Overarching issues on relevant pesticide transformation products in the aquatic environment: A review

Ecosystem risk-based prioritization of micropollutants in wastewater treatment plant effluents across China

Identifying priority pollutants in wastewater treatment plant (WWTP) effluents is crucial for optimizing monitoring efforts, improving regulations, and developing targeted mitigation strategies. Despite the presence of numerous trace organic pollutants in WWTP effluents, a comprehensive prioritization scheme is lacking, hindering effective control. This study screened 216 micropollutants, including pharmaceuticals, pesticides, and industrial chemicals, which had been detected in effluents from 46 WWTPs across China. A multi-criteria prioritization method was developed, considering exposure potential based on median concentrations and detection frequencies, as well as hazard potential determined by persistence, bioaccumulation, in vitro toxicity, and in vivo toxicity. Pollutants with low exposure or hazard potential were filtered out, and a priority index was calculated to rank the remaining 59 substances. The top 15 priority pollutants included regulated persistent organic pollutants like perfluorooctanoic acid and their alternatives such as perfluorobutane sulfonate, pesticide transformation products, and emerging contaminants such as bisphenol A, which are not currently regulated in WWTP effluents. This study provides a systematic approach to identify priority pollutants and generates a guiding framework for monitoring, regulation, and control of both well-recognized and overlooked contaminants in WWTP effluents.

Photodegradation of the novel herbicide pyraclonil in aqueous solution: Kinetics, identification of photoproducts, mechanism, and toxicity assessment

Pyraclonil is a new type of pyrazole herbicide, whose photochemical fate in aqueous solution has not been reported yet. In this study, effects on the photolysis rate such as light source, pH, NO3-, Fe3+, fulvic acid (FA) and riboflavin (RF) were investigated. Pyraclonil photodegraded in pure water under both UV and simulated sunlight with half-lives of 32.29 min and 42.52 h, respectively. Under UV, the degradation rate of pyraclonil in pH 4 solution (0.0299 ± 0.0033 min-1) was about twice higher than that in pH 9 (0.0160 ± 0.0063 min-1). Under simulated sunlight, low concentration (0.1-1 mg/L) of FA, NO3-, Fe3+ and RF noticeably promoted the photodegradation of pyraclonil. Then, with the combination of experimental UPLC-Q-TOF/MS and computational calculation of density functional theory (DFT), fourteen transformation products (TPs) of pyraclonil were identified with possible mechanism of C-N bond cleavage, photorearrangement, demethylation, hydroxylation and oxidation. Additionally, acute toxicity assessment was conducted through ECOSAR prediction and laboratory bioassays. The prediction results indicated that toxicity of TP157 to daphnid and green algae was 1.3 and 1.4 times higher than that of the parent, respectively. The bioassay results indicated that toxicities of TP157 and TP263 to C. vulgaris were about 1.6 and 5.9 times higher than that of the parent, respectively. The results provided a reference for elucidating the potential hazards of pyraclonil to non-target organisms and promoting its rational use.

Tracking atrazine degradation in soil combining 14C-mineralisation assays and compound-specific isotope analysis

The quantification of pesticide dissipation in agricultural soil is challenging. In this study, we investigated atrazine biodegradation in both liquid and soil experiments bioaugmented with distinct atrazine-degrading bacterial isolates. This was achieved by combining 14C-mineralisation assays and compound-specific isotope analysis of atrazine. In liquid experiments, the three bacterial isolates mineralised over 40% of atrazine, demonstrating their potential for extensive degradation. However, the kinetics of mineralisation and degradation varied among the isolates. Carbon stable isotope fractionation was similar for Pseudomonas isolates ADPT34 and ADP2T0, but slightly higher for Chelatobacter SR27. In soil experiments, atrazine primarily degraded into atrazine-desethyl, while atrazine-hydroxy was mainly observed in experiments with SR27. Atrazine mineralisation in soil by ADPT34 and SR27 exceeded 40%, whereas ADP2T0 exhibited a mineralisation rate of 10%. In experiments with ADPT34 and SR27, atrazine 14C-residues were predominantly found in the non-extractable fraction, whereas they accumulated in the extractable fraction in the experiment with ADP2T0. Compound-specific isotope analysis (CSIA) relies on changes of stable isotope ratios and holds potential to evaluate herbicide transformation in soil. CSIA of atrazine indicated atrazine biodegradation in water and solvent extractable soil fractions and varied between 29% and 52%, depending on the bacterial isolate. Despite atrazine degradation in both soil fractions, a significant portion of atrazine residues persisted, depending on the bacterial degrader, initial cell concentration, and mineralisation and degradation rates. Overall, our approach can aid in quantifying atrazine persistence and degradation in soil, and in optimizing bioaugmentation strategies for remediating soils contaminated with persistent herbicides.

Understanding Environmental Fate: Soil Variability and Rainfall Influence on Triafamone and Ethoxysulfuron Leaching

Considering the environmental impact of triafamone and ethoxysulfuron, it is crucial to investigate their leaching behaviour under different geographical conditions. The present study evaluates the effects of application rate, soil properties and rainfall conditions on leaching of these herbicides and their metabolites. Ethoxysulfuron leached up to 50-60 cm with 82.95 to 89.23% detected in leachates while triafamone leached only to 10-20 cm and was < 0.01 µg mL-1 in leachates. Highest leachability was observed in loamy sand followed by sandy loam and clay loam soil. M1 metabolite (N-(2-((4,6-dimethoxy-1,3,5-triazin-2-yl) (hydroxy) methyl) -6-fluorophenyl) -1,1-difluoro-N-methyl methane sulfonamide) was majorly present in 0 to 10 cm soil depth. With increase in rainfall, downward mobility of both parent and M1 increased. Amendment of loamy sand soil with farmyard manure reduced the leachability indicating it could mitigate groundwater pollution. However, the effect of different exogenous OM amendments on leaching behaviour of herbicides needs to be evaluated.

Co3O4/CuO@C catalyst based on cobalt-doped HKUST-1 as an efficient peroxymonosulfate activator for pendimethalin degradation: Catalysis and mechanism

Pendimethalin (PM) is an organic pollutant (herbicide), and systematic studies on PM degradation are scarce. The efficient degradation of PM in water remains a challenge that requires to be addressed. Herein, for the first time, elemental Co was doped into HKUST-1 using a solvothermal method to generate Co3O4/CuO@C via pyrolysis. The as-prepared catalyst was used to activate peroxymonosulfate (PMS) for PM degradation, obtaining a PM degradation efficiency of 98.2 % after 30 min. The assessment of the effects of various factors on the degradation efficiency revealed that 1O2 dominated PM degradation, whereas the contribution of SO4•- was negligible. Although 3Co3O4/CuO@C exhibited a good degradation performance against other organic pollutants, its degradation performance in real water was poor. The carbon layer reduced metal-ion leaching (Co and Cu), and the synergistic interactions between Co3O4 and CuO promoted PMS activation. The roles of the components of 3Co3O4/CuO@C in PM degradation by activated PMS were investigated in the presence of CoIV and Co-OOSO3-. Two possible PM degradation pathways were systematically proposed, and the toxicity of the intermediates was analyzed. Finally, a mechanism for PM degradation by 3Co3O4/CuO@C-activated PMS was proposed.

Pesticides in the environment: Degradation routes, pesticide transformation products and ecotoxicological considerations

Among rising environmental concerns, emerging contaminants constitute a variety of different chemicals and biological agents. The composition, residence time in environmental media, chemical interactions, and toxicity of emerging contaminants are not fully known, and hence, their regulation becomes problematic. Some of the important groups of emerging contaminants are pesticides and pesticide transformation products (PTPs), which present a considerable obstacle to maintaining and preserving ecosystem health. This review article aims to thoroughly comprehend the occurrence, fate, and ecotoxicological importance of pesticide transformation products (PTPs). The paper provides an overview of pesticides and PTPs as contaminants of emerging concern and discusses the modes of degradation of pesticides, their properties and associated risks. The degradation of pesticides, however, does not lead to complete destruction but can instead lead to the generation of PTPs. The review discusses the properties and toxicity of PTPs and presents the methods available for their detection. Moreover, the present study examines the existing regulatory framework and suggests the need for the development of new technologies for easy, routine detection of PTPs to regulate them effectively in the environment.

Prediction of Potential Risk for Flupyradifurone and Its Transformation Products to Hydrobionts

Flupyradifurone (FPF) is considered the latest generation of neonicotinoid insecticides. Here, we investigated the toxicity and ecological risk of FPF and its aerobic transformation products (TPs) to aquatic species using the method of prediction. We found that FPF exhibited moderate or high toxicity to some aquatic species. The 5% hazardous concentration of FPF was 3.84 μg/L for aquatic organisms. We obtained 91 aerobic TPs for FPF, and almost half of FPF TPs exhibited toxicity to fish or Daphnia. Eleven of the TPs of FPF exhibited a high or moderate risk to aquatic ecosystems. All FPF TPs with high and moderate risks contained a 6-chloropyridine ring structure, indicating that the derivant of a pyridine ring exhibits potential risks to aquatic ecosystems. Our results provide insight into the potential risk of FPF to aquatic ecosystems and could be used to help set criteria to control pollution caused by FPF.

Forever Pesticides: A Growing Source of PFAS Contamination in the Environment

BACKGROUND

Environmental contamination by fluorinated chemicals, in particular chemicals from the per- and polyfluoroalkyl substances (PFAS) class, has raised concerns around the globe because of documented adverse impacts on human health, wildlife, and ecosystem quality. Recent studies have indicated that pesticide products may contain a variety of chemicals that meet the PFAS definition, including the active pesticide ingredients themselves. Given that pesticides are some of the most widely distributed pollutants across the world, the legacy impacts of PFAS addition into pesticide products could be widespread and have wide-ranging implications on agriculture and food and water contamination, as well as the presence of PFAS in rural environments.

OBJECTIVES

The purpose of this commentary is to explore different ways that PFAS can be introduced into pesticide products, the extent of PFAS contamination of pesticide products, and the implications this could have for human and environmental health.

METHODS

We submitted multiple public records requests to state and federal agencies in the United States and Canada and extracted relevant data from those records. We also compiled data from publicly accessible databases for our analyses.

DISCUSSION

We found that the biggest contributor to PFAS in pesticide products was active ingredients and their degradates. Nearly a quarter of all US conventional pesticide active ingredients were organofluorines and 14% were PFAS, and for active ingredients approved in the last 10 y, this had increased to 61% organofluorines and 30% PFAS. Another major contributing source was through PFAS leaching from fluorinated containers into pesticide products. Fluorination of adjuvant products and "inert" ingredients appeared to be limited, although this represents a major knowledge gap. We explored aspects of immunotoxicity, persistence, water contamination, and total fluorine load in the environment and conclude that the recent trend of using fluorinated active ingredients in pesticides may be having effects on chemical toxicity and persistence that are not given adequate oversight in the United States. We recommend a more stringent risk assessment approach for fluorinated pesticides, transparent disclosure of "inert" ingredients on pesticide labels, a complete phase-out of post-mold fluorination of plastic containers, and greater monitoring in the United States. https://doi.org/10.1289/EHP13954.

Removal, transformation and ecological risk assessment of pesticide in rural wastewater by field-scale horizontal flow constructed wetlands of treated effluent

Constructed wetlands (CWs) are widely used in sewage treatment in rural areas, but there are only a few studies on field-scale CWs in treating wastewater-borne pesticides. In this study, the treatment and metabolic transformation of 29 pesticides in rural domestic sewage by 10 field-scale horizontal flow CWs (HF-CWs), each with a treatment scale of 36‒5000 m3/d and operated for 2‒10 years, in Guangzhou, Southern China was investigated. The risk of pesticides in treated effluent and main factors influencing such risk were evaluated. Results demonstrated that HF-CWs could remove pesticides in sewage and reduce their ecological risk in effluent, but the degree varied among types of pesticides. Herbicides had the highest mean removal rate (67.35 %) followed by insecticides (60.13 %), and the least was fungicides (53.22 %). In terms of single pesticide compounds, the mean removal rate of butachlor was the highest (73.32 %), then acetochlor (69.41 %), atrazine (68.28 %), metolachlor (58.40 %), and oxadixyl (53.28 %). The overall removal rates of targeted pesticides in each HF-CWs ranged from 11 %‒57 %, excluding two HF-CWs showing increases in pesticides in treated effluent. Residues of malathion, phorate, and endosulfan in effluent had high-risks (RQ > 5). The pesticide concentration in effluent was mainly affected by that in influent (P = 0.042), and source control was the key to reducing risk. The main metabolic pathways of pesticide in HF-CWs were oxidation, with hydroxyl group to carbonyl group or to form sulfones, the second pathways by hydrolysis, aerobic condition was conducive to the transformation of pesticides. Sulfones were generally more toxic than the metabolites produced by hydrolytic pathways. The present study provides a reference on pesticides for the purification performance improvement, long-term maintenance, and practical sustainable application of field-scale HF-CWs.

Occurrence and risk assessment of pesticides and their transformation products related to olive groves in surface waters of the Guadalquivir river basin

Pesticides are considered one of the main sources of contamination of surface waters, especially in rural areas highly influenced by traditional agricultural practices. The objective of this work was to evaluate the impact caused by pesticides and their transformation products (TPs) related to olive groves in surface waters with strong agricultural pressure. 11 streams were monitored during four sampling campaigns over 2 years. A solid-phase extraction, followed by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) analysis was used in the quantitative target approach, with more than 70 validated compounds. Target method was combined with a suspect screening strategy involving more than 500 pesticides and TPs, using ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS) to identify additional pesticides and TPs out of the scope of analysis. A total of 43 different compounds were detected with the target method. The herbicide MCPA was present in all samples and at the highest concentration (1260 ng L-1), followed by the fungicide carbendazim (1110 ng L-1), and the herbicide chlorotoluron (706 ng L-1). The suspect screening strategy revealed the presence of 7 compounds out of the target analysis (1 pesticide and 6 TPs). 6 analytes were confirmed with the analytical standards. Semi-quantification results revealed that TPs exhibited higher concentrations than their corresponding parent compounds, indicating higher persistency. Some small streams showed a comparable number of pesticides and concentrations to the most polluted large river. The determined pesticide and TPs concentrations represented an estimated environmental hazard in almost all sampling sites under study. This work underscores the importance of including pesticide TPs and small streams impacted by extensive agricultural activities in water quality monitoring programs.

Nontarget screening analysis of organic compounds in river sediments: a case study in the Taipu River of the Yangtze River Delta Region in China

Sediments are the vital fate of organic compounds, and the recognition of organic compounds in sediments is constructive in providing comprehensive and long-term information. In this study, a three-step nontarget screening (NTS) analysis workflow using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS) revealed the extensive existence of organic compounds in the Taipu River sediment. Organic compounds (705) were detected and divided into four structure-related groups or eight use-related classes. In the Taipu River's mainstream, a significant difference was found in the composition profiles of the identified organic compounds among various sites, demonstrating the organic compounds were more abundant in the midstream and downstream than in the upstream. Meanwhile, the hydrodynamic force was recognized as a potential factor influencing organic compounds' occurrence. Based on multiple statistical analyses, the shipping and textile printing industries were considered the significant contributors to the identified organic compounds. Considering the principles of the priority substances and the current status of the substances, two traditional pollutants and ten emerging organic compounds were recognized as the priority organic compounds for the Taipu River. Conclusively, this study established a workflow for NTS analysis of sediment samples and demonstrated the necessity of NTS analysis to evaluate the impact of terrestrial emissions of organic compounds on the aquatic environment.

Oxidative treatment of micropollutants present in wastewater: A special emphasis on transformation products, their toxicity, detection, and field-scale investigations

Micropollutants have become ubiquitous in aqueous environments due to the increased use of pharmaceuticals, personal care products, pesticides, and other compounds. In this review, the removal of micropollutants from aqueous matrices using various advanced oxidation processes (AOPs), such as photocatalysis, electrocatalysis, sulfate radical-based AOPs, ozonation, and Fenton-based processes has been comprehensively discussed. Most of the compounds were successfully degraded with an efficiency of more than 90%, resulting in the formation of transformation products (TPs). In this respect, degradation pathways with multiple mechanisms, including decarboxylation, hydroxylation, and halogenation, have been illustrated. Various techniques for the analysis of micropollutants and their TPs have been discussed. Additionally, the ecotoxicity posed by these TPs was determined using the toxicity estimation software tool (T.E.S.T.). Finally, the performance and cost-effectiveness of the AOPs at the pilot scale have been reviewed. The current review will help in understanding the treatment efficacy of different AOPs, degradation pathways, and ecotoxicity of TPs so formed.

Structural Elucidation of Agrochemical Metabolic Transformation Products Based on Infrared Ion Spectroscopy to Improve In Silico Toxicity Assessment

Toxicological assessments of newly developed agrochemical agents consider chemical modifications and their metabolic and biotransformation products. To carry out an in silico hazard assessment, understanding the type of chemical modification and its location on the original compound can greatly enhance the reliability of the evaluation. Here, we present and apply a method based on liquid chromatography-mass spectrometry (LC-MS) enhanced with infrared ion spectroscopy (IRIS) to better delineate the molecular structures of transformation products before in silico toxicology evaluation. IRIS facilitates the recording of IR spectra directly in the mass spectrometer for features selected by retention time and mass-to-charge ratio. By utilizing quantum-chemically predicted IR spectra for candidate molecular structures, one can either derive the actual structure or significantly reduce the number of (isomeric) candidate structures. This approach can assist in making informed decisions. We apply this method to a plant growth stimulant, digeraniol sinapoyl malate (DGSM), that is currently under development. Incubation of the compound in Caco-2 and HepaRG cell lines in multiwell plates and analysis by LC-MS reveals oxidation, glucuronidation, and sulfonation metabolic products, whose structures were elucidated by IRIS and used as input for an in silico toxicology assessment. The toxicity of isomeric metabolites predicted by in silico tools was also assessed, which revealed that assigning the right metabolite structure is an important step in the overall toxicity assessment of the agrochemical. We believe this identification approach can be advantageous when specific isomers are significantly more hazardous than others and can help better understand metabolic pathways.

Single and joint toxicity of azoxystrobin and cyproconazole to Prochilodus lineatus: Bioconcentration and biochemical responses

Fungicides are widely used across the world to protect crops and their presence in freshwater systems is increasing. However, the evaluation of their potential impacts on non-target organisms is in the minority of studies related to pesticides. In the current research, the single and joint toxicity of azoxystrobin (AZX) and cyproconazole (CYP) was investigated in juvenile fish Prochilodus lineatus. In particular, we evaluated bioconcentration and biochemical responses following a short-term exposure to environmentally relevant concentrations of the fungicides (alone and in mixture). We also determined interactions between the biological responses when the two compounds were used in mixture. Our results demonstrate that AZX and CYP pose a risk to native freshwater fish by causing deleterious effects. Both compounds, alone and in mixture, bioaccumulated in P. lineatus and triggered neurotoxicity and changes in oxidative stress biomarkers in several organs. Moreover, muscle was a target tissue for these fungicides and a synergistic interaction was observed for the mixture. Due to the lack of studies in fish assessing the effects following exposure to AZX-CYP mixtures and considering a realistic exposure situation in agriculture-impacted water bodies, these findings provide new and relevant information for future studies.

Chemical occurrence of pesticides and transformation products in two small lentic waterbodies at the head of agricultural watersheds and biological responses in caged Gasterosteus aculeatus

Recent monitoring campaigns have revealed the presence of mixtures of pesticides and their transformation products (TP) in headwater streams situated within agricultural catchments. These observations were attributed to the use of various agrochemicals in surrounding regions. The aim of this work was to compare the application of chemical and ecotoxicological tools for assessing environmental quality in relation to pesticide and TP contamination. It was achieved by deploying these methodologies in two small lentic water bodies located at the top of two agricultural catchments, each characterized by distinct agricultural practices (ALT: organic, CHA: conventional). Additionally, the results make it possible to assess the impact of contamination on fish caged in situ. Pesticides and TP were measured in water using active and passive samplers and suspended solid particles. Eighteen biomarkers (innate immune responses, oxidative stress, biotransformation, neurotoxicity, genotoxicity, and endocrine disruption) were measured in Gasterosteus aculeatus encaged in situ. More contaminants were detected in CHA, totaling 25 compared to 14 in ALT. Despite the absence of pesticide application in the ALT watershed for the past 14 years, 7 contaminants were quantified in 100 % of the water samples. Among these contaminants, 6 were TPs (notably atrazine-2-hydroxy, present at a concentration exceeding 300 ng·L-1), and 1 was a current pesticide, prosulfocarb, whose mobility should prompt more caution and new regulations to protect adjacent ecosystems and crops. Regarding the integrated biomarker response (IBRv2), caged fish was similarly impacted in ALT and CHA. Variations in biomarker responses were highlighted depending on the site, but the results did not reveal whether one site is of better quality than the other. This outcome was likely attributed to the occurrence of contaminant mixtures in both sites. The main conclusions revealed that chemical and biological tools complement each other to better assess the environmental quality of wetlands such as ponds.

Recommendations to reduce the streetlight effect and gray areas limiting the knowledge of the effects of plant protection products on biodiversity

Preserving biodiversity against the adverse effects of plant protection products (PPPs) is a major environmental and societal issue. However, despite intensive investigation into the ecotoxicological effects of PPPs, the knowledge produced remains fragmented given the sheer diversity of PPPs. This is due, at least in part, to a strong streetlight effect in the field of ecotoxicology. Indeed, while some PPPs have been investigated in numerous ecotoxicological studies, there are many for which the scientific literature still has little or no information on their ecotoxicological risks and effects. The PPPs under the streetlight include a large variety of legacy substances and a more limited number of more recent or currently-in-use substances, such as the herbicide glyphosate and the neonicotinoid insecticides. Furthermore, many of the most recent PPPs (including those used in biocontrol) and PPP transformation products (TPs) resulting from abiotic and/or biotic degradation are rarely addressed in the international literature in the field of ecotoxicology. Here, based on a recent collective scientific assessment of the effects of PPPs on biodiversity and ecosystem services in the French and European contexts, this article sets out to illustrate the limitations and biases caused by the streetlight effect and numbers of gray areas, and issue recommendations on how to overcome them.

Tannic Acid Interfacial Modification of Prochloraz Ethyl Cellulose Nanoparticles for Enhancing the Antimicrobial Effect and Biosafety of Fungicides

With the poorly soluble and intrinsically unstable feature, prochloraz (Pro) was confronted with lower bioavailability in the crop defense against fungal erosion. Therefore, it was a challenging project to explore the innovative antifungal compound delivery system for improving bioavailability. The superior adhesive fungicide formulation was supposed to be an efficient pathway to enhance transmembrane permeability and biological activity. According to abundant phenolic hydroxyl groups, tannic acid (TA) was an ideal modified adhesive biomaterial to improve interfacial interactions. The fundamental purpose of this research was focused on the synergistic mechanism of TA-interfacial-modified Pro-ethyl cellulose (EC) nanoparticles for improving bioavailability and biosafety. In the stability test, TA-modified Pro-EC nanoparticles had the capacity to reduce Pro initial release burst, extending a persistent validity and improving anti-photodegradation property. The toxicity index of Pro-EC and Pro-EC-TA was approximately 2.93-fold and 4.96-fold that of Pro technical against Fusarium graminearum (F. graminearum), respectively. Compared with nonmodified EC nanoparticles, TA-modified EC nanoparticles obtained eminent transmembrane permeability and superior adherence ability to F. graminearum, for hydroxyl and carboxyl groups of TA to enhance interaction with target cell membranes. The contents of cellular reactive oxygen species induced by Pro-EC and Pro-EC-TA nanoparticles were about 2.31 times and 3.00 times that of the control check (CK), respectively. Compared to the CK group, the membrane potential and ergosterol values of F. graminearum treated with Pro-EC-TA nanoparticles were drastically reduced by 74.91 and 56.20%, respectively. In the biosafety assay, the maximum half-lethal concentration value of the TA-modified Pro-EC nanoparticles indicated that the acute toxicity of the Pro-EC-TA nanoparticles to adult zebrafish was approximately 8.34-fold reduced compared to that of the Pro technical. These findings demonstrated that the successful interfacial modification of Pro-EC nanoparticles with TA was a highly efficient, environmentally safe, and promising alternative for sustainable agricultural application, thus making the fungicide formulation process more simplified, easier fabrication, and lower cost.

Effect of adsorption on ferrihydrite on the photoreactivity of dissolved black carbon for photodegradation of sulfadiazine

The selective adsorption of dissolved black carbon (DBC) on inorganic minerals is a widespread geochemical process in the natural environment, which could change the chemical and optical properties of DBC. However, it remains unclear how selective adsorption affects the photoreactivity of DBC for photodegradation of organic pollutants. This paper was the first to investigate the effect of DBC adsorption on ferrihydrite at different Fe/C molar ratios (Fe/C molar ratios of 0, 7.50 and 11.25, and marked as DBC₀, DBC_7.50 and DBC_11.25) on the photoproduction of reactive intermediates generated from DBC and their interaction with sulfadiazine (SD). Results showed that UV absorbance, aromaticity, molecular weight and contents of phenolic antioxidants of DBC were significantly decreased after adsorption on ferrihydrite, and higher decrease was observed at higher Fe/C ratio. Photodegradation kinetics experiments showed that observed photodegradation rate constant of SD (k_obs) increased from 3.99 × 10^-5 s^-1 in DBC₀ to 5.69 × 10^-5 s^-1 in DBC_7.50 while decreased to 3.44 × 10^-5 s^-1 in DBC_11.25, in which ³DBC* played important roles and ¹O₂ played a minor role, while ·OH was not involved in the reaction. Meanwhile, the second-order reaction rate constant between ³DBC* and SD (k_{SD, 3DBC*}) increased from 0.84 × 10⁸ M^-1 s^-1 for DBC₀ to 2.53 × 10⁸ M^-1 s^-1 for DBC_7.50 while decreased to 0.90 × 10⁸ M^-1 s^-1 for DBC_11.25. The above results might be mainly attributed to the fact that the decrease of phenolic antioxidants in DBC weakened the back-reduction of ³DBC* and reactive intermediates of SD as the Fe/C ratio increased, while the decrease of quinones and ketones reduced the photoproduction of ³DBC*. The research revealed adsorption on ferrihydrite affected the photodegradation of SD by changing the reactivity of ³DBC*, which was helpful to understand the dynamic roles of DBC in the photodegradation of organic pollutants.

Does climbazole instigate a threat in the environment as persistent, mobile and toxic compound? Unveiling the occurrence and potential ecological risks of its phototransformation products in the water cycle

Persistent, mobile, and toxic chemicals (PMT), such as the antimycotic climbazole-(CBZ), proliferate in water cycle and imperil drinking water quality, sparking off research about their environmental fate. Unlike the parent compound, its transformation products-(TPs) are scarcely investigated, much less as PMTs. To this end, phototransformation of CBZ was investigated. A novel suspect-screening workflow was developed and optimized by cross-comparing the results of the identified photo-TPs against literature data to create an enhanced HRMS-database for environmental investigations of CBZ/TPs in the water cycle. In total, 24 TPs were identified, 14 of which are reported for the first time. Isomerism, dechlorination, hydroxylation, and cleavage of the ether or C-N bond are suggested as the main transformation routes. A screening of CBZ/TPs was conducted in wastewater, leachates, surface, and groundwater, revealing a maximum concentration of 464.8 ng/L in groundwater. In silico and in vitro methods were used for toxicity assessment, indicating toxicity for CBZ and some TPs. Seemingly, CBZ is rightly considered as PMT, and a higher potential to occur in surface or groundwater than non-PM chemicals appears. Likewise, the occurrence of TPs due to PMT properties or emission patterns was evaluated.

Fitness assessment of Mytilus galloprovincialis Lamarck, 1819 after exposure to herbicide metabolite propachlor ESA

The lack of data on the chronic effects of chloroacetanilide herbicide metabolites on non-target aquatic organisms creates a gap in knowledge about the comprehensive impacts of excessive and repeated pesticide use. Therefore, this study evaluates the long-term effects of propachlor ethanolic sulfonic acid (PROP-ESA) after 10 (T1) and 20 (T2) days at the environmental level of 3.5 μg.L^-1 (E1) and its 10x fold multiply 35 μg.L^-1 (E2) on a model organism Mytilus galloprovincialis. To this end, the effects of PROP-ESA usually showed a time- and dose-dependent trend, especially in its amount in soft mussel tissue. The bioconcentration factor increased from T1 to T2 in both exposure groups - from 2.12 to 5.30 in E1 and 2.32 to 5.48 in E2. Biochemical haemolymph profile and haemocyte viability were not affected by PROP-ESA exposure. In addition, the viability of digestive gland (DG) cells decreased only in E2 compared to control and E1 after T1. Moreover, malondialdehyde levels increased in E2 after T1 in gills, and DG, superoxidase dismutase activity and oxidatively modified proteins were not affected by PROP-ESA. Histopathological observation showed several damages to gills (e.g., increased vacuolation, over-production of mucus, loss of cilia) and DG (e.g., growing haemocyte trend infiltrations, alterations of tubules). This study revealed a potential risk of chloroacetanilide herbicide, propachlor, via its primary metabolite in the Bivalve bioindicator species M. galloprovincialis. Furthermore, considering the possibility of the biomagnification effect, the most prominent threat poses the ability of PROP-ESA to be accumulated in edible mussel tissues. Therefore, future research about the toxicity of pesticide metabolites alone or their mixtures is needed to gain comprehensive results about their impacts on living non-target organisms.

Uncovering the Dissipation of Chlorantraniliprole in Tomatoes: Identifying Transformation Products (TPs) and Coformulants in Greenhouse and Laboratory Studies by UHPLC-Q-Orbitrap-MS and GC-Q-Orbitrap-MS

The present study addressed the dissipation of the insecticide chlorantraniliprole in tomatoes treated with Altacor 35 WG under laboratory and greenhouse conditions, as well as the identification of transformation products (TPs) and coformulants, performing suspect screening analysis. Analyses were performed by ultra-high-performance liquid and gas chromatography coupled to quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap-MS and GC-Q-Orbitrap-MS). In all cases, chlorantraniliprole was fitted to a biphasic kinetic model, with R² values greater than 0.99. Dissipation was noticeably faster in greenhouse studies, in which even 96% dissipation was achieved over 53 days. One TP, IN-F6L99, was tentatively identified in both greenhouse and laboratory studies and was semiquantified by using chlorantraniliprole as the analytical standard, yielding a top value of 354 μg/kg for laboratory studies, whereas values for greenhouse studies fell under the limit of quantitation (LOQ). Finally, a total of 15 volatile coformulants were identified by GC-Q-Orbitrap-MS.

Abiotic transformation of kresoxim-methyl in aquatic environments: Structure elucidation of transformation products by LC-HRMS and toxicity assessment

In this study, abiotic transformation of an important strobilurin fungicide, kresoxim-methyl, was investigated under controlled laboratory conditions for the first time by studying its kinetics of hydrolysis and photolysis, degradation pathways and toxicity of possibly formed transformation products (TPs). The results indicated that kresoxim-methyl showed a fast degradation in pH9 solutions with DT₅₀ of 0.5 d but relatively stable under neutral or acidic environments in the dark. It was prone to photochemical reactions under simulated sunlight, and the photolysis behavior was easily affected by different natural substances such as humic acid (HA), Fe³⁺and NO₃^-which are ubiquitous in natural water, showing the complexity of degradation mechanisms and pathways of this chemical compound. The potential multiple photo-transformation pathways via photoisomerization, hydrolyzation of methyl ester, hydroxylation, cleavage of oxime ether and cleavage of benzyl ether were observed. 18 TPs generated from these transformations were structurally elucidated based on an integrated workflow combining suspect and nontarget screening by high resolution mass spectrum (HRMS), and two of them were confirmed with reference standards. Most of TPs, as far as we know, have never been described before. The in-silico toxicity assessment showed that some of TPs were still toxic or very toxic to aquatic organisms, although they exhibit lower aquatic toxicity compared to the parent compound. Therefore, the potential hazards of the TPs of kresoxim-methyl merits further evaluation.

Photolysis of the novel meta-diamide insecticide broflanilide in solutions: Kinetics, degradation pathway, DFT calculation and ecotoxicity assessment

Broflanilide, as a novel meta-diamide insecticide, presents high bioactivity against agricultural pests. However, there was limited report regarding the photolysis fate of broflanilide. In this study, the photodegradation kinetics and influence factors of broflanilide, including different solvents, pH, iron, S₂O₈^2- and SO₃^2- were investigated under UV condition, and the reaction mechanism and transformation pathway were explored. The reaction rates (k) showed solvent-specificity in ultrapure water (0.015 min^-1), ethyl acetate (0.051 min^-1), methanol (0.084 min^-1) and acetonitrile (0.193 min^-1), correspondingly. The photolysis of broflanilide was slowest in the acid condition (pH = 4.0) compared with that in the neutral (pH = 7.0) and alkaline (pH = 9.0) conditions. The iron (Fe²⁺ and Fe³⁺) presented significant inhibition on the photodegradation due to the light shielding effect. Additionally, the UV/peroxydisulfate (S₂O₈^2-) and UV/sulfite (SO₃^2-) technologies could effectively accelerate the photodegradation of broflanilide, which has the potential for rapid treatment of pesticides in the aqueous environment. Six transformation products (TPs) were detected in water, peroxydisulfate and sulfite solutions, and the possible transformation pathways, including dehalogenation, cyclization, N-dealkylation, oxidation, reduction and hydrolysis, were proposed. Importantly, the reaction mechanism was explained through the analysis of molecular electrostatic potential and molecular orbitals. The predicted toxicity of the TPs indicated that several highly toxic TPs need to pay more attention in future risk assessments. This study provides a new perspective for evaluating the ecological fate and risks of pesticides.

Computer-aided toxicity prediction and potential risk assessment of two novel neonicotinoids, paichongding and cycloxaprid, to hydrobionts

Paichongding (IPP) and cycloxaprid (CYC) have been effectively used as the alternative products of imidacloprid (IMI) against IMI-resistant insects and exhibit a great market potential. However, risk assessment of IPP and CYC for non-target organisms, especially ecological risk assessment for non-target aquatic organisms, is still lacking. Here, we predicted the toxicity and potential risks of IPP, CYC, and their transformation products (TPs) to hydrobionts. The results indicated that IPP and CYC could generate 428 and 113 TPs, respectively, via aerobic microbial transformation. Nearly half of the IPP TPs and nearly 41 % of the CYC TPs exhibited high or moderate toxicity to Daphnia or fish. Moreover, we found that IPP, CYC, and 80 TPs of them posed potential risks to aquatic ecosystems. Almost all harmful TPs contained a 6-chloropyridine ring structure, suggesting that this structure may be associated with the strong toxicity of these TPs to aquatic organisms, and these TPs (IPP-TP2 or CYC-TP2, IPP-TP197 or CYC-TP71, IPP-TP198 or CYC-TP72, and IPP-TP212 or CYC-TP80) may appear in aquatic environments as final products. The risks posed by these TPs to aquatic ecosystems require more attention. This study provides insights into the toxicity and ecological risks of IPP and CYC.

Photodegradation of enestroburin in water by simulated sunlight irradiation: Kinetics, isomerization, transformation products identification and toxicity assessment

Enestroburin is the first strobilurin fungicide developed by China and has been widely used to control fungal disease for 15 years. Investigation of its photolytic behaviour is essential for the comprehensive evaluation of its ecological risk. The effects of solution pH, humic acid (HA) and Fe(III) ions on photolysis were studied. The direct photolysis rates of enestroburin in the acidic solution (pH = 4) was faster than that in the basic (pH = 7) or neutral condition (pH = 9). HA and Fe³⁺ ions inhibited photolysis by the light screening effect. The photolysis of enestroburin was very fast due to the generation of photo-isomers. Seven isomeric products of enestroburin were observed using SFC-MS/MS, and the reaction mechanism for photo-induced isomers was proposed. The reaction occurred on three double bonds, including tautomerism of enol ether and oxonium and the triplet energy transfer of the CC and CN double bond. 12 transformation products (TPs) were identified by screening suspect compounds and non-target compounds, and one product (M-381) was synthesized for confirmation and quantification. A probable transformation mechanism was suggested based on the identified TPs and DFT calculations. The main transformation reactions included hydration, hydrolysis, oxidation, reduction and decarboxylation. Finally, the toxicities of the identified TPs and parent compound to aquatic organisms were predicted using ECOSAR software, and the toxicities of enestroburin and M-381 to daphnia magna were tested in the laboratory. The toxicity classification proposed by ECOSAR is reliable to a certain extent. Enestroburin and 2 TPs (M-313 and M-327) were classified as "very toxic", which may pose a potential threat to aquatic ecosystems.

Towards circular economy: Sustainable soil additives from natural waste fibres to improve water retention and soil fertility

Human activity is accompanied by the introduction of excessive amounts of artificial materials, including geosynthetics, into the environment, causing global environmental pollution. Moreover, climate change continues to negatively affect global water resources. With the intensification of environmental problems, material reusability and water consumption limitations have been proposed. This study replaced synthetic soil additives with biodegradable materials and analysed the potential and sustainable processing of natural fibrous materials, which form problematic waste. Waste fibres are the basis of innovative soil water storage technologies in the form of biodegradable and water-absorbing geocomposites (BioWAG). We analysed the influence of BioWAGs on plant vegetation and the environment through a three-year field experiment. Furthermore, biomass increases, drought effect reductions, and biodegradation mechanisms were analysed. Natural waste fibres had a positive influence, as they released easily accessible nutrients into the soil during biodegradation. BioWAGs had a positive influence on the biometric parameters of grass, increasing biomass growth by 430 %. Our results indicated that this is an effective method of waste fibre management that offers the possibility to manufacture innovative, environmentally friendly materials in compliance with the objectives of circular economy and the expectations of users.

Current Role of Mass Spectrometry in the Determination of Pesticide Residues in Food

The extensive use of pesticides represents a risk to human health. Consequently, legal frameworks have been established to ensure food safety, including control programs for pesticide residues. In this context, the performance of analytical methods acquires special relevance. Such methods are expected to be able to determine the largest number of compounds at trace concentration levels in complex food matrices, which represents a great analytical challenge. Technical advances in mass spectrometry (MS) have led to the development of more efficient analytical methods for the determination of pesticides. This review provides an overview of current analytical strategies applied in pesticide analysis, with a special focus on MS methods. Current targeted MS methods allow the simultaneous determination of hundreds of pesticides, whereas non-targeted MS methods are now applicable to the identification of pesticide metabolites and transformation products. New trends in pesticide analysis are also presented, including approaches for the simultaneous determination of pesticide residues and other food contaminants (i.e., mega-methods), or the recent application of techniques such as ion mobility–mass spectrometry (IM–MS) for this purpose.

Facile pathway to construct mesoporous silica nanoparticles loaded with pyraclostrobin: Physicochemical properties, antifungal activity, and biosafety

BACKGROUND

A controlled-release formulation based on mesoporous silica nanoparticles (MSNs) provides an effective way for reducing pesticide use and protecting the ecological environment. In this study, MSNs loaded with pyraclostrobin (PYR@MSNs) were prepared using a one-pot method.

RESULTS

The characteristics of PYR@MSNs were systematically investigated, including morphology, loading content, ultraviolet (UV) resistance, release behavior, control effects against pathogens, and safety to nontarget organisms. The results show that the prepared PYR@MSNs presented characteristics of regular spherical shapes, uniform particle size (200 nm), high drug loading (38.9%), and enhanced UV resistance. Compared with traditional formulation, PYR@MSNs exhibited improved control effects against Fusarium graminearum, an extended control period, and lower toxicity to zebrafish, earthworms and BEAS-2B cells.

CONCLUSIONS

This research will facilitate the development of efficient and safe pesticide delivery systems. The PYR@MSNs has showed its potential as a new controlled-release formulation with increased efficacy and is expected to benefit the sustainable development of agriculture. © 2022 Society of Chemical Industry.

Occurrence of Phenylpyrazole and Diamide Insecticides in Lactating Women and Their Health Risks for Infants

To investigate the exposure of infants to phenylpyrazole and diamide insecticides during lactation, we collected 3467 breast milk samples of lactating women from 100 cities of 24 provinces in China and prepared 100 pooled samples together city-by-city. Among phenylpyrazole insecticides, fipronil and its metabolites (63-100%) were widely detected in breast milk, with total detection concentrations ranging from 178 to 2947 ng/L (median: 921 ng/L). Among diamide insecticides, chlorantraniliprole and flubendiamide were detected in breast milk, but their detection frequencies (20-85%) and concentration levels (nondetected to 89.9 ng/L) were far lower than those of total fipronils. The average estimated daily intake of infants exposed to total fipronils through breast milk is 209 ng/kg-bw/day by upper-bound scenario evaluation, which is higher than the acceptable daily intake (200 ng/kg-bw/day). This study indicates that infants have far higher exposure levels to fipronil than adults, while exposure levels to other types of phenylpyrazoles and diamide insecticides are low.