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Microplastics (MPs) are emerging pollutants of terrestrial ecosystems. The impacts of MP particle size on terrestrial systems remain unclear. The current study aimed to investigate the effects of six particle sizes (i.e., 4500, 1500, 500, 50, 5, and 0.5 μm) of polyethylene (PE) and polyvinyl chloride (PVC) on soil respiration, enzyme activity, bacteria, fungi, protists, and seed germination. MPs significantly promoted soil respiration, and the stimulating effects of PE were the strongest for medium and small-sized (0.5-1500 μm) particles, while those of PVC were the strongest for small particle sizes (0.5-50 μm). Large-sized (4500 μm) PE and all sizes of PVC significantly improved soil urease activity, while medium-sized (1500 μm) PVC significantly improved soil invertase activity. MPs altered the soil microbial community diversity, and the effects were especially pronounced for medium and small-sized (0.5-1500 μm) particles of PE and PVC on bacteria and fungi and small-sized (0.5 μm) particles of PE on protists. The impacts of MPs on bacteria and fungi were greater than on protists. The seed germination rate of Brassica chinensis decreased gradually with the decrease in PE MPs particle size. Therefore, to reduce the impact of MPs on soil ecosystems, effective measures should be taken to avoid the transformation of MPs into smaller particles in soil environmental management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

As an essential trace element for plant growth and development, manganese plays a crucial role in the uptake of the heavy metal cadmium by rice (Oryza sativa L.). In this study, we developed a novel slow-release manganese fertilizer named Mn@LNS-EL. Initially, lignin nanoparticles were derived from sodium lignosulfonate, and a one-step emulsification strategy was employed to prepare a water-in-oil-in-water (W/O/W) Pickering double emulsions. These double emulsions served as the template for interfacial polymerization of lignin nanoparticles and epichlorohydrin, resulting in the formation of microcapsule wall materials. Subsequently, manganese fertilizer (MnSO 4 ) was successfully encapsulated within the microcapsules. Hydroponic experiments were conducted to investigate the effects of Mn@LNS-EL on rice growth and the cadmium and manganese contents in the roots and shoots of rice under cadmium stress conditions. The results revealed that the treatment with Mn@LNS-EL markedly alleviated the inhibitory effects of cadmium on rice growth, leading to notably lower cadmium levels in the rice roots and shoots compared to the specimens treated without manganese fertilizer. Specifically, there was a reduction of 37.9 % in the root cadmium content and a 17.1 % decrease in the shoot cadmium content. In conclusion, this study presents an innovative approach for the high-value utilization of lignin through effective encapsulation and slow-release mechanisms of trace-element fertilizers while offering a promising strategy for efficiently remediating cadmium pollution in rice., Competing Interests: Declaration of competing interest The authors state that they have no known competing financial interests or personal relationships that might affect the work reported in this article., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Intensive sulphur fertilisation has been reported to improve the nutrient balance and growth of Cd-exposed plants, but the reasons of this phenomenon and the role of sulphur compounds in the resistance to cadmium are unclear. We investigated sulphur supplementation-induced changes in the surface properties of roots and the level of thiol peptides (PCs) in Cd-stressed Triticum aestivum L. (monocots clade) and Lactuca sativa L. (dicots clade) grown in nutrient solution. The combination of three sulphur (2 mM S-basic level, 6 or 9 mM S-elevated levels) and four cadmium (0, 0.0002, 0.02 or 0.04 mM Cd) concentrations was used. The physicochemical parameters of the roots were determined based on the apparent surface area (S r ), total variable surface charge (Q), cation exchange capacity (CEC) and surface charge density (SCD). In Cd-exposed plants supplied with sulphur, a different character and trend in the physicochemical changes (adsorption and ion exchange) of roots were noted. At the increased sulphur levels, as a rule, the S r , CEC, Q and SCD values clearly increased in the lettuce but decreased in the wheat in the entire range of the Cd concentrations, except the enhanced S r of wheat supplied with 6 mM S together with elevated (0.0002 mM) and unchanged (0.02, 0.04 mM Cd) value of this parameter at 9 mM S. This indicates a clade-specific and/or species-specific plant reaction. The 6 mM S appears to be more effective than 9 mM S in alleviation of the cadmium's toxic effects on roots. It was found that at 0.02 and 0.04 mM Cd, the use of 6 mM S limits the Cd accumulation in the roots of both species in comparison with the basic S fertilisation. Moreover, PC accumulation was much more efficient in wheat than in lettuce, and intensive sulphur nutrition generally induced biosynthesis of these chelating compounds. Physicochemical parameters together with quantitative and qualitative assessment of thiol peptides can be important indicators of the efficiency of root system functioning under cadmium stress. The differences between the species and the multidirectional character of the changes are a result of the involvement of a number of multi-level mechanisms engaged in the defence against metal toxicity., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Fungicides are commonly applied through root irrigation in tobacco fields to control soil-borne diseases, and they affect soil microorganisms. However, the effects of metalaxyl-M and hymexazol, used to manage tobacco black shank disease, on these soil microecology remain poorly understood. This study employed high-throughput sequencing technology to explore the soil physical and chemical properties, soil enzyme activity, and the diversity, community structure and function of soil fungi in tobacco fields following root irrigation with metalaxyl-M and hymexazol. The results revealed that ammonium nitrogen (NH 4 + -N), nitrate nitrogen (NO 3 - -N), soil organic matter (SOM), electrical conductivity (EC) and soil urease (UE) in soil were significantly increased and the pH decreased after root-irrigation with these two fungicides. The abundance of soil fungal community was significantly reduced after the root-irrigation of metalaxyl-M and hymexazol. The relative abundance of Ascomycota increased significantly after the treatment with metalaxyl-M. Following hymexazol treatment, the abundance of Achroiostachys, Nigrospora, Ustilaginoidea, and Trichoderma significantly decreased. Functional prediction analysis indicated an increase in the relative abundance of functional genes of saprophytic fungi after treatment with both fungicides. This study provides a foundational understanding of the environmental behavior and supports the scientific and rational use of metalaxyl-M and hymexazol in soil.

Arsenic (As) is a toxic non-essential metal. Its accumulation in rice has not only seriously affected the growth of rice, but also poses a significant threat to human health. Many reports have been published to decrease the arsenic accumulation in the rice plant by various additives such as chemicals, fertilizers, adsorbents, microorganisms and analyzing the mechanism. Nanobubble is a new technology widely used in agriculture because of its long existence time and high mass transfer efficiency. However, a few studies have investigated the effect of nanobubbles on arsenic uptake in rice. This study investigated the effect of oxygen nanobubbles on the growth and uptake of As in rice. The oxygen nanobubbles could rupture the salinity of nutrients and produce the hydroxyl radical. The hydroxyl radical caused the oxidation of arsenic As(III) to As (V) and the oxidation of ferrous ions. At the same time, the oxidized iron adsorbing As (V) created the iron plaque on the rice roots to stop arsenic introduction into the rice plant. The results indicated that the treatment of oxygen nanobubbles increased rice biomass under As stress, while they increased the chlorophyll content and promoted plant photosynthesis. Oxygen nanobubbles reduced the As content in rice roots to 12.5% and shoots to 46.4%. In other words, it significantly decreased As accumulation in rice. Overall, oxygen nanobubbles mitigated the toxic effects of arsenic on rice and had the potential to reduce the accumulation of arsenic in rice., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Dietary restriction (DR) and dietary deprivation (DD) have been shown to be significantly beneficial in terms of lifespan gains and stress alleviation in invertebrate and vertebrate species. Such beneficial effects, however, have yet to be clearly assessed in the presence of chemical stressors. We conducted a comparative evaluation of the toxicity of carbaryl in Eisenia fetida individuals subjected to a full diet (FD), DR and DD. For 14 days, groups of ten worms subjected to FD received 5 g oatmeal, those subjected to DR received 2.5 g oatmeal, and those subjected to DD received 0 g oatmeal weekly. We evaluated concentrations of 0, 7, 14 and 28 mg carbaryl.kg -1 soil and measured effects on survival, reproduction, biomass and biomarkers (Catalase- CAT and acetylcholine esterase- AChE). Carbaryl caused a total inhibition of reproduction in all the treatments. For each diet level, the 14-day LC 50 s were higher than 28 mg.kg -1 , but the 14-day LC 20 s for the earthworms subjected to FD, DR, and DD were 11.24, 20.51 and > 28 mg.kg -1 , respectively. This showed that the toxicity of carbaryl consistently decreased with the reduction in nutrients. Carbaryl caused a significant weight loss in the worms subjected to FD in the 7 mg.kg -1 treatment (P = 0.0065). Such weight loss was not found in any of the other treatments and diets. Both CAT and AChE were significantly inhibited in the two highest treatments (P = 0.0071 and P = 0.0073, respectively). Interestingly, the earthworms subjected to DD showed relatively lower biomarker inhibition, indicating a greater tolerance to oxidative and neurotoxic stresses in these starved earthworms. For all endpoints investigated, aside from reproduction, the starved earthworms fared better under carbaryl toxicity than those given the other diets. Overall, a positive correlation was observed between the amount of food and chemical toxicity as mortality rates, AChE and CAT inhibition increased with the increased amount of nutrients given to the worms. These results show that, in the presence of a chemical stressor, the beneficial effects of DR and DD were variably manifest for select lifecycle parameters and biomarker responses, further suggesting dietary reduction as a non-genetic intervention that could help extend lifespan and alleviate stress even under a chemical insult., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

This study investigated the combined effects of citric acid (CA) and Nocardiopsis sp. RA07 on the phytoremediation potential of lead (Pb)- and copper (Cu)-contaminated soils by Sorghum bicolor L. The strain RA07 was able to tolerate Pb and Cu, and exhibited plant growth-promoting features like siderophore production, indole-3-acetic acid (IAA) synthesis, 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity and phosphate solubilization. The combined application of CA and strain RA07 significantly increased S. bicolor growth, chlorophyll content and antioxidant enzymatic activity, and decreased oxidative stress (hydrogen peroxide and malondialdehyde content) under Pb and Cu stress circumstances as compared to individual treatments (i.e., CA and strain RA07). Furthermore, the combined application of CA and RA07 significantly enhanced S. bicolor ability to accumulate Pb and Cu by 64.41% and 60.71% in the root and 188.39% and 125.56% in the shoot, respectively, as compared to the corresponding uninoculated plants. Our results indicate that inoculation of Nocardiopsis sp. together with CA could be a useful practical approach to mitigate Pb and Cu stress on plant growth and increase the effectiveness of phytoremediation in Pb- and Cu-polluted soils., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Nowadays, Lead (Pb) and Cadmium (Cd) contamination in rice is an important worldwide environmental concern. Fe 3 O 4 nanoparticles (Fe 3 O 4 NPs) and Nano hydroxyapatite (n-HAP) are promising materials to manage Pb and Cd contamination. This study systematically investigated the effect of Fe 3 O 4 NPs and n-HAP on Pb and Cd stressed rice seedlings' growth, oxidative stress, Pb and Cd uptake and subcellular distribution in roots. Furthermore, we clarified the immobilization mechanism of Pb and Cd in the hydroponic system. Fe 3 O 4 NPs and n-HAP could reduce Pb and Cd uptake of rice mainly through decreasing Pb and Cd concentrations in culture solution and combining with Pb and Cd in root tissues. Pb and Cd were immobilized by Fe 3 O 4 NPs through complex sorption processes and by n-HAP through dissolution-precipitation and cation exchange, respectively. On the 7th day, 1000 mg/L Fe 3 O 4 NPs reduced the contents of Pb and Cd in shoots by 90.4% and 95.8%, in roots by 23.6% and 12.6%, 2000 mg/L n-HAP reduced the contents of Pb and Cd in shoots by 94.7% and 97.3%, in roots by 93.7% and 77.6%, respectively. Both NPs enhanced the growth of rice seedlings by alleviating oxidative stress and upregulating glutathione secretion and antioxidant enzymes activity. However, Cd uptake of rice was promoted at certain concentrations of NPs. The subcellular distribution of Pb and Cd in roots indicated that both NPs decreased the percentage of Pb and Cd in the cell wall, which was unfavorable for Pb and Cd immobilization in roots. Cautious choice was needed when using these NPs to manage rice Pb and Cd contamination., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Global warming and heavy metal-contaminated soils co-occur in natural ecosystems. Flavonoids and phenolic acids in plants have significant antioxidant activity and free radical scavenging ability, which can quickly increase under adverse environments. Arbuscular mycorrhizal fungi (AMF) colonization can affect the synthesis of flavonoids and phenolic acids in host plants. This study focused on the main effect of Glomus mosseae, cadmium (Cd, 8 mg kg -1 dry soils), and elevated temperature (ET, + 3 °C) on main flavonoids and phenolic acids in 120-d Medicago sativa L. (alfalfa). Elevated temperature decreased G. mosseae colonization ratio by 49.5% under Cd exposure. Except for p-hydroxybenzoic acid, flavonoids and phenolic acids content in shoots increased (p < 0.05) under G. mosseae + Cd relative to Cd only. G. mosseae and Cd showed significant effects on rutin, quercetin, apigenin, liquiritigenin, gallic acid, p-hydroxybenzoic acid, p-coumaric acid, and ferulic acid, and G. mosseae colonization led to increases in these compounds by 41.7%, 35.4%, 32.2%, 267.8%, 84.7%, 33.5%, 102.8%, and 89.4%, respectively, under ET + Cd. Carbon, N, and Cd in alfalfa and G. mosseae colonization rate were significant factors on flavonoids and phenolic acids accumulation. Additionally, P content in shoots significantly influenced flavonoids content. G. mosseae inoculation significantly stimulated the synthesis of main flavonoids and phenolic acids in alfalfa shoots under ET + Cd, which was helpful to understand the regulation of AMF on non-enzyme antioxidant system of plants grown in heavy metal-contaminated soils under global change scenarios., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Rhizoremediation is a promising method based on the synergism between plant and rhizobacteria to remediate soil co-contaminated with heavy metals and total petroleum hydrocarbons (TPHs). A plant growth-promoting (PGP) rhizobacterium with diesel-degrading capacity and heavy metal tolerance was isolated from the rhizosphere of tall fescue (Festuca arundinacea L.), after which the effects of its inoculation on rhizoremediation performance were evaluated in heavy metal- and diesel-contaminated soil planted with tall fescue. The bacterial isolate (Novosphingobium sp. CuT1) was characterized by its indole-3-acetic acid (IAA) production, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, and siderophore productivity as PGP traits. CuT1 was able to grow on 1/10 LB-agar plates containing 5 mM of Cu or 5 mM of Pb. To evaluate the remediation effect of heavy metal- and diesel-contaminated soil by CuT1 inoculation, the experimental conditions were prepared as follows. The soil was artificially contaminated with heavy metals (Cu and Pb) at a final concentration of 500 ppm. The soil was then further contaminated with diesel at final concentrations of 0, 10,000, and 30,000 ppm. Finally, all plots were planted with tall fescue, a representative hyperaccumulating plant. Compared to the rhizoremediation performance of the co-contaminated soil (Cu + Pb + diesel) without inoculation, the bioavailable Cu concentrations in the soil and the tall fescue biomass were significantly increased in CuT1 inoculation. Additionally, the root growth of tall fescue was also promoted in CuT1 inoculation. Correlation analysis showed that Cu bioavailability and bioconcentration factor were positively correlated with CuT1 inoculation. The diesel removal efficiency showed a positive correlation with CuT1 inoculation, although the diesel removal was below 30%. CuT1 inoculation was positively correlated with IAA and dehydrogenase activity in the soil. Moreover, the dry biomass of the tall fescue's roots was highly associated with CuT1 inoculation. Collectively, our findings suggest that Novosphingobium sp. CuT1 can be utilized as an applicable bioresource to enhance rhizoremediation performance in heavy metal- and TPH-contaminated soils., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

In this study, the differences in the accumulation of fipronil (F) and the glycosylated product glucose-fipronil (GTF) in Eisenia fetida within 48 h were investigated, and the reason for these differences was discussed. The accumulation of F and GTF in E. fetida and soil was determined by high-performance liquid chromatography (HPLC) after simple, rapid pretreatment; the mean recoveries of F and GTF were 84.79 ~ 95.83%, and the relative standard deviations were 3.39 ~ 9.21%, indicating that the methods could accurately detect the accumulation of F and GTF in E. fetida and soil. Results showed that the accumulation concentrations of F and GTF in E. fetida increased with exposure time; the concentrations of F in E. fetida were 3.1 ~ 6.2 times higher than those of GTF. In addition, the half-lives of GTF in soil (16.90 ~ 18.24 days) were significantly lower than those of F (24.75 ~ 26.65 days). After the addition of phlorizin, a hexose transport inhibitor, the accumulation of F in E. fetida did not change significantly, but the accumulation of GTF in E. fetida was significantly inhibited. The concentrations of GTF in E. fetida after adding phlorizin were 32.71 ~ 59.07% of those without phlorizin. Overall, our results indicated that the uptake and transport of F and GTF in E. fetida were significantly different; the uptake and transport of GTF was related to monosaccharide transporters, and glycosylation could reduce the bioaccumulation of fipronil to E. fetida and shorten the half-life of fipronil in soil, providing an important reference for the application of glucose-fipronil., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Bisphenol A (BPA) is an emerging organic pollutant, widely distributed and frequently detected in soil in recent years. BPA toxicity is a problem that needs to be solved in terms of both human health and agricultural production. Up to now, the toxic effect of BPA and its mechanism of action on plants, as well as the possibility of using plants to remediate BPA-contaminated soil, remain to be explored. In this study, six treatment groups were set up to evaluate the effects of different concentrations of BPA on the germination and growth of tobacco (Nicotiana tabacum L.) by medium experiments. Furthermore, the representative indexes of photosynthetic and antioxidant system were determined. Meanwhile, tobacco seedlings were cultivated in soil to further explore the effects of BPA on rhizosphere soil enzyme activity and bacterial community structure with or without 100 mg/kg BPA exposure. The enhancement of BPA removal efficiency from soil by phytoremediation using tobacco plants would also be estimated. Our results showed that high doses of BPA in solid medium remarkably inhibited tobacco seedling growth, and its toxicology effect was positively correlated with BPA concentration, while lower BPA exposure (< 20 mg/L) had little limitation on tobacco growth and induced hormesis effect, which was reflected mainly in the increase of root length. In pot experiments, the reducing of chlorophyll content (36.4%) and net photosynthetic rate (41.2%) meant the inhibition of tobacco photosynthetic process due to high concentration of BPA exposure (100 mg/kg) in soil. The increase of H 2 O 2 and O 2 - content suggested that BPA could destroy the balance of reactive oxygen species (ROS) in plants. However, tobacco plants still presented a high removal efficiency of BPA at the concentration of 100 mg/kg in soil, which could reach to 80% within 30 days. Furthermore, it was indicated that tobacco cultivation changed the structure of rhizosphere soil bacterial communities and the relative abundance of some valuable strains, including Proteobacteria, Acidobacteria and other strains, which might be participated in the BPA removal process. In addition, the tobacco-soil microbial system had the potential to reverse the negative effects caused by BPA through stimulating microorganism associated with soil nutrient cycling. In summary, tobacco is a competitive plant in phytoremediation of BPA-contaminated soil, though the growth of tobacco could be inhibited at high concentration of BPA. Moreover, tobacco might promote the removal efficiency of BPA by regulating the rhizosphere bacteria communities., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

High-throughput sequencing (HTS) of soil environmental DNA provides an advanced insight into the effects of pesticides on soil microbial systems. However, the association between the properties of the pesticide and its ecological impact remains methodically challenging. Risks associated with pesticide use can be minimized if pesticides with optimal structural traits were applied. For this purpose, we merged the 20 independent HTS studies, to reveal that pesticides significantly reduced beneficial bacteria associated with soil and plant immunity, enhanced the human pathogen and weaken the soil's ecological stability. Through the machine-learning approach, correlating these impacts with the physicochemical properties of the pesticides yielded a random forest model with good predictive capabilities. The models revealed that physical pesticide properties such as the dissociation constant (pKa), the molecular weight and water solubility, determined the ecological impact of pesticides to a large extent. Moreover, this study identified that eco-friendly pesticides should possess a value of pKa > 5 and a molecular weight in the range of 200-300 g/mol, which were found to be conducive to bacteria related to plant immunity promotion and exerted the lowest fluctuation of human opportunistic pathogen and keystone species. This guides the design of pesticides for which the impacts on soil biota are minimized., (© 2022 Society for Applied Microbiology and John Wiley & Sons Ltd.)

Soil microbial community is the main indicator having a crucial role in the remediation of polluted soils. These microbes can alter soil pH, organic matter in soils (SOM), soil physic-chemical properties, and potential soil respiration rate via their enzymatic activities. Similarly, heavy metals also have a crucial role in soil enzymatic activities. For this purpose, a number of methods are studied to evaluate the impact of soil pH (a key factor in the formation of biogeographic microbial patterns in bacteria) on bacterial diversity. The effects of pH on microbial activity are glamorous but still unclear. Whereas, some studies also indicate that soil pH alone is not the single key player in the diversity of soil bacteria. Ecological stability is achieved in a pollution-free environment and pH value. The pH factor has a significant impact on the dynamics of microbes' communities. Here, we try to discuss factors that directly or indirectly affect soil pH and the impact of pH on microbial activity. It is also discussed the environmental factors that contribute to establishing a specific bacterial community structure that must be determined. From this, it can be concluded that the environmental impact on soil pH, reducing soil pH and interaction with this factor, and reducing the effect of soil pH on soil microbial community., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: Some studies have suggested that mitochondrial dysfunction and a superoxide imbalance could increase susceptibility to chronic stressful events, contributing to the establishment of chronic inflammation and the development of mood disorders. The mitochondrial superoxide imbalance induced by some molecules, such as rotenone, could be evolutionarily conserved, causing behavioral, immune, and neurological alterations in animals with a primitive central nervous system., Objective: Behavioral, immune, and histological markers were analyzed in Eisenia fetida earthworms chronically exposed to rotenone for 14 days., Methods: Earthworms were placed in artificial soil containing 30 nM of rotenone distributed into a plastic cup that allowed the earthworms to leave and return freely into the ground. Since these organisms prefer to be buried, the model predicted that the earthworms would necessarily have to return to the rotenone-contaminated medium, creating a stressful condition. The effect on survival behavior in the immune and histological body wall and ventral nervous ganglia (VNG) structures, as well as gene expression related to inflammation and mitochondrial and neuromuscular changes., Results: Rotenone-induced loss of earthworm escape behavior and immune alterations indicated a chronic inflammatory state. Some histological changes in the body wall and VNG indicated a possible earthworm reaction aimed at protecting against rotenone. Overexpression of the nicotinic acetylcholine receptor gene (nAChR α5) in neural tissues could also help earthworms reduce the degenerative effects of rotenone on dopaminergic neurons., Conclusion: These data suggest that mitochondrial dysfunction could be an evolutionarily conserved element that induces inflammatory and behavioral changes related to chronic stress., Competing Interests: Conflicts of interest The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this paper., (Copyright © 2022 IBRO. Published by Elsevier Ltd. All rights reserved.)

Chitosan induces tolerance to abiotic stress agents in plants. However, studies on the different application forms of this biopolymer are limited. This study evaluated the effect of two forms of chitosan application on the morphophysiology of and metal accumulation by Talinum patens cuttings subjected to Cd to develop new cadmium (Cd) decontamination technologies. Cuttings from 75-day-old plants were transferred to a hydroponic system. For 30 days, three Cd concentrations (0, 7, and 14 mg L -1 ) and three forms of chitosan application (without application, root, and foliar) were applied. The cuttings were tolerant to Cd because the metal did not influence biomass production or photosynthetic efficiency. Neither chitosan application nor Cd increased the modified chlorophyll content and fluorescence parameters. However, foliar chitosan reduced the transpiration rate. At the highest concentration of Cd, the application of chitosan in the root reduced the Mg content of the root system and shoots. The root application of chitosan increased the surface area and volume of thicker roots at the expense of finer ones. The foliar application resulted in greater total root length and surface area, mainly those finer. Furthermore, chitosan applied to the leaves activated catalase in the roots and leaves. In contrast to the root application, foliar application increased the accumulation of Cd in the roots. The action of catalase and the increase of fine roots may have favored a greater absorption of the nutrient solution and Cd in the chitosan foliar application treatment. It is concluded that chitosan foliar spraying can improve Cd rhizofiltration with T. patens., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Phytoremediation is an ecofriendly technique to clean heavy metals from contaminated soil by the use of high biomass producing plant species. Chelators can help to improve this biological technique by increasing metal solubility. Therefore, a pot experiment was conducted to determine the effect of the chelators EDTA and citric acid (CA) in phytoremediation of Ni contaminated soil by using Brassica napus (canola). Two cultivars of B. napus, Con-II (tolerant) and Oscar (sensitive), were selected after screening and exposed to NiSO4 at 30 ppm at the time of sowing. CA (10 mM) and EDTA (1.5 mM) were applied either alone or in combination with each other after two weeks of Ni treatments. Different parameters like morpho-physiological and biochemical data were recorded after 15 days of chelate application. The results highlighted the successful use of chelating agents (CA and EDTA) not only to ameliorate Ni stress but also to enhance Ni accumulation which is prerequisite for phytoremediation. The basal application of 10 mMCA and 1.5 mM EDTA concentration proved to be effective for the growth of plants. The combination of chelating agents failed to show any synergistic effects.

Background: Biogenic metallic nanoparticles have been emerging as a promising alternative for the control of phytopathogens and as nanofertilizers. In this way, it is essential to investigate the possible impacts of these new nanomaterials on plants. In this study, the effects of soil contamination with biogenic silver (AgNPs) and iron (FeNPs) with known antifungal potential were investigated on morphological, physiological and biochemical parameters of soybean seedlings., Results: The exposure of plants/seedlings to AgNPs induced the reduction of root dry weight followed by oxidative stress in this organ, however, adaptive responses such as a decrease in stomatal conductance without impacts on photosynthesis and an increase in intrinsic water use efficiency were also observed. The seedlings exposed to FeNPs had shown an increase in the levels of oxygen peroxide in the leaves not accompanied by lipid peroxidation, and an increase in the expression of POD2 and POD7 genes, indicating a defense mechanism by root lignification., Conclusion: Our results demonstrated that different metal biogenic nanoparticles cause different effects on soybean seedlings and these findings highlight the importance of investigating possible phytotoxic effects of these nanomaterials for the control of phytopathogens or as nanofertilizers., (© 2022. The Author(s).)

This review considers potential approaches to solve an important problem concerning the impact of applied pesticides of various classes on living organisms, mainly agricultural crops used as food. We used the method of multi-residual determination of several pesticides in agricultural food products with its practical application for estimating pesticides in real products and in model experiments. The distribution of the pesticide between the components of the soil-plant system was studied with a pesticide of the sulfonylureas class, i.e., rimsulfuron. Autoradiography showed that rimsulfuron inhibits the development of plants considered as weeds. Cereals are less susceptible to the effects of pesticides such as acetamiprid, flumetsulam and florasulam, while the development of legume shoots was inhibited with subsequent plant death.

Background: Cadmium (Cd) is a toxic heavy metal that is harmful to the environment and human health. Cd pollution threatens the cultivation of rice (Oryza sativa L.) in many countries. Improving rice performance under Cd stress could potentially improve rice productivity., Results: In this study, 9 growth traits of 188 different cultivated rice accessions under normal and Cd stress conditions were found to be highly variable during the seedling stage. Based on ~3.3 million single nucleotide polymorphisms (SNPs), 119 Cd-mediated growth response (CGR) quantitative trait loci (QTL) were identified by a genome-wide association study (GWAS), 55 of which have been validated by previously reported QTL and 64 were new CGR loci. Combined with the data from the GWAS, transcriptome analysis, gene annotations from the gene ontology (GO) Slim database, and annotations and functions of homologous genes, 148 CGR candidate genes were obtained. Additionally, several reported genes have been found to play certain roles in CGRs. Seven Cd-related cloned genes were found among the CGR genes. Natural elite haplotypes/alleles in these genes that increased Cd tolerance were identified by a haplotype analysis of a diverse mini core collection. More importantly, this study was the first to uncover the natural variations of 5 GST genes that play important roles in CGRs., Conclusion: The exploration of Cd-resistant rice germplasm resources and the identification of elite natural variations related to Cd-resistance will help improve the tolerance of current major rice varieties to Cd, as well as provide raw materials and new genes for breeding Cd-resistant varieties., (© 2021. The Author(s).)

Unique bacterial associations were formed in the polluted soils from territory of the industrial factories Open Joint Stock Company "The Middle Volga Chemical Plant," Chapaevsk, Russia and Open Joint Stock Company "Lubricant Producing Plant," Perm, Russia. This study evaluates the influence of the biphenyl/polychlorinated biphenyls (PCB) on the formation of aerobic bacterial associations and their biodegradative potential. Enrichment cultivation of the soil samples from the territories of these industrial factories with PCB (commercial mixture Sovol) was lead for forming aerobic bacterial enrichment cultures showing a unique composition. The dominating in these bacterial cultures was the phylum Proteobacteria (Beta- and Gammaproteobacteria). Using biphenyl as a carbon source led to decrease of biodiversity in the final stable bacterial associations. Periodic cultivation experiments demonstrated that the association PN2-B has a high degradative potential among the six studied bacterial associations. PN2-B degraded 100% mono-chlorobiphenyls (94.5 mg/L), 86.2% di-chlorobiphenyls (22.3 mg/L), 50.9% Sovol, and 38.4% Delor 103 (13.8 mg/L). Qualitative analysis of metabolites showed that association performed transformation of chlorobenzoic acids (PCB degradation intermediates) into metabolites of citrate cycle. Twelve individual strain-destructors were isolated. The strains were found to degrade 17.7-100% PCB1, 36.2-100% PCB2, 18.8-100% PCB3 (94.5 mg/L), and 15.7-78.2% PCB8 (22.3 mg/L). The strains were shown to metabolize chlorobenzoic acids formed during degradation of chlorobiphenyls. A unique ability of strains Micrococcus sp. PNS1 and Stenotrophomonas sp. PNS6 to degrade ortho-, meta-, and para-monosubstituted chlorobenzoic acids was revealed. Our results suggest that PN2-B and individual bacterial strains will be perspective for cleaning of the environment from polychlorinated biphenyls., (© 2021. Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i.)

Spread of biosolids-borne antibiotic resistance is a growing public and environmental health concern. Herein, we conducted incubation experiments involving biosolids, which are byproducts of sewage treatment processes, and biosolids-amended soil. Quantitative reverse transcription-PCR (RT-qPCR) was employed to assess responses of select antibiotic resistance genes (ARGs) and mobile elements to environmentally relevant concentrations of two biosolids-borne antibiotics, azithromycin (AZ) and ciprofloxacin (CIP). Additionally, we examined sequence distribution of gyrA (encoding DNA gyrase; site of action of CIP) to assess potential shifts in genotype. Increasing antibiotic concentrations generally increased the transcriptional activities of qnrS (encoding CIP resistance) and ermB and mefE (encoding AZ resistance). The transcriptional activity of intl1 , a marker of class 1 integrons, was unaffected by CIP or AZ concentrations, but biosolids amendment increased intl1 activity in the soil by 4 to 5 times, which persisted throughout incubation. While the dominant gyrA sequences found herein were unrelated to known CIP-resistant genotypes, the increasing CIP concentrations significantly decreased the diversity of genes encoding the DNA gyrase A subunit, suggesting changes in microbial community structures. This study suggests that biosolids harbor transcriptionally active ARGs and mobile elements that could survive and spread in biosolids-amended soils. However, more research is warranted to investigate these trends under field conditions. IMPORTANCE Although previous studies have indicated that biosolids may be important spreaders of antibiotics and antibiotic resistance genes (ARGs) in environments, the potential activities of ARGs or their responses to environmental parameters have been understudied. This study highlights that certain biosolids-borne antibiotics can induce transcriptional activities of ARGs and mobile genetic elements in biosolids and biosolids-amended soil, even when present at environmentally relevant concentrations. Furthermore, these antibiotics can alter the structure of microbial populations expressing ARGs. Our findings indicate the bioavailability of the antibiotics in biosolids and provide evidence that biosolids can promote the activities and dissemination of ARGs and mobile genes in biosolids and soils that receive contaminated biosolids, thus, underscoring the importance of investigating anthropogenically induced antibiotic resistance in the environment under real-world scenarios.

Soil contamination with heavy metals is a major problem worldwide, due to the increasing impact mainly caused by anthropogenic activities. This research evaluated the phytoremediation capacity of, Lolium perenne for heavy metals such as cadmium (Cd 2+ ) and mercury (Hg 2+ ), and the effects of these metals on morphology, biomass production, and the changes on gene expression. Seeds of L. perenne were exposed to six concentrations of Cd 2+ and Hg 2+ in the range of 0 to 25 mg L -1 , and two mixtures of Cd 2+ -Hg 2 . The Non-Observed Effect Level (NOEL) was established with dose response curves and the expression of specific genes was evaluated applying a commercially available quantitative reverse transcription (RT-qPCR) assay. There was no significant effect when exposing the seeds to Hg 2+ , for Cd 2+ the maximum concentration was established in 0.1 mg L -1 , and for the two concentrations of mixtures, there was a negative effect. An increase of expression of genes that regulate antioxidant activity and stress was found when the plant was exposed to heavy metals. Given the high tolerance to metals analyzed that was reflected both, the development of the plant and in its molecular response, these results highlight that L. perenne is a plant with phytoremediator potential.

DNA methylation plays an important role in modulating plant growth plasticity in response to stress, but mechanisms involved in such control need further investigation. We used drm1 drm2 cmt3 mutant of Arabidopsis thaliana, defective in DNA methylation, to explore metabolic pathways downstream epigenetic modulation under cadmium (Cd) stress. To this aim, a transcriptomic analysis was performed on ddc and WT plants exposed to a long-lasting (21 d) Cd treatment (25/50 µM), focusing on hormone genetic pathways. Growth parameters and hormones amount were also estimated. Transcriptomic data and hormone quantification showed that, under prolonged Cd treatment, level and signalling of growth-sustaining hormones (auxins, CKs, GAs) were enhanced and/or maintained, while a decrease was detected for stress-related hormones (JA, ABA, SA), likely as a strategy to avoid the side effects of their long-lasting activation. Such picture was more effective in ddc than WT, already at 25 µM Cd, in line with its better growth performance. A tight relationship between methylation status and the modulation of hormone genetic pathways under Cd stress was assessed. We propose that the higher genome plasticity conferred to ddc by DNA hypomethylated status underlies its prompt response to modulate hormones genetic pathways and activity and assure a flexible growth.

This research aims to isolate and identify Zn- and Cd-tolerant endophytic bacteria from Murdannia spectabilis, identify their properties with and without Zn and Cd stress, and to investigate the effect of bacterial inoculation in an in vitro system. Twenty-four isolates could survive on trypticase soya agar (TSA) supplemented with Zn (250-500 mg L -1 ) and/or Cd (20-50 mg L -1 ) that belonged to the genera Bacillus, Pantoea, Microbacterium, Curtobacterium, Chryseobacterium, Cupriavidus, Siphonobacter, and Pseudomonas. Each strain had different indole-3-acetic acid (IAA), 1-aminocyclopropane-1-carboxylate (ACC) deaminase and siderophore production, nitrogen fixation, phosphate solubilization, and lignocellulosic enzyme characteristics. Cupriavidus plantarum MDR5 and Chryseobacterium sp. MDR7 were selected for inoculation into plantlets that were already occupied by Curtobacterium sp. TMIL due to them have a high tolerance for Zn and Cd while showing no pathogenicity. As determined via an in vitro system, Cupriavidus plantarum MDR5 remained in the plants to a greater extent than Chryseobacterium sp. MDR7, while Curtobacterium sp. TMIL was the dominant species. The Zn plus Cd treatment supported the persistence of Cupriavidus plantarum MDR5. Dual and mixed cultivation showed no antagonistic effects between the endophytes. Although the plant growth and Zn/Cd accumulation were not significantly affected by the Zn-/Cd-tolerant endophytes, the inoculation did not weaken the plants. Therefore, Cupriavidus plantarum MDR5 could be applied in a bioaugmentation process.

Virola surinamensis is a forest species widely distributed in the estuaries of the Amazon. These ecosystems are susceptible to contamination by Cadmium (Cd), indicating that the plant has strategies for tolerating this metal. The aim of this study was to assess the nitrogen and carbon metabolism of young plants of Ucuúba (Virola surinamensis) in the presence of cadmium with the perspective of the phytoremediation of contaminated environments. The used experimental design was a completely randomized design with five Cd concentrations (0, 15, 30, 45, and 60 mg L - 1 ), for 60 days. In general, Cd did not affect nitrate concentration in the root but had a positive effect on leaves. The reduction of nitrate reductase (NR) in plants exposed to Cd was followed by a decrease in ammonia, total soluble amino acids (TSA), and total soluble proteins (TSP). Cd promoted an increase in the concentration of total soluble carbohydrates (TSC), proline, sucrose, and reducing sugars in the plants. The increase in TSC, sucrose and proline, suggests a metabolic regulatory mechanism of V. surinamensis against Cd stress.

Polycyclic aromatic hydrocarbons, distributing extensively in the soil, would potentially threaten the soil organisms (Eisenia fetida) by triggering oxidative stress. As a ubiquitous antioxidant enzyme, catalase can protect organisms from oxidative damage. To reveal the potential impact of polycyclic aromatic hydrocarbon pyrene (Pyr) on catalase (CAT) and the possible protective effect of Ascorbic acid (vitamin C), multi-spectral and molecular docking techniques were used to investigate the influence of structure and function of catalase by pyrene. Fluorescence and circular dichroism analysis showed that pyrene would induce the microenvironmental changes of CAT amino acid residues and increase the α-helix in the secondary structure. Molecular simulation results indicated that the main binding force of pyrene around the active center of CAT is hydrogen bonding force. Furthermore, pyrene inhibited catalase activity to 69.9% compared with the blank group, but the degree of inhibition was significantly weakened after vitamin C added into the research group. Cell level experiments showed that pyrene can increase the level of ROS in the body cavity cell of earthworms, and put the cells under the threat of potential oxidative damage. Antioxidants-vitamin C has a protective effect on catalase and maintains the stability of intracellular ROS levels to a certain extent., Competing Interests: Declaration of competing interest No conflict of interest exits in the submission of this manuscript, and manuscript is approved by all authors for publication. I would like to declare that the work described was original research that has not been published previously, and not under consideration for publication elsewhere, in whole or in part. All the authors listed have approved the manuscript that is enclosed., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Treated waste water (TWW) quality varies due to the occurrence of polycyclic aromatic hydrocarbons (PAHs) up to low μg L -1 . In this study, a non-targeted metabolomic analysis was performed on lettuce (Lactuca sativa L) exposed to 4 PAHs by irrigation. The plants were watered with different concentrations of contaminants (0-100 μg L -1 ) for 39 days under controlled conditions and then harvested, extracted and analyzed by nuclear magnetic resonance (NMR). Different chemometric tools based on principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) are proposed for the analysis of the complex data sets generated in the different exposure experiments. Furthermore, Analysis of Variance Simultaneous Component Analysis (ASCA) of changes on metabolite peaks showed significant PAHs concentration and exposure time-dependent changes, clearly differentiating between exposed and non-exposed samples., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Hormesis of soil enzyme that involved in heavy metal has been attracting much more attention for risk assessment of heavy metal toxicity, but insufficient studies were conducted to define the hormetic responses induced by toluene or other organic pollutions. The objectives of this study were to investigate the hormetic responses of soil enzyme induced by toluene and explore the potential enzyme kinetic mechanism. Soil alkaline phosphatase (ALP) activity was regarded as the endpoint to explore the hormetic responses under different doses of toluene (0.0, 0.1, 0.5, 1.0, 2.0, 3.0, 5.0, 10.0, 50.0 and 100.0 μL g -1 ). Subsequently, we conducted the experiments of enzymatic reaction kinetics and pure enzyme to further verify the potential mechanisms of soil ALP's hormesis. Results showed that ALP activities at 0.1-1.0 μL g -1 toluene were significantly increased in contrast to the control (0 μL g -1 toluene) (P < 0.05) at the exposure time of 30, 36, 48 and 54 h, with the maximum stimulation magnitudes of 24-43%. ALP activities were almost not affected by toluene (2-100 μL L -1 ) in the whole experimental period (6-54 h). Meanwhile, the values of catalytic efficiency (the radio V max /K m , V max : maximum reaction velocity and K m : Michaelis constant) and V max significantly increased compared with the control, but the value of K m decreased from 2.5 to 1.6. Overall, low dose toluene can induce hormesis of soil ALP. The potential reason is that low-dose toluene could enhance the combination of soil ALP and substrates. We believe that this study will provide a new viewpoint for ecological risk assessment of toluene contaminated soils., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The most economical method of drill cuttings disposal may be their application in land reclamation which allows for the wastes recovery. However, the wastes application into the soil should ensure that the quality of the environment would not be deteriorated. These investigations were aimed at identifying the effect of drill cuttings, which were the mixture of different types of drilling wastes, on the physicochemical properties of acidic soil and growth of red clover (Trifolium pratense L.). The experimental design comprised 5 treatments, which differed in a dose of the drill cuttings: 0% (control), 2.5%, 5%, 10% and 15% of dry weight. A six-week pot experiment was conducted to determine the influence of the wastes on the plant growth. The results showed that the drill cuttings addition significantly changed the chemical and physicochemical properties of the soil, such as: electrical conductivity (EC), pH, base saturation, content of carbonate, alkaline cations (Ca2+, Na+, K+, Mg2+), organic matter, total organic carbon (TOC), and available phosphorus form. However, the most important factors that influenced the growth of red clover were pH, base saturation, content of Mg2+ and plant available phosphorus. The red clover biomass was increased from 1.5 to 2.5 times depending on the dose of wastes. We concluded that the examined wastes can be used for reclamation of the acid and unfertile degraded soils, but the amount of wastes should not exceed 5% of the soil, because the highest total clover biomass was observed just at this dose., Competing Interests: The author(s) received no specific funding for this work.

Microorganisms that display unique biotechnological characteristics are usually selected for industrial applications. Bacillus cereus NWUAB01 was isolated from a mining soil and its heavy metal resistance was determined on Luria-Bertani agar. The biosurfactant production was determined by screening methods such as drop collapse, emulsification and surface tension measurement. The biosurfactant produced was evaluated for metal removal (100 mg/L of each metal) from contaminated soil. The genome of the organism was sequenced using Illumina Miseq platform. Strain NWUAB01 tolerated 200 mg/L of Cd and Cr, and was also tolerant to 1000 mg/L of Pb. The biosurfactant was characterised as a lipopeptide with a metal-complexing property. The biosurfactant had a surface tension of 39.5 mN/m with metal removal efficiency of 69%, 54% and 43% for Pb, Cd and Cr respectively. The genome revealed genes responsible for metal transport/resistance and biosynthetic gene clusters involved in the synthesis of various secondary metabolites. Putative genes for transport/resistance to cadmium, chromium, copper, arsenic, lead and zinc were present in the genome. Genes responsible for biopolymer synthesis were also present in the genome. This study highlights biosurfactant production and heavy metal removal of strain NWUAB01 that can be harnessed for biotechnological applications.

Monitoring the ecological impacts of environmental pollution and the effectiveness of remediation efforts requires identifying relationships between contaminants and the disruption of biological processes in populations, communities, or ecosystems. Wildlife are useful bioindicators, but traditional comparative experimental approaches rely on a staunch and typically unverifiable assumption that, in the absence of contaminants, reference and contaminated sites would support the same densities of bioindicators, thereby inferring direct causation from indirect data. We demonstrate the utility of spatial capture-recapture (SCR) models for overcoming these issues, testing if community density of common small mammal bioindicators was directly influenced by soil chemical concentrations. By modeling density as an inhomogeneous Poisson point process, we found evidence for an inverse spatial relationship between Peromyscus density and soil mercury concentrations, but not other chemicals, such as polychlorinated biphenyls, at a site formerly occupied by a nuclear reactor. Although the coefficient point estimate supported Peromyscus density being lower where mercury concentrations were higher (β = -0.44), the 95% confidence interval overlapped zero, suggesting no effect was also compatible with our data. Estimated density from the most parsimonious model (2.88 mice/ha; 95% CI = 1.63-5.08), which did not support a density-chemical relationship, was within the range of reported densities for Peromyscus that did not inhabit contaminated sites elsewhere. Environmental pollution remains a global threat to biodiversity and ecosystem and human health, and our study provides an illustrative example of the utility of SCR models for investigating the effects that chemicals may have on wildlife bioindicator populations and communities., Competing Interests: The authors have declared that no competing interests exist.

This study aims to better understand the relationship between the response to acid mine drainage (AMD) stress of tolerant plants and changes in root-related bacterial communities. In this study, reed stems were planted in AMD-polluted and unpolluted soils, and high-throughput sequencing was conducted to analyze the bacterial community composition in the soil, rhizosphere, rhizoplane and endosphere. The results showed that the effect of AMD pollution on root-associated bacterial communities was greater than that of rhizo-compartments. Proteobacteria were dominant across the rhizo-compartments between treatments. The microbiomes of unpolluted treatments were enriched by Alphaproteobacteria and Betaproteobacteria and depleted in Gammaproteobacteria ranging from the rhizoplane into the endosphere. However, the opposite trend was observed in the AMD pollution treatment, namely, Gammaproteobacteria were enriched, and Alphaproteobacteria and Deltaproteobacteria were mostly depleted. In addition, endophytic microbiomes were dominated by Comamonadaceae and Rhodocyclaceae in the unpolluted treatment and by Enterobacteriaceae in the AMD-polluted soils. PICRUSt showed that functional categories associated with membrane transport, metabolism and cellular processes and signaling processes were overrepresented in the endosphere of the AMD-polluted treatment. In conclusion, our study reveals significant variation in bacterial communities colonizing rhizo-compartments in two soils, indicating that plants can recruit functional bacteria to the roots in response to AMD pollution., (© FEMS 2020.)

In this study, wheat ( Triticum aestivum L.) was exposed to three of the most typical chlorinated organophosphate esters (OPEs), which are widely present in farmland soil, at environmental concentrations to assess their accumulation, disruption on metabolism, and oxidative stress in wheat. The three OPEs accumulated distinctly in the root and then translocated to the shoot. After exposure for 7 days, the content of chlorophyll b decreased, while the levels of carotenoid and activities of antioxidases, malonaldehyde, and reactive oxygen species increased significantly in both the root and shoot, indicating that the target OPEs caused significant oxidative stresses and affected photosynthesis in wheat. Untargeted metabolomics revealed concentration- and species-dependent metabolic responses of the three OPEs. Saccharides were downregulated, which might be due to the reduced photosynthesis activities. On the other hand, the chlorinated OPEs induced increases in respiration and antioxidative metabolites, revealing that the antioxidant system of wheat was active in scavenging ROS. The disturbance of tris(1,3-dichloro-2-propyl)phosphate on the metabolisms in wheat tissues was the strongest. These results contribute to the food safety and crop quality assessment of chlorinated OPEs and clarify the underlying mechanisms of their phytotoxicities.

Acid mine drainage (AMD) is harmful to the environment and human health. Microorganisms-mineral interactions are responsible for AMD generation but can also remediate AMD contamination. Understanding the microbial response to AMD irrigation will reveal microbial survival strategies and provide approaches for AMD remediation. A terrace with sharp geochemical gradients caused by AMD flooding were selected to study the microbial response to changes in environmental parameters related to AMD contamination. AMD intrusion reduced soil microbial community diversity and further changed phylogenetic clustering patterns along the terrace gradient. We observed several genera seldom reported in AMD-related environments (i.e., Corynebacterium, Ochrobactrum, Natronomonas), suggesting flexible survival strategies such as nitrogen fixation, despite the poor nutritional environment. A co-occurrence network of heavily-contaminated fields was densely connected. The phyla Proteobacteria, Acidobacteria, Chloroflexi, and Euryarchaeota were all highly interconnected members, which may affect the formation of AMD. Detailed microbial response to different soil characterizations were highlighted by random forest model. Results revealed the top three parameters influencing the microbial diversity and interactions were pH, Fe(III), and sulfate. Various acidophilic Fe- and S-metabolizing bacteria were enriched in the lower fields, which were heavily contaminated by AMD, and more neutrophiles prevailed in the less-contaminated upper fields. Many indicator species in the lower fields were identified, including Desulfosporosinus, Thermogymnomonas, Corynebacterium, Shewanella, Acidiphilium, Ochrobactrum, Leptospirillum, and Allobaculum, representing acid-tolerant bacteria community in relevant environment. The detection of one known sulfate-reducing bacteria (i.e., Desulfosporosinus) suggested that biotic sulfate reduction may occur in acidic samples, which offers multiple advantages to AMD contamination treatment. Collectively, results suggested that the geochemical gradients substantially altered the soil microbiota and enriched the relevant microorganisms adapted to the different conditions. These findings provide mechanistic insights into the effects of contamination on the soil microbiota and establish a basis for in situ AMD bioremediation strategies., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The metal hyperaccumulator Azolla filiculoides is accompanied by a microbiome potentially supporting plant during exposition to heavy metals. We hypothesized that the microbiome exposition to selected heavy metals will reveal metal tolerant strains. We used Next Generation Sequencing technique to identify possible metal tolerant strains isolated from the metal-treated plant (Pb, Cd, Cr(VI), Ni, Au, Ag). The main dominants were Cyanobacteria and Proteobacteria constituting together more than 97% of all reads. Metal treatment led to changes in the composition of the microbiome and showed significantly higher richness in the Pb-, Cd- and Cr-treated plant in comparison with other (95-105 versus 36-44). In these treatments the share of subdominant Actinobacteria (0.4-0.8%), Firmicutes (0.5-0.9%) and Bacteroidetes (0.2-0.9%) were higher than in non-treated plant (respectively: 0.02, 0.2 and 0.001%) and Ni-, Au- and Ag-treatments (respectively: <0.4%, <0.2% and up to 0.2%). The exception was Au-treatment displaying the abundance 1.86% of Bacteroidetes. In addition, possible metal tolerant genera, namely: Acinetobacter, Asticcacaulis, Anabaena, Bacillus, Brevundimonas, Burkholderia, Dyella, Methyloversatilis, Rhizobium and Staphylococcus, which form the core microbiome, were recognized by combining their abundance in all samples with literature data. Additionally, the presence of known metal tolerant genera was confirmed: Mucilaginibacter, Pseudomonas, Mycobacterium, Corynebacterium, Stenotrophomonas, Clostridium, Micrococcus, Achromobacter, Geobacter, Flavobacterium, Arthrobacter and Delftia. We have evidenced that A. filiculoides possess a microbiome whose representatives belong to metal-resistant species which makes the fern the source of biotechnologically useful microorganisms for remediation processes., Competing Interests: The authors have declared that no competing interests exist.

Switchgrass ( Panicum Virgatum L.) has been recognized as the new energy plant, which makes it ideal for the development of phytoremediation on heavy metal contamination in soils with great potential. This study aimed to screen the best internal reference genes for the real-time quantitative PCR (RT-qPCR) in leaves and roots of switchgrass for investigating its response to various heavy metals, such as cadmium (Cd), lead (Pb), mercury (Hg), chromium (Cr), and arsenic (As). The stability of fourteen candidate reference genes was evaluated by BestKeeper, GeNorm, NormFinder, and RefFinder software. Our results identified U2AF as the best reference gene in Cd, Hg, Cr, and As treated leaves as well as in Hg, Pb, As, and Cr stressed root tissues. In Pb treated leaf tissues, 18S rRNA was demonstrated to be the best reference gene. CYP5 was determined to be the optimal reference gene in Cd treated root tissues. The least stable reference gene was identified to be CYP2 in all tested samples except for root tissues stressed by Pb. To further validate the initial screening results, we used the different sets of combinatory internal reference genes to analyze the expression of two metal transport associated genes ( PvZIP4 and PvPDB8 ) in young leaves and roots of switchgrass. Our results demonstrated that the relative expression of the target genes consistently changed during the treatment when CYP5/UBQ1 , U2AF/ACT12 , eEF1a/U2AF, or 18S rRNA/ACT12 were combined as the internal reference genes. However, the time-dependent change pattern of the target genes was significantly altered when CYP2 was used as the internal reference gene. Therefore, the selection of the internal reference genes appropriate for specific experimental conditions is critical to ensure the accuracy and reliability of RT-qPCR. Our findings established a solid foundation to further study the gene regulatory network of switchgrass in response to heavy metal stress.

Earthworms as ecosystem engineers partially improve soil properties by egesting casts. Our previous study confirmed that soil pollution affects the physico-chemical properties of earthworm casts. It is still unclear whether the biological properties (e.g. cellulase, urease, and acid and alkaline phosphatase activities, as well as microbial biomass carbon) of casts are affected by foreign substances in soil. The present study aimed to investigate the effect of phenanthrene (PHE) on the biological characteristics of earthworm (Eisenia fetida) casts. Furthermore, correlations between cast properties and the digestive and antioxidant systems were explored by the determination of digestive enzyme (urease, protease, acid and alkaline phosphatase) activities, antioxidant indexes [superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD)], as well as malondialdehyde (MDA) content. Exposure at a range of PHE doses (0, 2, 5, 10, and 20 mg kg -1 ) for 15 d resulted in the following observations: (1) Compared with urease, as well as acid and alkaline phosphatase activities, cellulase activities in both soil and casts were sensitive to PHE, and could potentially act as biomarkers to provide early-warning signals for soil pollution. (2) Microbial biomass carbon in casts was modified, but with no clear pattern. (3) Cellulase and POD activities, as well as MDA content in earthworms, increased with elevated exposure to PHE in soil. Protease, SOD, and CAT activities exhibited a biphasic dose response to PHE, while acid and alkaline phosphatase activities were inhibited under treatment conditions. (4) Correlation analysis suggested that microbial biomass carbon in casts significantly and positively correlated with cellulase and acid phosphatase activities of earthworms, but negatively correlated with protease activities. A significant but weak negative correlation between alkaline phosphatase activities in casts and POD activities was also observed. Based on these results, we concluded that PHE content in soil modified some biological properties of casts, by partially affecting the earthworm's digestive and antioxidant systems. This study advances our knowledge of earthworm ecology in polluted soil by providing a better understanding of their ecological functions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Due to the long growth period of plants, phytoremediation is time costly. Improving the accumulation of cadmium (Cd) in shoots of plants will promote the efficiency of phytoremediation. In this study, two senescence-relative phytohormones, abscisic acid (ABA) and salicylic acid (SA), were applied to strengthening phytoremediation of Cd by tall fescue (Festuca arundinacea S.). Under hydroponic culture, phytohormones treatment increased the Cd content of shoots 11.4-fold over the control, reaching 316.3 mg/kg (dry weight). Phytohormones-induced senescence contributes to the transport of heavy metals, and HMA3 was found to play a key role in this process. Additionally, this strategy could strengthen the accumulation of Cu and Zn in tall fescue shoots. Moreover, in soil pot culture, the strategy increased shoot Cd contents 2.56-fold over the control in tall fescue, and 2.55-fold over the control in Indian mustard (Brassica juncea L.), indicating its comprehensive adaptability and potential use in the field. In summary, senescence-induced heavy metal transport is developed as a novel strategy to strengthen phytoremediation. The strategy could be applied at the end of phytoremediation with an additional short duration (7 days) with comprehensive adaptability, and markedly strengthen the phytoremediation in the field., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Plastic residues could accumulate in soils as a consequence of using plastic mulching, which results in a serious environmental concern for agroecosystems. As an alternative, biodegradable plastic films stand as promising products to minimize plastic debris accumulation and reduce soil pollution. However, the effects of residues from traditional and biodegradable plastic films on the soil-plant system are not well studied. In this study, we used a controlled pot experiment to investigate the effects of macro- and micro- sized residues of low-density polyethylene and biodegradable plastic mulch films on the rhizosphere bacterial communities, rhizosphere volatile profiles and soil chemical properties. Interestingly, we identified significant effects of biodegradable plastic residues on the rhizosphere bacterial communities and on the blend of volatiles emitted in the rhizosphere. For example, in treatments with biodegradable plastics, bacteria genera like Bacillus and Variovorax were present in higher relative abundances and volatile compounds like dodecanal were exclusively produced in treatment with biodegradable microplastics. Furthermore, significant differences in soil pH, electrical conductivity and C:N ratio were observed across treatments. Our study provides evidence for both biotic and abiotic impacts of plastic residues on the soil-plant system, suggesting the urgent need for more research examining their environmental impacts on agroecosystems., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 The Author(s). Published by Elsevier B.V. All rights reserved.)

Copper (Cu) mining has to address a critical environmental issue related to the disposal of heavy metals and metalloids (HMs). Due to their deleterious effects on living organisms, Cu and arsenic (As) have gained global attention, and thus their monitoring in the environment is an important task. The aims of this study were: 1) to evaluate the alteration of soil enzyme activities (EAs) and soil microbial functional diversity with Cu/As contamination, and 2) to select the most reliable biochemical indicators of Cu/As contamination. A twelve-week soil experiment was performed with four increasing levels of Cu, As, and Cu/As from 150/15 to 1000/100 mg Cu/As kg -1 . Soil enzyme activities and soil community-level physiological profile (CLPP) using MicroResp™ were measured during the experiment. Results showed reduced EAs over time with increasing Cu and Cu/As levels. The most Cu-sensitive EAs were dehydrogenase, acid phosphatase, and arylsulfatase, while arginine ammonification might be related to the resilience of soil microbial communities due to its increased activity in the last experimental times. There was no consistent response to As contamination with reduced individual EAs at specific sampling times, being urease the only EA negatively affected by As. MicroResp™ showed reduced carbon (C) substrate utilization with increasing Cu levels indicating a community shift in C acquisition. These results support the use of specific EAs to assess the environmental impact of specific HMs, being also the first assessment of EAs and the use of CLPP (MicroResp™) to study the environmental impact in Cu/As contaminated soils., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Chlorsulfuron has been applied in wheat fields as a recognized herbicide worldwide, yet it was officially banned in China since 2014 for its soil persistence problem. On the basis of our previous research that 5-dimethylamino distinctively accelerated degradation rate in soils, a modified amino moiety ( Ia-c ) and monosubstituted amino group ( Id-e ) were introduced onto the fifth position of the benzene ring in sulfonylurea structures, as well as heterocyclic amino substituents ( If-g ) to seek a suitable soil degradation rate during such an in situ crop rotation system. Referring to the biological data and Sc AHAS inhibition and Sc AHAS docking results, they turned out to be AHAS inhibitors with high potent herbicidal activities. The various influence on soil degradation rate along with crop safety indicated that different substituents on the fifth position have exerted an apparent impact. Their united study of structure-activity-safety-degradation relationship has great potential to provide valuable information for further development of eco-friendly agrochemicals.

The most existing studies on the toxicity of antimony (Sb) were performed in limited types of soil and after short aging time. Effects of soil properties and long aging time on chronic toxicity of Sb(III) and Sb(V) to model organism Folsomia candida were studied in the laboratory studies. The results showed that after the Sb(V)-treated soils were aged for 365 d, the Sb exhibited no toxicity to survival and reproduction even at the nominal highest concentration of 12,800 mg kg -1 in ten types of soils with distinct differences in soil properties. In the Sb(III)-treated ten soils aged only for 30 d, the concentrations causing 50% mortality (LC 50 ) and concentrations inhibiting 50% reproduction (EC 50 ) were 1288-3219 mg kg -1 and 683-1829 mg kg -1 , respectively. The LC 50 were higher than the highest test concentration and the EC 50 significantly increased by 2.24-6.16 fold after the Sb(III)-treated soils were aged for 150 d, and soil pH was the most important single factor explaining the variance in aging effects. After the aging time was 365 d, similar with Sb(V)-treated soils, no toxicity were observed in the most Sb(III)-treated soils, indicating the increasing aging effects with aging time. Regression analysis indicated that the OM and pH were the most important single factor predicting Sb toxicity to reproduction in Sb(III)-treated soils aged for 30 and 150 d, respectively., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The aim of this study was to investigate whether the plant-growth-promoting rhizobacteria (PGPR) could enhance phytoremediation efficiency of Scirpus triqueter (S.triqueter) in the pyrene-Ni co-contaminated soil. We also expected to reveal the possible mechanism for the affected phytoremediation efficiency induced by PGPR. We used three kinds of contaminated soils (Ni-contaminated soil, pyrene-contaminated soil and pyrene-Ni co-contaminated soil) to conduct this pot study. After harvest, plants growth indicators, polyphenol oxidase (PPO) activity and soil microbial community structure of each treatment were investigated to explain the different dissipation rates of pyrene and removal rates of Ni between treatments with and without PGPR. The results showed that PGPR-inoculated S. triqueter increased dissipation rates of pyrene and removal rates of Ni in all three contaminated soils, among which Ni removal rates in Ni single contaminated soil was elevated most significantly, from 0.895‰ to 8.8‰, increasing nearly 9 folds. However, Ni removal rate efficiency in co-contaminated soil was weakened because more toxic and complicated co-contaminated soil restrained plant growth and Ni absorption. We also observed that co-contamination harmed the soil microbial community more severely than that in single pyrene or Ni contaminated soil through phospholipid fatty acids analysis. Furthermore, dissipation rates of pyrene and removal rates of Ni were found positively correlated to the PPO activity and the abundance of branched and saturated fatty acids reflected by Pearson correlation analysis., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

To assess the role of citric acid, as a typical low-molecular-weight organic acid from root exudates, on cerium (Ce) uptake, accumulation and translocation in rice seedlings (Oryza sativa L.) exposed to two CeO 2 nanoparticles (NPs) (14 nm and 25 nm). A hydroponic experiment was performed under two citric acid levels (0.01 and 0.04 mmol L -1 ) combined with iron plaque presence. Citric acid significantly enhanced surface-Ce, root-Ce and shoot-Ce accumulation, irrespective of NPs size and iron plaque presence. The increased surface-Ce was associated with the promoted interactive attraction between NPs and root surface, and the enhanced NPs dissolution. Surface-Ce (containing crystalline and amorphous fractions of iron plaque) accumulation increased with the increase of citric acid concentrations. However, the enhancement influence of 0.01 mmol L -1 citric acid on root-Ce, shoot-Ce accumulations, rice-Ce distribution and TF root-shoot was more remarkable than citric acid (0.04 mmol L -1 ), which suggested higher food security risk for human health with environment-level citric acid. Iron plaque presence attenuated the enhancement effect of citric acid on rice-Ce accumulation and distribution (containing surface-Ce, root-Ce and shoot-Ce) due to the reduced attractive interaction between NPs and root surface from the effect of Fe 2+ being dissolved by iron plaque. Above effect of citric acid and iron plaque was more remarkable in 25 nm NP than 14 nm NP., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Atrazine is a triazine herbicide that is widely used to control broadleaf weeds. Its widespread use over the last 50 years has led to the potential contamination of soils, groundwater, rivers, and lakes. Its main route of complete degradation is via biological means, which is carried out by soil microbiota using a 6-step pathway. The aim of the present study was to investigate whether application of atrazine to soil changes the soil bacterial community. We used 16S rRNA gene sequencing and qPCR to elucidate the microbial community structure and assess the abundance of the atrazine degradation genes atzA, atzD, and trzN in a Brazilian soil. The results obtained showed that the relative abundance of atzA and trzN, encoding triazine-initiating metabolism in Gram-negative and -positive bacteria, respectively, increased in soil during the first weeks following the application of atrazine. In contrast, the abundance of atzD, encoding cyanuric acid amidohydrolase-the fourth step in the pathway-was not related to the atrazine treatment. Moreover, the overall soil bacterial community showed no significant changes after the application of atrazine. Despite this, we observed increases in the relative abundance of bacterial families in the 4 th and 8 th weeks following the atrazine treatment, which may have been related to higher copy numbers of atzA and trzN, in part due to the release of nitrogen from the herbicide. The present results revealed that while the application of atrazine may temporarily increase the quantities of the atzA and trzN genes in a Brazilian Red Latosol soil, it does not lead to significant and long-term changes in the bacterial community structure.

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 (DT 50 ) of S-dichlorprop were 8.22 days in soil A and 8.06 days in soil D, while R-dichlorprop was more persistent with DT 50 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 .

Pollution is a concerning and highly studied area, especially in the arena of children's health. The focus of this concern, however, is typically limited to air and water pollution, leaving an important source under-studied and out of the concern of the general public. Soil pollution provides a unique threat to children's health, due to their increased exposure and susceptibility to its contaminants. The microbiome of a child is developed prior to birth and continues to evolve over their lifetime with each encounter to the outside world. The environment a child inhabits directly affects their microbiome and their overall health, and through interactions with contaminated soil, a child can accumulate adverse health outcomes. The aim of this article is to summarize the methods by which soil becomes contaminated and how children become exposed to the resulting toxicants., Competing Interests: Declaration of competing interest None of the authors have any conflicts of interest to disclose., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The purpose of the study was to examine biochar amendment, phosphorus (P) fertilizer and arbuscular mycorrhizal fungi (AMF) on the yield, nutrient and cadmium (Cd) absorption of Lolium multiflorum in acidic soil. It was shown that mycorrhizal inoculation had no positive influence on the plant shoot biomass and the contents of nitrogen (N), P, potassium (K), calcium (Ca) and magnesium (Mg) in plants at all biochar and P level treatments. Irrespective of mycorrhizal inoculation and P level, biochar amendments markedly elevated the soil available P and K uptake in plant tissues. In contrast, biochar significantly decreased the translocation factor of plants, soil exchangeable Cd, and acid and neutral phosphatase activities, regardless of the mycorrhizal inoculation and P fertilizer. Without P fertilization, biochar amendments significantly promoted shoot P content, while biochar amendments significantly reduced shoot P content when P fertilizer was applied. Without biochar application, P fertilizer application significantly promoted the biomass and N uptake of shoots in both AMF inoculation treatments, while P fertilizer increased these only in the presence of biochar and mycorrhizal inoculation. The increased N content induced by the biochar amendment elevated the shoot N:P ratio and alleviated the N deficiency with P fertilizer input. Thus, we concluded that the addition of biochar and P fertilizer showed more positive effects on the promotion of growth and nutrient uptake of L. multiflorum than AMF grown in acidic Cd-contaminated soils., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Organochlorine pesticides have been extensively used for many years to prevent insect diseases of rice (Oryza sativa L.), but little is known about their residual impacts on the underground micro-ecology in anaerobic environment. In this glasshouse study, we characterized the lindane effects on the assembly of root-associated microbiomes of commonly used indica, japonica and hybrid rice cultivars, and their feedback in turn, in modifying lindane anaerobic dissipation during 60 days' rice production. The results showed that rice growth inhibited the anaerobic dissipation of lindane, but was not affected apparently by lindane at initial spiked concentration of 4.62 and 18.54 mg kg -1 soil. Suppressed removal of lindane in rice planted treatments as compared with that in unplanted control was likely due to inhibited reductive dechlorination induced by a comprehensive effect of radial O 2 secretion of rice root and co-occurring Fe(III) reduction that consumed electron competitively in rice rhizosphere. However, the hybrid cultivar exhibited a less suppression than the conventional cultivars in high polluted soils. Bacteria was more sensitively responded to lindane pollution than fungal taxa, and Actinobacteria, Chloroflexi, Verrucomicrobia and Proteobacteria were the main different phyla between hybrid and conventional cultivars, with a more stable community structure exhibited in the hybrid rice under lindane stress. Our study highlights the assembly and variation of root-associated microbiomes in responses of lindane pollution, and suggests that hybrid rice cultivar might be most competent for cultivation in paddy fields polluted by lindane and other organochlorine pesticides, especially in the area with high residual levels., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)