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Contamination of soils by automotive residual oil represents a global environmental problem. Bioremediation is the technology most suitable to remove this contaminant from the medium. Therefore, this work aimed to evaluate the effectiveness of bioremediation of automotive residual oil-contaminated soils by biostimulation with enzymes, surfactant, and vermicompost. The bioremediation efficiency was examined using a factorial design of 24 to determine the effect of the time, pH and temperature conditions, biostimulation with enzyme-vermicompost, and biostimulation with enzyme-surfactant. Enzymes obtained from Ricinus communis L. seeds, commercial vermicompost, and Triton X-100 were used. Results showed that the highest removal efficiency (99.9%) was achieved at 49 days, with a pH of 4.5, temperature of 37 °C, and using biostimulation with enzyme-vermicompost (3% w/v-5% w/w). The addition of surfactant was not significant in increasing the removal efficiency. Therefore, the results provide adequate conditions to bioremediate automotive residual oil-contaminated soils by biostimulation using enzymes supported with vermicompost.
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Lipoproteínas , Tensoativos , Biodegradação Ambiental , Octoxinol , SoloRESUMO
The synergistic effect between heavy metals and microplastics can affect soil properties as well as plant performance and yield. The objective of this study was to evaluate the combined effect of microplastics and cadmium on a soil-plant system. Specifically, we proposed to explore changes in soil microbiological activity, the growth and yield parameters of strawberry plants, and to evaluate the accumulation of these pollutants in the soil and root system. Plants were planted in clay pots under greenhouse conditions. The experiment was set up as a completely randomized design, with four treatments (Control; MPs; Cd; and Cd + MPs) and five replicates. The results showed that MPs and/or Cd affected plant growth, plant biomass, the number of fruits, root characteristics, dehydrogenase activity, acid phosphatase, and microbial biomass, and increased the accumulation of Cd in the roots and soil. The increased bioavailability of Cd, due to the presence of microplastics, could explain the observed negative effects on soil properties and the performance of strawberry plants.
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This study aimed to investigate the phytoremediation potential promoted by Baccharis dracunculifolia DC. and Baccharis trimera (Less.) DC. in copper mining tailing area, in the Southern part of Brazil. The plants were selected considering their spontaneous growth in tailing area. The phytoremediation indexes including translocation factor (TF), bioconcentration factor (BCF), metal extraction ratio (MER), and plant effective number (PEN) were assessed. Both species showed higher concentrations of heavy metals in the roots than to the shoots. B. trimera has potential for phytoextraction of Zn, Cd, Cr, and Pb and phytostabilization of Ba and Ni, whereas B. dracunculifolia demonstrated potential for phytoextraction of Pb and phytostabilization of Cu, Zn, and Ba. B. trimera showed higher potential in phytoremediation of the metals such as Cu > Zn > Cr > Ni and Cd than the B. dracunculifolia plants. A smaller number B. trimera plants was required to remove 1 g of Cu, Zn, Cr, Pb, Ni, and Cd than B. dracunculifolia plants, and implies that B. trimera is more efficient for decontamination of the metals. Both species showed potential for phytoremediation of metals in the mining tailing area under study.
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Biodegradação AmbientalRESUMO
Biochar can enhance the phytoremediation of copper-contaminated soils by improving soil quality and increasing plant growth. However, the impact of biochar varies with the biomass feedstock and soil condition. Our study investigated the effect of biochar from orange bagasse-OBB and coconut husk-CHB and two copper concentrations (0.17 mg kg-1-CLS soil; 100 mg kg-1- CTS soil) on plant growth, copper uptake, and physiological response of Brassica juncea. The low- and high-Cu soils were also tested without biochar. We evaluated plant biomass, plant Cu, N and P, chlorophyll content, and chlorophyll's transient fluorescence. Plant growth was meager without biochar, indicating that the high Cu concentration was not the only limiting factor. Biochar (OBB and CHB) increased shoot mass by 300-574% and root mass by 50-2900%, and improved chlorophyll content and photosynthetic activity by 6-16%. Both biochars were efficient in the low-Cu soil as they increased plant biomass, shoot copper concentration, and translocation factor. In the high-Cu soil, both biochars increased plant biomass and copper uptake and reduced shoot copper concentration and translocation factor. The CHB and OBB removed 342% and 783% more Cu from the contaminated soil than the Control; therefore, the OBB was proven to be the best choice for phytoremediation.Novelty statement Our study showed that the orange bagasse biochar can be successfully applied for the phytoremediation of copper-contaminated soils using Brassica juncea. The orange bagasse biochar was effective regardless of the copper level in the soil, removing twice as much copper as the coconut biochar; therefore, it can speed up the process and reduce the time needed to clean up the site. HighlightsBiochar significantly improved the plant's physiological responseBiochar increased plant growth and copper uptake in the contaminated soilTranslocation factor was increased in the clean soil and reduced in the contaminated soilBiochar from orange bagasse is more effective than coconut husk for phytoremediation.
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Mostardeira , Poluentes do Solo , Biodegradação Ambiental , Biomassa , Carvão Vegetal , Cobre , Solo , Poluentes do Solo/análiseRESUMO
Biochar (BC) is a porous, carbonaceous material produced by slow pyrolysis of biomass under oxygen-limited conditions. BC production has been attracting research interest because it modifies soil physicochemical characteristics and improves the growth of plants in problem soils. These benefits may be best actualized for soils contaminated by metals, where remediation is hampered by metal toxicity to both plants and soil microbial communities. The objectives of this study were to evaluate the impact of the addition of chicken manure biochar (CMB), oat hull biochar (OHB), or pine bark biochar (PBB) on copper (Cu) bioavailability in a Cu-contaminated soil, the effectiveness of these BCs promoting plant growth, and its effects on soil microbial communities supporting these plants. A sandy soil (338 mg Cu kg-1) was amended with CMB, OHB, and PBB, and the metallophyte Oenothera picensis or the agricultural species Solanum lycopersicum and Lolium perenne were grown for 3 months. The BCs produced an increase in soil pH, reduced the exchangeable Cu, and increased Cu bound to organic matter and residual fractions. All BCs enhanced the quality of contaminated soil and increased the plant biomass production, notably for S. lycopersicum, which grew until 12 times more than plants in non-amended soil. While BC addition reduced the concentration of Cu in soil pore water, the amendment did not reduce the concentrations of Cu in shoot tissues. BC additions also stimulated soil microorganisms, increasing basal respiration and DHA activity and modifying microbial communities, especially in soils supporting L. perenne. These results indicate that BCs represent an effective tool to remediate Cu-contaminated sandy soils.
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Carvão Vegetal , Cobre/química , Produtos Agrícolas , Microbiologia do Solo , Poluentes do Solo/química , Animais , Disponibilidade Biológica , Biomassa , Galinhas , Chile , Cobre/análise , Cobre/farmacocinética , Produtos Agrícolas/efeitos dos fármacos , Produtos Agrícolas/metabolismo , Concentração de Íons de Hidrogênio , Lolium/efeitos dos fármacos , Lolium/metabolismo , Solanum lycopersicum/efeitos dos fármacos , Solanum lycopersicum/metabolismo , Esterco , Oenothera/efeitos dos fármacos , Oenothera/metabolismo , Solo/química , Poluentes do Solo/análise , Poluentes do Solo/farmacocinéticaRESUMO
Persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) are a group of high-risk synthetic substances for human and environmental health. Currently, the study of sites contaminated by the spillage of equipment PCBs containing have been considered targeted areas for the study of bacterial communities with potential for PCBs degradation. There in isolation of bacterial strains is vital for use in biodegradable processes, such as bacterial bioaugmentation, which accelerates the development of phenomena such as natural attenuation of contaminated sites. The objective of this study was to assess biodiversity of bacteria contained in anthropogenic contaminated soils (HS and HP) with PCBs compared to a control sample without contaminant and the modified forest (F) and agricultural (A) soil in the laboratory with 100 mg L-1 PCB. For the analysis of 16S rRNA genes amplified from DNA extracted from the soils evaluated, the latest generation of Illumina Miseq and Sanger sequencing for the cultivable strains were detected. The bacteria identified as the most abundant bacterial phyla for HS and HP soil was Proteobacteria (56.7%) and Firmicutes (22.9%), which decreased in F and A soils. The most abundant bacterial genera were Burkholderia, Bacillus, Acinetobacter, Comamonas and Cupriavidus. Several species identified in this study, such as Bacillus cereus, Burkholderia cepacia, Comamonas testosteroni and Acinetobacter pittii have been reported as PCBs degraders. Finally, by means of a principal component analysis (PCA), a correlation between the physical and chemical characteristics of the soils in relation to the relative abundances of the bacteria identified was obtained. The C/N ratio was directly related to the control soil (without contaminant), while SOM maintained a relationship with F and A soils and the bacterial abundances were directly related to Hs and Hp soils due to the presence of aroclor 1260. Bacteria with the ability to tolerate high concentrations of this pollutant are considered for future use in biostimulation and bioaugmentation processes in contaminated soils.
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The validity of soil toxicity databases for predicting ecological impacts in the field is rarely explored. The present study was set up to test whether laboratory toxicity data and the combined concepts of metal availability and mixture toxicity can predict ecological impact in mining-affected soils. Metal and As contamination gradients were sampled approximately 5 different mines in Mexico where plant cover and abundances exhibited clear dose-related responses. Soils were analyzed for total and isotopically exchangeable (labile) concentrations of Ni, Cu, Cd, Pb, and As and for soil properties affecting the availability of these elements. Six different indices of toxic doses were compared to evaluate their accuracy in describing the field response expressed as relative abundance and cover. Each index was based on a different method to calculate the sum of toxic units ( Σ TUs) in soil, with 1 toxic unit equal to the concentration of the element in soil yielding 50% adverse effect on plants with median sensitivity as recorded in a recent database of salt-spiked soils. Toxic concentrations in the mine-impacted soils were dominated by Zn and As. In the field, 50% reduced cover or abundance was found at 10 to 13 Σ TUs if these were based on total soil concentrations and thresholds derived from freshly spiked soils, indicating a largely overestimated toxic effect. If thresholds were corrected for differences in availability among freshly spiked soils and spiked and laboratory-aged soils, the overestimation of field toxicity was 5- to 6-fold, irrespective of the consideration of soil properties. Finally, the Σ TU calculated only with labile metals and As overestimated the field toxicity by factors 1.1 to 1.6 (95% confidence interval 1-7; i.e., rather accurate and indicating some Zn-As antagonism as confirmed in experimental studies). That latter index of dose yielded a bell-shaped response on species richness peaking at approximately 1.6 Σ TU. Overall, the present study shows that the current toxicity databases of metals can predict the impact of metal contamination on plant communities within factor 2, expressing the dose as soil-labile concentrations and using the concentration addition concept in these mixed polluted environments. Environ Toxicol Chem 2020;39:1826-1838. © 2020 SETAC.
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Biodiversidade , Bases de Dados como Assunto , Metais/análise , Mineração , Plantas , Solo/química , Arsênio/análise , México , Plantas/efeitos dos fármacos , Medição de Risco , Poluentes do Solo/toxicidadeRESUMO
Background: Microbial community analysis of electronic waste (e-waste)-polluted environments is of interest to understand the effect of toxic e-waste pollutants on the soil microbial community and to evaluate novel microorganisms resisting the toxic environment. The present study aims to investigate the bacterial community structure in soils contaminated with e-waste from various sites of Loni and Mandoli (National Capital Region (NCR), India) where e-waste dumping and recycling activities are being carried out for many years. Results: Interferences to soil metagenomic DNA extraction and PCR amplification were observed because of the presence of inhibiting components derived from circuit boards. Whole-metagenome sequencing on the Illumina MiSeq platform showed that the most abundant phyla were Proteobacteria and Firmicutes. Deltaproteobacteria and Betaproteobacteria were the most common classes under Proteobacteria. Denaturing gradient gel electrophoresis (DGGE) analysis of the bacterial 16S rRNA gene showed that e-waste contamination altered the soil bacterial composition and diversity. There was a decrease in the number of predominant bacterial groups like Proteobacteria and Firmicutes but emergence of Actinobacteria in the contaminated soil samples. Conclusions: This is the first report describing the bacterial community structure of composite soil samples of ewaste-contaminated sites of Loni and Mandoli, Delhi NCR, India. The findings indicate that novel bacteria with potential bioremediating properties may be present in the e-waste-contaminated sites and hence need to be evaluated further.
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Microbiologia do Solo , Bactérias/isolamento & purificação , Bactérias/genética , Resíduo Eletrônico/análise , Poluentes do Solo , Reação em Cadeia da Polimerase , Metais Pesados , Proteobactérias/isolamento & purificação , Metagenômica , Eletroforese em Gel de Gradiente Desnaturante , Microbiota , Firmicutes/isolamento & purificação , ÍndiaRESUMO
In this study, hematological and behavioral changes in Wistar rats exposed to soil collected from urban areas next to an industrial complex were investigated. Animals were exposed to soil samples placed at the bottom of cages for 4 days. After this period, behavioral parameters were measured by the open field test and the elevated plus-maze. Blood was collected to measure hematological parameters. The soil from the vicinity of the oil refining industry caused changes in hematological parameters and altered behavioral parameters in both tests. The soil from the vicinity of the petroleum refining industry and fertilizer industries increased the density of white blood cells and decreased exploratory activity in the exposed animals. The results demonstrate that contact with contaminated soils, even for short periods, can cause physiological damage in organisms and that special attention should be given to people who live under constant exposure to these soils.
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Comportamento Animal/efeitos dos fármacos , Exposição Ambiental/efeitos adversos , Metais Pesados/toxicidade , Poluição por Petróleo/efeitos adversos , Poluentes do Solo/toxicidade , Solo/química , Animais , Contagem de Células Sanguíneas , Brasil , Exposição Ambiental/análise , Aprendizagem em Labirinto/efeitos dos fármacos , Metais Pesados/análise , Poluição por Petróleo/análise , Ratos Wistar , Poluentes do Solo/análise , Testes de ToxicidadeRESUMO
We characterized humic substances (HS) extracted from a Cu-contaminated soil without compost addition (C) or amended with a wheat straw-based compost (WSC) (H1), co-composted with Fe2O3 (H2), or co-composted with an allophane-rich soil (H3). Extracted HS were characterized under electron microscopy (SEM/TEM), energy-dispersive X-ray (X-EDS), and Fourier transform infrared (FTIR) spectroscopy. In addition, HS extracted from WSC (H4) were characterized at pH 4.0 and 8.0 with descriptive purposes. At pH 4.0, globular structures of H4 were observed, some of them aggregating within a large network. Contrariwise, at pH 8.0, long tubular and disaggregated structures prevailed. TEM microscopy suggests organo-mineral interactions at scales of 1 to 200 nm with iron oxide nanoparticles. HS extracted from soil-compost incubations showed interactions at nanoscale with minerals and crystal compounds into the organic matrix of HS. Bands associated to acidic functional groups of HS may suggest potential sorption interactions with transition metals. We conclude that metal ions and pH have an important role controlling the morphology and configuration of HS from WSC. Characterization of H4 extracted from WSC showed that physicochemical protection of HS could be present in composting systems treated with inorganic materials. Finally, the humified fractions obtained from compost-amended soils may have an important effect on metal-retention, supporting their potential use in metal-contaminated soils.
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Cobre/química , Substâncias Húmicas , Poluentes do Solo/química , Compostagem , Compostos Férricos , SoloRESUMO
Boron is widespread in the environment. Although contaminated soils are hard to recover different strategies have been investigated in the recent years. Bioremediation is one of the most studied because it is eco-friendly and less costly than other techniques. The aim of this research was to evaluate whether two Streptomyces strains isolated from boron contaminated soils in Salta, Argentina, may help remove boron from such soils. For this, they were grown in different liquid media with two boric acid concentrations and their specific growth rate and specific boric acid consumption rate were determined. Both strains showed great capacity to remove boron from the media. Increasing boric acid concentrations affected negatively the specific growth rate, however the specific boric acid consumption rate was superior. Boron bio-precipitates were observed when the strains grew in the presence of boric acid, probably due to an adaptive response developed by the cells to the exposure, for which many proteins were differentially synthetized. This strategy to tolerate high concentrations of boron by immobilizing it in bio-precipitates has not been previously described, to the best of our knowledge, and may have a great potential application in remediating soils contaminated with boron compounds.
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In recent decades, the concentration of trace elements has increased in soil and water, mainly by industrialization and urbanization. Recovery of contaminated areas is generally complex. In that respect, microorganisms can be of vital importance by making significant contributions towards the establishment of plants and the stabilization of impacted areas. Among the available strategies for environmental recovery, bioremediation and phytoremediation outstand. Arbuscular mycorrhizal fungi (AMF) are considered the most important type of mycorrhizae for phytoremediation. AMF have broad occurrence in contaminated soils, and evidences suggest they improve plant tolerance to excess of certain trace elements. In this review, the use of AMF in phytoremediation and mechanisms involved in their trace element tolerance are discussed. Additionally, we present some techniques used to study the retention of trace elements by AMF, as well as a summary of studies showing major benefits of AMF for phytoremediation.
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Micorrizas/fisiologia , Poluentes do Solo/análise , Oligoelementos/metabolismo , Biodegradação Ambiental , Raízes de Plantas/microbiologia , Plantas/microbiologia , Microbiologia do SoloRESUMO
Investigations of the redox process and chemical speciation of Hg(II) lead to a better understanding of biogeochemical processes controlling the transformation of Hg(II) into toxic and bioaccumulative monomethyl mercury, mainly in areas contaminated with Hg(0). This study investigates the speciation and redox processes of Hg in soil samples from a small area contaminated with Hg(0) as a result of gold mining activities in the rural municipality of Descoberto (Minas Gerais, Brazil). Soil samples were prepared by adding Hg(0) and HgCl2 separately to dry soil, and the Hg redox process was monitored using thermodesorption coupled to atomic absorption spectrometry. A portion of the Hg(0) added was volatilized (up to 37.4±2.0%) or oxidized (from 36±7% to 88±16%). A correlation with Mn suggests that this oxidation is favored, but many other factors must be evaluated, such as the presence of microorganisms and the types of organic matter present. The interaction of Hg with the matrix is suggested to involve Hg(II)-complexes formed with inorganic and organic sulfur ligands and/or nonspecific adsorption onto oxides of Fe, Al and/or Mn. The kinetics of the oxidation reaction was approximated for two first-order reactions; the faster reaction was attributed to the oxidation of Hg(0)/Hg(I), and the slower reaction corresponded to Hg(I)/Hg(II). The second stage was 43-139 times slower than the first. The samples spiked with Hg(II) showed low volatilization and a shifting of the signal of Hg(II) to lower temperatures. These results show that the extent, rate and type of redox process can be adverse in soils. Descoberto can serve as an example for areas contaminated with Hg(0).
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Compostos de Mercúrio/metabolismo , Mercúrio/metabolismo , Poluentes do Solo/metabolismo , Adsorção , Brasil , Monitoramento Ambiental , Mineração , Oxirredução , Espectrofotometria Atômica , VolatilizaçãoRESUMO
The purpose of this study was to assess the impact of metallurgical industry wastes on the semiarid soil microbiota using physico-chemical and microbiological parameters, highlighting the filamentous fungi assembly. Soil samples were collected in an area of industrial waste deposit contaminated with lead and mixed with natural soil (control soil) in seven different concentrations (0, 7.5, 15, 30, 45, 60 and 100%). The results showed alterations on the physico-chemical properties of the soil treated with industrial wastes, with a gradate increase of the soil's pH (5.6-10.4) and electrical conductivity (0.3-14.7 dS m-1) and also reduction of organic matter (7.0-1.8%). The use of microbiological parameters (fungal richness and diversity, CO2 emission, and the carbon on the microbial biomass) enabled the identification of alterations on the microbial community due to stress caused by the exposure to industrial wastes, despite the presence of Thielavia, Chaetomium and Aspergillus tolerant to high concentrations of the scoria. Therefore, these filamentous fungi could be used in biomonitoring and bioremediation studies in the soils contaminated by industrial wastes.
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The Salta Province - in the northwest of Argentina - is the main worldwide producer of hydroboracite and leads in exports of boron mineral and its derivatives in Latin America. In addition to the natural presence of boron compounds in the soils, there are others contaminated due to the boron mining industry. Although some bacteria are known to require boron for their growth or to be capable of storing boron, no studies have been published about Streptomyces or Lentzea genera's capacity to tolerate high boron concentrations, or about their metabolic capacities in boron contaminated environments. The results of this research show the isolation and molecular characterization of eight strains belonging to the actinobacteria phylum collected from different soils contaminated with high boron concentration in Salta state. The boron tolerance assays, which show that three of the strains were able to tolerate up 60-80 mM boron, demonstrate the potential capability of this group of bacteria to grow and maybe to remove boron from the environment. They appear to be promising, considering that these microorganisms are infrequent pathogens, are metabolically versatile and many Streptomyces can synthesize boron containing metabolites.