Development of a novel bio-organic fertilizer for the removal of atrazine in soil

Potential utilization of bivalve hemolymph as a biomonitoring tool for assessment of atrazine contamination

This study evaluated temporally dynamic bioaccumulation, fates, and biotransformation of atrazine (ATZ) in bivalve hemolymph. Male and female mussels, Hyriopsis bialata, were exposed to ATZ at environmentally-relevant (0.02 and 0.2 mg/L) and high (2 mg/L) concentrations. Untreated mussels served as a control. The hemolymph was collected from the anterior adductor muscle during 28 days of exposure. Pooled hemolymph from individuals of the same sex was subjected to chromatographic analysis of ATZ and its derivatives: desethylatrazine (DEA), desisopropylatrazine (DIA), and hydroxyatrazine (HA). The hemolymph was also used to determine phase I biotransformation via 7-ethoxyresorufin-O-deethylase activity. ATZ-treated mussels showed bioaccumulation of ATZ and its derivatives in their hemolymph, but the control mussels had none. There were no gender-dependent bioaccumulation patterns for these compounds, among which DEA revealed dose- and time-dependent bioaccumulation. Besides, hemolymph-to-water concentration ratios (HWRs) of DEA exhibited concentration and time dependency on nominal ATZ concentrations, especially in the female mussels. ATZ exposure generally did not alter phase I biotransformation capacity in the hemolymph. Interestingly, DEA, aside from ATZ, was a promising candidate marker representing degrees of ATZ contamination. Overall, this study offered opportunity for utilizing the bivalve hemolymph of minimal amounts for rapid, time-series biomonitoring of ATZ contamination in water.

Mitigating risks from atrazine drift to soybeans through foliar pre-spraying with a degrading bacterium

Herbicides play a crucial role in managing weeds in agriculture, ensuring the productivity and quality of crops. However, herbicide drift poses a significant threat to sensitive plants, necessitating the consideration of ecosystem-based solutions to address this issue. In this study, foliar pre-spraying of atrazine-degrading Paenarthrobacter sp. AT5 was proposed as a new approach to mitigate the risks associated with atrazine drift on soybeans. Exposure to atrazine reduced chlorophyll levels and disturbed the antioxidant system and metabolic processes in soybean leaves, ultimately causing leaves to turn yellow. However, by pre-spraying, strain AT5 successfully colonized the surface of soybean leaves and mitigated the harmful effects of atrazine. This was achieved by slowing down atrazine absorption, expediting its reduction (half-life decreased from 2.22 d to 0.86 d), altering its degradation pathway (enhancing hydroxylation while weakening alkylation), and enhancing the interaction within phyllosphere bacteria communities. This study introduces a new approach that is both eco-friendly and user-friendly for reducing the risks of herbicide drift to sensitive crops, hence promoting the development of mixed cropping.

Nickel oxide nanoparticles decrease the accumulation of atrazine in earthworms

Nickel oxide nanoparticles (NiO-NPs) are common nanomaterials that may be released into the environment, affecting the toxicity of other contaminants. Atrazine (ATZ) is a commonly used herbicide that can harm organisms due to its persistence and bioaccumulation in the environment. Although the toxicity of ATZ to earthworms is well-documented, the risk of co-exposure with NiO-NPs increases as more nanoparticles accumulate in the soil. In this study, we investigated the effects and mechanisms of NiO-NPs on the accumulation of ATZ in earthworms. The results showed that after day 21, the antioxidant system of the cells under ATZ treatment alone was adversely affected, with ROS content 36.05 % higher than that of the control (CK) group. However, the addition of NiO-NPs reduced the ROS contents in the earthworms by 0.6 %- 32.3 %. Moreover, analysis of earthworm intestinal sections indicates that NiO-NPs mitigated cellular and tissue damage caused by ATZ. High-throughput sequencing revealed that NiO-NPs in earthworm intestines increased the abundance of Pseudomonas aeruginosa and Aeromonas aeruginosa. Additionally, the enhanced function of the ABC transport system in the gut resulted in lower accumulation of ATZ in earthworms. In summary, NiO-NPs can reduce the accumulation and thus the toxicity of ATZ in earthworms. Our study contributes to a deeper understanding of the effects of NiO-NPs on co-existing pollutants.

Bio-derived carbon-based materials for sustainable environmental remediation and wastewater treatment

Biosynthesized nanocomposites, particularly those incorporating carbon-based materials, exhibit exceptional tunability and multifunctionality, surpassing the capabilities of conventional materials in these aspects. Developing practical solutions is critical to address environmental toxins from pharmaceuticals, heavy metals, pesticides, and dyes. Biomass waste is a readily available carbon source, which emerges as a promising material for producing biochar due to its inherent advantages: abundance, low cost, and environmentally friendly nature. This distribution mainly uses carbon-based materials (CBMs) and biomass waste in wastewater treatment. This review paper investigates several CBM types, including carbon aerogels, nanotubes, graphene, and activated carbon. The development of bio-derived carbon-based nanomaterials are discussed, along with the properties and composition of carbon materials derived from biomass waste and various cycles, such as photodegradation, adsorption, and high-level oxidation processes for natural remediation. In conclusion, this review examines the challenges associated with biochar utilization, including cost, recovery, and practical implementation.

Advances in understanding and mitigating Atrazine's environmental and health impact: A comprehensive review

Atrazine is a widely used herbicide in agriculture, and it has garnered significant attention because of its potential risks to the environment and human health. The extensive utilization of atrazine, alongside its persistence in water and soil, underscores the critical need to develop safe and efficient removal strategies. This comprehensive review aims to spotlight atrazine's potential impact on ecosystems and public health, particularly its enduring presence in soil, water, and plants. As a known toxic endocrine disruptor, atrazine poses environmental and health risks. The review navigates through innovative removal techniques across soil and water environments, elucidating microbial degradation, phytoremediation, and advanced methodologies such as electrokinetic-assisted phytoremediation (EKPR) and photocatalysis. The review notably emphasizes the complex process of atrazine degradation and ongoing scientific efforts to address this, recognizing its potential risks to both the environment and human health.

MicroRNA-217-5p triggers dopaminergic neuronal degeneration via autophagy activation under Atrazine exposure

Atrazine (ATR) is a widely used agricultural herbicide, and its accumulation in soil and water can cause various environmental health problems. ATR has neurotoxic effects on dopaminergic neurons, which can lead to a Parkinson's disease (PD)-like syndrome. Epigenetics regulates gene expression dynamically through DNA methylation, histone post-translational modification, microRNA (miRNA) interaction, and RNA methylation. MicroRNA (miRNA), representing one of the primary epigenetic mechanisms responsible for regulating gene expression, plays a crucial role in maintaining normal cellular function, while dysregulation of miRNA expression has been observed in PD. This study aims to investigate the regulatory mechanisms of miRNA in ATR exposure. The results show that ATR-exposure significantly upregulates the expression level of miR-217-5p. Both miR-217-5p overexpression and ATR exposure is able to trigger the autophagy process and apoptosis. Conversely, inhibiting the expression of miR-217-5p can reverse the levels of ATR-induced autophagy and apoptosis. Moreover, ATR causes damage to dopaminergic neurons, as indicated by the altered expression of tyrosine hydroxylase and α-synuclein. Taken together, these results suggest that ATR-induced autophagy can accelerate the progression of neurodegenerative diseases and that miR-217-5p is probably an important target involved in ATR-induced dopaminergic damage, shedding important light on the development of a novel strategy for treating neurodegenerative diseases.

Bacterial chemotaxis of herbicide atrazine provides an insight into the degradation mechanism through intermediates hydroxyatrazine, N-N-isopropylammelide, and cyanuric acid compounds

In recent times, the herbicide atrazine (ATZ) has been commonly used before and after the cultivation of crop plants to manage grassy weeds. Despite its effect, the toxic residues of ATZ affect soil fertility and crop yield. Hence, the current study is focused on providing insight into the degradation mechanism of the herbicide atrazine through bacterial chemotaxis involving intermediates responsive to degradation. A bacterium was isolated from ATZ-contaminated soil and identified as Pseudomonas stutzeri based on its morphology, biochemical and molecular characterization. Upon ultra-performance liquid chromatography analysis, the free cells of isolated bacterium strain was found to utilize 174 μg/L of ATZ after 3-days of incubation on a mineral salt medium containing 200 μg/L of ATZ as a sole carbon source. It was observed that immobilized based degradation of ATZ yielded 198 μg/L and 190 μg/L by the cells entrapped with silica beads and sponge, respectively. Furthermore, the liquid chromatography-mass spectroscopy revealed that the secretion of three significant metabolites, namely, cyanuric acid, hydroxyatrazine and N- N-Isopropylammelide is responsive to the biodegradation of ATZ by the bacterium. Collectively, this research demonstrated that bacterium strains are the most potent agent for removing toxic pollutants from the environment, thereby enhancing crop yield and soil fertility with long-term environmental benefits.

Reinforced Bioremediation of Excessive Nitrate in Atrazine-Contaminated Soil by Biodegradable Composite Carbon Source

Bioremediation is a good alternative to dispose of the excessive nitrate (NO₃^-) in soil and alleviate the secondary salinization of soil, but the presence of atrazine in soil interferes with the bioremediation process. In the present study, the biodegradable composite carbon source with different dosages was added to the atrazine-contaminated soil to intensify the bioremediation of excessive NO₃^-. The atrazine-contaminated soil with a 25 g/kg composite carbon source achieved the optimal NO₃^- removal performance (92.10%), which was slightly higher than that with a 5 g/kg composite carbon source (86.15%) (p > 0.05). Unfortunately, the negative effects of the former were observed, such as the distinctly higher emissions of N₂O, CO₂ and a more powerful global warming potential (GWP). Microbial community analysis showed that the usage of the composite carbon source clearly decreased the richness and diversity of the microbial community, and greatly stimulated nitrogen metabolism and atrazine degradation (p < 0.05). To sum up, the application of a 5 g/kg composite carbon source contributed to guaranteeing bioremediation performance and reducing adverse environmental impacts at the same time.

Amended compost alleviated the stress of heavy metals to pakchoi plants and affected the distribution of heavy metals in soil-plant system

With the development of the social economy, soil heavy metal pollution has become a common worldwide issue. Therefore, the remediation of soil heavy metal pollution is imminent. This study aimed to investigate the effect of amended compost on reducing heavy metal bioavailability in soil and relieving heavy metals stress on plants under Cu and Zn stress in a pot experiment. To model the restoration of heavy metal-polluted farming soil, conventional compost (CKw), activated carbon compost (ACw), modified biochar compost (BCw) and rhamnolipid compost (RLw) were utilized. The results showed that the application of amended compost could promote the growth and quality of pakchoi and enhance the stress ability of malondialdehyde and antioxidant enzymes to heavy metals. The distribution of Cu and Zn in different subcellular parts of pakchoi was also affected. The application of amended compost significantly reduced the heavy metals content in the shoot of pakchoi, among which the content of Cu and Zn in the shoot of pakchoi in RLw was significantly decreased by 57.29% and 60.07%, respectively. Our results can provide a new understanding for efficient remediation of contaminated farmland soil by multiple heavy metals.

Grass-Legume Mixture with Rhizobium Inoculation Enhanced the Restoration Effects of Organic Fertilizer

The establishment of artificial grassland is crucial in restoring degraded grassland and resolving the forage-livestock conflict, and the application of organic fertilizer and complementary seeding of grass-legume mixture are effective methods to enhance grass growth in practice. However, its mechanism behind the underground is largely unclear. Here, by utilizing organic fertilizer in the alpine region of the Qinghai-Tibet Plateau, this study assessed the potential of grass-legume mixtures with and without the inoculation of Rhizobium for the restoration of degraded grassland. The results demonstrated that the application of organic fertilizer can increase the forage yield and soil nutrient contents of degraded grassland, and they were 0.59 times and 0.28 times higher than that of the control check (CK), respectively. The community composition and structure of soil bacteria and fungi were also changed by applying organic fertilizer. Based on this, the grass-legume mixture inoculated with Rhizobium can further increase the contribution of organic fertilizer to soil nutrients and thus enhance the restoration effects for degraded artificial grassland. Moreover, the application of organic fertilizer significantly increased the colonization of gramineous plant by native mycorrhizal fungi, which was ~1.5-2.0 times higher than CK. This study offers a basis for the application of organic fertilizer and grass-legume mixture in the ecological restoration of degraded grassland.

Exogenous application of Bradyrhizobium japonicum AC20 enhances soybean tolerance to atrazine via regulating rhizosphere soil microbial community and amino acid, carbohydrate metabolism related genes expression

Atrazine is used to control broad-leaved weeds in farmland and has negative impacts on soybean growth. Legume-rhizobium symbiosis plays an important role in regulating abiotic stress tolerance of plants, however, the mechanisms of rhizobia regulate the tolerance of soybean to atrazine based on the biochemical responses of the plant-soil system are limited. In this experiment, Glycine max (L.) Merr. Dongnong 252, planted in 20 mg kg^-1 of atrazine-contaminated soil, was inoculated with Bradyrhizobium japonicum AC20, and the plant growth, rhizosphere soil microbial diversity and the expression of the genes related to soybean carbon and nitrogen metabolism were assessed. The results indicated that strain AC20 inoculation alleviated atrazine-induced growth inhibition via increasing the contents of leghemoglobin and total nitrogen in soybean seedlings. The psbA gene expression level of the soybean seedlings that inoculated strain AC20 was 1.4 times than that of no rhizobium inoculating treatments. Moreover, the inoculated AC20 increased the abundance of Acidobacteria and Actinobacteria in soybean rhizosphere. Transcriptome analysis demonstrated that strain AC20 regulated the genes expression of amino acid metabolism and carbohydrate metabolism of soybean seedlings. Correlation analysis between 16S rRNA and transcriptome showed that strain AC20 reduced Planctomycetes abundance so as to down-regulated the expression of genes Glyma. 13G087800, Glyma. 12G005100 and Glyma.12G098900 involved in starch synthesis pathway of soybean leaves. These results provide available information for the rhizobia application to enhance the atrazine tolerate in soybean seedlings.

Mitigation of atrazine-induced oxidative stress on soybean seedlings after co-inoculation with atrazine-degrading bacterium Arthrobacter sp. DNS10 and inorganic phosphorus-solubilizing bacterium Enterobacter sp. P1

Atrazine toxicity is one of the limiting factors inhibiting sensitive plant growth. Previous studies showed that atrazine-degrading bacteria could alleviate atrazine toxicity. However, there is limited information on how atrazine-degrading bacteria and plant growth-promote bacteria alleviate atrazine toxicity in soybeans. Therefore, the current study aimed to explore the atrazine removal, phosphorus utilization, and the oxidative stress alleviation of atrazine-degrading bacterium Arthrobacter sp. DNS10 and/or inorganic phosphorus-solubilizing bacterium Enterobacter sp. P1 in the reduction of atrazine toxicity in soybean. The results showed that atrazine exposure to soybean seedlings led to significant inhibition in growth, atrazine removal, and phosphorus utilization. However, the co-inoculatied strains significantly increased seedlings biomass, chlorophyll a/b contents, and total phosphorus in leaves accompanied by great reduction of the atrazine-induced antioxidant enzymes activities and malonaldehyde (MDA) contents, as well as atrazine contents in soil and soybeans under atrazine stress. Furthermore, transcriptome analysis highlighted that co-inoculated strains increased the expression levels of genes related to photosynthetic-antenna proteins, carbohydrate metabolism, and fatty acid degradation in leaves. All the results suggest that the co-inoculation mitigates atrazine-induced oxidative stress on soybean by accelerating atrazine removal from soil and phosphorus accumulation in leaves, enhancing the chlorophyll contents, and regulating plant transcriptome. It may be suggested that co-inoculation of atrazine-degrading bacteria and inorganic phosphorus-solubilizing bacteria can be used as a potential method to alleviate atrazine toxicity to the sensitive crops.

Noval bio-organic fertilizer containing Arthrobacter sp. DNS10 alleviates atrazine-induced growth inhibition on soybean by improving atrazine removal and nitrogen accumulation

Herbicide atrazine restricts nutrient accumulation and thus inhibits the growth of sensitive crops. The application of organic fertilizer is a common measure that contributes to modulating abiotic tolerance of crops and providing nutrients, but its advantages in combination with atrazine degrading microorganisms as bio-organic fertilizer to alleviate atrazine stress on sensitive crops and the associated mechanisms are unknown. We investigated the beneficial effects of organic and bio-organic fertilizer (named DNBF10) containing Arthrobacter sp. DNS10 applications on growth, leaf nitrogen accumulation, root surface structure and root physiological properties of soybean seedlings exposed to 20 mg kg^-1 atrazine in soil. Compared with organic fertilizer, bio-organic fertilizer DNBF10 exhibited more reduction in soil atrazine residue and plant atrazine accumulation, as well as alleviation in atrazine-induced root oxidative stress and damaged cells of soybean roots. Transcriptome analysis revealed that DNBF10 application enhanced nitrogen utilization by improving the expression of genes involved in nitrogen metabolism in soybean leaves. Besides, genes expression of cytochrome P450 and ABC transporters involved in atrazine detoxification and transport in soybean leaves were also down-regulated by DNBF10 to diminish phytotoxicity of atrazine to soybean seedlings. These results illustrate the molecular mechanism by which the application of DNBF10 alleviates soybean seedlings growth under atrazine stress, providing a step forward for mitigate the atrazine induced inhibition on soybean seedlings growth through decreasing atrazine residues as well as enhancing damaged root repair and nitrogen accumulation.

Watermelon responds to organic fertilizer by enhancing root-associated acid phosphatase activity to improve organic phosphorus utilization

Organic fertilizer is commonly used to increase crop yields and improve soil quality. However, it is unclear whether crops adapt to organic fertilizer by regulating metabolic pathways that are involved in nutrient utilization. In this study, we focused on the organic phosphorus (P_o) in organic fertilizer and, using watermelon, investigated changes in gene expression and metabolic pathways in response to organic fertilizer and the combination of chemical fertilizer and organic fertilizer (chemical fertilizer 70% and organic fertilizer 30%, based on phosphorus supply). Purple acid phosphatase (PAP) gene expression was upregulated in leaves and roots of watermelon grown in organic fertilizer alone and in the combination of chemical/organic fertilizer, resulting in enhanced phosphatase activity in roots. When the ratio of chemical to organic fertilizer was 85/15, root-associated acid phosphatase (APase) activity increased over chemical fertilizer alone. This formulation also resulted in increased inorganic phosphate (P_i) concentration in roots and leaves, and the upregulation of the secretory APase genes ClaPAP10/12/15/26, and ClaPAP18 in roots. In conclusion, watermelon responds to organic fertilizer by upregulating expression of secretory ClaPAP genes, subsequently enhancing root-associated APase activity further improving the hydrolysis of phosphomonoesters, and ultimately facilitating P_o utilization by roots. The mechanisms of P utilization by roots comprise the enhancement of APase and phytase activity, absorption of small P_o molecules, uptake of P_i, and the increase of lateral root number when organic fertilizer is applied to the plants. These findings help to establish the mechanisms by which plants respond to organic fertilizer by regulating metabolic pathways at the transcriptional level.

Recent advances in bioremediation of heavy metals and persistent organic pollutants: A review

Heavy metals and persistent organic pollutants are causing detrimental effects on the environment. The seepage of heavy metals through untreated industrial waste destroys the crops and lands. Moreover, incineration and combustion of several products are responsible for primary and secondary emissions of pollutants. This review has gathered the remediation strategies, current bioremediation technologies, and their primary use in both in situ and ex situ methods, followed by a detailed explanation for bioremediation over other techniques. However, an amalgam of bioremediation techniques and nanotechnology could be a breakthrough in cleaning the environment by degrading heavy metals and persistant organic pollutants.

Toxicological effects, environmental behaviors and remediation technologies of herbicide atrazine in soil and sediment: A comprehensive review

Atrazine has become one of the most popular applied triazine herbicides in the world due to its high herbicidal efficiency and low price. With its large-dosage and long-term use on a global scale, atrazine can cause widespread and persistent contamination of soil and sediment. This review systematically evaluates the toxicological effects, environmental risks, environmental behaviors (adsorption, transport and transformation, and bioaccumulation) of atrazine, and the remediation technologies of atrazine-contaminated soil and sediment. For the adsorption behavior of atrazine on soil and sediment, the organic matter content plays an extremely important role in the adsorption process. Various models and equations such as the multi-media fugacity model and solute transport model are used to analyze the migration and transformation process of atrazine in soil and sediment. It is worth noting that certain transformation products of atrazine in the environment even have stronger toxicity and mobility than its parent. Among various remediation technologies, the combination of microbial remediation and phytoremediation for atrazine-contaminated soil and sediment has wide application prospects. Although other remediation technologies such as advanced oxidation processes (AOPs) can also efficiently remove atrazine from soil, some potential problems still need to be further clarified. Finally, some related challenges and prospects are proposed.

An Insight into Microbial Inoculants for Bioconversion of Waste Biomass into Sustainable "Bio-Organic" Fertilizers: A Bibliometric Analysis and Systematic Literature Review

The plant-microbe holobiont has garnered considerable attention in recent years, highlighting its importance as an ecological unit. Similarly, manipulation of the microbial entities involved in the rhizospheric microbiome for sustainable agriculture has also been in the limelight, generating several commercial bioformulations to enhance crop yield and pest resistance. These bioformulations were termed biofertilizers, with the consistent existence and evolution of different types. However, an emerging area of interest has recently focused on the application of these microorganisms for waste valorization and the production of "bio-organic" fertilizers as a result. In this study, we performed a bibliometric analysis and systematic review of the literature retrieved from Scopus and Web of Science to determine the type of microbial inoculants used for the bioconversion of waste into "bio-organic" fertilizers. The Bacillus, Acidothiobacillus species, cyanobacterial biomass species, Aspergillus sp. and Trichoderma sp. were identified to be consistently used for the recovery of nutrients and bioconversion of wastes used for the promotion of plant growth. Cyanobacterial strains were used predominantly for wastewater treatment, while Bacillus, Acidothiobacillus, and Aspergillus were used on a wide variety of wastes such as sawdust, agricultural waste, poultry bone meal, crustacean shell waste, food waste, and wastewater treatment plant (WWTP) sewage sludge ash. Several bioconversion strategies were observed such as submerged fermentation, solid-state fermentation, aerobic composting, granulation with microbiological activation, and biodegradation. Diverse groups of microorganisms (bacteria and fungi) with different enzymatic functionalities such as chitinolysis, lignocellulolytic, and proteolysis, in addition to their plant growth promoting properties being explored as a consortium for application as an inoculum waste bioconversion to fertilizers. Combining the efficiency of such functional and compatible microbial species for efficient bioconversion as well as higher plant growth and crop yield is an enticing opportunity for "bio-organic" fertilizer research.

Biochar-based composites for remediation of polluted wastewater and soil environments: Challenges and prospects

Pharmaceuticals, heavy metals, pesticides, and dyes are the main environmental contaminants that have serious effects on both land and aquatic lives and necessitate the development of effective methods to mitigate these issues. Although some conventional methods are in use to tackle soil contamination, but biochar and biochar-based composites represent a reliable and sustainable means to deal with a spectrum of toxic organic and inorganic pollutants from contaminated environments. The capacity of biochars and derived constructs to remediate inorganic dyes, pesticides, insecticides, heavy metals, and pharmaceuticals from environmental matrices is attributed to their extensive surface area, surface functional groups, pore size distribution, and high sorption capability of these pollutants in water and soil environments. Application conditions, biochar feedstock, pyrolysis conditions and precursor materials are the factors that influence the capacity and functionality of biochar to adsorb pollutants from wastewater and soil. These factors, when improved, can benefit biochar in agrochemical and heavy metal remediation from various environments. However, the processes involved in biochar production and their influence in enhancing pollutant sequestration remain unclear. Therefore, this paper throws light on the current strategies, operational conditions, and sequestration performance of biochar and biochar-based composites for agrochemical and heavy metal in soil and water environments. The main challenges associated with biochar preparation and exploitation, toxicity evaluation, research directions and future prospects for biochar in environmental remediation are also outlined.

Impacts of earthworm casts on atrazine catabolism and bacterial community structure in laterite soil

Atrazine accumulation in agricultural soil is prone to cause serious environmental problems and pose risks to human health. Vermicomposting is an eco-friendly approach to accelerating atrazine biodegradation, but the roles of earthworm cast in the accelerated atrazine removal remains unclear. This work aimed to investigate the roles of earthworm cast in promoting atrazine degradation performance by comprehensively exploring the change in atrazine metabolites and bacterial communities. Our results showed that earthworm cast amendment significantly increased soil pH, organic matters, humic acid, fulvic acid and humin, and achieved a significantly higher atrazine removal efficiency. Earthworm cast addition also remarkably changed soil microbial communities by enriching potential soil atrazine degraders (Pseudomonadaceae, Streptomycetaceae, and Thermomonosporaceae) and introducing cast microbial degraders (Saccharimonadaceae). Particularly, earthworm casts increased the production of metabolites deethylatrazine and deisopropylatrazine, but not hydroxyatrazine. Some bacterial taxa (Gaiellaceaea and Micromonosporaceae) and humus (humic acid, fulvic acid and humin) were strongly correlated with atrazine metabolism into deisopropylatrazine and deethylatrazine, whereas hydroxyatrazine production was benefited by higher pH. Our findings verified the accelerated atrazine degradation with earthworm cast supplement, providing new insights into the influential factors on atrazine bioremediation in vermicomposting.

Mechanism for various phytotoxicity of atrazine in soils to soybean: Insights from soil sorption abilities and dissolved organic matter properties

The pollutants in soils with different physicochemical properties usually exhibit various phytotoxicity due to their diverse environmental behavior. However, it is not clear that some components of dissolved organic matter (DOM) in soil affect the bioavailability of pollutants. In this study, the different phytotoxicity of atrazine in two different soils, black soil (BS) and yellow brown earth (YBE), to soybeen seedlings was investigated, and the potential mechanism were further discussed by examining the adsorption properties of atrazine with BS and YBE as well as the fluorescent characteristic variation of these two kinds of DOM extracted from BS and YBE during binding with atrazine. The results suggest that atrazine showed different phytotoxicity to soybean seedlings grown in BS and YBE. Specifically, the EC50 of atrazine on plant height and root length of soybean seedling in BS were 23.44 mg kg-1 and 54.29 mg kg-1, while those in YBE were 12.79 mg kg-1 and 21.48 mg kg-1. The adsorption amounts of BS and YBE was 41.56 mg kg-1 and 32.95 mg kg-1. In addition, 3D-EEM showed that humic acid-like substances were the main components of DOM in the two soils. With the increase of atrazine concentration, the fluorescence of these two kind of DOM was gradually quenched, but DOM-BS had a faster quenching rate. FT-IR showed that DOM-BS contained more polysaccharides and richer lipophilic groups. Meanwhile, the results of PARAFAC found that DOM-BS was easier to combine with atrazine. The findings of this study are significant to reveal phytotoxicity of atrazine in BS and YBE. The above results are helpful to better understand the components of DOM in different soils and their different role in regulating the environmental behavior and phytotoxicity of organic pollutants.

Exploring the Influence Mechanism of Farmers’ Organic Fertilizer Application Behaviors Based on the Normative Activation Theory

This paper establishes an analysis framework to investigate the effect of the awareness of consequences and the ascription of responsibility on farmers’ organic fertilizer application behaviors (OFABs). Using questionnaire survey data from Hubei Province, one of the main grain-producing areas in China, this study employed both mediating effects and moderating effect analytical methods to analyze the influencing mechanism of the awareness of consequences and ascription of responsibility on farmers’ OFABs. The results show that, firstly, the awareness of consequences and ascription of responsibility have a significant positive impact on farmers’ OFABs. The improvement in farmers’ awareness of consequences and ascription of responsibility can effectively promote the utilization of organic fertilizers for enhanced ecological production. Secondly, the awareness of consequences and ascription of responsibility have a significant positive impact on farmers’ OFABs through individual farmers’ personal norms. Increasing farmers’ awareness of consequences and ascription of responsibility firstly stimulates their personal norms; then, personal norms have a positive impact on farmers’ OFABs. Thirdly, farmers’ social norms can positively regulate the relationship between personal norms and their OFABs. The higher the social norms of farmers, the more their social norms can have a positive regulating effect on their OFABs. Therefore, in the future, it will be necessary to vigorously promote farmers’ awareness of consequences and ascription of responsibility, in order to enhance farmers’ social norms, and to improve the level of farmers’ social norms, in order to greatly promote farmers’ engagement in OFABs. This will ultimately better promote rural ecological environmental protection and ecological civilization construction.

Accelerated atrazine degradation and altered metabolic pathways in goat manure assisted soil bioremediation

The intensive and long-term use of atrazine in agriculture has resulted in serious environmental pollution and consequently endangered ecosystem and human health. Soil microorganisms play an important role in atrazine degradation. However, their degradation efficiencies are relatively low due to their slow growth and low abundance, and manure amendment as a practice to improve soil nutrients and microbial activities can solve these problems. This study investigated the roles of goat manure in atrazine degradation performance, metabolites and bacterial community structure. Our results showed that atrazine degradation efficiencies in un-amended soils were 26.9-35.7% and increased to 60.9-84.3% in goat manure amended treatments. Hydroxyatrazine pathway was not significantly altered, whereas deethylatrazine and deisopropylatrazine pathways were remarkably enhanced in treatments amended with manure by encouraging the N-dealkylation of atrazine side chains. In addition, goat manure significantly increased soil pH and contents of organic matters and humus, explaining the change of atrazine metabolic pathway. Nocardioides, Sphingomonas and Massilia were positively correlated with atrazine degradation efficiency and three metabolites, suggesting their preference in atrazine contaminated soils and potential roles in atrazine degradation. Our findings suggested that goat manure acts as both bacterial inoculum and nutrients to improve soil microenvironment, and its amendment is a potential practice in accelerating atrazine degradation at contaminated sites, offering an efficient, cheap, and eco-friendly strategy for herbicide polluted soil remediation.

Improved photocatalyst: Elimination of triazine herbicides by novel phosphorus and boron co-doping graphite carbon nitride

A non-metallic and low-cost novel phosphorus and boron co-doping graphite carbon nitride (PB-g-C₃N₄) photocatalyst was prepared by a facile thermal copolymerization of urea with B₂O₃ and (NH₄)₂·HPO₄. The novel PB-g-C₃N₄ exhibited excellent optical and electrical properties and the photocatalytic elimination efficiency for atrazine (AT, can make feminization of male frogs in the wild, and even induce reproductive cancers in humans.) has been greatly improved compared with the pristine g-C₃N₄. The results of characterization techniques indicate that the introduced B and P atoms most probably to substitute for sp²-hybridized C atoms in triazine rings. O₂^- and h⁺ are the dominant active species to induce the elimination of AT demonstrated by the radical-trapping experiments. And a possible elimination pathway is proposed according to the detected main intermediates. In addition, PB-g-C₃N₄ was applied to the simultaneous photocatalytic elimination of 9 triazine herbicides, and the effects of different initial concentrations, pH, fulvic acid (FA) and ion species on their elimination effects were studied. And it was proved that the photocatalytic performance of PB-g-C₃N₄ did not significant decrease after 4 times of reuse.

Effects of tall fescue biochar on the adsorption and desorption of atrazine in different types of soil

The excessive application of atrazine in agriculture has resulted in serious environmental contamination. The addition of biochar could reduce the bioavailability and mobility of atrazine in soil through adsorption-desorption processes. In this study, tall fescue biochar was prepared at 500 °C, and its effect on the adsorption-desorption behavior of atrazine in red soil, brown soil, and black soil was investigated. The tall fescue biochar with the pH value of 9.64 had a developed porous structure and large specific area that contained abundant surface functional groups. The element composition of the tall fescue biochar was C (50.46%), O (15.01%), N (4.54%), H (2.56%), and S (1.47%). The adsorption process of atrazine in the three soil types with and without biochar addition was divided into a fast stage, slow stage, and equilibrium stage. A pseudo second-order kinetic model was suitable for fitting the adsorption process of atrazine, and the determination coefficient (R²) ranged from 0.985 to 0.999. The adsorption-desorption processes of atrazine were described accurately by the Freundlich model (R² of 0.967-0.999). The adsorption capacity of the three soil types for atrazine increased significantly with the addition of biochar, whereby the equilibrium adsorption amount increased from an initial range of 3.968 to 5.902 μg g^-1 to a final range of 21.397 to 21.968 μg g^-1. The desorption of atrazine was also inhibited as the hysteresis coefficient (HI) increased from an initial range of 0.451 to 0.586 to a final range of 0.916 to 0.941. The adsorption capacity of the red soil improved more than did the brown soil or black soil. Moreover, spontaneous adsorption of atrazine by the biochar-soil system occurred more easily at 35 °C than at 15 °C and 25 °C. Overall, tall fescue biochar was a prospective soil amendment material.

Atrazine biodegradation by mycoinsecticide Metarhizium robertsii: Insights into its amino acids and lipids profile

Atrazine, is one of major concern pesticides contaminating agricultural areas and ground water. Its microbial biodegradation seems to be the most efficient in terms of economic and environmental benefits. In the present work the cometabolic biodegradation of atrazine by the fungus Metarhizum robertsii IM 6519 during 10-day batch cultures was characterized. The herbicide was transformed to several hydroxy-, dechlorinated or dealkylated metabolites with the involvement of cytochrome P450 monooxygenases. The obtained metabolomics data revealed that atrazine induced oxidative stress (increased the levels of L-proline, L-ornithine, L-arginine, GABA and L-methionine), disruptions of the carbon and nitrogen metabolism (L-aspartic acid, L-asparagine, L-tyrosine, L-threonine, L-isoleucine, L-phenylalanine, 1-methyl-L-histidine, L-tryptophan, L-valine, L-alanine, O-phospho-L-serine, L-sarcosine or L-lysine) and caused an increase in the membrane fluidity (a rise in the phosphatidylcholines/phosphatidylethanolamines (PC/PE) ratio together with the growth of the taurine level). The increased level of hydroxyl derivatives of linoleic acid (9-HODE and 13-HODE) confirmed that atrazine induced lipid peroxidation. The presented results suggesting that M. robertsii IM 6519 might be applied in atrazine biodegradation and may bring up the understanding of the process of triazine biodegradation by Metarhizum strains.