a facile pyrolysis method and then comprehensively evaluated as adsorbents for enhanced co-uptake of arsenate (AsV) and fluoride (F-) from synthetic water. The mBC shows a high specific surface area of 205 m2 g-1, which dropped to 116, 80, and 114 m2 g-1 upon the anchoring of Al, Mg, and Mg + Al, respectively. Our results suggest that the adsorption of either AsV or F- is highly pH-dependent, and pH 4-6 is the optimal range for maximum adsorption. The adsorption isotherm data indicate that the MgAl-mBC adsorbent outranks all other mBCs for co-uptake of both AsV and F-. The adsorption capacity maxima of MgAl-mBC are 34.45, and 21.59 mg g-1 for AsV and F-, respectively (pH = 5, T = 10 °C), also highly outstripping other biochars reported in the literature. The magnetic feature of these mBCs enables us to fast reclaim and regenerate the exhausted adsorbents by an external magnet and dilute NaOH. The Al- and Mg-anchored mBCs are expected to be used as highly efficient adsorbents for environmental remediation of waters contaminated by both AsV and F-.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Adsorção , Alumínio , Arseniatos , Carvão Vegetal , Fluoretos , Cinética , Óxido de Magnésio , Fenômenos Magnéticos , Água
17.
Fish Shellfish Immunol ; 114: 229-237, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33979692

RESUMO

The freshwater aquifers of the Indo-Gangetic plains support rich biodiversity which is under the threat of arsenic contamination. The filter feeding bivalve mollusc Lamellidens marginalis is a sessile and sentinel resident of these freshwater habitats. In the present study, the classical cell behaviours of adhesion and aggregation were monitored in the circulating haemocytes of the freshwater bivalve under the exposure of sodium arsenite (NaAsO2) at sublethal concentrations in controlled laboratory conditions for a maximum time-span of sixteen days. The toxic metalloid significantly inhibited non-self adhesion, inter-haemocyte interactions and haemocyte aggregation in a dose and time dependent manner. The natural occurrence of the filopods on the haemocytes was significantly diminished in the bivalves exposed to the inorganic arsenite. Moreover, a significant fall in the kinetics of phagocytosis index and haemocyte adhesion was observed under the in vitro exposure to NaAsO2. Compromised non-self adhesion, cell-cell aggregation and phagocytosis of non-self particles by the bivalve haemocytes probably indicate susceptible immunological status of the bivalve. Such vulnerable immunity of the bivalve probably signifies the nature of imminent threat to the freshwater ecosystem as a whole under inorganic arsenite exposure. The findings would be helpful to design bivalve haemocyte based inexpensive biomonitoring tool to assess the health of freshwater ecosystem under potential arsenic threat.


Assuntos
Arsênio/toxicidade , Bivalves/citologia , Adesão Celular/fisiologia , Agregação Celular/fisiologia , Hemócitos/fisiologia , Fagocitose/fisiologia , Animais , Arseniatos/toxicidade , Poluentes Químicos da Água/toxicidade
18.
Environ Pollut ; 287: 117189, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34023660

RESUMO

Micronized Cu (µ-Cu) is used as a wood preservative, replacing toxic chromated copper arsenate (CCA). Micronized Cu is malachite [Cu2CO3(OH)2] that has been milled to micron/submicron particles, with many particle diameters less than 100 nm, mixed with biocides and then used to treat wood. In addition to concerns about the fate of the Cu from µ-Cu, there is interest in the fate of the nano-Cu (n-Cu) constituents. We examined movement of Cu from µ-Cu-treated wood after placing treated-wood stakes into model wetland ecosystems. Release of Cu into surface and subsurface water was monitored. Surface water Cu reached maximum levels 3 days after stake installation and remained elevated if the systems remained inundated. Subsurface water Cu levels were 10% of surface water levels at day 3 and increased gradually thereafter. Sequential filtering indicated that a large portion of the Cu in solution was associating with soluble organics, but there was no evidence for n-Cu in solution. After 4 months, Cu in thin-sections of treated wood and adjacent soil were characterized with micro X-ray absorption fine structure spectroscopy (µ-XAFS). Localization and speciation of Cu in the wood and adjacent soil using µ-XAFS clearly indicated that Cu concentrations decreased over time in the treated wood and increased in the adjacent soil. However, n-Cu from the treated wood was not found in the adjacent soil or plant roots. The results of this study indicate that Cu in the µ-Cu-treated wood dissolves and migrates into adjacent soil and waters primarily in ionic form (i.e., Cu2+) and not as nano-sized Cu particles. A reduced form of Cu (Cu2S) was identified in deep soil proximal to the treated wood, indicating strong reducing conditions. The formation of the insoluble Cu2S effectively removes some portion of dissolved Cu from solution, reducing movement of Cu2+ to the water column and diminishing exposure.


Assuntos
Poluentes do Solo , Madeira , Arseniatos , Cobre/análise , Ecossistema , Solo , Poluentes do Solo/análise , Áreas Alagadas , Madeira/química
19.
Environ Sci Pollut Res Int ; 28(37): 51088-51104, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33974205

RESUMO

Exposure time, metal bio-accumulation, and upregulation of ascorbate-glutathione (AsA-GSH) cycle are the key factor that provide tolerance against heavy metal stress. Thus, the current study is an endeavor to prove our hypothesis that regulation of arsenate (AsV: 50, 100, and 150 mM) and arsenite (AsIII: 50, 100, and 150 µM) toxicity is time dependent (48-96 h) due to modulation in bio-accumulation pattern, AsA-GSH cycle, and non-enzymatic antioxidants in two paddy field cyanobacteria Nostoc muscorum ATCC27893 and Anabaena sp. PCC7120. After 48 h, reduction in growth associated with increased sensitivity index, As bio-accumulation, and oxidative stress was observed which further intensified after 96 h but the degree of damage was lesser than 48 h. It denotes a significant recovery in growth after 96 h which is correlated with decreased As bio-accumulation and oxidative stress due to increased efficiency of AsA-GSH cycle and non-enzymatic antioxidants. Both the species of As caused significant rise in oxidative biomarkers as evident by in -vitro analysis of O2·-, H2O2, and MDA equivalent contents despite appreciable rise in the activity antioxidative enzymes APX, DHAR, and GR. The study concludes that among both forms of arsenic, AsIII induced more toxic effect on growth by over-accumulating the ROS as evident by weak induction of AsA-GSH cycle to overcome the stress as compared to AsV. Further, with increasing the time exposure, apparent recovery was noticed with the lower doses of AsV, i.e., 50 and 100 mM and AsIII, i.e., 50 and 100 µM; however, the toxicity further aggravated with higher dose of both AsV and AsIII. Study proposes the deleterious impact of AsV and AsIII on cyanobacteria N. muscorum and Anabaena sp. but the toxicity was overcome by time-dependent recovery.


Assuntos
Anabaena , Arsenitos , Cianobactérias , Nostoc muscorum , Anabaena/metabolismo , Antioxidantes , Arseniatos/toxicidade , Arsenitos/toxicidade , Cianobactérias/metabolismo , Glutationa/metabolismo , Peróxido de Hidrogênio , Nostoc muscorum/metabolismo , Estresse Oxidativo
20.
Environ Sci Pollut Res Int ; 28(36): 50908-50918, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33973122

RESUMO

To understand the arsenic (As) toxicity to aquatic organisms in the phosphors-polluted aquatic ecosystem, the growth, the physiological response of Chlorella vulgaris exposed to As (V), and the underlying mechanism were investigated under different phosphorus (P) levels (0, 6, 13, 32 µM). Results showed that As toxicity to the marine microalga C. vulgaris was enhanced under P-limited condition. P supply distinctly altered the effect of As on the light-harvesting efficiency of photosystem. Insufficient P supply also resulted in an enhanced level of membrane integrity loss, which probably facilitated As entering cells and led to stronger toxicity to C. vulgaris under low P supply. At high concentrations of As, the relative superoxide dismutase (SOD) activity was significantly enhanced. When phosphorus was limited, the activation of peroxidase (POD) was significantly enhanced after adding As (V). When intracellular SOD activity was at its highest level, the level of membrane peroxidation (MDA) was also at the highest level, and membrane peroxidation level was positively related to the level of membrane integrity loss (Pearson R2=0.8977). These results suggested that alternation of light-harvesting efficiency of photosystem and As-induced oxidative damage, resulting in membrane peroxidation and integrity loss, were the possible mechanism of As toxicity to C. vulgaris. This study provided insight into the understanding of As toxicity to algae in the eutrophication aquatic system and the potential application of algae in As remediation.


Assuntos
Chlorella vulgaris , Microalgas , Arseniatos/toxicidade , Ecossistema , Fósforo , Superóxido Dismutase
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