Environmental disappearance of acetochlor and its bioavailability to weed: A general prototype for reduced herbicide application instruction

Biodegradation of acetochlor by microbial consortium AT1: microcosm centric microbiomic-metabolomics mechanisms and environmental remediation feasibility

The excessive use of herbicide acetochlor (ACT) threatens crop health and the environment, necessitating effective remediation strategies. This study focused on a consortium named AT1, enriched from ACT-contaminated soil. Under optimized conditions (25 °C, pH 7, 1 % inoculum), AT1 almost completely degraded ACT (50-1000 mg/L) within 6-12 days. High-throughput sequencing of 16S rRNA gene revealed a reduction in community diversity over time, with Sphingomonas (58.6 %) and Diaphorobacter (26.43 %) as dominant taxa. A structure model and network analysis indicated strong microbial competition during the peak degradation. Predicted functions and liquid chromatography-mass spectrometry based metabolomics data identified benzene ring intermediates during ACT degradation, including 2,6-dimethylaniline, resorcinol, phenol, 3-ethyl-1,2-benzenediol, 1,2,3-trihydroxybenzene, phloroglucinol, and benzene-1,2,4-triol. Joint omics analysis revealed that AT1 likely degrades ACT via N-dealkylation by Pseudomonas, amide bond hydrolysis by Diaphorobacter, and carboxylation and hydroxylation by Sphingomonas, leading to the formation of these intermediate metabolites. Moreover, AT1 efficiently degraded key intermediates, particularly 2,6-dimethylaniline, phenol, and resorcinol, further enhancing ACT mineralization. Notably, AT1 efficiently degraded ACT in soil, resulting in a significant decrease in ACT environmental residues. These findings provide valuable insights for the discovery and identification of herbicide-degrading bacterial resources and the metabolic transformation of herbicides, and developing approaches for pollution control and biodegradation of amide herbicides.

Bio-transformation of poultry litter and activated sewage sludge to produce biomixtures for the remediation of water polluted with pesticides

The aim of this study was to formulate novel biomixtures with the ability to dissipate globally used pesticides. For this, an effective stabilization of two wastes, poultry litter and activated sewage sludge, was achieved through a combination of composting and vermicomposting, with the aid of the earthworm Eisenia fetida. Hence, two different mixtures were prepared combining the wastes with and without the addition of sewage sludge, and their physicochemical and microbiological characterization was examined during both processes. Earthworms reproduction was promoted by more than fourteen times the initial number of individuals introduced. This step made it possible to obtain substrates rich in organic matter, stable and non-pathogenic. The resulting vermicomposted substrates (V-C1 and V-C2) were used to produce two different biomixtures with wheat stubble (WS) and soil (S): SWSV-C1 and SWSV-C2, and they were tested for the remediation of a solution of five pesticides (2,4-D, cypermethrin, imidacloprid, acetochlor and dimethoate) in a 119-days assay. Comparisons were made with a WS-only biomixture (SWS) and a soil control. All biomixtures were more successful in dissipating the pesticides than soil; 2,4-D, dimethoate, and acetochlor degradation reached more than 99% in the three biomixtures after 28-56 days of assay. Biomixtures containing either vermicomposts acted faster than SWS, particularly for 2,4-D, dimethoate and cypermethrin. The total microbial activity was found to be higher in the two biomixtures containing vermicompost, which can be linked to their enhanced performance in the degradation of pesticides. Although the germination of Lactuca sativa proved that neither of the three spent biomixtures were phytotoxic at the end (germination index >60%), only SWSV-C1 and SWSV-C2 proved to be safe for the survival of E. fetida. This work confirms that vermicompost improves the success of biomixtures, not only in terms of pesticide removal, but also providing non-toxic spent biomixtures.

Effects of environmental relevant concentrations of acetochlor on growth, hematology, serum biochemistry and histopathology of Japanese quail

Acetochlor is frequently applied to various food crops in agriculture sector, and long-term exposure can cause significant endocrine-disrupting effects in exposed animals including impacts on human health. This study aimed to evaluate the effects of acetochlor on the growth, hematology, serum biochemistry, and histopathological alterations in Japanese quail. Eighty male quail were obtained and divided into four groups (A-D) and given acetochlor orally for the period of 45 days. Group A was served as the control, while groups B, C, and D received 20mg/kg, 30mg/kg, and 40mg/kg acetochlor, respectively. The study found that Japanese quail administered higher doses of acetochlor exhibited reduced frequency of crowing and foam production. The results showed that increased concentrations of acetochlor led to adverse effects on the growth parameters of Japanese quail. Hematology analysis indicated that birds exposed to higher concentrations of acetochlor experienced a significant decrease in red blood cell count, hemoglobin concentration, hematocrit (HCT), mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC), along with a significant increase in white blood cell count compared to the control group. Additionally, higher concentrations of acetochlor led to a significant increase in various serological indices including urea, creatinine, alanine aminotransferase (ALT), and aspartate aminotransferase (AST), while the values of total proteins, albumin, and plasma proteins declined. The histopathology results of treated Japanese quail exposed to higher concentrations of acetochlor showed a range of pathological lesions in the testes, heart, and brain. The study concluded that even low concentrations of acetochlor can cause slight to significant changes in Japanese quail, affecting their physical, hematological, histopathological and serum biochemical parameters.

Comprehensive Assessment of Herbicide Toxicity on Navicula sp. Algae: Effects on Growth, Chlorophyll Content, Antioxidant System, and Lipid Metabolism

This study investigated the effects of herbicide exposure on Navicula sp. (MASCC-0035) algae, focusing on growth density, chlorophyll content, antioxidant system, and lipid metabolism. Navicula cultures were exposed to different concentrations of atrazine (ATZ), glyphosate (Gly), and acetochlor (ACT) for 96 h. Results showed a significant decrease in cell numbers, with higher herbicide concentrations having the most noticeable impacts. For instance, Gly-G2 had reduced cell populations by 21.00% at 96 h. Chlorophyll content varied, with Gly having a greater impact on chlorophyll a compared to ATZ and ACT. Herbicide exposure also affected the antioxidant system, altering levels of soluble sugar, soluble protein, and reactive oxygen species (ROS). Higher herbicide rates increased soluble sugar content (e.g., ATZ, Gly, and ACT-G2 had increased by 14.03%, 19.88%, and 19.83%, respectively, at 72 h) but decreased soluble protein content, notably in Gly-G2 by 11.40%, indicating cellular stress. Lipid metabolism analysis revealed complex responses, with changes in free proline, fatty acids, and lipase content, each herbicide exerting distinct effects. These findings highlight the multifaceted impacts of herbicide exposure on Navicula algae, emphasizing the need for further research to understand ecological implications and develop mitigation strategies for aquatic ecosystems.

Degradation of Three Herbicides and Effect on Bacterial Communities under Combined Pollution

Pesticide residues in soil, especially multiple herbicide residues, cause a series of adverse effects on soil properties and microorganisms. In this work, the degradation of three herbicides and the effect on bacterial communities under combined pollution was investigated. The experimental results showed that the half-lives of acetochlor and prometryn significantly altered under combined exposure (5.02-11.17 d) as compared with those of individual exposure (4.70-6.87 d) in soil, suggesting that there was an antagonistic effect between the degradation of acetochlor and prometryn in soil. No remarkable variation in the degradation rate of atrazine with half-lives of 6.21-6.85 d was observed in different treatments, indicating that the degradation of atrazine was stable. 16S rRNA high-throughput sequencing results showed that the antagonistic effect of acetochlor and prometryn on the degradation rate under combined pollution was related to variation of the Sphingomonas and Nocardioide. Furthermore, the potential metabolic pathways of the three herbicides in soil were proposed and a new metabolite of acetochlor was preliminarily identified. The results of this work provide a guideline for the risk evaluation of combined pollution of the three herbicides with respect to their ecological effects in soil.

Evaluating the effects of manual hoeing and selective herbicides on maize (Zea mays L.) productivity and profitability

The objective of this study was to evaluate maize production and the economic profitability of weed management techniques. Field trials were conducted at the Kasapa farm during the 2021/22 growing seasons using a split-plot design with three repetitions. The main factor was the herbicides applied in pre-emergence alone (2L ha-1: acetochlor, bentazon, imazethapyr and 60 g ha-1 chlorimuron-ethyl), then mixed (1L ha-1: acetochlor plus bentazon plus imazethapyr plus 30g ha-1chlorimuron-ethyl), manual hoeing (3-5WAS) including the non-weeding. The secondary factor: maize varieties (GV672A, GV673A, GV664A and Sam4vita). The highest maize dry grain yield (7.66 t ha-1) was associated with imazethapyr, while those of acetochlor and chlorimuron-ethyl (6.86 and 6.92 t ha-1) compared to manual hoeing (7.62 t ha-1, respectively) were low, but much higher than no weeding (1.21 t ha-1). The yields of varieties GV672A and GV664A were higher (6.87 and 6.77 t ha-1), compared to Sam4vita (5.64 t ha-1). The total dry weight of weeds was negatively correlated with all crop parameters, with its maximum value (127.56 g m-2) characterizing non-weeding, and the minimum for manual hoeing (18.83 g m-2). The Ratio Cost Value showed that all treatments were profitable: imazethapyr > bentazon > chlorimuron-ethyl > combination > acetochlor > manual hoeing. However, imazethapyr was economically more profitable and could replace manual hoeing when the field to be weeded increases and labor is scarce.

Dissipation and Dietary Risk Assessment of Prochloraz in Strawberries under Greenhouse Conditions

Prochloraz and its metabolites in strawberries have not been determined until now. Meanwhile, few reports in the literature have concerned the dissipation behavior and risk assessment of prochloraz and its metabolites in strawberries under greenhouse conditions in Beijing. A method for the determination of prochloraz and its metabolites in strawberries was developed using QuEChERS in combination with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Prochloraz and its metabolites recovered from strawberries were present in concentrations of 73.06% to 116.01%, their RSDs ranged from 1.12% to 9.17%, and their limits of detection ranged from 0.1 to 1 μg kg-1. Then, a study was conducted on the dissipation of prochloraz in strawberries under greenhouse conditions. The dissipation of prochloraz in strawberries followed the first-order kinetic equation, and its half-life was 8.06 days. The health risk associated with prochloraz in strawberries was evaluated using the target hazard quotient (THQ) method and EFSA PRIMo model. The results showed that the THQ values, %ARfD values, and %ADI values were less than 1. These results indicate that no health concerns of prochloraz are associated with the consumption of the studied strawberries. The government can use the results of this study to support the establishment of a maximum residue level for prochloraz in strawberries.

Human health risk assessment based on direct and indirect exposure to endocrine disrupting herbicides in drinking, ground, and surface water in Croatia

The recognition of certain herbicides as endocrine disrupting compounds has raised concerns due to their ability to interfere with the normal functioning of the endocrine system, which regulates various physiological processes in organisms. The objective of this study was to assess the possible human health risks associated with terbuthylazine and endocrine-disrupting herbicides atrazine, acetochlor, and metolachlor in the drinking, surface, and groundwater of the Zagreb city region, Croatia. We relied on advanced statistical methods and principal component analysis (PCA), which revealed higher levels of atrazine and acetochlor in drinking and groundwater samples and higher presence of metolachlor and terbuthylazine in surface waters. To evaluate the danger to human health, various exposure scenarios have been assessed. The risk of direct human exposure to analyzed herbicides through drinking or bathing with drinking (tap) or groundwater, as well as from recreational activities like swimming in rivers, streams, and lakes, has been quantified. In addition to these direct exposure scenarios, indirect ones based on consumer goods, fruits, and vegetables, treated with surface and groundwater for irrigation, were assessed to investigate the danger to human health. Judging by the reported herbicide levels there was no significant risk of carcinogenic (CR ≤ 1 × 10-6) or non-carcinogenic (HI < 1) diseases, not even when we assessed the so-called "cocktail effect" of combined the herbicide exposure in different waters.

The health risk of acetochlor metabolite CMEPA is associated with lipid accumulation induced liver injury

Liver injury may cause many diseases, such as non-alcoholic fatty liver disease (NAFLD). Acetochlor is one of the representative chloroacetamide herbicides, and its metabolite 2-chloro-N-(2-ethyl-6-methyl phenyl) acetamide (CMEPA) is the main form of exposure in the environment. It has been shown that acetochlor can cause mitochondrial damage of HepG2 cells and induce apoptosis by activating Bcl/Bax pathway (Wang et al., 2021). But there has been less research on CMEPA. we explored the possibility of CMEPA and liver injury through biological experiments. In vivo, CMEPA (0-16 mg/L) induced liver damage in zebrafish larvae, including increased lipid droplets, changes in liver morphology (>1.3-fold) and increased TC/TG content (>2.5-fold). In vitro, we selected L02 (human normal liver cells) as the model, and explored its molecular mechanism. We found that CMEPA (0-160 mg/L) induced apoptosis (similar to 40%), mitochondrial damage and oxidative stress in L02 cells. CMEPA induced intracellular lipid accumulation by inhibiting AMPK/ACC/CPT-1A signaling pathway and activating SREBP-1c/FAS signaling pathway. Our study provides evidence of a link between CMEPA and liver injury. This raises concerns regarding the health risks of pesticide metabolites to liver health.

Superabsorbent hydrogel as a formulation to promote mineralization and accelerate degradation of acetochlor in soils

The excessive use of herbicides had caused serious environmental pollution and ecological problems. Therefore, it is imperative to explore an effective method to reduce herbicide residues and pollution. In the present study, we used superabsorbent hydrogels coated ¹⁴C-acetochlor (SH-ACE) to investigate its behavior in different soils under oxic conditions. After 100 days, the mineralization by SH-ACE was increased by 2.3%, 2.5% and 3.3% in the red clay soils, fluvio-marine yellow loamy soils and coastal saline soils, respectively, compared to the control group. This result indicated that the SH-ACE treatment resulted in more complete degradation and detoxification of acetochlor. In addition, the dissipation rates of acetochlor were significantly faster in the SH-ACE treatment, which reduced the persistence of acetochlor. The probable degradation pathways of acetochlor involved dechlorination, hydroxylation, deethoxymethylation, and the formation of thioacetic acid derivatives in the two treatments, but the contents of transformation products were completely different. These findings suggest that the SH-ACE treatment has a significant effect to accelerate the degradation of acetochlor. When developing green pesticides, we emphasize that superabsorbent hydrogel coating treatment should be considered as a promising method for ecological safety in the environment.

Estimating the bioavailability of acetochlor to wheat using in situ pore water and passive sampling

The intensive use of acetochlor in China leads to its extensive existence in soil which may result in contamination of crops and commodities. Therefore, it is vital to assess the bioavailability and phytotoxicity of acetochlor to crops. In this study, four measurements involved in in situ pore water extraction (C_IPW), passive sampling extraction (C_free), ex situ pore water extraction (C_EPW), and organic solvent extraction (C_soil) were conducted to assess the bioavailability and phytotoxicity of acetochlor to wheat plant plants in five soils. The results showed that the acetochlor concentrations accumulated in wheat foliage and roots were in the range of 0.11-0.87 mg/kg and 0.09-2.02 mg/kg in the five tested soils, respectively, and had a significant correlation with the acetochlor values analyzed by C_IPW (R² = 0.83-0.90, p < 0.0001) or the C_free method (R² = 0.86-0.92, p < 0.0001). The acetochlor concentrations in the five soils measured by these two methods were also correlated with the IC₅₀ values of acetochlor in wheat foliage and roots (R² > 0.69, p ≤ 0.05). The results indicated that the C_IPW and C_free methods were effective in evaluating acetochlor toxicity to wheat and the acetochlor concentrations in wheat. The effects of soil physical and chemical properties including pH, organic matter content (OMC), clay content, and cation exchange capacity (CEC) on the acetochlor toxicity to wheat were analyzed, and soil OMC was found to be the dominant factor affecting the toxicity of acetochlor in the soil-wheat system.

Recent Progress and Prospects in Catalytic Water Treatment

Presently, conventional technologies in water treatment are not efficient enough to completely mineralize refractory water contaminants. In this context, the implementation of catalytic processes could be an alternative. Despite the advantages provided in terms of kinetics of transformation, selectivity, and energy saving, numerous attempts have not yet led to implementation at an industrial scale. This review examines investigations at different scales for which controversies and limitations must be solved to bridge the gap between fundamentals and practical developments. Particular attention has been paid to the development of solar-driven catalytic technologies and some other emerging processes, such as microwave assisted catalysis, plasma-catalytic processes, or biocatalytic remediation, taking into account their specific advantages and the drawbacks. Challenges for which a better understanding related to the complexity of the systems and the coexistence of various solid-liquid-gas interfaces have been identified.

Exposure to acetochlor impairs swim bladder formation, induces heat shock protein expression, and promotes locomotor activity in zebrafish (Danio rerio) larvae

Acetochlor is one of the most widely used herbicides in the world, however, there are few data on the sub-lethal effects of acetochlor on early developmental stages of fish. To address this, we measured survival, deformity, swim bladder formation, embryo oxygen consumption rates, reactive oxygen species (ROS) levels, transcripts (related to swim bladder formation, oxidative damage response, and apoptosis) and behavior responses following exposure to acetochlor (0.001 µM up to 125 µM). Exposure to acetochlor at concentrations 50 µM and above exerted 100% mortality after 3 dpf, and significantly reduced the size of the swim bladder (25 µM). In embryos, basal respiration, oligomycin-induced ATP production, and maximal respiration were decreased 30-60% following a 24 h exposure to 125 μM acetochlor. Acetochlor did not affect ROS levels up to 25 µM in larvae with acute exposure. Acetochlor at 25 µM increased mRNA levels of bax1, hsp70, and hsp90a by ~4-fold in larval zebrafish. In both the visual motor response and light-dark preference test, 25 µM acetochlor increased locomotor activity of larval fish. At lower exposure concentrations, 100 and 1000 nM acetochlor increased the mean time spent in the dark zone, suggesting promotion of anxiolytic behavior. This study presents a comprehensive evaluation of sublethal effects of acetochlor, spanning molecular responses to behavior, which can be used to refine risk assessment decisions for aquatic environments.

The enantioselective study of the toxicity effects of chiral acetochlor in HepG2 cells

Acetochlor is one of the most widely used chiral herbicides in the world, and it is usually produced and used as racemic form (Rac). The potential effects of acetochlor in human body are mainly induced by its residue in agriculture food. The direct target exposed is the liver in human body. However, the potential toxic and mechanism threat to human liver cells caused by chiral acetochlor has been rarely reported. The purpose of this study is to explore the potential mechanism of the toxicity caused by chiral acetochlor in HepG2 cells. The results revealed that acetochlor and its enantiomers could inhibit cell activity and cause DNA damage in HepG2 cells. The toxicity of Rac was higher than that of the two enantiomers, mainly derived from S configuration. The mechanism is through inducing decreased membrane potential (△Ψ), up-regulated Bax/BcL-2 expression, caused a cascade reaction, activated casepase-3 and casepase-9 and cleaved PARP, which maybe lead to cell death through apoptotic-signaling pathway in the end. These results illuminate that the genotoxic and cytotoxic risks of chiral acetochlor are major coming from S configuration. It provides a theoretical basis for the production of single pesticide to reduce the effects of human health.