Herbicide Contamination Research Articles

Estimating Rapid Diversity Changes During Acute Herbicide Contamination Using Environmental DNA

ABSTRACTThe biodiversity of freshwater ecosystems globally is facing severe threats due to various anthropogenic stressors, such as habitat degradation, introduction of invasive species, and pollution. Assessing the effects of human‐induced environmental stressors on population and community persistence requires accurate biodiversity estimates. While environmental DNA (eDNA) metabarcoding has emerged as a promising tool, its effectiveness in capturing rapid biodiversity responses to acute stressors across levels of biological organization (community, population, and intra‐specific levels) remains to be investigated. In this study, we tested the efficacy of eDNA metabarcoding in assessing rapid changes in aquatic zooplankton and insect communities by conducting a two‐month mesocosm experiment with pulses of glyphosate‐based herbicide under contrasting nutrient levels (mesotrophic and eutrophic). We examined the effects of treatments on community assemblages, family richness, and intraspecific diversity, and compared our findings with those obtained through a microscopy approach. Metabarcoding revealed partially congruent ecological findings with microscopy, indicating its potential in assessing rapid community changes. The herbicide induced shifts in community composition and differentially impacted zooplankton and insect family richness (increase in insects, and decrease in crustaceans and rotifers), suggesting a gradient of tolerance to the herbicide among taxa and potential top‐down regulation by insect larvae that may counteract the advantage gained by herbicide‐tolerant zooplankton. Finally, we showed that nutrient enrichment exacerbated the negative effects of the herbicide on intraspecific diversity, highlighting concerns about genetic erosion. Our findings underscore the complexity of responses to herbicide and nutrient enrichment in freshwater ecosystems. We conclude that eDNA metabarcoding can not only be used to estimate rapid changes in invertebrate communities but also provides additional value by offering a broader perspective on diversity dynamics and potential cascading effects at different scales of biological organization.

Picloram drift in Peltophorum dubium, a species native to the Brazilian Cerrado.

Peltophorum dubium, a common tree in areas close to agricultural activity in the Brazilian Cerrado, is vulnerable to damage from the drift of picloram, an herbicide widely used in pastures and agriculture in Brazil. The aim was to evaluate the application of 0.0; 19.2; 38.4; 76.8; 153.6; 307.2 g e. a. ha-1 of picloram, in simulated drift, on P. dubium, as well as its use as a bioindicator plant for herbicide contamination. The doses of picloram applied to the plants caused symptoms typical of the action of picloram on sensitive plants and led to the death of P. dubium at the highest doses tested. At its highest dose, picloram caused a 52.86% reduction in photosynthetic rate, 42.51% in transpiration rate, and 64.28% in stomatal conductance compared to the non-treated control. Picloram at a dose of 19.2 g e. a. ha-1 caused a reduction in N content and utilization and reduced plant protein. Picloram drift causes severe damage to P. dubium, reinforcing the concern about the risks of contamination with the herbicide. The species acted as a bioindicator of picloram in the environment and could be used in biomonitoring herbicide contamination.

Degradation Characteristics of Nicosulfuron in Water and Soil by MnO2 Nano-Immobilized Laccase.

As a typical sulfonylurea herbicide, nicosulfuron is mainly used to control grass weeds and some broadleaf weeds in corn fields. However, as the amount of use continues to increase, it accumulates in the environment and eventually becomes harmful to the ecosystem. In the present study, a new metallic nanomaterial, δ-MnO2, was prepared, which not only has a similar catalytic mechanism as laccase but also has a significant effect on pesticide degradation. Therefore, the bicatalytic property of MnO2 can be utilized to improve the remediation of nicosulfuron contamination. Firstly, MnO2 nanomaterials were prepared by controlling the hydrothermal reaction conditions, and immobilized laccase was prepared by the adsorption method. Next, we investigate the effects of different influencing factors on the effect of immobilized laccase, MnO2, and free laccase on the degradation of nicosulfuron in water and soil. In addition, we also analyze the metabolic pathway of nicosulfuron degradation in immobilized laccase and the bicatalytic mechanism of MnO2. The results demonstrated that the degradation rate of nicosulfuron in water by immobilized laccase was 88.7%, and the optimal conditions were 50 mg/L, 25 h, 50 °C, and pH 5. For nicosulfuron in soil, the optimal conditions for the degradation by immobilized laccase were found to be 151.1 mg/kg, 46 °C, and pH 5.9; under these conditions, a degradation rate of 90.1% was attained. The findings of this study provide a theoretical reference for the immobilized laccase treatment of sulfonylurea herbicide contamination in water and soil.

A novel combination of wetland plants (Eichhornia crassipes) and biochar derived from palm kernel shells modified with melamine for the removal of paraquat from aqueous medium: a green and sustainable approach

Herbicide contamination in aquatic systems has become a global concern due to their long- term persistence, accumulation and health risks to humans. Paraquat, a widely used and cost-effective nonselective herbicide, is frequently applied in agricultural fields for pest control. Consequently, the removal of paraquat from contaminated water is crucial. This research presents a sustainable and environmentally benign method for paraquat removal from aqueous system by integrating wetland plants (Eichhornia crassipes) with biochar derived from melamine-modified palm kernel shells. The prepared biochar was characterized by using various analytical techniques. The effectiveness of biochar in enhancing phytoremediation was evaluated through a series of experiments, showing significant paraquat removal efficiencies of 99.7, 98.3, and 82.8% at different paraquat concentrations 50, 100, and 150 mg L−1, respectively. Additionally, present study examined the impact of biochar on the growth of E. crassipes, highlighting its potential to reduce the toxic effects of paraquat even present at higher concentrations. The paraquat removal mechanism was elucidated, focusing on the synergistic role of biochar adsorption and phytoremediation capability of E. crassipes. This innovative approach is an effective, feasible, sustainable and eco-friendly technique that can contribute to the development of advanced and affordable water remediation processes for widespread application.

The Impact of Metolachlor Applications and Phytoremediation Processes on Soil Microorganisms: Insights from Functional Metagenomics Analysis.

This study assessed the impact of phytoremediation on reducing the residual concentration of metolachlor in soil treated with doses of 530.7 and 1061.4 g/ha and its effect on microbial biodiversity in contaminated areas. For the plant species Avena sativa and Medicago sativa, a significant efficacy of 54.5 and 36.4% was observed in the dissipation of the herbicide, especially at higher doses. Although metolachlor application reduced soil microbial biodiversity, phytoremediating plants, especially M. sativa, promoted greater richness and distribution of microbial species, mitigating the negative effects of the herbicide. Principal component analysis revealed the influence of these plants and metolachlor on the composition of the microbial community. These results highlight the importance of phytoremediation in promoting soil biodiversity and reducing herbicide contamination, providing crucial insights for remediation strategies in contaminated areas.

Construction of Immobilized Laccase System Based on ZnO and Degradation of Mesotrione.

Mesotrione (MES) is a new environmental pollutant. Some reports have indicated that microbial enzymes could be utilized for MES degradation. Laccase is a green biocatalyst whose potential use in environmental pollutant detoxification has been considered limited due to its poor stability and reusability. However, these issues may be addressed using enzyme immobilization. In the present study, we sought to optimize conditions for laccase immobilization, to analyze and characterize the characteristics of the immobilized laccase, and to compare its enzymatic properties to those of free laccase. In addition, we studied the ability of laccase to degrade MES, and analyzed the metabolic pathway of MES degradation by immobilized laccase. The results demonstrated that granular zinc oxide material (G-ZnO) was successfully used as the carrier for immobilization. G-ZnO@Lac demonstrated the highest recovery of enzyme activity and exhibited significantly improved stability compared with free laccase. Storage stability was also significantly improved, with the relative enzyme activity of G-ZnO@Lac remaining at about 54% after 28 days of storage (compared with only 12% for free laccase). The optimal conditions for the degradation of MES by G-ZnO@Lac were found to be 10 mg, 6 h, 30 °C, and pH 4; under these conditions, a degradation rate of 73.25% was attained. The findings of this study provide a theoretical reference for the laccase treatment of 4-hy-droxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicide contamination.

A Review of Remediation Strategies for Diphenyl Ether Herbicide Contamination.

In agriculture, diphenyl ether herbicides are a broad-spectrum family of pesticides mainly used to control annual weeds in agriculture. Although diphenyl ether herbicides have a long-lasting effect in weed control, they can also be harmful to succeeding crops, as well as to the water and soil environment. Residual herbicides can also harm a large number of non-target organisms, leading to the death of pest predators and other beneficial organisms. Therefore, it is of great significance to control and remediate the contamination caused by diphenyl ether herbicide residues for the sake of environmental, nutritional, and biological safety. This review provides an overview of the techniques used for remediating diphenyl ether herbicide contamination, including biological, physical, and chemical remediation. Among these techniques, bioremediation, particularly microbial biodegradation technology, is extensively employed. The mechanisms and influencing factors of different remediation techniques in eliminating diphenyl ether herbicide contamination are discussed, together with a prospect for future development directions. This review serves as a scientific reference for the efficient remediation of residual contamination from diphenyl ether herbicides.

A novel molecularly imprinted photoelectrochemical sensor utilizing Ag/SnO2 for the highly sensitive and selective detection of 2,4-dichlorophenoxyacetic acid

The pervasive use of herbicides in agriculture has necessitated the development of sensitive and selective detection methods for environmental monitoring. In this work, a novel photoelectrochemical sensor based on molecular imprinting technology was engineered to specifically detect 2,4-dichlorophenoxyacetic acid (2,4-D) using an Ag/SnO2 composite. The SnO2 was chosen as the photoelectric material due to its abundant surface defects, excellent thermal stability, and high electron carrier density, which are essential for enhanced photoelectrochemical reactions. The introduction of Ag to the SnO2 matrix exploited the surface plasmon resonance effect to bridge its wide band gap, thereby improving the photoelectric conversion efficiency. This Ag/SnO2 composite was then deposited onto an indium tin oxide (ITO) substrate to utilize its high conductivity and optical transparency, followed by the strategic layering of molecularly imprinted polymers (MIPs) that offer selective recognition sites for 2,4-D. To ensure the robustness of the sensor, a Nafion solution was meticulously applied dropwise, which served to immobilize the MIPs/Ag/SnO2 complex on the ITO surface and enhance the sensor's durability. Under optimized conditions, the sensor exhibited a broad linear detection range from 3 × 10-12 to 3 × 10-5 mol/L and a low detection limit of 1.13 × 10-12 mol/L (S/N = 3). The sensor also demonstrated exceptional performance in the analysis of 2,4-D in complex matrices, such as milk, tap water, and beef, highlighting its potential for practical applications in the accurate monitoring of herbicide contamination. These findings affirm the sensor's superior photoelectrochemical properties and introduce an innovative method for the sensitive detection of 2,4-D in environmental and food samples.

Herbicide contamination of Batak plain agricultural soils and risk assessment

Herbicide residue levels were analyzed in agricultural soils of Batak plain and health risk assessments were made for relevant pesticides. Herbicide contamination levels were analyzed with the use of Quick-Easy-Cheap-Efficient-Rugged-Safe (QuEChERS)-liquid chromatography/tandem mass spectrometry (LC–MS/MS) procedure. Herbicide-free soil samples were spiked at two different levels. Overall recovery of the method was 87.32%. Present findings were parallel to SANTE recovery limits. About 50% of collected samples from the study sites contained herbicides at different concentrations. Totally, eight herbicides were detected, and herbicide concentrations ranged between 1.085 and 1724.23 μg kg−1. Metolachlor had the highest concentration (1724.23 μg kg−1) in a sample taken close to the pesticide waste disposal area. Six herbicides were detected at different concentrations in the same sample. Persistent herbicides (terbuthylazine and pendimethalin) were detected in 35 samples. Risk assessments revealed that hazard index (HI) and hazard quotient (HQ) were less than 1. The greatest HQ values were identified for terbuthylazine as 2772.48 × 10−7 and 20793.61 × 10−7 for adults and children, respectively. The HI for all herbicides were 3916.05 × 10−7 for adult and 29370.39 × 10−7 for children.

Adverse effects of 2,4-D dimethylammonium based-herbicide on Acetylcholinesterase expression in Nile tilapia (Oreochromis niloticus)

In this study, the evaluation of a 2,4-D dimethylammonium based-herbicide impacted on Nile tilapia was done. The effects focus on Acetylcholinesterase (AChE) expression in the brain, gill, muscle, and plasma using antibody techniques. Our findings revealed a decrease in AChE expression with prolonged exposure. For these, AChE was purified using hydroxyapatite column chromatography. Moreover, the isolated protein was characterized as AChE by Polyclonal Ab specific to AChE through the Western blot. For interpretation at the cellular and molecular level, we employed two analytical techniques, histology, and optical coherence tomography (OCT). Alterations in the gill, liver, and muscle were observed to increase with increased exposure time. Field study concludes that AChE could serve as a biomarker to detect herbicide contamination in water and its accumulation in aquatic animals. This study may aid in surveillance and strategy formulation for managing contamination from such substances in various water sources.

УГЛЕВОДОРОДОКИСЛЯЮЩИЕ БАКТЕРИИ, УСТОЙЧИВЫЕ К ГЕРБИЦИДАМ, ПЕРСПЕКТИВНЫЕ ДЛЯ ФИТОБИОРЕМЕДИАЦИИ

The most environmentally friendly and cost-effective way to clean the environment is the microbiological method. Most often, anthropogenic pollution is complex. Therefore, bacteria-destructors must have additional useful characteristics, such as resistance to additional pollutants and growth-promoting activity. The purpose of the work was to study the possibility of using six hydrocarbon-oxidizing microorganisms of the genus Pseudomonas to enhance the growth of remediant plants in areas with combined oil and herbicide pollution. All strains were tolerant to the herbicides Tapir (active substance imazethapyr), Spetsnaz (active substance tribenuron-methyl) and Octapon extra (active substance 2,4-D) in the concentration range of 1 10 ml (g)/ l and the ability to decompose them by 3.9-41.5% (with the exception of P. frederiksbergensis UOM 11). Pollutants had different effects on the ability of bacteria to biodegrade oil (Spetsnaz had no effect, others reduced it up to 3-4 times), IAA production (oil and Octapone Extra stimulated, Tapir suppressed), phosphate mobilization (oil and herbicides reduced the solubilization index, especially Tapir), suppression of the growth of phytopathogens (oil reduced, Tapir enhanced). The use of bacteria had a positive effect on the growth characteristics of barley and clover plants in soil contaminated with oil and Tapir. The results obtained indicate the prospects of using the studied microorganisms to clean soil from oil and herbicide contamination together with phytomeliorant plants.

Biodegradation of Imazethapyr by Bacterial Strain IM9601 Isolated from Agricultural Soil

The widespread utilization of the herbicide imazethapyr presents significant challenges to crop rotation and results in detrimental soil degradation issues. Bacterial biodegradation has emerged as a promising and eco-friendly approach for mitigating pesticide residues contamination in the environment. In this study, a novel bacterium, identified as Brevibacterium sp. IM9601, was isolated and characterized based on morphological, physiological, and biochemical characteristics, as well as 16S rRNA gene sequence. This strain exhibited the ability to utilize imazethapyr as its sole carbon source for growth. Response surface methodology (RSM) was applied to optimize the degradation conditions. The most favorable conditions were determined to be a temperature of 27 °C, pH of 6.0, and an initial inoculum with a final OD600 of 0.15. Under these optimized condition, bacterial strain IM9601 exhibited substantial imazethapyr degradation, with removal rates of 90.08 and 87.05% for initial imazethapyr concentrations of 50 and 100 mg L−1, respectively, achieved within a 5-day incubation period. This investigation highlights imazethapyr-degrading capabilities of the Brevibacterium genus bacterial strain IM9601, marking it as a potentially novel and effective solution for addressing the environmental pollution resulting from the usage of imazethapyr. The study contributes to the growing body of research on bioremediation approaches, offering a sustainable and environmentally friendly method for mitigating the adverse impacts of herbicide contamination in agricultural settings.

Field assessment of coconut-based activated carbon systems for the treatment of herbicide contamination

Once released into the environment, herbicides can move through soil or surface water to streams and groundwater. Filters containing adsorbent media placed in fields may be an effective solution to herbicide loss in the environment. However, to date, no study has investigated the use of adsorbent materials in intervention systems at field-scale, nor has any study investigated their optimal configuration. Therefore, the aim of this paper was to examine the efficacy of low-cost, coconut-based activated carbon (CAC) intervention systems, placed in streams and tributaries, for herbicide removal. Two configurations of interventions were investigated in two agricultural catchments and one urban area in Ireland: (1) filter bags and (2) filter bags fitted into polyethylene pipes. Herbicide sampling was conducted using Chemcatcher® passive sampling devices in order to identify trends in herbicide exceedances at the sites, and to quantifiably assess, compare, and contrast the efficiency of the two intervention configurations. While the Chemcatcher® passive sampling devices are capable of analysing eighteen different acid herbicides, only six different acid herbicides (2,4-D, clopyralid, fluroxypyr, MCPA, mecoprop and triclopyr) were ever detected within the three catchment areas, which were also the only acid herbicides used therein. The CAC was capable of complete herbicide removal, when the water flow was slow (0.5–1 m3 s−1), and the interventions spanned the width and depth of the waterway. Overall, the reduction in herbicide concentrations was better for the filter pipes than for the filter bags, with a 48% reduction in detections and a 37% reduction in exceedances across all the sampling sites for the filter pipe interventions compared to a 13% reduction in the number of detections and a 24% reduction in exceedances across all sampling sites for the filter bag interventions (p < 0.05). This study demonstrates, for the first time, that CAC may be an effective in situ remediation strategy to manage herbicide exceedances close to the source, thereby reducing the impact on environmental and public health.

Spatial distribution and ecological-health risks associated with herbicides in soils and crop kernels of the black soil region in China

Herbicides are vital inputs for food production; however, their associated risks and hazards are pressing concerns. In black soil, the cumulative toxic effects of compound herbicides and potential risks to humans are not yet fully understood. Thus, this study conducted a comprehensive investigation to assess herbicide residue characteristics and the associated ecological health risks in representative black soil regions where major food crops (maize, soybean, and rice) are cultivated. Findings revealed that the soil harbored a collective presence of 29 herbicides, exhibiting total concentrations ranging from 111.92 to 996.14 μg/kg dry weight (dw). This can be attributed to the extensive use of herbicides over the years and their long half-lives, which results in the accumulation of multiple herbicide residues in the soil. Similarly, the total herbicide levels in maize, soybean, and rice kernels were 1173–61,564, 1721–9342, and 3775–8094 ng/kg dw, respectively. Multiple herbicide residues at all monitored sites were attributed to continuous crop barriers in soybean fields and the adoption of soybean and maize crop rotations. Notably, herbicides pose ecological risks in the black soil region, exhibiting high-risk levels of 79 %, 24 %, and 14 % at the sites monitored for oxyfluorfen, clomazone, and butachlor, respectively. Carcinogenic atrazine exhibited low- and medium-risk levels in 34 % and 63 % of soil samples, respectively. These results can serve as a scientific basis for establishing herbicide residue thresholds in agricultural soils within black soil areas and for implementing effective control measures to prevent herbicide contamination in agricultural ecosystems.

A perspective on how glyphosate and 2,4-D in wetlands may impact climate change

An increase in herbicide use is occurring due to a growing population and herbicide-resistant crops in agriculture, which has resulted in more herbicide tolerant target species. Glyphosate and 2,4-Dichlorophenoxyacetic acid (2,4-D) are two of the most commonly used herbicides worldwide and are more recently being used in combination in pre-mixed commercial formulas. Subsequently, herbicide contamination of wetlands will increase exposure of microorganisms to multiple chemical stressors. Methane is a potent greenhouse gas naturally emitted from wetlands, but herbicides may disrupt biogeochemical processes leading to an unbalanced methane cycle. We review the impacts of these herbicides on aquatic microbial communities from glyphosate-derived nutrient enrichment and 2,4-D inhibition of methane oxidation, and examine how these altered metabolic processes may lead to increased methane production in wetlands. The response of wetland ecosystems to herbicide contamination will vary across regions, in part due to the complexity of microbial communities, however, this perspective gives a glimpse into the potential global implications of continuing herbicide use on wetlands and demonstrates the importance for research on ecosystem-level co-stressors.

Hairy root culture: a potent method for improved secondary metabolite production of Solanaceous plants.

Secondary metabolites synthesized by the Solanaceous plants are of major therapeutic and pharmaceutical importance, many of which are commonly obtained from the roots of these plants. 'Hairy roots', mirroring the same phytochemical pattern of the corresponding root of the parent plant with higher growth rate and productivity, are therefore extensively studied as an effective alternative for the in vitro production of these metabolites. Hairy roots are the transformed roots, generated from the infection site of the wounded plants with Agrobacterium rhizogenes. With their fast growth, being free from pathogen and herbicide contamination, genetic stability, and autotrophic nature for plant hormones, hairy roots are considered as useful bioproduction systems for specialized metabolites. Lately, several elicitation methods have been employed to enhance the accumulation of these compounds in the hairy root cultures for both small and large-scale production. Nevertheless, in the latter case, the cultivation of hairy roots in bioreactors should still be optimized. Hairy roots can also be utilized for metabolic engineering of the regulatory genes in the metabolic pathways leading to enhanced production of metabolites. The present study summarizes the updated and modern biotechnological aspects for enhanced production of secondary metabolites in the hairy root cultures of the plants of Solanaceae and their respective importance.

Investigation of golf course chemical and herbicide contamination

In golf course management, fertilizers and herbicides are often used to maintain the healthy growth of green and fairway grass. Using these chemicals often comes with the drawback that they tend to leech into local water bodies, from where they are dispersed outside of the golf course, harming organisms. In this study twelve water samples were collected from two golf courses in Shanghai and tested them from several indicators such as total, chemical oxygen demand, and common herbicides. The experiment found that the total nitrogen in each of the twelve samples exceeds the level rated for drinking and industrial use. Levels of chemicals other than nitrogen, however, resembles those rated for drinking water reserves, while herbicide levels are borderline undetectable. Results from this study provide insight regarding the identification of pollutant based on the abnormality of some indicators, helping golf course management in achieving eco-friendliness.

Greener Method for the Application of TiO2 Nanoparticles to Remove Herbicide in Water.

TiO2 nanoparticles have emerged as a great photocatalyst to degrade organic contaminants in water; however, the nanoparticles dispersed in water could be difficult to be recovered and potentially become contaminant. Herbicide like 2,4-dichlorophenoxyacetic acid (2,4-D) used in agriculture usually ends up with a large fraction remaining in water and sediment, which may cause potential risk to human health and the ecosystem. This study proposes a greener method to utilize TiO2 as photocatalyst to remove 2,4-D from water. Accordingly, TiO2 nanoparticles (10-45 nm) were synthesized and grafted on lightweight fired clay to generate a TiO2-based floating photocatalyst. Experimental testing revealed that 60.2% of 2,4-D (0.1 mM) can be decomposed in 250 min under UV light with TiO2-grafted lightweight fired clay floating on water. Degradation fits well into the pseudo-first-order kinetic model. The floating photocatalysts can degrade approximately 50% 2,4-D in 250 min under sunlight and the degradation efficiency is stable for cycles. The results revealed that the fabrication of floating photocatalyst could be a promising and greener way to remove herbicide contaminants in water using TiO2.

Acute toxicity of three herbicide formulations of Astyanax altiparanae (Characiformes, Characidae), an emerging neotropical fish model species

ABSTRACT Herbicides are used in agriculture to control harmful crop weeds, prevent algae proliferation, and enhance macrophyte growth. Herbicide contamination of water bodies might exert toxic effects on fish in different development stages. Sperm, embryos, and adults of Astyanax altiparanae were used as a model to examine the detrimental effects of the following herbicide formulations: Roundup Transorb® (glyphosate), Arsenal® NA (imazapyr), and Reglone® (diquat). The lethal concentration 50 (LC50) values for adults using glyphosate and imazapyr were 3.14 mg/L and 4.59 mg/L, respectively, while the LC50 was higher than 28 mg/L for diquat. For the initial stages of embryo development, LC50 values were 16.52 mg/L glyphosate, 9.33 mg/L imazapyr, and 1084 mg/L diquat. Inhibition of sperm motility was noted at 252 mg/L glyphosate, 137 mg/L imazapyr, and 11,300 mg/L diquat, with an average sperm viability of 12.5%, 73.2%, and 89.3%, respectively, compared to 87.5% detected to control. A. altiparanae exhibited different sensitivities to the herbicide formulations investigated in the developmental stages evaluated. Roundup Transorb® exposure was more toxic for adults, while Arsenal® NA was most harmful for early embryonic development and inhibited sperm motility. Reglone® demonstrated low toxicity for A. altiparanae compared to Roundup Transorb® and Arsenal® NA. A. altiparanae may be considered an emerging fish model for toxicological studies for the neotropical region due to its wide distribution and biological characteristics.

Nicosulfuron on the Atrazine-degrading Arthrobacter sp. DNS10 by assays of intracellular accumulation of substrates, Zeta potential, EPS, and stress responses

Atrazine is often formulated with nicosulfuron as a commercial herbicide to enhance the weed control effect, however, the effect of nicosulfuron on the degradation of atrazine-degrading strain Arthrobacter sp. DNS10 was still unclear. In this study, the accumulation of atrazine in Arthrobacter sp. DNS10, as well as the cell surface characteristics (Zeta potential and extracellular polymers constitution) and antioxidant enzyme activity at different concentrations of nicosulfuron exposure for 48 h were measured. The results showed that the quantity of atrazine accumulation in strain DNS10 and the Zeta potential on strain cell surface were increased when nicosulfuron exposure level was increased. Three-dimensional fluorescence spectrum analysis found that nicosulfuron exposure could quench the peaks which represent the aromatic protein substances and soluble microbial metabolites in EPS of strain DNS10 In addition, the co-existed nicosulfuron could positively induce the activity of antioxidant enzymes (SOD and CAT) and malondialdehyde content, and also induce cell damage. This work proposes the mechanism by which nicosulfuron inhibits the biodegradation of atrazine, which is of great significance for improving the bioremediation of mixed herbicide contamination.