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1.
Ecotoxicol Environ Saf ; 208: 111411, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33080425

RESUMO

Octanol-water partition coefficient (logKow) and soil organic carbon content normalized sorption coefficient (logKoc) values are two important physicochemical properties in the context of bioaccumulation and environmental fate of organic compounds and their environmental risk assessment. Simple, interpretable and easy-to-derive extended topochemical atom (ETA) indices obtained from 2D structural representation of compounds were used for quantitative structure-property relationship (QSPR) modeling of these two endpoints. Linear regression based models developed using only ETA indices show encouraging statistical and validation results. Based on the information obtained from developed QSPR models, we may conclude that molecular volume, branching pattern, presence of hydrophobic Cl atoms, cyclicity/fusion, polar environment, electron density, unsaturation content, hydrogen bonding propensity or hydrogen bond donor atoms, local topology, presence of heteroatoms and aromaticity are crucial factors in controlling the logKow and logKoc values of the compounds. The suggested explanatory features for different classes of chemicals or the whole diverse set can help in safer designing of chemicals, which is one of the primary agenda of the "Green Chemistry" program.


Assuntos
Compostos Orgânicos/toxicidade , Relação Quantitativa Estrutura-Atividade , Poluentes do Solo/toxicidade , Carbono , Modelos Lineares , Octanóis/química , Compostos Orgânicos/química , Solo/química , Poluentes do Solo/química , Água/química
2.
Ecotoxicol Environ Saf ; 208: 111510, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33120259

RESUMO

Environment functional materials have been widely used, but whether their effects on the contaminated environment could facilitate phytoremediation is not yet well understood. In this study, starch stabilized nanoscale zerovalent iron (SN), multiwall carbon nanotubes (MW) and tea waste derived biochar (TB) were used to facilitate the phytoremediation of cadmium (Cd) contaminated sediments by Boehmeria nivea (L.) Gaudich. Results showed that 100 mg/kg SN, 500 mg/kg MW and 500 mg/kg TB facilitated phytoremediation, as evidenced by increasing Cd accumulation and/or promoting plant growth. These concentrations of materials increased the reducible fraction of Cd by 9-10% and decreased the oxidizable proportion of Cd by 48-52%, indicating the improvement of Cd bioavailability through converting the oxidizable Cd into reducible form. The activities of urease, phosphatase and catalase, which related to nutrient utilization and oxidative stress alleviation, increased by 20-24%, 25-26%, and 8-9% in the sediments treated with 500 mg/kg MW and 500 mg/kg TB, respectively. In addition, the 16S rRNA gene sequence results showed that these concentrations of materials changed the bacterial diversity. The abundance of Acidobacteria, Actinobacteria, Nitrospirae and Firmicutes were increased by some of the applied materials, which could promote plant growth, change Cd bioavailability and reduce Cd toxicity. These findings indicated that the applied environment functional materials could facilitate the phytoremediation of Cd contaminated environment by changing Cd fractions, sediments properties and bacterial community structure.


Assuntos
Biodegradação Ambiental , Cádmio/química , Microbiota , Poluentes do Solo/química , Bactérias , Disponibilidade Biológica , Cádmio/análise , Carvão Vegetal , Ferro/química , Nanotubos de Carbono , RNA Ribossômico 16S , Solo/química , Poluentes do Solo/análise
3.
Ecotoxicol Environ Saf ; 208: 111506, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33120269

RESUMO

Chromium (Cr) pollution in soil is a global problem owing to its wide industrial use. The mobility, toxicity, and crop uptake of Cr depends on its valence state. Cr(VI) is highly mobile and toxic whereas Cr(III) is generally considered immobile and less toxic. We performed a pot experiment to investigate the combined effects of rice straw-derived biochar and water management on transformation of Cr and its uptake by rice in contaminated soils. The main plots had water management treatments of alternating wetting and drying (AWD) and continuous flooding (CF), and the subplots had three levels of straw biochar (0, 5, and 10 g kg-1). The results showed that water management and the addition of biochar had a significant effect on the dynamics of soil redox potential (Eh), pH, dissolved organic carbon (DOC), and Fe(II) concentration. As these parameters are important factors affecting Cr transformation in paddy soils, the dynamics of the Cr(III) and Cr(VI) concentrations were clearly different under different treatments. The highest reduction of Cr(VI) was observed in the treatment with CF water management in combination with 10 g kg-1 of biochar amendment, which resulted in a 62% reduction of Cr(VI) to Cr(III) in soil. The alterations in the oxidation state of Cr greatly affected its accumulation in the rice grains. The CF combined with 10 g kg-1 of biochar treatment, caused the Cr concentration in rice grains to be 66.2% lower compared with that of the unamended control under AWD water management. Possibly owing to the reduction in phytotoxic effects of Cr(VI), the combined treatment showed an improvement in rice grain weight. In conclusion, the combination of 10 g kg-1 of biochar amendment and CF water management may potentially be used in Cr-contaminated soil to mitigate the impacts of Cr contamination on rice production.


Assuntos
Irrigação Agrícola/métodos , Carvão Vegetal/metabolismo , Cromo/metabolismo , Oryza/metabolismo , Poluentes do Solo/metabolismo , Biotransformação , Cromo/análise , Cromo/química , Grão Comestível/química , Grão Comestível/metabolismo , Inundações , Oryza/química , Oxirredução , Solo/química , Poluentes do Solo/análise , Poluentes do Solo/química
4.
Chemosphere ; 262: 128352, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182087

RESUMO

As organic pollution of soil and groundwater increases, the effective and economical remediation of contaminated sites has drawn growing attention. In this study, running-water (RW) was designed to modify alkali-heat/persulfate (MAH/PS) for integrated remediation of an actual organic-contaminated site. The degradation efficiency mainly reached 60%-99% for Benz[a]anthracene, Benzo[a]pyrene and total petroleum hydrocarbons (TPHs). MAH/PS was more effective in degrading Benzene and 1,2-Dichloroethane with simple molecular configurations. The pollutant degradation efficiencies decreased with increasing site depth and increased with increasing pollutant concentrations. Migration with RW enhanced site remediation. By monitoring the groundwater after remediation, it was found that residual TPHs presented anomalous diffusion; SO42- ranged from 8.00 to 237.00 mg L-1 to 8.00-290.00 mg L-1 and pH presented alkalescence (7.00-8.20). Mathematical models were established to describe the reaction process including the solubility equilibrium of calcium hydroxide, temperature equilibrium, and reaction kinetics. Moreover, MAH/PS provided a cost-saving approach for site remediation.


Assuntos
Recuperação e Remediação Ambiental/métodos , Poluentes do Solo/análise , Poluentes do Solo/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Álcalis , Benzo(a)pireno/química , China , Água Subterrânea/análise , Água Subterrânea/química , Temperatura Alta , Hidrocarbonetos/química , Modelos Teóricos , Oxirredução , Petróleo/análise , Poluição por Petróleo , Solo/química , Sulfatos/química
5.
Chemosphere ; 263: 127947, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32822930

RESUMO

Microplastic (MP) pollution in soil has been becoming an emerging environmental hot spot, but little is known about the interaction between MPs and chemical contaminants in soil. In this study, batch experiments were performed to study adsorption-desorption behavior and mechanism of triclosan (TCS) on MPs, polyethylene (PE) and polystyrene (PS), and soil particles. PE showed the highest adsorption rate (29.3 mg µg-1 h-1) and equilibrium capacity (1248 µg g-1), while the similar profiles between PS (0.27 mg µg-1 h-1 and 1033 µg g-1, respectively) and soil (0.60 mg µg-1 h-1 and 961 µg g-1, respectively). Two adsorption stages, representing liquid-film and intra-particle diffusion were observed obviously for PE. Adsorption isotherm results revealed that the interaction between MPs and TCS was relatively weak. The sorption potential of soil was lower than that of MPs especially at high concentrations. PE addition induced TCS sorption increase in soil, while PS had no significant (P > 0.05) influence. For MP-soil systems, TCS preferred to adsorb on MPs, which was more pronounced for PE than PS. The desorption rate of TCS was the highest for soil, followed by PE and PS, while equilibrium release amount ranked: PE > PS > soil. Moreover, soil solution better facilitated the desorption, with the amount increasing by 38% for PE compared with 0.01 M CaCl2 solution. Therefore, MPs, especially PE with high adsorption and desorption potentials may serve as a source and carrier to TCS, and its amendment can change TCS environmental behavior and further risk in soil.


Assuntos
Microplásticos/química , Poluentes do Solo/química , Triclosan/química , Adsorção , Difusão , Plásticos , Polietileno , Poliestirenos , Solo
6.
PLoS One ; 15(11): e0242915, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33253305

RESUMO

Magnesium isotope ratios (26Mg/24Mg) can provide insights into the origin of Mg pools and fluxes in catchments where Mg sources have distinct isotope compositions, and the direction and magnitude of Mg isotope fractionations are known. Variability in Mg isotope compositions was investigated in three small, spruce-forested catchments in the Czech Republic (Central Europe) situated along an industrial pollution gradient. The following combinations of catchment characteristics were selected for the study: low-Mg bedrock + low Mg deposition (site LYS, underlain by leucogranite); high-Mg bedrock + low Mg deposition (site PLB, underlain by serpentinite), and low-Mg bedrock + high Mg deposition (site UDL, underlain by orthogneiss). UDL, affected by spruce die-back due to acid rain, was the only investigated site where dolomite was applied to mitigate forest decline. The δ26Mg values of 10 catchment compartments were determined on pooled subsamples. At LYS, a wide range of δ26Mg values was observed across the compartments, from -3.38 ‰ (bedrock) to -2.88 ‰ (soil), -1.48% (open-area precipitation), -1.34 ‰ (throughfall), -1.19 ‰ (soil water), -0.99 ‰ (xylem), -0.95 ‰ (needles), -0.82 ‰ (bark), -0.76 ‰ (fine roots), and -0.76 ‰ (runoff). The δ26Mg values at UDL spanned 1.32 ‰ and were thus less variable, compared to LYS. Magnesium at PLB was isotopically relatively homogeneous. The δ26Mg systematics was consistent with geogenic control of runoff Mg at PLB. Mainly atmospheric/biological control of runoff Mg was indicated at UDL, and possibly also at LYS. Our sites did not exhibit the combination of low-δ26Mg runoff and high-δ26Mg weathering products (secondary clay minerals) reported from several previously studied sites. Six years after the end of liming at UDL, Mg derived from dolomite was isotopically undetectable in runoff.


Assuntos
Monitoramento Ambiental , Magnésio/isolamento & purificação , Poluentes do Solo/isolamento & purificação , Chuva Ácida , Carbonato de Cálcio/química , República Tcheca/epidemiologia , Poluição Ambiental/prevenção & controle , Europa (Continente) , Humanos , Isótopos/química , Magnésio/química , Solo/química , Poluentes do Solo/química , Árvores/química , Poluentes Químicos da Água/química
7.
PLoS One ; 15(11): e0241398, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33137143

RESUMO

The core of urbanization is land use change, resulting in the urban sprawl and urban population explosion. The problem of land resources shortage and ecological environment destruction has become increasingly prominent. Land use change and human activities can directly lead to urban soil pollution. This study analyzed the concentration of Cd, Cr, Cu, Ni, Pb, Zn, Hg and As in the original site of Xi'an chlor-alkali chemical plant, which was know as a brownfield. The results showed the concentrations of Hg, Pb and Zn in research areas were obviously higher than soil background value. Through pollution index (PI) method and Geo-accumulation Index (Igeo) method, totally 26 sample points in different areas (A, B, C, D) were classified into different pollution degrees. The CPI results indicated 9 sample points were heavily polluted, accounting for 34.6% of the total. Among them, 6 out of 9 were located in area A. 12 samples points were not polluted. The average Igeo values of single heavy metal were arranged in the order of Hg (1.83) > Zn (1.26) > Pb (0.33). The pollution of Hg was relatively serious and extensive, especially in area A. It was mainly because of the historical pollution produced by chemical plant. The pollution of Pb in each point was quite different. Mainly influenced by automobile related activities, Igeo(Pb) in sample point 15 and 16 were all beyond 4.00. The average potential ecological risk (PER) of each area was in the order of A (1428) > B (297) > D (249) > C (163). The ecological risk was mainly determined by previous industrial production and present human activity at the same time. People and land are interdependent and interactive. The understanding on the mechanism of man-land interralations, regarding to urban land use and ecological environment, will promote urban sustainability.


Assuntos
Ecologia , Metais Pesados/toxicidade , Poluentes do Solo/toxicidade , Solo/química , China/epidemiologia , Poluição Ambiental/prevenção & controle , Humanos , Metais Pesados/química , Medição de Risco , Poluentes do Solo/química , Urbanização
8.
PLoS One ; 15(11): e0242703, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33232363

RESUMO

The potential hazard to human health from exposure to heavy metals in surface soil was assessed using 66 soil samples collected from Ahvaz oil field. To this end, the contents of heavy metals were measured by the inductively coupled plasma spectroscopy (ICP-OES). Mean levels of As, Cd, Co, Cr, Cu, Ni, Pb, V, and Zn were 5.9, 0.4, 7.1, 36.5, 41.2, 39.8, 67.4, 31.5, and 77.6 mg/kg, respectively. Contents of all studied heavy metals, with the exception of Co, Cr, and V, were several times higher than that of baselines. Correlation coefficients and principal component analysis (PCA) identified two main groups as sources of heavy metals in the surface soil of Ahvaz oil-field. Metals such as Co, Cr, and V were observed to originate from natural sources and As, Cd, Cu, Ni, Pb, and Zn originated from anthropogenic sources such as petroleum leakage and the pollution caused by drilling mud from oil wells. Pb and Zn were of significantly high EF mean enrichment value, and Co, Cu, Cd, and As had high enrichment in surface soil. Pb, Cr, V, Zn, Co, Cu, Ni, and As had a low potential ecological risk (PER) whereas Cd had a moderate PER. The risk of carcinogenic and non-carcinogenic diseases was detected to be higher in children than in adults. The carcinogenic risk (Cr) calculation was more than 1 × 10-6 for children and adults. Additionally, the CR of Cr for both children and adults indicated risk under control conditions.


Assuntos
Exposição Ambiental/efeitos adversos , Monitoramento Ambiental , Metais Pesados , Campos de Petróleo e Gás/química , Poluentes do Solo/análise , Adulto , Criança , Feminino , Humanos , Irã (Geográfico) , Masculino , Metais Pesados/efeitos adversos , Metais Pesados/análise , Metais Pesados/química , Fatores de Risco , Poluentes do Solo/efeitos adversos , Poluentes do Solo/química
9.
PLoS One ; 15(11): e0242350, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33237922

RESUMO

In Brazil, the atrazine has been applied frequently to join with glyphosate to control resistant biotypes and weed tolerant species to glyphosate. However, there are no studies about atrazine's behavior in soil when applied in admixture with glyphosate. Knowledge of atrazine's sorption and desorption mixed with glyphosate is necessary because the lower sorption and higher desorption may increase the leaching and runoff of pesticides, reaching groundwaters and rivers. Thereby, the objective of this study was to evaluate the adsorption mechanisms of atrazine when isolated and mixed with glyphosate formulations in a Red-Yellow Latosol. The maximum adsorbed amount of atrazine in equilibrium (qe) was not altered due to glyphosate formulations. The time to reach equilibrium was shortest when atrazine was mixed with the Roundup Ready® (te = 4.3 hours) due to the higher adsorption velocity (k2 = 2.3 mg min-1) in the soil. The highest sorption of atrazine occurred when mixed with the Roundup WG®, with the Freundlich sorption coefficient (Kf) equal to 2.51 and 2.43 for both formulation concentrations. However, other glyphosate formulations did not affect the sorption of atrazine. The desorption of atrazine was high for all treatments, with values close to 80% of the initial adsorbed amount, without differences among isolated and mixed treatments. The change in the velocity and capacity of sorption for the atrazine mixed with some glyphosate formulations indicates that further studies should be conducted to identify the mechanisms involved in this process.


Assuntos
Atrazina/química , Glicina/análogos & derivados , Poluentes do Solo/química , Solo/química , Adsorção , Brasil , Argila/química , Glicina/química , Cinética , Resíduos de Praguicidas/química , Areia/química , Temperatura
10.
Ecotoxicol Environ Saf ; 205: 111316, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-33007600

RESUMO

The interaction between multi-walled carbon nanotubes (MWCNTs) and soil heavy metals was rarely studied. With the convenience of detecting multiple metal elements by ICP-AES, this paper examined the potential effectiveness of MWCNTs on extractability of antimony (Sb) and cadmium (Cd) in contaminated soil. Three-step sequential extraction procedure, toxicity characteristic leaching procedure, bioaccessibility and CaCl2 single extraction were employed to evaluate Sb and Cd speciations and their extractabilities. According to our results, only at low Sb content level of 100 mg/kg, antimony bioavailability reduced with MWCNTs addition of 0.3% and 0.9% by 22.97% and 20.74%, respectively, which might due to the increase of adsorption point, nevertheless, the excess Sb(OH)6- was not adsorbed more efficiently. Secondly, due to the difference in effective specific surface area, only under the condition of high content level and MWCNTs addition of 0.1%, the mild acid-soluble fraction increased at most by 15.40% for Sb and 9.40% for Cd, respectively. However, in terms of TCLP-extractable Sb and Cd and CaCl2-extractable Sb and Cd, no significant, continuous, regular extractability pattern were found. Overall, MWCNTs were selective on extractability of soil heavy metals due to mechanisms of physical adsorption. This paper provides data reference for the interaction between MWCNTs and soil heavy metals extractability.


Assuntos
Cádmio/química , Nanotubos de Carbono/química , Poluentes do Solo/química , Adsorção , Antimônio , Disponibilidade Biológica , Poluição Ambiental , Metais Pesados , Solo
11.
Ecotoxicol Environ Saf ; 206: 111197, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32882572

RESUMO

In the present study, Zea mays seedlings grown under nano Cu(OH)2 (nCu), bulk Cu(OH)2 (bCu), and ionic CuSO4 (iCu) compound exposure were harvested after six days. The nutritional profile was determined to be significantly disrupted in the roots by 1000 ppm bCu treatment, resulting in a 58.7% reduction in potassium compared to the control. In the shoots, a significant decrease of manganese was observed for 10 and 1000 ppm iCu treatments with 55.7% and 64.2% reductions, respectively. The overall protein content and catalase (CAT) enzymatic activity, however, remained unaffected in either roots or shoots, while an absence of polyphenol oxidase (PPO) activity was observed for all samples. The genetic expression of defense-related genes, metallothionein (MT), CAT, ascorbate peroxidase (APX), and PPO was assessed. The genetic expression of MT was upregulated 50-fold in roots treated with 1000 ppm bCu. There were no significant differences in CAT transcripts among the various treatments, while APX was upregulated 28 and 19-fold in shoots treated with 10 ppm bCu and 10 ppm nCu, respectively. Meanwhile, APX mRNA levels were downregulated five-fold in shoots treated with 1000 ppm iCu. Thus, indicating that the role of APX in plant defense was reinforced in seedlings exposed to low concentration of particulate Cu compounds. Remarkably, no PPO expression was found in any of the treatments and controls, which suggests this enzyme is expressed only under specific external factors or seedlings have an "immature" cascade signaling activation of the PPO system. Taken together, these results show that bCu and nCu treatments at a low concentration do not compromise vital cell machinery but rather elicit the enhancement of defense responses as observed through the increase in APX expression. Furthermore, under optimal concentrations, these Cu treatments show promise in enhancing corn defense responses, which can ultimately lead to increases in future global crop yields.


Assuntos
Antioxidantes/metabolismo , Ascorbato Peroxidases/genética , Cobre/toxicidade , Poluentes do Solo/toxicidade , Zea mays/efeitos dos fármacos , Ascorbato Peroxidases/metabolismo , Cobre/química , Relação Dose-Resposta a Droga , Íons , Manganês/metabolismo , Oxirredução , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Potássio/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Poluentes do Solo/química , Zea mays/genética , Zea mays/crescimento & desenvolvimento , Zea mays/metabolismo
12.
Bull Environ Contam Toxicol ; 105(4): 639-644, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32955595

RESUMO

Arsenic (As) and cadmium (Cd) are common soil pollutants whose opposing geochemical behaviors must be taken into account in the development of cost-effective, environmentally friendly remediation strategies. In this study, a pot experiment with lettuce and a field experiment with wheat were performed to examine the impacts of zeolite, biochar, MnO2, zero-valent iron (ZVI) individually and in binary combinations thereof on As-Cd pollution. The results of the pot experiment showed that biochar, MnO2 and ZVI had good passivation effects on As and Cd when provided individually, but the effects of a combination of 0.2% ZVI/0.5% biochar or 0.2% MnO2/0.5% ZVI were even better. These amendments were further investigated in a field experiment, which confirmed the positive effect of 0.2% MnO2/0.5% ZVI. Therefore, ZVI/biochar and MnO2/ZVI mixtures may offer effective solutions to the remediation of farmland soil contaminated with both As and Cd.


Assuntos
Arsênico/química , Cádmio/química , Recuperação e Remediação Ambiental/métodos , Poluentes do Solo/química , Arsênico/análise , Cádmio/análise , Carvão Vegetal , Poluição Ambiental , Fazendas , Ferro , Alface , Compostos de Manganês , Óxidos , Solo , Poluentes do Solo/análise , Triticum
13.
Ecotoxicol Environ Saf ; 206: 111105, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32866887

RESUMO

Soil is an important sink for perfluorooctane sulfonate (PFOS) that is a typical persistent organic pollutant with high toxicity. Understanding of PFOS sorption to various particle-size fractions of soil provides an insight into the mobility and bioavailability of PFOS in soil. This study evaluated kinetics, isotherms, and mechanisms of PFOS sorption to six soil particle-size fractions of paddy soil at environmentally relevant concentrations (0.01-1 µg/mL). The used soil particle-size fractions included coarse sand (120.4-724.4 mm), fine sand (45.7-316.2 mm), coarse silt (17.3-79.4 mm), fine silt (1.9-39.8 mm), clay (0.5-4.4 mm), and humic acid fractions (8.2-83.7 mm) labeled as F1~F6, respectively. PFOS sorption followed pseudo-second-order kinetics related to film diffusion and intraparticle diffusion, with speed-limiting phase acted by the latter. PFOS sorption isotherm data followed Freundlich model, with generally convex isotherms in larger size fractions (F1~F3) but concave isotherms in smaller size fractions (F4 and F5) and humic acid fraction (F6). Increasing organic matter content, Brunner-Emmet-Teller surface area, and smaller size fractions were conducive to PFOS sorption. Hydrophobic force, divalent metal ion-bridging effect, ligand exchange, hydrogen bonding, and protein-like interaction played roles in PFOS sorption. But hydrophobic force controlled the PFOS sorption, because its relevant organic matter governed the contribution of the soil fractions to the overall PFOS sorption. The larger size fractions dominated the PFOS sorption to the original soil because of their high mass percentages (~80%). This likely caused greater potential risks of PFOS migration into groundwater and bioaccumulation in crops at higher temperatures and ce values, based on their convex isotherms with an exothermic physical process.


Assuntos
Ácidos Alcanossulfônicos/química , Fluorcarbonetos/química , Poluentes do Solo/química , Solo/química , Adsorção , Ácidos Alcanossulfônicos/análise , Argila/química , Fluorcarbonetos/análise , Substâncias Húmicas/análise , Interações Hidrofóbicas e Hidrofílicas , Cinética , Tamanho da Partícula , Poluentes do Solo/análise , Termodinâmica
14.
Sci Rep ; 10(1): 15091, 2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32934307

RESUMO

Engineering bacteria to clean-up oil spills is rapidly advancing but faces regulatory hurdles and environmental concerns. Here, we develop a new technology to harness indigenous soil microbial communities for bioremediation by flooding local populations with catabolic genes for petroleum hydrocarbon degradation. Overexpressing three enzymes (almA, xylE, p450cam) in Escherichia coli led to degradation of 60-99% of target hydrocarbon substrates. Mating experiments, fluorescence microscopy and TEM revealed indigenous bacteria could obtain these vectors from E. coli through several mechanisms of horizontal gene transfer (HGT), including conjugation and cytoplasmic exchange through nanotubes. Inoculating petroleum-polluted sediments with E. coli carrying the vector pSF-OXB15-p450camfusion showed that the E. coli cells died after five days but a variety of bacteria received and carried the vector for over 60 days after inoculation. Within 60 days, the total petroleum hydrocarbon content of the polluted soil was reduced by 46%. Pilot experiments show that vectors only persist in indigenous populations when under selection pressure, disappearing when this carbon source is removed. This approach to remediation could prime indigenous bacteria for degrading pollutants while providing minimal ecosystem disturbance.


Assuntos
Bactérias/genética , Biodegradação Ambiental , Ecossistema , Escherichia coli/genética , Proteínas de Escherichia coli/genética , Hidrocarbonetos/metabolismo , Petróleo/metabolismo , Poluição por Petróleo , Solo/química , Microbiologia do Solo , Poluentes do Solo/química
15.
Ecotoxicol Environ Saf ; 206: 111325, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32979721

RESUMO

The problem of heavy metal pollution in sediments attracts increasing attention with the process of industrialization. In this study, a novel sediments amendment granular activated carbon (GAC)-supported titanium dioxide nanoparticles (GATN) was synthesized to amend copper (Cu)-contaminated sediments. The effect of the amendments on the potential mobility and bioavailability of Cu was evaluated by the concentration of Cu in the overlying water and the chemical speciations of Cu in sediments. After 35 days of incubation, GATN and GAC were separated from the GATN-amended sediments and the GAC-amended sediments. The European Community Bureau of Reference (BCR) sequence extraction procedure was performed on the separated sediments. Compared with the control group, the addition of 20% GATN amended sediments for 35 days, the Cu concentration in the overlying water decreased by 90.75%. Compared with original sediments, the exchangeable fraction and reducible fraction of Cu decreased from 42.30% to 17.36%-3.63% and 6.57%, respectively, and the oxidizable fraction and residual fraction of Cu increased from 13.57% to 26.77%-33.21% and 56.58%, respectively. The potential mobility and bioavailability of Cu were significantly reduced. According to the BCR sequence extraction results of the remaining sediments after the separation of the GATN, the Cu adsorbed on the GATN surface is mainly an oxidizable fraction, which is generated by the complexation reaction of hydroxyl (-OH) and Cu2+. Meanwhile, the present of GATN also can enhance the remediation capacity of sediments, which plays an important role during the amendment process. The pH was measured after GATN-amended sediments adding. Results showed that GATN improved their remediation capacity of sediments by optimizing the pH in sediments. The enzyme activity-experiment indicated that GATN effectively reduces the biological toxicity of Cu in Cu-contaminated sediments. Results verified that GATN, as a sediments amendment, has good application potential.


Assuntos
Cobre/química , Recuperação e Remediação Ambiental/métodos , Nanopartículas/química , Poluentes do Solo/química , Titânio/química , Adsorção , Disponibilidade Biológica , Carvão Vegetal , Cobre/análise , Poluição Ambiental , Sedimentos Geológicos , Concentração de Íons de Hidrogênio , Metais Pesados/análise , Poluentes do Solo/análise
16.
PLoS One ; 15(9): e0239137, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32997670

RESUMO

Sediment and soil contamination with toxic heavy metals, including cadmium (Cd2+) and lead (Pb2+), represents a major long-term remediation challenge. Resuspension of contaminated sediments into the water column, or the uptake of toxic metals from top soil, can lead to exposure of aquatic or terrestrial organisms, followed by bioconcentration, bioaccumulation and biomagnification, which may pose a threat to public health. We have developed a novel nanoscale engineered material, namely ligand-coated dense nanoparticles (Ligand DNPs), which contain a dense WO3 nanoparticle core and a shell functionalized with a metal-binding organic ligand (EDTA), to effectively sequester heavy metal ions deeper into the soil and sediments. We demonstrate that one application of Ligand DNPs can remove from 60% to almost 80% of the Cd and Pb in two different soil matrices, driving these metal ions deeper into the sediment or soil column via gravity, and making them less bioavailable. Ligand DNPs can provide a relatively fast, convenient, and efficient in-situ approach for the remediation of sediments and soils contaminated with heavy metals.


Assuntos
Quelantes/química , Recuperação e Remediação Ambiental/métodos , Metais Pesados/química , Óxidos/química , Poluentes do Solo/química , Tungstênio/química , Engenharia Química , Poluição Ambiental/efeitos adversos , Estudos de Viabilidade , Sedimentos Geológicos/análise , Sedimentos Geológicos/química , Ligantes , Metais Pesados/análise , Nanocompostos/química , Nanopartículas/química , Nanotecnologia , Solo/química , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Fatores de Tempo
17.
Ecotoxicol Environ Saf ; 203: 110990, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888601

RESUMO

The presence of sulfamethoxazole (SMX) in croplands has become an international concern. The environmental behavior and fate of SMX in agricultural soils are not well understood, especially when the adsorption behavior is disturbed by the dissolved organic matter (DOM) released by crop straw. As canola straw is one of the biomasses widely returned to farmlands, we characterized DOM derived from pristine and decomposed canola straw, and explored the effects and mechanisms of the DOMs on regulating SMX adsorption to purple paddy soils. The spectral analysis showed that the molecular weight, aromaticity, and hydrophobicity of canola straw-derived DOM increased as decomposition proceeded. These physicochemical properties collectively determined the effects of the DOM on SMX adsorption. The DOM derived from pristine canola straw increased SMX maximum adsorption capacity of the soils by approximately 2.6 times, but this positive effect gradually decreased to a steady state by day 90 in the straw decomposition period. Nevertheless, the SMX adsorption behavior in the soils was invariably determined by the DOM extracts. These adsorption processes of SMX were well fitted by the double-chamber kinetics model and the Langmuir and Freundlich thermodynamic models. Thermodynamic parameters indicated that SMX adsorption onto the soils was spontaneous and endothermic, and this adsorption characteristics was not significantly (p > 0.05) changed by the DOM extracts. However, the adsorption kinetics were altered by those DOMs, i.e., the fast and slow adsorption processes were both diminished. Correspondingly, co-adsorption and cumulative adsorption were identified as the main mechanisms determining SMX adsorption to the purple paddy soils in the presence of the straw-derived DOMs. These results collectively indicated that the DOMs released by straw in croplands may decrease the ecological risks of organic pollutants by inhibiting their migration processes.


Assuntos
Brassica/química , Poluentes do Solo/química , Solo/química , Sulfametoxazol/química , Adsorção , Agricultura , Oryza/crescimento & desenvolvimento , Silagem
18.
J Environ Sci Health B ; 55(11): 974-982, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32757814

RESUMO

Enantioselective biodegradation of racemic dichlorprop in two soils was investigated in the laboratory. Chiral separation of racemic dichlorprop was achieved by using HPLC with Phenomenex Lux Amylose-2. The first-order kinetic model fitted well the dissipation data of racemic dichlorprop and its pure R- and S-enantiomers. S-dichlorprop was preferentially degraded in both soils and enantioselectivity was affected by soil pH. The half-lives (DT50) of S-dichlorprop were 8.22 days in soil A and 8.06 days in soil D, while R-dichlorprop was more persistent with DT50 of 12.93 days in soil A and 12.38 days in soil D, respectively. Dichlorprop dissipated faster in soil D with lower organic matter content. In sterilized soils, neglected dissipation was observed and enantiomer fraction values remained constant, indicating that the enantioselective degradation was mainly controlled by soil microorganisms. Soil microbial community structure and diversity was assessed by Illumina MiSeq sequencing of 16S rRNA genes from dichlorprop and no dichlorprop contaminated microcosms. Compared with controls, dichlorprop application had no significant effect on microbial community structures at phylum level, but increased bacterial diversity and dichlorprop degradation related taxa in both soils. S-dichlorprop preferential degradation might be attributed to the S-enantiomer preferred degraders in the family of Sphingomonadaceae.


Assuntos
Ácido 2,4-Diclorofenoxiacético/análogos & derivados , Microbiota/efeitos dos fármacos , Microbiologia do Solo , Poluentes do Solo/farmacologia , Ácido 2,4-Diclorofenoxiacético/análise , Ácido 2,4-Diclorofenoxiacético/química , Ácido 2,4-Diclorofenoxiacético/farmacocinética , Ácido 2,4-Diclorofenoxiacético/farmacologia , Agricultura , Bactérias/efeitos dos fármacos , Bactérias/genética , Bactérias/metabolismo , Biodegradação Ambiental , Cinética , Michigan , Microbiota/genética , RNA Ribossômico 16S , Solo/química , Poluentes do Solo/análise , Poluentes do Solo/química , Poluentes do Solo/farmacocinética , Estereoisomerismo
20.
Ecotoxicol Environ Saf ; 205: 111132, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32836155

RESUMO

Due to high sorption capacity for heavy metals, magnetic biochar (MBC) has the potential to adsorb heavy metals in soils, which are then removed together with MBC from soils by a magnetic field. In this study, two magnetic biochars (MBC300 and MBC700) were derived from the magnetization of wheat straw biochars pyrolyzed at 300 and 700 °C. Strong binding of Pb with iron oxide particles deposited on biochar was observed. After the MBCs (7.5%, w/w) were applied to two naturally Pb-polluted soils (named as He-soil and Hu-soil) for 720 h, the removal efficiency of Pb from the soil by MBC300 (26.8-40.1%) was similar (p > 0.05) to that by MBC700 (25.1-42.1%). This is because MBC300 has lower sorption capacity for Pb but higher recovery percentage from soils as a result of lower saturation magnetization. The removal efficiencies of Pb by the two MBCs were 13-17% higher for He-soil than for Hu-soil, which was due to higher proportion of mobile forms of Pb in He-soil (82.3%) than in Hu-soil (51.5%). Spectroscopic analysis indicated that Pb in soils tended to bind onto the surface of MBC in more stable forms. Moreover, removing Pb from soils by MBC could decrease Pb concentration in ryegrass by about 30%. Therefore, it might be a potential method to remedy Pb-polluted soils.


Assuntos
Recuperação e Remediação Ambiental/métodos , Chumbo/química , Poluentes do Solo/química , Adsorção , Carvão Vegetal , Poluição Ambiental/análise , Chumbo/análise , Lolium , Fenômenos Magnéticos , Metais Pesados/análise , Pirólise , Solo/química , Poluentes do Solo/análise , Triticum
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