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1.
Chemosphere ; 281: 130889, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34289602

RESUMO

Scientists around the world have long been searching for effective strategies to reduce the bioavailability of metals in contaminated soils. In case of metal-spiked soils, some studies have proposed gypsum as a soil amendment to alleviate metal phytotoxicity. However, for real field-collected soils, evidence on the efficacy of gypsum as a metal phytotoxicity amendment is limited. Therefore, the present study was designed to examine the effect of gypsum on plant growth in soils polluted by a copper smelter. We grew perennial ryegrass on untreated and gypsum-treated soils (at a dose of 3% by weight) under laboratory conditions. We found that gypsum had no effect on alleviating metal phytotoxicity in our soils. We also demonstrated - for the first time - that gypsum increased the concentrations of soluble metals in the soil, enhancing metal uptake by plants. The calcium ions from gypsum displace metals in the soil exchangeable complex; however, the metals do not get immobilized in soils because gypsum is a neutral salt. While our results contrast with the Terrestrial Biotic Ligand Model, that Model has never been tested on real industrially polluted soils but only on metal-spiked soils. Our main conclusion is that gypsum is ineffective in alleviating metal phytotoxicity in real industrially polluted soils and, moreover, its use is inappropriate as a soil remediation method, because it increases the environmental hazard rather than reducing it. Our study is the very first attempt to recognize that gypsum is a hazardous material when used to ameliorate soils polluted by metals.


Assuntos
Metais Pesados , Poluentes do Solo , Sulfato de Cálcio , Poluição Ambiental , Metais , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
2.
Chemosphere ; 281: 130940, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34289610

RESUMO

Copper-based nanoparticles (Cu-based NPs) have been gaining wide attention in agricultural applications due to their diverse characteristics and multipurpose properties. This includes their use in agrochemicals for efficient delivery and controlled release of pesticides and fertilizers. However, their excessive usage over a long duration of time could pose potential risks to the soil system. Further, they are known for their well-established anti-microbial effects which could be detrimental to soil health, particularly to the activities of soil microbes, which play a significant role in the functioning of terrestrial and agroecosystems. Thus, there is a great need to clearly understand these uniquely nanospecific properties of Cu-based NPs along with mode-of-action, effect on soil processes, soil organisms, and plants. This paper examines the current literature on Cu-based NPs to provide a systematic understanding of their potential impacts on the soil-plant environment. It explores their rising application and usage in agriculture along with their possible interaction with various soil components and the potential factors influencing it. It further investigates their uptake, translocation, and distribution in plants in various exposure media. It summarises that the dissolution, biotransformation, and bioavailability of Cu-based NPs in the soil are governed by several factors, like soil type, soil pH, and organic matter content. Further, environmental factors, time duration, and presence of other pollutants could also influence their biotransformation and soil toxicity. Finally, this review seeks to provide future perspectives that need attention for investigation purposes.


Assuntos
Nanopartículas Metálicas , Nanopartículas , Poluentes do Solo , Cobre/toxicidade , Plantas , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
3.
Huan Jing Ke Xue ; 42(8): 3997-4004, 2021 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-34309286

RESUMO

As a representative of second-generation bioenergy plants, Miscanthus has received increasing attention in the studies of heavy metal (HM)-contaminated soil remediation. Currently, few studies have examined the effects of using Miscanthus to remediate HM-contaminated soils on the composition and function of microbial communities. In this study, the Miscanthus cultivar M. saccariflorus was examined for its tolerance and enrichment abilities when grown in soils containing 100 mg ·kg-1 of cadmium (Cd). The structure, function, and co-occurrence network of their rhizosphere bacterial communities were analyzed during the remediation process. MiSeq sequencing showed that the Miscanthus rhizosphere bacterial community comprised 32 phyla and 425 genera, including plant growth-promoting rhizobacteria (PGPR), such as Sphingomonas, Bacillus, Gemmatimonas, and Streptomyces. The addition of Cd affected the Miscanthus rhizosphere bacterial community and reduced community diversity. Phylogenetic molecular ecological networks indicated that Cd addition reduced the interactions between Miscanthus rhizosphere bacteria to generate a simpler network structure, increased the number of negative-correlation links, enhanced the competition between rhizosphere bacterial species, and changed the composition of key bacteria. PICRUSt functional predictive analysis indicated that Cd stress reduced soil bacterial functions in the Miscanthus rhizosphere. The results of this study provide a reference for the subsequent regulation of efficient Miscanthus remediation by PGPRs or key bacteria.


Assuntos
Rizosfera , Poluentes do Solo , Cádmio/análise , Cádmio/toxicidade , Filogenia , Solo , Microbiologia do Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
4.
Huan Jing Ke Xue ; 42(8): 4053-4060, 2021 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-34309292

RESUMO

Phytochelatins (PCs) can chelate heavy metal ions due to their large number of thiols and play an important role in heavy metal accumulation and detoxification. A. hypochondriacus K472, a cadmium (Cd) enriched plant, was selected as the research object. Six Cd treatment concentrations, namely 0 (CK), 10 (T1), 25 (T2), 50 (T3), 100 (T4), and 200 mg ·kg-1 (T5), were used to analyze the variation of PCs in different growth stages under different degrees of Cd stress and to explore the mechanism by which PCs chelate and detoxify Cd. The results showed that the plant height, root length, and biomass of K472 decreased significantly with increasing Cd concentration, and the range of decrease gradually became less pronounced with the growth and development of K472. K472 exhibited the maximum ability to enrich Cd during the middle vegetative growth period. The maximum concentration was 6695.35 mg, and the maximum bioconcentration factor was 6.3. In addition, with increasing Cd concentration, the Cd content of K472 roots, stems, and leaves was positively correlated with the concentration of PCs. PC3 had the strongest response to Cd stress in roots and stems, whereas PC2 responded to stress in leaves. For practical applications, harvesting K472 in the middle of vegetative growth is an optimal strategy for the remediation of Cd-contaminated soil.


Assuntos
Amaranthus , Poluentes do Solo , Biodegradação Ambiental , Cádmio/análise , Cádmio/toxicidade , Fitoquelatinas , Raízes de Plantas/química , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
5.
Braz J Biol ; 82: e237604, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34105671

RESUMO

This study goal to evaluate the effects of different concentrations of lead (Pb) and silver (Ag) on germination, initial growth and anatomical alterations of Lactuca sativa L. Plants use various mechanisms to reduce the impacts caused by anthropic action, such as xenobiotic elements of soils and water contaminated by heavy metals. These metals were supplied as lead nitrate and silver nitrate and the following treatments were established: control for both metals, maximum dose of heavy metals, for arable soils, allowed by the National Council of the Environment (Ag = 25 mg. Kg-1, Pb = 180 mg. Kg-1), double (Ag = 50 mg. Kg-1, Pb = 360 mg. Kg-1) and triple (Ag = 75 mg. Kg-1, Pb = 540 mg. Kg -1) of this dosage. Vigor and germination tests of the seeds and possible anatomical changes in the leaves and roots of lettuce plants were performed. The species showed a high capacity to germinate under Pb and Ag stress, and the germination was never completely inhibited; however, the germination decreased with increasing Pb concentrations, but not under Ag stress. The use of increasing doses of metals reduced seed vigor and increased chlorophyll content. An increase in biomass was also observed in plants from treatments submitted to Pb. The phytotoxic effects of metals were more pronounced at 15 days after sowing. Anatomically, L. sativa was influenced by metal concentrations, and had a reduction of up to 79.9% in root epidermis thickness at the highest Pb concentration, although some structures did not suffer significant changes. The results suggest that L. sativa presents tolerance to high concentrations of heavy metals, showing possible mechanisms to overcome the stress caused by these metals. In this research lettuce possibly used the mechanism of exclusion of metals retaining Pb and Ag in the roots preserving the photosynthetic apparatus in the aerial part of the plants. In general, the chemical element Pb was more toxic than Ag, in these experimental conditions.


Assuntos
Metais Pesados , Poluentes do Solo , Chumbo/toxicidade , Alface , Metais Pesados/análise , Metais Pesados/toxicidade , Nitratos/toxicidade , Nitrato de Prata , Solo , Poluentes do Solo/toxicidade
6.
Sci Total Environ ; 783: 147494, 2021 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-34088122

RESUMO

Heavy metals are considered major environmental pollutants. Soil microorganisms represent a predominant component of soils ecosystems, yet there is little information regarding hormetic responses of soil microorganisms to single and combined exposures to heavy metals. In the present study, to explore and predict the hormetic response of soil microorganisms, dose-response relationships of bacterial and fungal populations to single and combined treatments of cadmium (Cd) and lead (Pb) were evaluated. The results revealed hormetic responses of bacterial and fungal populations to both single and combined Cd and Pb treatments. The maximum stimulation (Mmax; relative to control treatment with no metals) of bacterial and fungal populations was 40% at 2 mg Cd/kg and 60% at 160 mg Pb/kg. An enhanced Mmax occurred in bacterial (50%) and fungal (75%) populations in the presence of the binary mixtures of 0.6 mg Cd/kg + 160 mg Pb/kg and 4.0 mg Cd/kg + 200 mg Pb/kg, suggesting positive additivity. This study showed that the hormetic effects of the mixtures were related to the independent effect of Cd and Pb, but they could not be predicted by the single effect of Cd or Pb. These new findings of the hormetic response of soil microorganisms to single treatments of Cd and Pb and their binary mixtures can facilitate the determination and minimization of ecological risks in heavy metal-polluted soils.


Assuntos
Metais Pesados , Poluentes do Solo , Bactérias , Cádmio/toxicidade , Ecossistema , Fungos , Hormese , Chumbo/toxicidade , Metais Pesados/toxicidade , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
7.
J Environ Sci (China) ; 105: 150-162, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34130832

RESUMO

Eco-toxicity investigation of polymer materials was considered extremely necessary for their potential menace, which was widely use as mulching materials in agricultural. In this study, polyethylene (PE), polystyrene (PS) and synthetic biomaterials-Ecoflex and cellulose were applying into soil cultivated with two potential indicator plants species: oat (Avena sativa) and red radish (Raphanus sativum). Variety of chemical, biochemical parameters and enzyme activity in soil were proved as effective approach to evaluate polymers phytotoxicity in plant-soil mesocosm. The F-value of biomass, pH, heavy metal and electoral conductivity of Raphanus behaved significant different from T0. Significant analysis results indicated biodegradation was fast in PE than PS, besides, heavy metals were dramatically decrease in the end implied the plant absorption may help decrease heavy metal toxicity. The increase value at T2 of Dehydrogenase activity (0.84 higher than average value for Avena & 0.91 higher for Raphanus), Metabolic Index (3.12 higher than average value for Avena & 3.81 higher for Raphanus) means during soil enzyme activity was promoted by biodegradation for its heterotrophic organisms' energy transportation was stimulated. Statistics analysis was carried on Biplot PC1 (24.2% of the total variance), PC2 (23.2% of the total variance), versus PC3 (22.8% of the total variance), which indicated phosphatase activity and metabolic index was significant correlated, and high correlation of ammonium and protease activity. Furthermore, the effects were more evident in Raphanus treatments than in Avena, suggesting the higher sensitivity of Raphanus to polymers treatment, which indicate biodegradation of polymers in Raphanus treatment has produced intermediate phytotoxic compounds.


Assuntos
Raphanus , Poluentes do Solo , Biodegradação Ambiental , Polímeros/toxicidade , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
8.
Braz J Biol ; 82: e246979, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34133578

RESUMO

The influence of pharmaceutical residues and heavy metals on living organisms has received global attention. The present study assessed the interactive effect of antibiotic residues and heavy metals in soil, as contaminated food with cadmium (Cd) and oxytetracycline (OTC) on the isopod Porcellio leavis. It was fed on fresh plant leaves contaminated with different concentrations of cadmium, Cd+OTC1000 ppm, Cd+OTC2000 ppm and Cd+OTC3000 ppm for 4 weeks. The changes in the feeding patterns, protein, lipid peroxidation (LPO), catalase activity (CAT), and total free amino acids (TFAA) were recorded. There were significant differences in the obtained results where Cd reduced the egestion ratio (ER) however, OTC enhanced this ratio. Biochemical analysis illustrated that combination between OTC and Cd inhibits the toxic effects of Cd at low concentration (1000 ppm), while at high concentration (3000 ppm) raise the toxicity. Detailed studies are required for further understanding of the interaction between OTC and heavy metals, and also its impact on soil animals and for improving soil risk evaluation.


Assuntos
Isópodes , Metais Pesados , Oxitetraciclina , Poluentes do Solo , Animais , Cádmio/toxicidade , Metais Pesados/análise , Oxitetraciclina/toxicidade , Solo , Poluentes do Solo/toxicidade
9.
Sci Total Environ ; 788: 147921, 2021 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-34134388

RESUMO

Pesticides pose a serious risk to ecosystems. In this study, we used European Food Safety Authority methods, such as risk quotient (RQ) and toxicity exposure ratios (TER), to assess the potential ecological risks of 15 pesticide residues detected in agricultural soils in the Gaidahawa Rural Municipality of Nepal. The mean and maximum concentrations of the detected pesticide residues in the soil were used for risk characterization related to soil organisms. RQmean, TERmean and RQmaximum, TERmaximum were used to determine general and the worst-case scenarios, respectively. Of all the detected pesticides in soils, the no observed effect concentration (NOEC) for 27% of the pesticides was not available in literature for the tested soil organisms and their TER and RQ could not be calculated. RQ threshold value of ≥1 indicates high risk for organisms. Similarly, TER threshold value of ≥5, which is acceptable trigger point value for chronic exposure, indicates an acceptable risk. The results showed that the worst-case scenario (RQmaximum) indicated a high risk for soil organisms from chlorpyrifos [RQmaximum > 9 at depths (cm) of 0-5, 15-20 and 35-40 soil layer]; imidacloprid (1.78 in the 35-40 cm soil layer) and profenofos (3.37 in the 0-5 cm and 1.09 in the 35-40 cm soil layer). Likewise, for all the soil depths, the calculated TER for both the general and worst-case scenarios for chlorpyrifos ranged from 0.37 to 3.22, indicating chronic toxicity to F. candida. Furthermore, the risk of organophosphate pesticides for soil organisms in the sampling sites was mainly due to chlorpyrifos, except for two study sites where the risk was from profenofos. Ecological risk assessment (EcoRA) of the pesticide use in the study area indicated that the EFSA soil organisms were at risk at some of the localities where farmers practiced conventional farming.


Assuntos
Resíduos de Praguicidas , Praguicidas , Poluentes do Solo , Ecossistema , Nepal , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/toxicidade , Praguicidas/análise , Praguicidas/toxicidade , Medição de Risco , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Verduras
10.
Chemosphere ; 280: 130724, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34162085

RESUMO

The mechanisms of the stimulatory effect of external magnetic fields on plant growth have been revealed; however, the role of magnetic fields in the efficiency of phytoremediation with Celosia argentea grown under drought stress which results in detrimental influences on food security has not been reported. Therefore, this study evaluated the physiological responses of C. argentea to the interactions between exposure to a magnetic field and drought stress. Compared with a control, a drought treatment negatively affected the dry weight, transpiration rate, and Cd extraction efficiency of the species and caused oxidative damage in plant cells, as manifested by the increase in malondialdehyde levels and antioxidant enzyme activities. The biomass production, pigment levels, Cd content, and phytoremediation efficiency of the plant were positively affected by all magnetic field treatments compared to the control. All magnetic treatments, except those at 30 mT, alleviated the detrimental effects induced by a 10-day irrigation regime by enhancing the dry weight, chlorophyll content, and activities of antioxidant enzymes in the leaves of the plant. In terms of the interaction between pre-sowing magnetic field seed treatment and drought stress, a 100 mT treatment increased most of the measured parameters, particularly under a 3-day irrigation regime; this corresponded to the optimal phytoremediation efficiency. The results suggest that magnetic field treatment is a novel, economical, and practicable strategy by which to increase the efficiency of phytoremediation using C. argentea under drought stress.


Assuntos
Celosia , Poluentes do Solo , Biodegradação Ambiental , Cádmio/análise , Secas , Campos Magnéticos , Sementes/química , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
11.
Chemosphere ; 280: 130830, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34162097

RESUMO

Biochar has the potential to control the bioavailability and transformation of heavy metals in soil, thereby ensuring the safe crop production. A three seasons field experiment was conducted to investigate the effect of crop straw-derived biochar on the bioavailability and crop accumulation of Cd and Cu in contaminated soil. Wheat straw biochar (WSB), corn stalk biochar (CSB), and rice husk biochar (RHB) were applied at the rate of 0, 1.125, and 2.25 × 104 kg ha-1, respectively. The results showed that all types of biochar significantly increased soil pH, organic carbon and cation exchangeable capacity (CEC), compared to the control. The reduction in DTPA extractable Cd and Cu contents was much greater under high dosage biochar application, with a prominence at RHB treatment throughout the three cropping seasons, compared to the control. Moreover, the biological accumulation of Cd and Cu in the grains of rapeseed and corn significantly decreased after biochar application. Linear regression also confirmed the effective role of biochar in controlling the translocation and accumulation of Cd and Cu due to their inactive bioavailability. In addition, the sequential extraction indicated that exchangeable fraction (EXF) of Cu and Cd had decreased, while residual fraction (RSF) had increased under all biochar amendments. Contrarily, the oxidizable fraction (OXF) of Cd decreased while OXF of Cu increased under biochar treatments. Biochar application, especially RHB, could be an effective measure to enhance Cd and Cu adsorption and immobilization in polluted soils and thereby reducing its uptake and translocation to crops.


Assuntos
Oryza , Poluentes do Solo , Disponibilidade Biológica , Cádmio/análise , Carvão Vegetal , Cobre/toxicidade , Rotação , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Zea mays
12.
Ecotoxicol Environ Saf ; 221: 112403, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34147863

RESUMO

The advent of the nanotechnology era offers a unique opportunity for sustainable agriculture provided that the exposure and toxicity are adequately assessed and properly controlled. The global production and application of cerium oxide nanoparticles (CeO2-NPs) in various industrial sectors have tremendously increased. Most of the nanoparticles end up in water and soil where they interact with soil microorganisms and plants. Investigating the uptake, translocation and accumulation of CeO2-NPs is critical for its safe application in agriculture. Plant uptake of CeO2-NPs may lead to their accumulation in different plant tissues and interference with key metabolic processes of plants. Soil microbes can also be affected by increasing CeO2-NPs in soil, leading to changes in the physiology and enzymatic activity of soil microorganisms. The interactions between CeO2-NPs, microbes and plants in the agricultural system need systemic research in ecologically relevant conditions. In the present review, The uptake pathways and in-planta translocation of CeO2-NPs,and their impact on plant morphology, nutritional values, antioxidant enzymes and molecular determinants are presented. The role of CeO2-NPs in modifying soil microbial community in plant rhizosphere is also discussed. Overall, the review aims to provide a comprehensive account on the behaviour of CeO2-NPs in soil-plant systems and their potential impacts on the soil microbial community and plant health.


Assuntos
Cério/toxicidade , Nanopartículas Metálicas/toxicidade , Microbiota/efeitos dos fármacos , Nanopartículas/toxicidade , Plantas/efeitos dos fármacos , Poluentes do Solo/toxicidade , Plantas/metabolismo , Microbiologia do Solo
13.
Ecotoxicol Environ Saf ; 221: 112437, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34153540

RESUMO

Agricultural soils are receiving higher inputs of trace elements (TEs) from anthropogenic activities. Application of nanoparticles (NPs) in agriculture as nano-pesticides and nano-fertilizers has gained rapid momentum worldwide. The NPs-based fertilizers can facilitate controlled-release of nutrients which may be absorbed by plants more efficiently than conventional fertilizers. Due to their large surface area with high sorption capacity, NPs can be used to reduce excess TEs uptake by plants. The present review summarizes the effects of NPs on plant growth, photosynthesis, mineral nutrients uptake and TEs concentrations. It also highlights the possible mechanisms underlying NPs-mediated reduction of TEs toxicity at the soil and plant interphase. Nanoparticles are effective in immobilization of TEs in soil through alteration of their speciation and improving soil physical, chemical, and biological properties. At the plant level, NPs reduce TEs translocation from roots to shoots by promoting structural alterations, modifying gene expression, and improving antioxidant defense systems. However, the mechanisms underlying NPs-mediated TEs uptake and toxicity reduction vary with NPs type, mode of application, time of NPs exposure, and plant conditions (e.g., species, cultivars, and growth rate). The review emphasizes that NPs may provide new perspectives to resolve the problem of TEs toxicity in crop plants which may also reduce the food security risks. However, the potential of NPs in metal-contaminated soils is only just starting to be realized, and additional studies are required to explore the mechanisms of NPs-mediated TEs immobilization in soil and uptake by plants. Such future knowledge gap has been highlighted and discussed.


Assuntos
Nanopartículas , Plantas/efeitos dos fármacos , Oligoelementos/metabolismo , Oligoelementos/toxicidade , Agricultura , Metais/metabolismo , Metais/toxicidade , Raízes de Plantas/metabolismo , Plantas/metabolismo , Solo/química , Poluentes do Solo/metabolismo , Poluentes do Solo/toxicidade
14.
Environ Sci Technol ; 55(13): 8654-8664, 2021 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-34156836

RESUMO

This study compared the impact and uptake of root-administered CeO2 nanoparticles (NPs) in rice growing under flooded and aerobic soil conditions, which are two water regimes commonly used for rice cultivation. CeO2 NPs at 100 mg/kg improved photosynthesis and plant growth by reducing the oxidative damage and enhancing plant tolerance to stress, while a higher concentration (500 mg/kg) of CeO2 NPs negatively affected plant growth. More significant effects were observed under the flooded condition than under the aerobic condition. CeO2 NPs of 100 and 500 mg/kg resulted in 78% and 70% higher accumulation of Ce in shoots under the flooded condition compared to the aerobic condition. CeO2 NPs partially transformed to Ce(III) species in soils and plants under both conditions. A higher extent of transformation under the flooded condition, which was partly attributed to the lower soil pH and redox potential under the flooded condition, leads to higher plant uptake of Ce. A higher extent of transformation in rhizosphere soil was observed. A higher plant transpiration rate (TR) under flooded conditions resulted in a higher accumulation of CeO2 species in shoots. This study, for the first time, reported that water regimes influenced the biotransformation of CeO2 NPs and their uptake and impact in rice plants.


Assuntos
Cério , Nanopartículas , Oryza , Poluentes do Solo , Cério/toxicidade , Raízes de Plantas/química , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
15.
Ecotoxicol Environ Saf ; 221: 112443, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34166939

RESUMO

It is important to assess the toxic effects posed by soil pollutants toward plants. However, plant toxicology experiments normally involve a considerable amount of manpower, consumables and time. Therefore, the use of metal toxicity prediction models, independent of toxicity tests, is critical. In this study, we investigated the toxicity of different metal ions to wheat using hydroponic experiments. We employed the methods of soft-hard ion grouping, soft-hard ligand theory and K (conditional binding constant based on the biotic ligand model principle) in combination with hydroponic experiments to explore the application of quantitative ion character-activity relationships in predicting phytotoxicity. The results showed that the toxicity of the 19 metal ions tested varied significantly, with EC50 ranging from 0.27 µM to 4463.36 µM. The linear regression relationships between the toxicity of these metal ions and their physicochemical properties were poor (R2 = 0.237-0.331, p < 0.05). These relationships were improved after grouping the metals according to the soft-hard theory (R2 = 0.527-0.744 and p < 0.05 for soft ions; R2 = 0.445-0.743 and p < 0.05 for hard ions). The application of soft-hard ligand theory, based on the binding affinity of the metals to the ligands, showed poor prediction of the phytotoxicity of metals, with R2 = 0.413 (p = 0.024) for the softness consensus scale (σCon) and R2 = 0.348 (p = 0.218) for the normalized hard ligands scale (HLScale). However, the method of K provided the closest fit in predicting toxicity (R2 = 0.803, p < 0.001). Our results showed that the application of soft-hard ion grouping and log K can improve prediction of the phytotoxicity of metals relatively well, which can potentially be used for deriving the toxicity of elements with limited toxicity data.


Assuntos
Metais/toxicidade , Testes de Toxicidade/métodos , Triticum/efeitos dos fármacos , Íons/química , Ligantes , Poluentes do Solo/toxicidade
16.
Ecotoxicol Environ Saf ; 221: 112436, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34171689

RESUMO

Nanoparticles (NPs), as a novel source of industrial materials, have been extensively used in recent years which ultimately ends up in soils and may cause toxic effects on plants. Gibberellic acid (GA), phytohormone, has ability to minimize abiotic stresses in plants. The role of GA in minimizing titanium dioxide (TiO2) NPs stress in plants is still unknown. In current study, soil was spiked with TiO2 NPs (0, 100, 200, 400, 600 mg/kg) while GA was foliar-sprayed at different concentrations during wheat growth. The findings revealed that TiO2 NPs increased the growth, chlorophyll contents, and nutrient (P, K, Fe, Mn) concentrations in tissues till 400 mg/kg and then decrease was observed at 600 mg/kg level of NPs whereas the values of these parameters were higher compared to control irrespective of NPs levels. The NPs enhanced the antioxidant activities (SOD, POD, CAT, APX) and reduced the oxidative stress (EL, H2O2, MDA) in leaves over the control. Foliar GA further improved the growth, yield, nutrients and antioxidant activities while minimized the oxidative stress compared to respective sole NPs- treatments. The interactive effects of NPs and GA were dose dependent. The results proved that studied doses of TiO2 NPs were not toxic to wheat plants except the highest level (600 mg/kg) used and GA positively affected the yield of wheat under TiO2 NPs application. The GA can be used to improve crop growth in the presence of NPs which, however, needs further investigation at higher doses of TiO2 NPs in various crops.


Assuntos
Giberelinas/farmacologia , Nanopartículas/toxicidade , Titânio/toxicidade , Triticum/efeitos dos fármacos , Antioxidantes/farmacologia , Transporte Biológico/efeitos dos fármacos , Minerais/metabolismo , Nutrientes/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Folhas de Planta/química , Folhas de Planta/metabolismo , Poluentes do Solo/toxicidade
17.
Ecotoxicology ; 30(6): 1071-1083, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34101047

RESUMO

Salinity may increase metal mobilization with a potentially significant consequence for soil enzymatic activity and nutrient cycling. The goal of this study was to investigate changes in soil enzyme activity in response to salinization of a clay loam soil artificially polluted with cadmium (Cd) and lead (Pb) during a 120-day incubation experiment. Soil samples were polluted with Cd (10 mg Cd kg-1), Pb (150 mg Pb kg-1), and a combination of Cd and Pb, then preincubated for aging and eventually salinized with three levels of NaCl solution (control, low and high). NaCl salinity consistently increased the mobilization of Cd (12-22%) and Pb (5-16%) with greater increases at high (17-22% for Cd, 9-16% for Pb) than low (12% for Cd, 5-7% for Pb) salinity levels. While the increased Cd mobilization was greater in co-polluted (22%) than Cd-polluted (17%) soils, the increase of Pb mobilization was lower in co-polluted (9%) than Pb-polluted (16%) soils at high salinity level. The salinity-induced increases in metal mobilization significantly depressed soil microbial respiration (up to 43%), microbial biomass content (up to 63%), and enzymatic activities (up to 87%). The multivariate analysis further supported that the increased soil electrical conductivity, Cd mobilization, and pH after salinization were the most important factors governing microbial activity and biomass in metal-polluted soils. Results showed that changes in microbial biomass and mobile metal pool with increasing salinity had a major effect on enzyme activities, particularly under the combined metals. This study indicated that the secondary salinization of metal-polluted soils would impose an additional stress on enzymatic activities as biochemical indicators of soil quality, and therefore should be avoided for the maintenance of soil microbial and biochemical functions, especially in arid regions. In metal-polluted soils, the observed responses of extracellular and intracellular enzymes to salinity can be used to advance our knowledge of microbial processes when modeling the carbon and nutrient cycling.


Assuntos
Poluentes do Solo , Solo , Biomassa , Cádmio/análise , Poluição Ambiental , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
18.
Ecotoxicology ; 30(6): 1029-1042, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34191243

RESUMO

Lead acetate (AcPb) is an important raw material used in chemical industries worldwide. The potential toxicity of AcPb is generally attributed to the presence of Pb. However, the effect of AcPb on the environment as a whole is still poorly known. This study aimed to evaluate AcPb toxicity on three standard species of soil invertebrates and two plant species using ecotoxicology tests. Three tropical soils (Oxisol, Inceptisol, and Tropical Artificial Soil (TAS)) were contaminated with different concentrations of AcPb and one dose of K-acetate (positive control). These soils were used in tests with Eisenia andrei (earthworm), Folsomia candida (springtail), Enchytraeus crypticus (enchytraeid), Zea mays (maize), and Phaseolus vulgaris (common bean). Dose-response curves obtained in the laboratory tests were used to estimate the EC50 values for each species. Among invertebrates, the highest sensitivity to AcPb was observed for E. crypticus in the TAS (EC50 = 29.8 mg AcPb kg-1), whereas for E. andrei and F. candida the highest sensitivity was observed in the Oxisol (EC50 = 141.9 and 1835 mg AcPb kg-1, respectively). Folsomia candida was the least sensitive invertebrate species to AcPb in all soils. Among plant species, Z. mays was less sensitive (EC50 = 1527.5 mg AcPb kg-1) than P. vulgaris (EC50 = 560.5 mg AcPb kg-1) in the Oxisol. The present study evidenced that the toxicity of AcPb should not be attributed uniquely to the presence of Pb, as the treatment containing uniquely Ac provoked the same toxicity as the highest dose of AcPb.


Assuntos
Artrópodes , Oligoquetos , Poluentes do Solo , Animais , Chumbo/toxicidade , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
19.
Ecotoxicol Environ Saf ; 221: 112441, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34174738

RESUMO

The coexistence of multi-walled carbon nanotubes (MWCNTs) with cadmium (Cd) in soil may cause the combined biological effects, but few study reported about their joint toxic effects on earthworms. Therefore, this study investigated the effects of sub-lethal levels of MWCNTs (10, 50, 100 mg/kg) and Cd (2.0, 10 mg/kg) on earthworms Eisenia fetida for 14 days. The changes in multi-level biomarkers of growth inhibition rate, cytochrome P450 isoenzymes (CYP1A2, 2C9 and 3A4), and small molecular metabolites (metabolomics) were determined. The toxic interaction between MWCNTs and Cd was characterized by the combination of the biomarker integration index (BRI), joint effect index concentration addition index (CAI), and the effect concentration addition index (EAI). The results showed that the single MWCNTs exposure caused insignificant change in most biomarkers, while the combined exposure of MWCNTs (50-100 mg/kg) and 10 mg/kg Cd led to significant changes in ten most important metabolites identified by metabolomics and activities of CYP1A2, 2C9, and 3A4. Compared with the toxicity of Cd alone, the combined toxicity of the mixture was significantly reduced. According to the integration of BRI and CAI/EAI, a clearly antagonistic interaction at relatively low effects was observed between MWCNTs and Cd. The responses of multiple biomarkers suggest the toxic action mode of the mixture on earthworms was related to the oxidative injury, and the disruption of amino acid, purine, and pyrimidine metabolism, and the urea cycle.


Assuntos
Cádmio/toxicidade , Nanotubos de Carbono/toxicidade , Oligoquetos/efeitos dos fármacos , Poluentes do Solo/toxicidade , Animais , Biomarcadores/metabolismo , Solo/química
20.
J Hazard Mater ; 415: 125657, 2021 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-34088178

RESUMO

Rhodococcus qingshengii strain FF is a soil ubiquitous strain that has a high polycyclic aromatic hydrocarbons (PAHs) biodegradation capability. In this work, phenanthrene was used as a PAH model compound. The accumulated pattern of the metabolites of phenanthrene by strain FF was investigated, and their toxicity to Vibrio fischeri, effect on microbiota diversity of farmland soil and influence on seed of wheat were evaluated. Total of 29 main intermediates were observed for the phenanthrene degradation process. Pyrogallol was the predominant accumulated metabolite, and 59% of the accumulated metabolites were oxygen-containing PAHs that have only one benzene ring. The acute toxicity assessment showed the accumulated metabolites in later phase were more toxic to Vibrio fischeri. Microbe and wheat seed response to the different stages of phenanthrene metabolites indicated pollution significantly decreased microbial richness and evenness of farmland soil and lower germinal length, root length or root number of wheat seed. These results indicated that not only the elimination of PAHs, but also the easily accumulated metabolites produced during the PAHs degradation process should be paid enough attention. The comprehensive evaluation of toxicity during the degradation process would provide useful information for the use of microbe-orientated strategies in PAHs bioremediation.


Assuntos
Fenantrenos , Hidrocarbonetos Policíclicos Aromáticos , Poluentes do Solo , Biodegradação Ambiental , Fenantrenos/toxicidade , Hidrocarbonetos Policíclicos Aromáticos/análise , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Rhodococcus , Solo , Microbiologia do Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
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