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1.
Rev Environ Contam Toxicol ; 252: 97-129, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31346776

RESUMO

Human milk may sometimes contain chemical contaminants, which could have adverse effects on neonates or nursing infants. Lead (Pb) is of considerable interest due to its toxicity and occurrence. Furthermore, it has been suggested that human milk is a significant potential source of lead exposure to nursing infants. A systematic literature search in PubMed, Science Direct, and Google Scholar databases was performed to identify relevant studies, published in English until 2017, that investigated and explored common factors affecting the level of lead in human milk among lactating women around the world. Forty-nine papers were rated and explored the effect of one or several factors on the level of lead in human milk from 28 countries and carried out over a wide time frame from 1983 to 2017 and through Europe, Asia, America, and Africa, reviewing more than 5,000 subjects. Place of residence, maternal age, stage of lactation, smoking habits, maternal dietary intakes, and parity were the mostly assessed factors among the studies and considered as the main factors affecting Pb levels in BM. Other factors were not studied well enough and considered minor because few surveys evaluated their impacts. However, the literature findings are very controversial.


Assuntos
Poluentes Ambientais/metabolismo , Lactação , Chumbo/metabolismo , Leite Humano/metabolismo , Feminino , Humanos , Recém-Nascido , Gravidez
2.
Bull Environ Contam Toxicol ; 103(2): 330-335, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31263937

RESUMO

The immobilization effect and mechanism of nano-hydroxyapatite(NHAP) on Pb in the ryegrass rhizosphere soil were studied by root-bag experiment. The speciation analysis results revealed that the residual Pb concentrations in the rhizosphere soil significantly increased after NHAP application. The acid-soluble and reducible Pb concentrations significantly decreased, indicating that NHAP had obviously immobilized Pb. Meanwhile, NHAP significantly promoted the secretion of tartaric acid from ryegrass roots, resulting the rhizosphere soil pH had been below that of the control group. This helped to relieve the stress of Pb on ryegrass, also promoted the dissolution of NHAP, resulting the formation of stable precipitation with more Pb ions. NHAP increased the rhizosphere soil pH by 0.03 to 0.17, which promoted the conversion of Pb to non-utilizable bioavailability. The total Pb mass balance indicated only a very small proportion Pb transferred to the shoots through ryegrass roots. The formation of pyromorphite by Pband NHAP in soil was accordingly to interpret the dominant mechanism for Pb immobilization.


Assuntos
Durapatita/química , Chumbo/análise , Lolium/crescimento & desenvolvimento , Nanoestruturas/química , Rizosfera , Poluentes do Solo/análise , Adsorção , Disponibilidade Biológica , Concentração de Íons de Hidrogênio , Chumbo/metabolismo , Lolium/metabolismo , Minerais/química , Modelos Teóricos , Fosfatos/química , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Solo/química , Poluentes do Solo/metabolismo , Tartaratos/metabolismo
3.
Environ Sci Pollut Res Int ; 26(23): 23460-23470, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31201701

RESUMO

Lead (Pb) contamination of agroecosystems is a serious issue as Pb is a persistent pollutant that is retained in soil for long, causing toxicities to organisms. This study examines biotransfer of Pb from soils treated with different concentrations of Pb through a broad bean (Vicia faba L.)-aphid (Aphis fabae Scop.)-ladybird (Coccinella transversalis Fabricius) food chain and its consequent inference for natural biological control, the ladybird. The soil was amended with Pb at the rates of 0, 25, 50, 75 and 100 mg kg-1 (w/w). The amount of Pb in plant, aphid and ladybird increased in a dose-dependent manner to Pb contents in the soil. The results showed that Pb biomagnified from soil to root with transfer coefficient always > 1. Biominimization of Pb occurred at the second trophic level in aphids and at the third trophic level in ladybirds as their respective transfer coefficients from shoot to aphid and aphid to ladybird were always < 1. The increased elimination of Pb via aphid excreta (honeydew) and pupal exuviae in a dose-dependent manner suggests that these are possible detoxification mechanisms at two different trophic levels which control Pb bioaccumulation along the food chain. The statistically significant (p ≤ 0.05) decreases in biomass and predation rate of predatory ladybirds at 100 mg kg-1 Pb indicate that high dose of Pb in soil may have sub-lethal effects on ladybirds. Further studies at cellular and sub-cellular levels are needed to further document the potential mechanisms of achieving Pb homeostasis in ladybirds under Pb stress.


Assuntos
Afídeos , Besouros , Cadeia Alimentar , Chumbo/metabolismo , Poluentes do Solo/metabolismo , Animais , Biomassa , Plantas Comestíveis , Comportamento Predatório , Solo , Poluentes do Solo/toxicidade , Vicia faba
4.
Environ Sci Pollut Res Int ; 26(23): 23788-23797, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31209746

RESUMO

Lead (Pb) is known for its low mobility and persistence in soils. The main aim of the present study was to explore potential of different fungal strains to promote phytoextraction of Pb-contaminated soils. Five non-pathogenic fungal strains (Trichoderma harzianum, Penicillium simplicissimum, Aspergillus flavus, Aspergillus niger, and Mucor spp.) were tested for their ability to modify soil properties (pH and organic matter) and to increase Pb phytoavailability at varying concentrations. Lead tolerance of fungal strains followed the decreasing order as A. niger > T. harzianum > A. flavus > Mucor sp. > P. simplicissimum. Lead solubility induced by A. flavus and Mucor spp. was increased by 1.6- and 1.8-fold, respectively, as compared to the control soil (Pb added, without fungi). A. flavus and Mucor spp. lowered the soil pH by - 0.14 and - 0.13 units, in soils spiked with 2000 mg Pb kg-1. The maximum increase in the percentage of organic matter (OM) recorded was 1.7-fold for A. flavus at 500 mg Pb kg-1 soil. Plant growth-promoting assays confirmed the beneficial role of these fungal strains. Significantly high production of IAA (249 µg mL-1) and siderophores (61%) was observed with A. niger, and phosphate solubilization with P. simplicissimum (58 µg mL-1). Based on the results in Pb-contaminated soils, Pelargonium hortorum L. inoculated with Mucor spp. showed the potential to enhance phytoextraction of Pb by promoting Pb phytoavailability in soil and improving plant biomass production through plant growth-promoting activities.


Assuntos
Biodegradação Ambiental , Chumbo/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Adaptação Fisiológica/fisiologia , Aspergillus , Biomassa , Tolerância a Medicamentos , Fungos/metabolismo , Chumbo/análise , Desenvolvimento Vegetal , Solo/química , Poluentes do Solo/análise , Trichoderma
5.
Ecotoxicology ; 28(5): 520-527, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31119593

RESUMO

Halophytes have been considered promising candidates for accumulating heavy metals from saline soils; however, little information has been given on plant physiological responses and heavy metal transportation and accumulation in halophytes that grow in heavy metal-polluted saline soils. This study hypothesized that salinity or heavy metals could induce alterations in plant growth, antioxidant enzyme activities and accumulation and transportation of heavy metals or sodium (Na) in Suaeda salsa. Pot experiments were conducted to test the above hypothesis. Lead (Pb) was selected as the representative heavy metal, and NaCl was added to simulate the Pb-polluted saline soil. The results showed that 0.5% NaCl addition alleviated the inhibition of plant growth under moderate Pb stress (35 and 100 mg kg-1 Pb levels), while the phytotoxicity on plants was magnified by 1.0% NaCl addition. NaCl weakened the oxidative stress in Pb-treated plants by increasing the activity levels of antioxidative enzymes (dismutase (SOD), peroxidase (POD) and catalase (CAT)). At all Pb levels, as the NaCl addition increased, significant increases were observed in the concentration of Na. The 100 mg kg-1 Pb induced a greater increase in Na concentrations than the 35 mg kg-1 Pb did, while the latter induced a greater increase than the 300 mg kg-1 Pb did. NaCl improved Pb translocation factor and its accumulation in Suaeda salsa under Pb stress, indicating that NaCl improves Pb uptake and translocation from roots to shoots and enhances the phytoextraction of Pb. Compared with the 0.1% NaCl treatment, the 0.5 and 1.0% NaCl treatments increased the concentrations of bioavailable Pb in the rhizosphere by 15.0-19.2 and 28.6-35.1%, respectively, indicating the contribution of salinity in producing more available Pb for plant uptake. Moderate salinity may be profitable for Pb transportation and accumulation in plants when there are positive effects on plant growth, antioxidant enzyme activities and Pb availability. These facts suggest that the halophyte Suaeda salsa may be exploited to remediate heavy metal-contaminated saline soils.


Assuntos
Antioxidantes/metabolismo , Chenopodiaceae/efeitos dos fármacos , Estresse Salino/fisiologia , Plantas Tolerantes a Sal/efeitos dos fármacos , Poluentes do Solo/metabolismo , Biodegradação Ambiental , Chenopodiaceae/enzimologia , Chenopodiaceae/crescimento & desenvolvimento , Chenopodiaceae/metabolismo , Chumbo/metabolismo , Plantas Tolerantes a Sal/enzimologia , Plantas Tolerantes a Sal/crescimento & desenvolvimento , Plantas Tolerantes a Sal/metabolismo , Sódio/metabolismo
6.
Environ Sci Pollut Res Int ; 26(20): 20610-20618, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31104244

RESUMO

The present study was designed to investigate the protective role of dietary supplementation of Spirulina platensis (SP) against cytotoxic and genotoxic effects of lead nitrate in Clarias gariepinus. Four groups of fishes were used: first group as control which fed on basal diet, second group fed on basal diet and exposed to (1 mg/L of lead nitrate), third group fed on diet containing 0.25% SP and exposed to (1 mg/L of lead nitrate), and fourth group fed on diet containing 0.5%SP and exposed to (1 mg/L of lead nitrate). Fish samples were taken at 2nd and 4th week of exposure. The hematological indices of lead nitrate-exposed group were decreased significantly compared to the control group at 2nd and 4th week of exposure. Lead nitrate caused a significant increase in the percentage of poikilocytosis, micronuclei, and apoptotic cells as well as comet tail length and olive tail moment compared with the control group at 2nd and 4th week of exposure. The highest level of damage was found on 4th week of exposure with all parameters. Dietary inclusion of SP ameliorated these cytotoxic and genetic changes, as well as this amelioration was concentration and time dependent. Consequently, the present study proposed that the addition of SP to the fish diet can be used as a promising protective agent to oppose cytotoxic and genotoxic effects of lead nitrate in aquaculture. Graphical abstract.


Assuntos
Peixes-Gato/metabolismo , Chumbo/toxicidade , Nitratos/toxicidade , Substâncias Protetoras/farmacologia , Spirulina/fisiologia , Poluentes Químicos da Água/toxicidade , Ração Animal/análise , Animais , Biomarcadores/sangue , Peixes-Gato/sangue , Peixes-Gato/genética , Dano ao DNA/efeitos dos fármacos , Suplementos Nutricionais , Chumbo/metabolismo , Nitratos/metabolismo , Substâncias Protetoras/análise , Poluentes Químicos da Água/metabolismo
7.
Sci Total Environ ; 677: 466-473, 2019 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-31063889

RESUMO

Mercury (Hg), cadmium (Cd), and lead (Pb) are of great concern for food safety and infants are especially sensitive to exposure to the maternal body burden. We quantified these elements in breast milk from Norwegian mothers and determined their association with dietary habits, maternal amalgam fillings, and smoking. Breast milk (n = 300) from the Norwegian Human Milk Study (HUMIS) was analyzed using triple quadrupole inductively coupled plasma mass spectrometry, after an acidic decomposition using microwave technique. We used multiple linear regression to examine predictors of Hg and Cd in breast milk, and logistic regression to test predictors of Pb above the quantification limit. The median breast milk concentrations (minimum - maximum) were 0.20 µg Hg/kg (<0.058-0.89), 0.057 µg Cd/kg (0.017-1.2), and <0.67 µg Pb/kg (<0.2-7.5). Cadmium showed no significant relation with any exposure variable investigated. Lead was associated with intake of liver and kidneys from game. For Hg concentration in breast milk, number of amalgam fillings and high fish consumption were significant predictors (p < 0.001). We detected a significant association (p < 0.01) between Hg in breast milk and maternal consumption of Atlantic halibut, lean fish, mussels and scallops and lifetime consumption of crab. Seafood intake alone explained 10% of variance, while together with amalgam explained 46% of variance in Hg concentration in breast milk. Our findings emphasize the importance of following consumer advice with respect to fish and seafood and points to amalgam as an important source for Hg exposure.


Assuntos
Cádmio/metabolismo , Amálgama Dentário/análise , Dieta , Poluentes Ambientais/metabolismo , Chumbo/metabolismo , Mercúrio/metabolismo , Leite Humano/química , Adulto , Feminino , Humanos , Mães/estatística & dados numéricos , Noruega , Adulto Jovem
8.
Environ Sci Pollut Res Int ; 26(19): 19770-19784, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31090001

RESUMO

Cd and Pb are a toxic environmental pollutant, and their elevated concentrations in the waters and soils could exert detriment effects on human health by food chain. In order to evaluate the capacity to heavy metal accumulation and the physiochemical responses of two Salix genotypes, a 35-day hydroponic seedling experiment was implemented with Salix matsudana Koidz. 'Shidi1' (A42) and Salix psammophila C. 'Huangpi1' (A94) under different concentrations of Cd (15 and 30 µM) or Pb (250 and 300 µM). The results showed that the biomass of A94 severely reduced more than that of A42. The accumulation ability of Cd in different plant organs followed the sequence of leaves > roots > stems. Pb primarily accumulated in the roots for both Salix genotypes (54.27 mg g-1 for A42 and 54.52 mg g-1 for A94). Translocation factors based on accumulation (TF') for Cd were more than 8.0, while TF's for Pb were less than 1.0 in both A42 and A94, implying they could be applied in the phytoremediation of Cd-contaminated sites due to their stronger ability to Cd phytoextraction. The stress of Cd or Pb significantly increased malondialdehyde (MDA) contents and increased photosynthetic rates in leaves of two Salix genotypes. Transpiration rates of willow were positively correlated with its Cd translocation. Both catalase (CAT) and peroxidase (POD) activities were suppressed, while the superoxide dismutase (SOD) was boosted with increasing Cd and Pb levels in the leaves and roots of the two willow genotypes, suggesting SOD plays an important role in the removal of ROS. The inconsistency of the changes in enzyme activity suggests that the integrated antioxidative mechanisms regulate the tolerance to Cd and Pb stress.


Assuntos
Antioxidantes/metabolismo , Cádmio/análise , Chumbo/análise , Salix/efeitos dos fármacos , Salix/crescimento & desenvolvimento , Poluentes do Solo/análise , Biodegradação Ambiental , Biomassa , Cádmio/metabolismo , Genótipo , Hidroponia , Chumbo/metabolismo , Salix/metabolismo , Poluentes do Solo/metabolismo
9.
Life Sci ; 230: 132-140, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31136753

RESUMO

AIMS: The testis is one of the main target organs for lead (Pb) toxicity. The current study was investigated the mechanism (s) of the therapeutic potential of thymoquinone (TQ), the active principle of Nigella sativa seed, against testicular toxicity following subchronic Pb exposure in the light of cytopathic effects, apoptotic signaling pathways, oxidative stress, serum sex hormones levels and testicular aromatase gene expression. MATERIALS AND METHODS: Thirty-two male albino rats were randomly allocated into control, PbAc (20 mg PbAc/kg bwt, orally), TQ (5 mg TQ/kg bwt dissolved in corn oil, orally), and PbAc + TQ groups for 56 successive days. KEY FINDINGS: PbAc-treated rats showed significant decrease of testes and epididymes weights, sperm count, motility and viability, spermatogenesis score and serum FSH, LH, testosterone and estradiol levels, as well as a significant decreased testicular antioxidant molecules (Superoxide dismutase enzyme and reduced glutathione), and a significant elevation of sperm abnormalities, oxidative biomarkers (Malondialdehyde and Nitric oxide) compared to a control group. In addition, Pb induced significant downregulation of aromatase gene expression, activation of Bax and Caspase-3 apoptotic pathways. Moreover, Pb caused complete seminiferous tubules hyalinization (38%), germinal epithelium sloughing (15%) and hypocellularity (8%). However, administration of TQ with PbAc improved sperm quality, testicular histology and oxidative/antioxidative status, and serum levels of LH, testosterone and E2 with respect to PbAc group. Additionally, TQ with PbAc significantly lessen the staining intensity and the area of Bax and Caspase-3 immunoexpression. SIGNIFICANCE: TQ might exert its acceptable therapeutic potential against Pb-induced testicular and spermotoxicity via anti-oxidative, endocrine and anti-apoptotic pathways.


Assuntos
Benzoquinonas/farmacologia , Espermatogênese/efeitos dos fármacos , Testículo/efeitos dos fármacos , Animais , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Aromatase/efeitos dos fármacos , Aromatase/genética , Benzoquinonas/metabolismo , Glutationa/metabolismo , Chumbo/efeitos adversos , Chumbo/metabolismo , Masculino , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Endogâmicos , Espermatozoides/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Testosterona/sangue
10.
Bull Environ Contam Toxicol ; 102(6): 887-891, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30976836

RESUMO

A long term experiment was conducted to verify the phytoremediation effect of large biomass plants and to seek the balance between remediation effect and economy. Eucalyptus globulus were planted with rotation periods of respectively 3, 6 and 9 years to examine the effect on soil remediation. Biomass and concentrations of Cd, Pb and Cu in E. globulus were measured after each harvest. The economic value of the plant was estimated. Results showed E3 (9th year uprooted) had the best soil remediation effect and economic benefit. Therefore, soil remediation and economy were best balanced when E. globulus were not cut.


Assuntos
Eucalyptus/metabolismo , Poluentes do Solo/metabolismo , Solo/química , Biodegradação Ambiental , Biomassa , Cádmio/análise , Cádmio/química , Cádmio/metabolismo , Cobre/análise , Cobre/química , Cobre/metabolismo , Eucalyptus/crescimento & desenvolvimento , Chumbo/análise , Chumbo/química , Chumbo/metabolismo , Poluentes do Solo/análise , Fatores de Tempo
11.
Mater Sci Eng C Mater Biol Appl ; 101: 686-695, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31029362

RESUMO

An efficient material is always welcoming for the water treatment due to the need of clean water to safe the human health. The conjugate adsorbent (CJA) was fabricated by functional ligand embedded onto the highly porous silica material for selective lead (Pb(II)) ion monitoring and removal from wastewater. The study was achieved not only investigating the beginning material but also the performing extrusion as novel conjugate material, this defining the material novelty of this study considers to the modern state-of-art. The fabricated material was characterized in all aspects and then the experimental works for Pb(II) ion assessing were carried in batch mode. The CJA was exposed the color and signal intensity upon addition of Pb(II) ion from low to high concentrations. The optimum pH was considered at 5.50 based on the sensitivity, the color formation ability and high adsorption of Pb(II) ion. The determined limit of low detection was 0.18 µg/L, which was the extraordinary performance for the Pb(II) ion monitoring ability by the CJA. The adsorption efficiency, specific attention was remunerated to the influence of solution pH, reaction time, foreign ion, initial Pb(II) amounts and regeneration. The CJA was exhibited high kinetic performances and showed high adsorption Pb(II) ion compared with the different forms of material. The adsorption was completely fitted with the Langmuir adsorption as defining the monolayer coverage as expected of the homogeneous porosity of the CJA. The maximum adsorption was determined as high as 175.16 mg/g. In addition, the foreign ions were not affected in the Pb(II) adsorption by the CJA, and the adsorbent was regenerated using 0.20 M HCl for several cycles used without significant loss of the initial performance. Considering these advantages, the CJA demonstrated the potential low-cost material for competitive use in wastewater remediation, especially in the developing countries.


Assuntos
Poluentes Químicos da Água/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Chumbo/metabolismo , Águas Residuárias , Purificação da Água
12.
Chemosphere ; 227: 225-236, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30991197

RESUMO

Ombrotrophic peatlands are widely used to reconstruct atmospheric metal deposition histories. Here, we estimated the long-term atmospheric Pb deposition flux using ombrotrophic peatland data from the Changbai Mountains, northeast China. A peat profile of 320-cm depth was sampled and cut into 164 slices for measurement of Pb and other elements by ICP-MS and ICP-AES and radiometric dating by 210Pb, 137Cs and 14C. Pb concentration in the peat ranged from 2.18 to 68.33 mg kg-1, while the atmospheric Pb deposition flux ranged from 0.12 to 12.49 mg m-2 a-1. The Little Ice Age (cold and wet climate) led to low Pb concentration, Pb/Sc ratio, and Pb deposition flux (4.40 ±â€¯0.70 mg kg-1, 2.04 ±â€¯0.38, and 0.28 ±â€¯0.09 mg m-2 a-1, respectively). On the other hand, intense volcanic eruptions resulted in high Pb concentration, Pb/Sc ratio, and P flux (54.48 ±â€¯13.08 mg kg-1, 7.85 ±â€¯2.09, and 8.15 ±â€¯2.85 mg m-2 a-1, respectively). In addition, rapid economic development since the 1980s resulted in a gradual increase of anthropogenic Pb concentration from 1.54 mg kg-1 to 5.85 mg kg-1; thus, the anthropogenic Pb deposition flux (0.43 ±â€¯0.21 mg m-2 a-1) was high during this period. In general, peat Pb concentration and atmospheric Pb deposition fluxes in this region have been affected by climate change, volcanic eruptions, and human activities. It was further demonstrated that atmospheric Pb emissions and deposition in China decreased since leaded gasoline was phased out in 2001. The results are critical to understand the geochemistry of Pb and to assess the effects of human activities on atmospheric Pb emissions and deposition in China.


Assuntos
Monitoramento Ambiental/métodos , Fenômenos Geológicos , Atividades Humanas , Chumbo/metabolismo , Solo/química , Poluentes Atmosféricos/análise , China , Humanos , Camada de Gelo , Radioisótopos/análise , Poluentes do Solo/análise , Erupções Vulcânicas
13.
Chemosphere ; 227: 172-178, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30986599

RESUMO

The subcellular distribution and chemical forms of lead (Pb) were examined in the red algae, Porphyra yezoensis. The algae was exposed to three different Pb treatments (0.01, 0.1 and 1.0 mg L-1) for up to 144 h. In the control groups, about 45% of Pb was localized in the cell wall, and 27.5% in the organelle and soluble fractions respectively. The dominant chemical forms of Pb was extracted by 80% ethanol (52.9%), while the form extracted by NaCl (1 M) was lowest. In the treatment groups, the cell wall and the organelle fraction were the main subcellular fractions for the 0.10 mg L-1 and 1.0 mg L-1 groups; while for the 0.01 mg L-1 groups, Pb was approximately distributed in the cell wall, organelle and the soluble fractions. The dominant ethanol extractable form of Pb in the control and 0.01 mg L-1 groups were replaced by less active 2% acetic acid (HAc) extractable form in the 0.1 and 1.0 mg L-1 groups. Different from other terrestrial plants, the proportion of 1 M NaCl extractable form of the pectates and protein integrated Pb in P. yezoensis was lowest for both control and treatment groups. The strategy with deposition Pb in the cell wall and formation the precipitation of less active HAc extractable form maybe one of the mechanisms for accumulation, transportation and detoxification of Pb in P. yezoensis.


Assuntos
Chumbo/metabolismo , Porphyra/metabolismo , Poluentes Químicos da Água/metabolismo , Parede Celular , Plantas
14.
Water Sci Technol ; 79(4): 627-634, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30975929

RESUMO

The biosorption of Pb(II) from aqueous solutions by lactic acid bacterium, Lactobacillus brevis, was studied. The effects of initial pH, contact time, initial Pb(II) concentration, bacterial concentration, rotation speed and temperature of biosorption of Pb(II) from aqueous solutions were investigated. The optimal condition for Pb2+ ions adsorption was observed at pH 6, with the rotational speed of 120 rpm.min-1, bacterial concentration of 3 g.L-1, temperature of 40 °C and contact time of 12 h. The correlation regression coefficients showed that the biosorption process can be well fitted with the Redlich-Peterson, Langmuir, Freundlich and Temkin isotherm models. The equilibrium adsorption capacity reached 53.632 mg.g-1. Binding energy value was 0.264 kJ/mol, which indicated that the adsorption process seemed to involve chemisorption and physisorption. Kinetics of adsorption was found to fit well with the pseudo-second-order and Elovich kinetic equations. Thermodynamic parameters revealed the feasibility, spontaneity and endothermic nature of adsorption.


Assuntos
Lactobacillales/metabolismo , Chumbo/metabolismo , Poluentes Químicos da Água/metabolismo , Adsorção , Biodegradação Ambiental , Concentração de Íons de Hidrogênio , Cinética , Chumbo/análise , Soluções , Termodinâmica , Poluentes Químicos da Água/análise
15.
J Basic Microbiol ; 59(5): 477-486, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30900761

RESUMO

In the present study, a lead (Pb)-resistant bacterium, Staphylococcus hominis strain AMB-2 was isolated from Mandoli industrial area, Delhi and selected for heavy metal biosorption considering multiple heavy metal resistance. In the batch experiment, both living and dead biomasses of strain AMB-2 showed biosorption of Pb and cadmium (Cd) in single and binary systems as analyzed through Inductively coupled plasma-optical emission spectrometry. Living biomass exhibited more biosorption of metals than dead biomass in both single and binary systems. However, in the binary system, metals competed for the attachment sites on the bacterial surface, where Pb got more preference over Cd for the same. The underlying mechanism for the biosorption was attachment of the metal ions through functional groups onto the surface of the biomass as revealed by scanning electron microscope-energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction. Conclusively, this study displayed an effective biotreatment of Pb and Cd from aqueous medium using a low-cost biosorbent prepared from S. hominis strain AMB-2 considering biosafety of microorganisms and an eco-friendly approach.


Assuntos
Chumbo/metabolismo , Metais Pesados/metabolismo , Staphylococcus hominis/metabolismo , Poluentes Químicos da Água/metabolismo , Adsorção , Biodegradação Ambiental , Biomassa , Cádmio/metabolismo , Testes de Sensibilidade Microbiana , Filogenia , Microbiologia do Solo , Staphylococcus hominis/classificação , Staphylococcus hominis/isolamento & purificação , Staphylococcus hominis/ultraestrutura
16.
Artigo em Inglês | MEDLINE | ID: mdl-30845745

RESUMO

Aegean Sea albacore (T. alalunga), fresh or processed, is marketed locally in Greece or exported, mainly to Japan, Italy, Spain, and France. To provide information for consumers and biomonitoring programs and assess the potential human health risks, concentrations of mercury (Hg), cadmium (Cd) and lead (Pb) were determined in albacore edible muscle samples from two fishing grounds of the Aegean Sea, Greece via graphite furnace atomic absorption spectrometry (GF-AAS). Of the 82 individuals, 28 contained Cd and three contained Pb above the permissible limits set by the European Union (0.1 mg kg-1 wet wt and 0.3 mg kg-1 wet wt, respectively). None of the samples contained mercury above the limit (1.0 mg kg-1 wet wt). Potential health risks to human via dietary intake of albacore were estimated by the total target hazard quotients (TTHQs), which indicated that the consumers could acquire health problems due to consumption of Aegean Sea albacore. Thus consequently, concentrations of toxic heavy metals in albacore, especially mercury, must be monitored regularly and comprehensively with respect to consumer health.


Assuntos
Cádmio/metabolismo , Chumbo/metabolismo , Mercúrio/metabolismo , Atum/metabolismo , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/toxicidade , Animais , Cádmio/toxicidade , Exposição Dietética , Monitoramento Ambiental/métodos , Contaminação de Alimentos/análise , Grécia , Humanos , Japão , Chumbo/toxicidade , Região do Mediterrâneo , Mercúrio/toxicidade , Fatores de Risco , Água do Mar , Espectrofotometria Atômica
17.
Bioresour Technol ; 283: 86-95, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30901592

RESUMO

This study depicts successful employment of fixed bed column bioreactor for adsorption of lead in continuous mode using lentil husk as sorbent. Design parameters considerably controlled the reactor performance, amongst which height of the fixed bed and flow rate were crucial in generating cleaner effluent. Adsorption capacity was found to shoot up to the level of 205.87 mg g-1 at 10 cm bed height, 100 mg L-1 feed concentration and 20 mL min-1 flow rate. Kinetic study done at regular intervals of time revealed high percentage removal of lead (99-96%) throughout entire span of reactor operation. Experimental data were well interpreted by Thomas model and Yoon-Nelson model. The reactor bed was regenerated after each adsorption and loaded metal was recovered up to the extent of ∼96%. The column reactor was efficient enough to treat lead containing actual industrial effluents.


Assuntos
Reatores Biológicos , Chumbo/metabolismo , Lens (Planta)/metabolismo , Adsorção , Cinética
18.
Ecotoxicol Environ Saf ; 174: 699-705, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30878010

RESUMO

In the present study, we investigated the role of calcite, i.e., microbiologically-induced precipitate by ureolytic Trichoderma sp. MG, in remediation of soils contaminated with arsenic (As) and lead (Pb). The fungus tolerates high concentrations of As (500 mg/L) and Pb (650 mg/L). The effects of three factors, i.e., urea concentration, CaCl2 concentration and pH, on urease production and bio-mineralization of As and Pb were investigated using Box-Behnken design. The maximum urease production (920 U/mL) and metal removal efficiency (68% and 59% for Pb and AS, respectively) were observed in the medium containing urea of 300 mM and CaCl2 of 75 mM at pH 9.0. Fourier transform infrared spectroscopy result revealed the formation of metal carbonates by the isolate MG. Sequential extraction of metals revealed that the carbonate fractions of As and Pb were increased to 46.4% and 42.4% in bioremediated soil, whereas in control they were 35.5% and 32.5%, respectively. The X-ray powder diffraction result further confirmed the role of calcite precipitate in bioremediation of As- and Pb-contaminated soils. The results points out that the microbiologically-induced calcite precipitation is a feasible, eco-friendly technology for the bioremediation of As- and Pb-contaminated sites.


Assuntos
Arsênico/metabolismo , Chumbo/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Trichoderma/metabolismo , Arsênico/química , Biodegradação Ambiental , Carbonato de Cálcio/química , Carbonatos/química , Chumbo/química , Solo/química , Trichoderma/enzimologia , Urease/biossíntese
19.
Ecotoxicol Environ Saf ; 174: 255-262, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30831474

RESUMO

This study aimed to assess the effects of endophyte infection on Pb accumulation, organic acids (OAs) and mineral element contents by comparing endophyte-uninfected (E-) and endophyte-infected (E+) rice exposed to 0, 10.36, 20.72, 31.08 and 41.44 mg/L Pb2+ for 10 days. Pb2+ stress decreased growth, dry weight, and chlorophyll (Chl) content in E- and E+ in a concentration-dependent manner. Pb2+ accumulation was similar in E- and E+. Under Pb2+ stress, E+ accumulated more malate and fumarate in the leaves compared to E-, as well as more tartrate, malate, succinate and fumarate in the roots. Furthermore, E+ secreted more malate and lactate under 41.44 mg/L Pb2+ stress. Malate accumulation was induced by endophyte infection under Pb2+ exposure suggesting that malate is the most obvious candidate ligand for Pb2+. Endophyte infection increased Ca, Mg, P, Fe and Ni contents in the leaves and Ni contents in the roots under Pb2+ stress, but reduced Fe content in the roots under high Pb2+ stress. Under same Pb2+ concentration, endophyte infection significantly increased plant height, the dry weight of the shoots, and Chl content. The effects of endophyte infection might be due to changes in OAs accumulation and exudation and improvements in mineral uptake under Pb2+ stress.


Assuntos
Ascomicetos/metabolismo , Endófitos/metabolismo , Chumbo/metabolismo , Malatos/metabolismo , Minerais/metabolismo , Oryza/microbiologia , Poluentes do Solo/metabolismo , Antioxidantes/metabolismo , Ascomicetos/crescimento & desenvolvimento , Endófitos/crescimento & desenvolvimento , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia
20.
Sci Total Environ ; 669: 471-480, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30884269

RESUMO

Poisoning, including secondary lead poisoning, is cited as the single most important cause of vulture mortalities in Africa. To evaluate the prevalence of lead poisoning among South Africa's Gyps vultures compared to other, non-scavenging birds, we obtained blood and bone samples from Cape (Gyps coprotheres) and White-backed (G. africanus) vultures. We found that 66% of White-backed Vultures (n = 110, including 85 nest-bound chicks sampled at Dronfield Nature Reserve) and 80% of Cape Vultures (n = 15) had blood [Pb] in excess of 10 µg/dL, the upper limit of background exposure. Average blood [Pb] were 15.4 µg/dL and 29.7 µg/dL for White-backed and Cape vultures, respectively. Bone samples revealed that 12% of White-backed Vultures (n = 18) and 9% of Cape Vultures (n = 75) suffered from subclinical to severe clinical lead poisoning upon their deaths. By contrast, none of the 40 blood, bone or liver samples obtained from non-scavenging bird species were found to exceed background exposure levels. Our results suggest that, unlike non-scavenging birds, the scavenging lifestyle of Gyps vultures subjects them to lead poisoning on a regular basis. Had environmental sources of lead (e.g., dust) been the source of the lead poisoning at the White-backed Vulture breeding colony at Dronfield, all the chicks would have displayed similar blood lead concentrations. Instead the values ranged from barely detectable to very high, leading us to conclude that metallic lead fragments regurgitated by parents during feeding are responsible for the elevated lead levels in some of the chicks at this site. We conclude the likely source of these particles to be fragments of lead ammunition embedded in the carcasses of hunted animals. These results add to a growing body of evidence underscoring the threat posed by the use of lead ammunition and its potential role in the declines of vultures and other scavenging taxa.


Assuntos
Monitoramento Ambiental , Poluentes Ambientais/metabolismo , Falconiformes/metabolismo , Chumbo/metabolismo , Animais , Osso e Ossos/metabolismo , Poluentes Ambientais/sangue , Chumbo/sangue , África do Sul
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