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1.
Chemosphere ; 254: 126904, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957297

RESUMO

Estimating bioaccessible content of mercury in soils is essential in evaluating risks that contaminated soils pose. In this study, soil samples spiked with HgCl2 through adsorption were used to test the effects of liming, soil organic matter, soil depth, and Hg concentration on the following bioaccessibility tests: dilute nitric acid at room temperature, dilute nitric acid at body temperature, Simplified Bioaccessibility Extraction Test (SBET) method, and gastric phase of the In vitro Gastrointestinal (IVG) protocol. Soil and sediment samples from Descoberto, Minas Gerais (Brazil), a city with a well-known record of Hg contamination from artisanal mining, were subjected to these bioaccessibility tests for the first time, and the different methods of estimating bioaccessible content were compared. Bioaccessible fractions in spiked samples ranged from 10% to 60%, and this high bioaccessibility was due to the highly soluble species of Hg and the short time under adsorption. In general, clay and organic matter decreased bioaccessible content. Although the soil in Descoberto is undoubtedly polluted, mercury bioaccessibility in that area is low. In general, dilute nitric acid estimated higher bioaccessible content in soil samples, whereas the SBET method estimated higher bioaccessible content in sediment samples. In multivariate analysis, two groups of bioaccessibility tests arise: one with the two nitric acid tests, and the other with SBET and the gastric phase of the IVG protocol. The addition of pepsin and glycine in the last two tests suggests a more reliable test for assessing mercury bioaccessibility.


Assuntos
Argila/química , Substâncias Húmicas/análise , Mercúrio/análise , Mineração , Poluentes do Solo/análise , Solo/química , Adsorção , Disponibilidade Biológica , Brasil , Cidades , Mucosa Gástrica/metabolismo , Humanos , Mucosa Intestinal/metabolismo , Mercúrio/metabolismo , Modelos Biológicos , Ácido Nítrico/química , Poluentes do Solo/metabolismo
2.
Ecotoxicol Environ Saf ; 203: 110961, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888621

RESUMO

Cadmium (Cd), which seriously affects plant growth and crop production, is harmful to humans. Previous studies revealed ryegrass (Lolium multiflorum Lam.) exhibits Cd tolerance, and may be useful as a potential hyperaccumulator because of its wide distribution. In this study, the physiological and transcriptional responses of two ryegrass cultivars [i.e., high (LmHC) and low (LmLC) Cd tolerance] to Cd stress were investigated and compared. The Cd tolerance of LmHC was greater than that of LmLC at various Cd concentrations. The uptake of Evans blue dye revealed that Cd-induced root cell mortality was higher in LmLC than in LmHC after a 12-h Cd treatment. Furthermore, the content and influx rate of Cd in LmLC roots were greater than in LmHC roots under Cd stress conditions. The RNA sequencing and quantitative real-time PCR data indicated that the Cd transport regulatory genes (ABCG37, ABCB4, NRAMP4, and HMA5) were differentially expressed between the LmLC and LmHC roots. This expression-level diversity may contribute to the differences in the Cd accumulation and translocation between LmLC and LmHC. These findings may help clarify the physiological and molecular mechanisms underlying ryegrass responses to Cd toxicity. Additionally, ryegrass may be able to hyperaccumulate toxic heavy metals during the phytoremediation of contaminated soil.


Assuntos
Adaptação Biológica , Cádmio/metabolismo , Lolium/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Poluentes do Solo/metabolismo , Transcrição Genética/efeitos dos fármacos , Adaptação Biológica/efeitos dos fármacos , Adaptação Biológica/genética , Biodegradação Ambiental , Cádmio/análise , Cádmio/toxicidade , Genes de Plantas , Lolium/química , Lolium/genética , Raízes de Plantas/química , Raízes de Plantas/genética , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
3.
Chemosphere ; 258: 127337, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947656

RESUMO

The experiment was designed to evaluate the roles of Rhizophagus irregularis on chlorophyll fluorescence and chromium bioaccumulation in a grass species (Brachiaria mutica) by supplementing Cr+6 at different concentrations. Arbuscular Mycorrhizal Fungi (AMF) association facilitated lessening of chromium level in contaminated soil and enhanced chromium bioavailability in Brachiaria mutica. The mycorrhizal inoculated increased the chlorophyll (0.925 mg/g), carotenoid (0.127 mg/g), protein (2.883 mg/g), proline (0.889 mg/g) contents and activities of antioxidant enzymes like catalase, ascorbate peroxidase and glutathione peroxidase. The mycorrhizal inoculated plants also showed enhanced overall photosynthetic performance (PIϕ = 2.473) and enhanced PS-II to PS-I electron transport as evident from yield parameter (0.712) and TR0/RC (2.419) for 60 mg/kg Cr+6 treatment. The observations suggest that AMF association could defend the plants from chromium stress by elevating the number of antioxidants in plants. Rhizophagus irregularis was found to maintain a successful symbiotic relationship with Brachiaria mutica in chromium contaminated soil. The observations recommended that Rhizophagus irregularis in association with Brachiaria mutica would be an innovative approach for decontamination of Cr+6.


Assuntos
Biodegradação Ambiental , Brachiaria/metabolismo , Cromo/metabolismo , Poluentes do Solo/metabolismo , Antioxidantes/metabolismo , Bioacumulação , Clorofila/metabolismo , Cromo/análise , Glomeromycota/metabolismo , Micorrizas/metabolismo , Fotossíntese , Plantas/metabolismo , Poaceae/metabolismo , Solo , Poluentes do Solo/análise , Simbiose
4.
Chemosphere ; 258: 127405, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947677

RESUMO

Chelation of lead (Pb) is an important factor in enhancing the Pb mobility thereby improving availability to promote phytoremediation of Pb from contaminated soil. The study was conducted to evaluate the effect of amendments in enhancing the phytoremediation of Pb in soil. For this purpose, soil was spiked to obtain desired Pb concentrations (0-1500 mg kg-1) and pots were filled. One month old and uniform seedlings of Pelargonium hortoum were transplanted into each pot. Five different amendments i.e. compost (0-10%), ammonium nitrate (0-10 mmol kg-1), TiO2NPs (0-100 mg kg-1), citric acid (0-10 mmol kg-1) and EDTA (0-5 mmol kg-1), were applied. Overall, ammonium nitrate, EDTA and citric acid application increased the Pb concentration, however, compost and TiO2NPs decreased the concentration in roots and shoots. At 1500 mg Pb kg-1, Pb concentration in shoots was increased by 0.9-, 0.6- & 0.8-folds and in roots by 1.8-, 1.3- & 1.7-folds upon EDTA, ammonium nitrate and citric acid application, respectively. TiO2NPs and compost application decreased Pb concentration by 29% & 35% in shoots and 25% & 51% in roots, respectively. At the highest level of Pb (1500 mg kg-1), plant biomass was increased by 26.6%, 19.5%, 17.9% and 18.4% upon application of compost, TiO2 NPs, ammonium nitrate and citric acid, respectively. However, EDTA reduced the plant dry biomass by 28.4%. The accumulated Pb content was recovered as Pb-nanoparticles, which were in anatase phase, size ranged between 98 and 276 nm. Among all the studied amendments, citric acid efficiently increased Pb phytoaccumulation without any toxicity.


Assuntos
Biodegradação Ambiental , Chumbo/análise , Poluentes do Solo/análise , Biomassa , Quelantes , Ácido Cítrico , Compostagem , Ácido Edético , Chumbo/metabolismo , Pelargonium , Raízes de Plantas , Solo , Poluentes do Solo/metabolismo
5.
Chemosphere ; 258: 127342, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947679

RESUMO

Environmental contaminations by potentially toxic metals (PTMs) are associated with energy exploitation and present a significant problem in urban areas due to their impacts on human health. The PTMs status in Urumqi total environment inevitably impacted by extensive development of coal and oil industries has been lack of understanding comprehensively. A series of PTMs (As, Ba, Ce, Co, Cr, Cu, Ga, La, Mn, Ni, Pb, Rb, Sr, Th, U, V, Y, Zn, Zr) in the soil-dust-plant (foliage of Ulmus pumila L.) system of Urumqi (NW China) were screened by XRF and ICPMS. Multivariate statistics, risk models, GIS-based geostatistics, Positive Matrix Factorization (PMF) receptor modelling and blood lead levels of 0-6 aged children evaluated by IEUBK model are used to determine the priority pollutants, sources and health effects of the investigated elements. The spatial distribution of PTMs in soil-dust-plant system significantly coincides with coal combustion, traffic emission, and industrial activity. Although all PTM toxicants in soil, dust and tree foliage show some effects, the priority contaminants are observed for Cu, Pb and Zn as single element. The total carcinogenic and non-carcinogenic risks from PTMs are beyond the tolerance range of 0-6 year's old children, and the dust (TCR = 1.07E-04) PTMs pose approximatively equivalent carcinogenic risk to soil PTMs (TCT = 1.09E-04). The predicted BLLs (75-83 µ g·L-1) of 1-2 years children are most strongly influenced by Pb in soil and dust, and therefore more attention should be focused on sources of Pb to support the primary health care of the toddlers in Urumqi.


Assuntos
Exposição Ambiental/estatística & dados numéricos , Metais Pesados/sangue , Poluentes do Solo/sangue , Carcinógenos , China , Poeira/análise , Monitoramento Ambiental , Poluentes Ambientais , Poluição Ambiental/estatística & dados numéricos , Substâncias Perigosas , Humanos , Indústrias , Chumbo/sangue , Metais Pesados/análise , Metais Pesados/metabolismo , Medição de Risco , Solo , Poluentes do Solo/análise , Poluentes do Solo/metabolismo
6.
Ecotoxicol Environ Saf ; 203: 110999, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888604

RESUMO

Aluminium (Al) is a key element that plays a major role in inhibiting plant growth and productivity under acidic soils. While lipids may be involved in plant tolerance/sensitivity to Al, the role of monogalactosyldiacylglycerol (MGDG) in Al response remains unknown. In this study, Arabidopsis MGDG synthase (AtMGD) mutants (mgd1, mgd2 and mgd3) and wild-type (Col-0) plants were treated with AlCl3; the effect of aluminium on root growth, aluminium distribution, plasma membrane integrity, lipid peroxidation, hydrogen peroxide content and membrane lipid compositions were analysed. Under Al stress, mgd mutants exhibited a more severe root growth inhibition, plasma membrane integrity damage and lipid peroxidation compared to Col-0. Al accumulation in root tips showed no difference between Col-0 and mutants under Al stress. Lipid analysis demonstrated that under Al treatment the MGDG content in all plants and MGDG/DGDG (digalactosyldiacylglycerol) remarkably reduced, especially in mutants impairing the stability and permeability of the plasma membrane. These results indicate that the Arabidopsis mgd mutants are hypersensitive to Al stress due to the reduction in MGDG content, and this is of great significance in the discovery of effective measures for plants to inhibit aluminium toxicity.


Assuntos
Alumínio/toxicidade , Arabidopsis/efeitos dos fármacos , Galactolipídeos/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Poluentes do Solo/toxicidade , Alumínio/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Galactolipídeos/genética , Galactosiltransferases/genética , Galactosiltransferases/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Lipídeos de Membrana/metabolismo , Mutação , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Poluentes do Solo/metabolismo
7.
Ecotoxicol Environ Saf ; 204: 111086, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32781345

RESUMO

In the present research, Silene vulgaris as a representative species growing on both unpolluted and heavy metal (HM) polluted terrains were used to identify ecotype-specific responses to metallic stress. Growth, cell ultrastructure and element accumulations were compared between non-metallicolous (NM), calamine (CAL) and serpentine (SER) specimens untreated with HMs and treated with Pb, Cd and Zn ions under in vitro conditions. Moreover, proteins' modifications related to their level, carbonylation and degradations via vacuolar proteases were verified and linked with potential mechanisms to cope with ions toxicity. Our experiment revealed diversified strategy of HM uptake in NM and both metallicolous ecotypes, in which antagonistic relationship of Zn and Pb/Cd ions provided survival benefits for the whole organism. Despite this similarity, growth rate and metabolic pathways induced in CAL and SER shoots varied significantly. Exposition to HMs in CAL culture led to drop in protein level by approximately 16% compared to the control. This parameter nearly correlated with the enhanced activity of proteases at pH 5.2 as well as possible glutamate changes to proline and reduced glutathione, resulting in intensified growth and first signs of cell senescence. In turn, SER shoots were characterized by growth retardation (to 53% of the control), although protein level and carbonylation were not modified, while a deeper insight into protein network showed its remodeling towards production of polyamines and 2-oxoglutarate delivered to the Krebs cycle. Contrary, an uncontrolled HM influx in NM shoots contributed to morpho-structural disorders accompanied by an increase activity of proteases involved in the degradation of oxidized proteins, what pointed to metal-induced autophagy. Taken together, S. vulgaris ecotypes respond to stress by triggering various mechanisms engaged their survival and/or death under HM treatment.


Assuntos
Cádmio/toxicidade , Chumbo/toxicidade , Proteínas de Plantas/metabolismo , Silene/efeitos dos fármacos , Poluentes do Solo/toxicidade , Zinco/toxicidade , Autofagia/efeitos dos fármacos , Bioacumulação/efeitos dos fármacos , Cádmio/metabolismo , Ecótipo , Glutationa/metabolismo , Chumbo/metabolismo , Modelos Teóricos , Estresse Oxidativo/efeitos dos fármacos , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/metabolismo , Brotos de Planta/ultraestrutura , Silene/crescimento & desenvolvimento , Silene/metabolismo , Silene/ultraestrutura , Poluentes do Solo/metabolismo , Zinco/metabolismo
8.
Ecotoxicol Environ Saf ; 204: 111020, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32810706

RESUMO

Over the past 30 years, the ever-rising demands of the modern and growing population have led to the rapid development of agricultural and industrial sectors worldwide. However, this expansion has exposed the environment to various pollutants including heavy metal (HM)s. Almost all HMs are serious toxicants and can pose serious health risks to living organisms in addition to their bioaccumulative and non-biodegradable nature. Different techniques have been developed to restore the ecological functions of the HM-contaminated soil (HMCS). However, the major downfalls of the commonly used remediation technologies are the generation of secondary wastes, high operating costs, and high energy consumption. Phytoremediation is a prominent approach that is more innocuous than the existing remediation approaches. Some microbes-plant interactions enhance the bioremediation process, with heavy metal resistant-plant growth promoting bacteria (HMRPGPB) being widely used to assist phytoremediation of HMs. However, the most common of all major microbial assisted-phytoremediation disturbances is that the HM-contaminated soil is generally deficient in nutrients and cannot sustain the rapid growth of the applied HMRPGPB. In this case, biochar has recently been approved as a potential carrier of microbial agents. The biochar-HMRPGPB-plant association could provide a promising green approach to remediate HM-polluted sites. Therefore, this review addresses the mechanisms through which biochar and HMRPGPB can enhance phytoremediation. This knowledge of biochar-HMRPGPB-plant interactions is significant with respect to sustainable management of the HM-polluted environment in terms of both ecology and economy, and it offers the possibility of further development of new green technologies.


Assuntos
Bactérias/metabolismo , Biodegradação Ambiental , Carvão Vegetal/farmacologia , Embriófitas/metabolismo , Metais Pesados/metabolismo , Poluentes do Solo/metabolismo , Desenvolvimento Vegetal/efeitos dos fármacos , Desenvolvimento Vegetal/fisiologia , Solo/química
9.
Ecotoxicol Environ Saf ; 204: 111038, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32739674

RESUMO

Soil management using fertilizers can modify soil chemical, biochemical and biological properties, including the concentration of trace-elements as cadmium (Cd), chromium (Cd) and nickel (Ni). Bacterial isolates from Cd, Cr, and Ni-contaminated soil were evaluated for some characteristics for their use in bioremediation. Isolates (592) were obtained from soil samples (19) of three areas used in three maize cultivation systems: no-tillage and conventional tillage with the application of mineral fertilizers; minimum tillage with the application of sewage sludge. Four isolates were resistant to Cr3+ (3.06 mmol dm-3) and Cd2+ (2.92 mmol dm-3). One isolate was resistant to the three metals at 0.95 mmol dm-3. All isolates developed in a medium of Cd2+, Cr3+ and Ni2+ at 0.5 mmol dm-3, and removed Cd2+ (17-33%) and Cr6+ (60-70%). They were identified by sequencing of the gene 16S rRNA, as bacteria of the genera Paenibacillus, Burkholderia, Ensifer, and two Cupriavidus. One of the Cupriavidus isolate was able to remove 60% of Cr6+ from the culture medium and showed high indole acetic acid production capacity. We evaluated it in a microbe-plant system that could potentially be deployed in bioremediation by removing toxic metals from contaminated soil.


Assuntos
Bactérias/metabolismo , Cádmio/metabolismo , Cromo/metabolismo , Níquel/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Agricultura , Bactérias/isolamento & purificação , Biodegradação Ambiental , Brasil , Clima Tropical
10.
Chemosphere ; 260: 127668, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32758779

RESUMO

A series of pollutants can be removed from soil using a Fenton-like oxidation and biological treatment. As a natural mineral, tourmaline has been used for as a material of Fenton-like reaction. In the present study, the risks of remediation technology tourmaline catalyzed Fenton-like reaction (TCFR) combined with Phanerochaete chrysosporium (TCFR + P) were assessed through measuring soil properties, physiological response of plant, and PBDEs migration from soil to plant. Batch pot experiments showed that the silicon contents, specific surface area and soil pore size of soil in TCFR and 5%TCFR + P groups increased obviously. TCFR and TCFR + P treatments promoted the lettuce growth compared to control. Moreover, chlorophyll content of lettuce in 2%TCFR + P and 5%TCFR + P group increased by 46.74% and 44.57% than that in the CK, respectively. The treatment of 2%TCFR decreased the total concentration of PBDEs in rhizosphere soil and non-rhizosphere soil by 52.0.2% and 64.17%, respectively, after 60 days compared to the soil of CK, and did not prompt the uptake of lower-brominated PBDEs by lettuce. TCFR and TCFR + P can alter the migration of BDE isomers from soil to plant, the ratio of BDE99/BDE100 in lettuce shoots decreased slightly. BDE-99/BDE-100 ratios in the shoots were lower than those in the roots, while BDE153/BDE154 ratios were higher than 1.0 and ratios in shoots were higher than those in roots. Therefore, our findings illustrated that the TCFR could be applied to remediate the agricultural soil, considering the appropriate doses of tourmaline.


Assuntos
Biodegradação Ambiental , Éteres Difenil Halogenados/metabolismo , Silicatos/química , Poluentes do Solo/metabolismo , Catálise , Éteres Difenil Halogenados/análise , Alface , Minerais , Phanerochaete , Raízes de Plantas/química , Bifenil Polibromatos , Rizosfera , Solo , Poluentes do Solo/análise
11.
Ecotoxicol Environ Saf ; 202: 110929, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800215

RESUMO

The aim of this study was to investigate the bioremediation potential of polychlorinated biphenyls (PCBs) in soil, mimicking three strategies: (a) mycoaugmentation: by the addition of Trametes sanguinea and Pleurotus sajor-caju co-cultures immobilized on sugarcane bagasse; (b) biostimulation: by supplementation of sugarcane bagasse; and (c) natural attenuation: no amendments. The experiments were done in microcosms using Ultisol soil. Remediation effectiveness was assessed based on pollutants content, soil characteristics, and ecotoxicological tests. Biostimulation and mycoaugmentation demonstrated the highest PCBs-removal (approx. 90%) with a significant toxicity reduction at 90 d. The studied strains were able to survive during the incubation period in non-sterilized soil. Laccase, manganese-peroxidase and endoxylanase activities increased significantly in co-cultures after 60 d. Sugarcane bagasse demonstrated to be not only a suitable support for fungal immobilization but also an efficient substrate for fungal colonization of PCBs-contaminated soils. Mycoaugmentation and biostimulation with sugarcane bagasse improved oxidable organic matter and phosphorous contents as well as dehydrogenase activity in soil. Therefore, biostimulation with sugarcane bagasse and mycoaugmentation applying dual white-rot fungal cultures constitute two efficient bioremediation alternatives to restore PCBs-contaminated soils.


Assuntos
Biodegradação Ambiental , Poluentes do Solo/metabolismo , Celulose , Ecotoxicologia , Lacase , Peroxidases , Fósforo , Bifenilos Policlorados , Saccharum , Solo/química , Microbiologia do Solo , Poluentes do Solo/análise , Trametes
12.
Ecotoxicol Environ Saf ; 202: 110908, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800243

RESUMO

Chinese milk vetch is an efficient approach to reduce Cd accumulation in rice, nevertheless, its reduction mechanism is not well understood. In this study, we investigated the rice grain Cd, soil properties and microbial community in a Cd-polluted paddy field amended with milk vetch residue (MV) or without (CK) during rice growth period. We found that milk vetch residue averagely decreased the Cd content in rice grain by 45%. Decrease of Cd in rice mainly attributed to the inhibition of Cd activation by milk vetch residue at heading stage probably by the formation of HA-Cd (Humic Acid) and CdS. Increased pH and organic matter (OM) promoted the reduction of available Cd. In addition, nonmetric multidimensional scaling (NMDS) analysis revealed that microbial community structure was significantly different between MV and CK treatment (r = 0.187, p = 0.002), and the core functions of differentially abundant genera were mainly associated with N-cycling, organic matter degradation and sulfate-reducing. The application of milk vetch residue increased the abundance of sulfate-reducing bacteria (SRB) by 8-112% during the rice growth period, which may involve in promoting the transformation of Cd to a more stably residual Cd (CdS). Canonical correspondence analysis (CCA) and mantel test analysis indicated that available K (p = 0.004) and available N (p = 0.005) were the key environmental factors of shaping the SRB. Altogether, changes in soil properties affected microbial structure and functional characteristics, especially the response of SRB in MV treatment would provide valuable insights into reducing the bioavailability of Cd in soil.


Assuntos
Astrágalo (Planta)/metabolismo , Cádmio/metabolismo , Oryza/metabolismo , Poluentes do Solo/metabolismo , Animais , Astrágalo (Planta)/microbiologia , Disponibilidade Biológica , Grão Comestível/química , Substâncias Húmicas/análise , Resíduos Industriais , Microbiota , Leite , Solo/química , Poluentes do Solo/análise
13.
Ecotoxicol Environ Saf ; 202: 110917, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800252

RESUMO

Cadmium (Cd) is an extremely toxic environmental pollutant with high mobility in soils, which can contaminate groundwater, increasing its risk of entering the food chain. Yeast biosorption can be a low-cost and effective method for removing Cd from contaminated aqueous solutions. We transformed wild-type Saccharomyces cerevisiae (WT) with two versions of a Populus trichocarpa gene (PtMT2b) coding for a metallothionein: one with the original sequence (PtMT2b 'C') and the other with a mutated sequence, with an amino acid substitution (C3Y, named here: PtMT2b 'Y'). WT and both transformed yeasts were grown under Cd stress, in agar (0; 10; 20; 50 µM Cd) and liquid medium (0; 10; 20 µM Cd). Yeast growth was assessed visually and by spectrometry OD600. Cd removal from contaminated media and intracellular accumulation were also quantified. PtMT2b 'Y' was also inserted into mutant strains: fet3fet4, zrt1zrt2 and smf1, and grown under Fe-, Zn- and Mn-deficient media, respectively. Yeast strains had similar growth under 0 µM, but differed under 20 µM Cd, the order of tolerance was: WT < PtMT2b 'C' < PtMT2b 'Y', the latter presenting 37% higher growth than the strain with PtMT2b 'C'. It also extracted ~80% of the Cd in solution, and had higher intracellular Cd than WT. Mutant yeasts carrying PtMT2b 'Y' had slightly higher growth in Mn- and Fe-deficient media than their non-transgenic counterparts, suggesting the transgenic protein may chelate these metals. S. cerevisiae carrying the altered poplar gene offers potential for bioremediation of Cd from wastewaters or other contaminated liquids.


Assuntos
Biodegradação Ambiental , Cádmio/metabolismo , Metalotioneína/genética , Proteínas de Plantas/genética , Populus/genética , Saccharomyces cerevisiae/genética , Poluentes do Solo/metabolismo , Cádmio/toxicidade , Metalotioneína/metabolismo , Metais Pesados/análise , Populus/metabolismo , Saccharomyces cerevisiae/metabolismo , Solo
14.
Bull Environ Contam Toxicol ; 105(3): 490-495, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32740747

RESUMO

Persistence and environmental implication of pharmaceuticals in agricultural soil is determined depending on adsorption, bioavailability and toxicity. This study aims to assess adsorption/partitioning behaviour of diclofenac (DCF) and its impact on microbial activity in four agricultural soils, differing in pH, organic carbon content, and cation exchange capacity. Results from batch studies suggests that soil/water partition coefficients of DCF are essentially nonlinear, i.e. depends on drug amount (p = 0.001), and positively correlated with soil organic carbon (p = 0.008). The adsorption data can effectively be modelled using Freundlich isotherm (regression coefficients between 0.84 and 0.90). In soil incubation studies, DCF could not be detected after 6 days of spiking (20 µg/g) in all soil types, including abiotic control. This suggests an interplay of combined biotic/abiotic process in DCF removal. Though microbial activity (based on tetrazolium reduction) declined with incubation time, but was not correlated with DCF exposure, particularly in soils rich in organic carbon.


Assuntos
Diclofenaco/toxicidade , Microbiologia do Solo , Poluentes do Solo/toxicidade , Adsorção , Agricultura , Disponibilidade Biológica , Carbono , Diclofenaco/metabolismo , Solo/química , Poluentes do Solo/análise , Poluentes do Solo/metabolismo
15.
Ecotoxicol Environ Saf ; 202: 110950, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800226

RESUMO

Human exposure to methylmercury (MeHg) through rice consumption is raising health concerns. It has long been recognized that MeHg found in rice grain predominately originated from paddy soil. Anaerobic conditions in paddy fields promote Hg methylation, potentially leading to high MeHg concentrations in rice grain. Understanding the transformation and migration of Hg in the rice paddy system, as well as the effects of farming activities, are keys to assessing risks and developing potential mitigation strategies. Therefore, this review examines the current state of knowledge on: 1) sources of Hg in paddy fields; 2) how MeHg and inorganic Hg (IHg) are transformed (including abiotic and biotic processes); 3) how IHg and MeHg enter and translocate in rice plants; and 4) how regular farming activities (including the application of fertilizer, cultivation methods, choice of cultivar), affect Hg cycling in the paddy field system. Current issues and controversies on Hg transformation and migration in the paddy field system are also discussed.


Assuntos
Produção Agrícola/métodos , Monitoramento Ambiental/métodos , Mercúrio/análise , Compostos de Metilmercúrio/análise , Oryza/efeitos dos fármacos , Poluentes do Solo/análise , Fertilizantes/análise , Humanos , Mercúrio/metabolismo , Compostos de Metilmercúrio/metabolismo , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Solo/química , Poluentes do Solo/metabolismo
16.
Ecotoxicol Environ Saf ; 202: 110958, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800230

RESUMO

Phytoremediation is an effective way to repair heavy metal contaminated soil and rhizosphere microorganisms play an important role in plant regulation. Nevertheless, little information is known about the variation of microbial metabolic activities and community structure in rhizosphere during phytoremediation. In this study, the rhizosphere soil microbial metabolic activities and community structure of Trifolium repensL. during Cd-contaminated soil phytoremediation, were analyzed by Biolog EcoPlate™ and high-throughput sequencing. The uptake in the roots of Trifolium repensL. grown in 5.68 and 24.23 mg/kg Cd contaminated soil was 33.51 and 84.69 mg/kg respectively, causing the acid-soluble Cd fractions decreased 7.3% and 5.4%. Phytoremediation significantly influenced microbial community and Trifolium repensL. planting significantly increased the rhizosphere microbial population, diversity, the relative abundance of plant growth promoting bacteria (Kaistobacter and Flavisolibacter), and the utilization of difficultly metabolized compounds. The correlation analysis among substrate utilization and microbial communities revealed that the relative abundance increased microorganisms possessed stronger carbon utilization capacity, which was beneficial to regulate the stability of plant-microbial system. Collectively, the results of this study provide fundamental insights into the microbial metabolic activities and community structure during heavy metal contaminated soil phytoremediation, which may aid in the bioregulation of phytoremediation.


Assuntos
Cádmio/toxicidade , Microbiota/efeitos dos fármacos , Rizosfera , Microbiologia do Solo , Poluentes do Solo/toxicidade , Solo/química , Trifolium/efeitos dos fármacos , Biodegradação Ambiental , Cádmio/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Poluentes do Solo/metabolismo , Trifolium/crescimento & desenvolvimento , Trifolium/metabolismo , Trifolium/microbiologia
17.
Ecotoxicol Environ Saf ; 202: 111011, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800236

RESUMO

Boron (B) deficiency and surplus are the main factors that affect plant growth and yield. A better understanding of the response mechanisms of plant reproductive organs to stress induced by B deficiency and surplus could provide new insights to potential strategies for improving seed yield and quality. In this study, we aimed to elucidate the mechanisms of tolerance to B-induced stress in the reproductive organs of alfalfa (Medicago sativa L. cv. 'Aohan'). We initially used five B concentrations (0 mg B L-1, 400 mg B L-1, 800 mg B L-1, 1200 mg B L-1, and 1600 mg B L-1) to determine the B deficient, sufficient, and surplus levels in the field. Secondly, we examined changes in metabolite profiles of alfalfa 'Aohan' reproductive organs in response to B deficiency (0 mg B L-1), B sufficiency (800 mg B L-1), and B surplus (1600 mg B L-1) conditions using gas chromatography-mass spectrometry (GC-MS). Flowers and seeds from alfalfa 'Aohan' showed different metabolite profiles and resistance capacity under B deficiency and surplus conditions. B deficiency led to the excessive accumulation of sugars and phenolic compounds in alfalfa 'Aohan' and seeds, respectively, thus causing abscission or the abortion of reproductive organs. In contrast, B surplus severely reduced the levels of metabolites associated with amino acid and carbohydrate metabolism, resulting in the flowers falling and, therefore, low seed yield. Overall, B deficiency predominantly reduced seed yield and quality of alfalfa 'Aohan', while B surplus mainly affected seed yield of alfalfa 'Aohan'.


Assuntos
Boro/deficiência , Boro/toxicidade , Células Germinativas Vegetais/efeitos dos fármacos , Medicago sativa/crescimento & desenvolvimento , Sementes/efeitos dos fármacos , Poluentes do Solo/toxicidade , Aminoácidos/metabolismo , Metabolismo dos Carboidratos/efeitos dos fármacos , Cromatografia Gasosa-Espectrometria de Massas , Células Germinativas Vegetais/metabolismo , Medicago sativa/metabolismo , Metabolômica , Sementes/metabolismo , Poluentes do Solo/metabolismo
18.
Ecotoxicol Environ Saf ; 203: 110983, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32678760

RESUMO

Chelating agents have been considered as an important phytoremediation strategy to enhance heavy metal extraction from contaminated soil. A pot experiment was conducted to explore the effects of low molecular weight organic acids (LMWOAs) on the phytoremediation efficiency of copper (Cu) by castor bean, and soil enzyme activities. Results indicated that the addition of all the three kinds of LMWOAs (citric, tartaric, oxalic acids) did not decrease the biomass of castor bean, despite the fact they reduced the concentration of chlorophyll-a in leaves compared to the control. The Cu concentrations in the roots and shoots significantly increased by 6-106% and 5-148%, respectively, in the LMWOAs treatments so that the total accumulation of Cu by whole plants in all the LMWOAs treatments increased by 21-189% in comparison with the control. The values of the translocation factor (TF) and bio-concentration factor (BCF) of Cu in castor bean also rose following the addition of LMWOAs, indicating that the LMWOAs enhanced the uptake and transportation of Cu. Moreover, the application of LMWOAs did not significantly change the soil pH but significantly increased the activity of soil enzymes (urease, catalase, and alkaline phosphatase). The addition of exogenous LMWOAs increased the available Cu significantly in the soil, thus promoted the phytoextraction efficiency of Cu by castor bean. These results will provide some new insights into the practical use of LMWOAs for the phytoremediation of heavy-metal-contaminated soil employing castor bean.


Assuntos
Bioacumulação , Semente de Rícino/metabolismo , Quelantes/química , Cobre/metabolismo , Compostos Orgânicos/química , Poluentes do Solo/metabolismo , Solo/química , Ácidos/administração & dosagem , Ácidos/química , Biodegradação Ambiental , Semente de Rícino/efeitos dos fármacos , Quelantes/administração & dosagem , Peso Molecular , Compostos Orgânicos/administração & dosagem
19.
Ecotoxicol Environ Saf ; 203: 110988, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32678761

RESUMO

The screening and identification of hyperaccumulators is the key to the phytoremediation of soils contaminated by heavy metal (HM). Arbuscular mycorrhizal fungus (AMF) can improve plant growth and tolerance to HM; therefore, AMF-assisted phytoextraction has been regarded as a potential technique for the remediation of HM-polluted soils. A greenhouse pot experiment was conducted to determine whether Sphagneticola calendulacea is a Cd-hyperaccumulator and to investigate the effect of the AMF-Funneliformis mosseae (FM) on plant growth and on the accumulation, subcellular distribution and chemical form of Cd in S. calendulacea grown in soils supplemented with different Cd levels. At 25, 50 and 100 mg Cd kg-1 level, S. calendulacea showed high Cd tolerance, the translocation factor and the bioconcentration factor exceeded 1, and accumulation of more than 100 mg Cd kg-1 was observed in the aboveground parts of the plant, meeting the requirements for a Cd-hyperaccumulator. Moreover, FM colonization significantly increased both biomasses and Cd concentration in S. calendulacea. After FM inoculation, the Cd concentrations and proportions increased in the cell walls, but exhibited no significant change in the organelles of the shoots. Meanwhile, FM symbiosis contributed to the conversion of Cd from highly toxic chemical forms (extracted by 80% ethanol and deionized water) to less toxic chemical forms (extracted by 1 M NaCl, 2% acetic acid, 0.6 M HCl) of Cd in the shoots. Overall, S. calendulacea is a typical Cd-hyperaccumulator, and FM symbiosis relieved the phytotoxicity of Cd and promoted plant growth and Cd accumulation, and thus greatly increasing the efficiency of phytoextraction for Cd-polluted soil. Our study provides a theoretical basis and application guidance for the remediation of Cd-contaminated soil by the symbiont of S. calendulacea with FM.


Assuntos
Asteraceae/metabolismo , Bioacumulação , Cádmio/metabolismo , Glomeromycota/fisiologia , Micorrizas/fisiologia , Poluentes do Solo/metabolismo , Asteraceae/crescimento & desenvolvimento , Asteraceae/microbiologia , Biodegradação Ambiental
20.
Chemosphere ; 259: 127280, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32650174

RESUMO

Over-exploitation of rare-earth elements causes cadmium (Cd)- and lead (Pb)-contamination of rare-earth mine tailings. Here, Paspalum conjugatum was used as a hyperaccumulating perennial herb to evaluate its phytoextraction potential for removing metals in a hydroponic experiment. Further, an in-situ experiment was conducted for two years (2016-2018) to investigate the potential of P. conjugatum for reducing soil metal concentrations and to assess microbiome recovery on abandoned rare-earth mining land. Pinus massoniana was used for control treatments. We found that P. conjugatum produced metal transfer coefficients of 0.85 and 0.89 for Cd and Pb, respectively. The concentrations of Cd and Pb accumulated in P. conjugatum were 98.33 mg kg-1 and 137 mg kg-1, respectively. Using P. conjugatum, soil Pb and Cd concentrations were significantly decreased, and Cd concentrations approached acceptable levels (0.209 mg kg-1). The bacterial diversity in P. conjugatum-restored soil was higher than that in soil of P. massoniana. The bacterial genera Chloroflexi, Acidobacteria, and Actinobacteria were predominant in the restored soils. P. conjugatum was tolerant to drought and exhibited enhanced enzymatic activity. These results suggest that P. conjugatum can be used for efficient phytoremediation of Pb- and Cd-contaminated soils.


Assuntos
Biodegradação Ambiental , Metais Terras Raras/metabolismo , Paspalum/metabolismo , Poluentes do Solo/metabolismo , Bactérias , Cádmio , Metais Pesados/análise , Mineração , Solo , Poluentes do Solo/análise
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