Pesticides In Aquatic Environment Research Articles

Bee bread collected by honey bees (Apis mellifera) as a terrestrial pesticide biomarker to complement water studies.

Pesticides in aquatic environments are frequently studied, yet those in terrestrial environments remain relatively unexplored. This study monitored bee bread collected from two apiaries located in a typical agricultural environment in Switzerland from March to August 2022 as a proxy for terrestrial pesticide inputs. The temporal appearance of the selected pesticides was compared to their profiles in the water of a small catchment within this area. Overall, 62% (31 of 50) of the targeted pesticides were detected in bee bread, with occurrences in both apiaries largely overlapping (23 pesticides), demonstrating a similar agricultural landscape across the region. Furthermore, nine pesticides were detected in bee bread and water, two pesticides were detected only in bee bread, and two additional pesticides were detected only in water. Comparative temporal analysis revealed that pesticides with moderate-to-high movement potential [Groundwater ubiquity score (GUS) ≥ 2.19] appeared simultaneously in bee bread and water (azoxystrobin, boscalid, flufenacet and terbuthylazine). However, pesticides with low movement potential (GUS ≤ 1.86) showed different profiles in both matrices (cyprodinil, prosulfocarb, tebuconazole and thiacloprid), indicating the difficulty of predicting their fate, given that they adhere to soil particles and cannot be covered by current water monitoring programmes. Our findings present bee bread as a viable biomarker for monitoring pesticides by complementing the conventional water monitoring, and permitting a more comprehensive assessment of the exposure of terrestrial organisms to pesticides. Bee bread allows immediate recording of the applied pesticides and promptly reflects the seasonal variation in pesticide use. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Neonicotinoids as emerging contaminants in China's environment: a review of current data.

Neonicotinoids (NEOs), the most widely used class of insecticides, are pervasive in the environment, eliciting concerns due to their hydrophilicity, persistence, and potential ecological risks. As the leading pesticide consumer, China shows significant regional disparities in NEO contamination. This review explores NEO distribution, sources, and toxic risks across China. The primary NEO pollutants identified in environmental samples include imidacloprid, thiamethoxam, and acetamiprid. In the north, corn cultivation represents the principal source of NEOs during wet seasons, while rice dominates in the south year-round. The high concentration levels of NEOs have been detected in the aquatic environment in the southern regions (130.25ng/L), the urban river Sects.(157.66ng/L), and the downstream sections of the Yangtze River (58.9ng/L), indicating that climate conditions and urban pollution emissions are important drivers of water pollution. Neonicotinoids were detected at higher levels in agricultural soils compared to other soil types, with southern agricultural areas showing higher concentrations (average 27.21ng/g) than northern regions (average 12.77ng/g). Atmospheric NEO levels were lower, with the highest concentration at 1560pg/m3. The levels of total neonicotinoid pesticides in aquatic environments across China predominantly exceed the chronic toxicity ecological threshold of 35ng/L, particularly in the regions of Beijing and the Qilu Lake Basin, where they likely exceed the acute toxicity ecological threshold of 200ng/L. In the future, efforts should focus on neonicotinoid distribution in agriculturally developed regions of Southwest China, while also emphasizing their usage in urban greening and household settings.

A review on the enantioselective distribution and toxicity of chiral pesticides in aquatic environment.

Chiral pesticides account for about 40% of the total pesticides. In the process of using pesticides, it will inevitably flow into the surface water and even penetrate into the groundwater through surface runoff and other means, as a consequence, it affects the water environment. Although the enantiomers of chiral pesticides have the same physical and chemical properties, their distribution, ratio, metabolism, toxicity, etc. in the organism are often different, and sometimes even show completely opposite biological activities. In this article, the selective fate of different types of chiral pesticides such as organochlorine, organophosphorus, triazole, pyrethroid and other chiral pesticides in natural water bodies and sediments, acute toxicity to aquatic organisms, chronic toxicity and other aspects are summarized to further reflect the risks between the enantiomers of chiral pesticides to non-target organisms in the water environment. In this review, we hope to further explore its harm to human society through the study of the toxicity of chiral pesticide enantiomers, so as to provide data support and theoretical basis for the development and production of biochemical pesticides.

Biosynthesized CS-MgO/zeolite hybrid material: An efficient adsorbent for chlorpyrifos removal - Kinetic studies and response surface methodology

The prevalence of organophosphate pesticides in aquatic environments raises severe concerns on a global scale. Chlorpyrifos, an insecticide, is included in a class of organophosphate pesticides. It is widely used on agricultural lands to control pests in cotton, fruit, and vegetables. The acute toxicity of chlorpyrifos is still dangerous to all aquatic living organisms. Then the treatment of water contaminated with chlorpyrifos is an important aspect. The recent decade has witnessed adsorption technology emerging as an advanced organophosphate pesticide wastewater treatment with great potential and a grand blueprint, in which the specific surface area and active sites of the adsorbent are considered to be the two most important characteristics largely impacting the adsorption performance. In this study, a CS-MgO/Zeolite composite was prepared by the microbial method as an effective adsorbent for the removal of chlorpyrifos from an aqueous solution. The adsorbent's properties were carefully characterized using X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy. The refinement of experimental conditions, encompassing variations in adsorbent dosage, contact time, and chlorpyrifos concentration at five discrete levels, was systematically undertaken through the utilization of a composite central design rooted in response surface methodology. The solution pH played a key role in chlorpyrifos removal, and a pH of 7.0 was selected according to its high adsorption ability. The highest removal (80.9%) of chlorpyrifos by CS-MgO/Zeolite was obtained at an optimum pH of 7, a contact time of 40 min, an adsorbent dosage of 0.4 g/L, and a chlorpyrifos concentration of 5 mg/L−1. The adsorption results were highly fitted with the Freundlich adsorption isotherm model, and the maximum adsorption was 83.3 mg/g. Kinetic studies indicate that the removal of chlorpyrifos followed the pseudo-second-order model of adsorption (0.994). The thermodynamic parameters indicate the spontaneous and endothermic nature of chlorpyrifos sorption on CS-MgO/Zeolite sorbent. The results revealed that introducing chitosan could improve the adsorption capacity and rate effectively even though it sacrificed part of the specific surface areas of the MgO/Zeolite, indicating that active sites might play a dominant role during chlorpyrifos adsorption. The fabricated CS-MgO/Zeolite adsorbent nanocomposite displayed high reusability based on the elution and simultaneous regeneration ability. Therefore, as a cheap green nanocomposite adsorbent with high adsorption performance for chlorpyrifos, the CS-MgO/Zeolite nanocomposite adsorbent is expected to become one of the best candidate materials for chlorpyrifos removal aqueous solutions.

New insights into pesticide occurrence and multicompartmental monitoring strategies in stream ecosystems using periphyton and suspended sediment

Streams are susceptible to pesticide pollutants which are transported outside of the intended area of application from surrounding agricultural fields. It is essential to monitor the occurrence and levels of pesticides in aquatic ecosystems to comprehend their effects on the aquatic environment. The common sampling strategy used for monitoring pesticides in stream ecosystems is through the collection and analysis of grab water samples. However, grab water sampling may not effectively monitor pesticides due to its limited ability to capture temporal and spatial variability, potentially missing fluctuations and uneven distribution of pesticides in aquatic environments. Monitoring using periphyton and sediment sampling may offer a more comprehensive approach by accounting for accumulative processes and temporal variations.Periphyton are a collective of microorganisms that grow on hard surfaces in aquatic ecosystems. They are responsive to chemical and biological changes in the environment, and therefore have the potential to act as a cost-effective, integrated sampling tool to monitor pesticide exposures in aquatic ecosystems. The objective of this study was to assess pesticides detected through periphyton, suspended sediment, and conventional grab water sampling methods and identify the matrix that offers a more comprehensive characterization of a stream's pesticide exposure profile. Ten streams across Southern Ontario were sampled in 2021 and 2022. At each stream site, water, sediment and periphyton, colonizing both artificial and natural substrates, were collected and analyzed for the presence of ~500 pesticides. Each of the three matrices detected distinctive pesticide exposure profiles. The frequency of detection in periphyton, sediment and water matrices were related to pesticides' log Kow and log Koc (P < 0.05). In addition, periphyton bioconcentrated 22 pesticides above levels observed in the ambient water. The bioconcentration factors of pesticides in periphyton can be predicted from their log Kow (simple linear regressions, P < 0.05). The results demonstrate that sediment and periphyton accumulate pesticides in stream environments. This highlights the importance of monitoring pesticide exposure using these matrices to ensure a complete and comprehensive characterization of exposure in stream ecosystems.

Large monitoring datasets reveal high probabilities for intermittent occurrences of pesticides in European running waters

Many studies have investigated short-term peak concentrations of pesticides in surface waters resulting from agricultural uses. However, we lack information to what extent pesticides reoccur over medium (> 4 days) and longer time periods (> 10 days). We use here large-scale pesticide monitoring data from across Europe (~ 15 mil. measurements, i.e., quantified concentrations in water at > 17,000 sites for 474 pesticide compounds) to evaluate the degree to which pesticides were not only detected once, but in sequences of a compound repeatedly quantified in the same area (0.015 km2) within 4–30 days. Reoccurrence was observed at ~ 18% of sites for > 76% of compounds, ~ 40% of which not a priori considered to chronically expose aquatic ecosystems. We calculated a probability of reoccurrence (POR) over medium-term (4–7 days) and long-term (8–30 days) time periods for ~ 360 pesticides. Relative PORs (ratio between long-term and medium-term POR) revealed three occurrence patterns: ephemeral, intermittent and permanent. While fungicides dominated intermittently occurring substances, aligning with application strategies and physico-chemical properties, neonicotinoids and legacy pesticides were among substances permanently occurring. The results of this study shed new light on previously underestimated longer-term occurrence of many pesticides in aquatic environments (35% of investigated substances occurring intermittently or permanently were previously not considered to pollute the aquatic environment chronically), entailing new challenges for chronic risk assessments and the evaluation of pesticide effects on aquatic biodiversity.

Efficient degradation of thiamethoxam pesticide in water by iron and manganese oxide composite biochar activated persulfate

Neonicotinoid pesticides in aquatic environments pose a risk to the sustainability of ecosystems and human health. However, there is limited research on the removal of these pesticides from aquatic systems. In this study, biochar doped with different Fe/Mn ratios (FeMn­BC) were prepared at various pyrolysis temperatures and used for the degradation of a typical neonicotinoid pesticide, thiamethoxam (TMX), by activated persulfate (PS). From the experimental results, it is known that the biochar with a Fe/Mn ratio of 3/1 prepared at 600 °C has the most excellent removal efficiency. Optimal degradation conditions were investigated, and under these conditions, TMX removal rates of up to 99.0 % in 90 min were achieved. The applicability of this system in natural surroundings were tested by investigating the effects of inorganic anions and humic acid and in real water samples on TMX removal. In addition, the TMX removal remainly reach to 90.0 % by FeMn-BC activated PS and basically no change after five reuse cycles. Free radical quenching experiments and electron paramagnetic resonance analysis revealed that SO4− and OH radicals on the catalyst surface were the main radicals promoting TMX degradation. Combining the catalyst characterization and experimental results, the possible mechanisms were proposed: the interaction of iron and manganese ions and the oxygen-containing functional groups on the catalyst surface together promote the generation of reactive radicals. This study provides a novel approach for removing neonicotinoid pesticides using modified biochar.

Effect of Pesticides in Aquatic Environment

Effect of Pesticides in Aquatic Environment

Fe3O4@ZIF-8@SiO2 Core–Shell Nanoparticles for the Removal of Pyrethroid Insecticides from Water

Residues of pyrethroid pesticides in aquatic environments seriously threaten aquatic organisms and the human health. Herein, a novel highly dispersed and recyclable composite ZIF-8 and SiO2 double-layer-modified Fe3O4 nanoparticle, named Fe3O4@ZIF-8@SiO2 nanoparticle, was synthesized via a layer-by-layer assembly method to remove pyrethroid insecticides (namely, fenvalerate, β-cyfluthrin, and tetramethrin) from water. The physical properties of the Fe3O4@ZIF-8@SiO2 nanoparticles were characterized via scanning electron microscopy, elemental mapping, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma spectroscopy, thermogravimetric analysis, Brunauer–Emmett–Teller surface area analysis, dispersion analysis, and vibrating sample magnetometry. The prepared Fe3O4@ZIF-8@SiO2 nanoparticles exhibited excellent adsorption performance and high dispersibility and could be rapidly separated from water using an external magnetic field. The Fe3O4@ZIF-8@SiO2 nanoparticles exhibited the strongest adsorption effect at an adsorbent dosage of 10 mg, an adsorption time of 40 min, and a pH of 7. The fitted model for the adsorption process was consistent with the proposed secondary kinetic model and Sips isotherm model. The Fe3O4@ZIF-8@SiO2 nanoparticles exhibited maximum adsorption capacities of 316.23, 364.43, and 258.69 mg g–1 for fenvalerate, β-cyfluthrin, and tetramethrin, respectively. The Fe3O4@ZIF-8@SiO2 nanoparticles retained most of their adsorption capacity after five reuse cycles when acetone was used as an eluent for desorption. The mechanisms involved in the adsorption process included π–π stacking interactions, hydrogen bonds, hydrophobic interactions, and pore filling effects. This study provides a potential design for rapidly recoverable and reusable nanoparticles that can be used to effectively adsorb pyrethroid insecticides in wastewater.

Chiral pesticides levels in peri-urban area near Yangtze River and their correlations with water quality and microbial communities.

Pesticides are considered to be the second-largest non-point source pollution in water. Our research assayed the river network of typical agricultural areas in the middle and lower Yangtze River as the study area. Pesticides residues in aquatic environment were determined by QuEChERS, combined with high-performance liquid chromatography tandem mass spectrometry, or gas chromatograph-mass spectrometer. At chiral pesticides' levels, we detected pesticides contents in water, classified and counted the types of pesticides, and analyzed their environmental risk assessment. Furthermore, potential correlations between chiral pesticides concentrations and water quality indicators were assayed. Additionally, we explored their relations with microbial communities at species levels. Enantiomers of Diclofop-methyl, Ethiprole, Difenoconazole and Epoxiconazole were enantioselectively distributed. More interestingly, due to various chiral environment of the sampling site, the enantiomers of Tebuconazole Acetochlor, Glufosinate ammonium and Bifenthrin had completely different distributions at different sites. Based on that, the chiral pesticides Diclofop-methyl, Bifenthrin, Ethiprole, Tebuconazole and Difenoconazole are enantioselective to the risk of aquatic environment. Generally, enantiomeric selectivity had high positive correlations with total nitrogen and phosphorus. Then we found that chiral fate behavior of Tebuconazole and Paichongding in water might be affected by prokaryotes. In addition, the chiral behavior of Diclofop-methyl, Propiconazole, Difenoconazole, and Tebuconazole isomers in water might be negatively affected by eukaryotes. That research helped us to comprehensively understand the impact of non-point source pollution of chiral pesticides in aquatic environment and provided basic data support for developing biological and water quality indicators for monitoring pollution in aquatic environment.

Multi-walled carbon nanotubes impact on the enantioselective bioaccumulation and toxicity of the chiral insecticide bifenthrin to zebrafish (Danio rerio)

The effects of different multi-walled carbon nanotubes on the enantioselective bioaccumulation and toxicity of the chiral pesticide bifenthrin to zebrafish were investigated in this work. The results showed that MWCNTs and MWCNTs-COOH did not affect the preferential bioaccumulation of 1R-cis-BF in zebrafish following exposure to cis-BF enantiomers for 28 days, but which increased cis-BF accumulation amount by 1.03–1.48 times. Further research demonstrated that the genes related to immunity, endocrine activity and neurotoxicity showed enantioselective expression in different zebrafish tissues, and sex-specific differences were observed. The levels of c-fos, th, syn2a, 17β-hsd and cc-chem were expressed as 1.09–2.84 times higher in females and males treated with 1R-cis-BF than in the 1S-cis-BF-treated groups. However, in the presence of MWCNTs or MWCNTs-COOH, c-fos, th, syn2a, 17β-hsd and cc-chem levels were expressed as 1.53–14.92 times higher in females and males treated with 1S-cis-BF than in 1R-cis-BF-treated groups, which indicated that enantioselective expression was altered. The effects of different types of MWCNTs on the enantioselective bioaccumulation and toxicity of BF in zebrafish have little difference. In summary, the presence of MWCNTs or MWCNTs-COOH increased the impact of BF on zebrafish. Therefore, the risks posed by coexisting nanomaterials and chiral pesticides in aquatic environments should be considered.

The Fate of Atrazine in Tropical Environments: Photolysis, Acute Toxicity and Endocrine Disruptor Potential

Triazine herbicides are widely used both in Brazil and internationally and are frequently detected in natural environments and drinking water. This study assesses atrazine degradation through solar radiation under tropical conditions and determines the toxicity of the intermediates. Atrazine degradation is tested through ultrapure water, humic acid solution and natural water experiments, with exposure to sunlight to simulate a natural environment. A yeast estrogen screen (YES) assay and Artemia salina test are carried out during the abiotic degradation. The atrazine degradation depends on the radiation intensity, since the experiments conducted in the summer reached 50% after ca. 17 days. No significant variations in this herbicide concentration are observed after 90 days of exposure in the fall. Atrazine degradation is observed only in humic acid and is responsible for indirect photolysis. Intermediates, namely, desethylatrazine (DEA) and deisopropylatrazine (DIA), are identified and quantified at the μg L–1 level. Thus, with the degradation of atrazine in water, the medium toxicity may decrease, since DEA and DIA have mean effective concentrations that kill 50% of Artemia salina (EC50) similars to atrazine (13 mg L–1). No estrogenic activity in the YES is detected for atrazine and its metabolites. These findings evidence that radiation intensity and organic substances in tropical countries influence the half-life of pesticides in aquatic environments.

Biochar enhanced the performance of microalgae/bacteria consortium for insecticides removal from synthetic wastewater

The presence of pesticides in aquatic environments has threatened marine food resources, aquaculture, fisheries and human health; therefore, two most used insecticides were removed during this study. Two photobioreactors, including biochar and Chlorella vulgaris/activated sludge (reactor 1), and Chlorella vulgaris/activated sludge (reactor 2) were run to remove chlorpyrifos (CPF) and cypermethrin (CYP). Proteobacteria, Bacteroidetes and Chloroflexi were the dominant phyla of activated sludge. The optimization performance of both reactors was conducted by response surface methods. The performance of first photobioreactor was better than that in the second reactor, achieving abatement of 88.80% CPF and 93.12% CYP, at 69.7 h contact time and 0.32 mg/L initial concentration. The toxicity of CPF and CYP to Chlorella vulgaris was monitored under 0–4 mg/L of insecticide concentrations and 0–72 h contact time. The minimum chlorophyll content (2 mg/L) and protein (16.7%), and maximum growth inhibition (89.7%) were recorded at 4 mg/L insecticides concentration and 72 h contact time. Moreover, molecular docking simulation for catalytic enzyme degradation of Proteobacteria, Bacteroidetes and microalgae was carried out using individual hydrolase enzymes: carboxypeptidase in microalgae, isochorismatase hydrolase in Proteobacteria and alpha-L-arabinofuranosidase in Bacteroidetes. Ligand-binding energy, affinity and dimensions of ligands-binding sites in the enzyme cavity were calculated in each case. Hydrolase is an enzyme group that offers a promising practical application for the degradation of CYP and CPF due to its cavity features. This analysis demonstrated the mode of interaction of ligands with hydrolase enzymes in different species.

Electrosynthesis of metal-organic frameworks (MOFs) using 4,4′methylene dianiline polymer and metals (Al, Cu, and Fe) for imidacloprid pesticide adsorption in the aquatic environment

ABSTRACT Extensive use of imidacloprid in pest control and its unfavourable removal efficiency has resulted contamination of aquatic environments. Herein, 4,4ʹ-methylenedianiline nano-polymer (MDANP) as organic linkers and Cu, Fe, and Al as metal sources were used to synthesise several metal-organic frameworks (MOFs) nanomaterials. Three MOFs (MDANP/Cu, MDANP/Fe, and MDANP/Al) were synthesised by the electrochemical polymerisation method and used as a nano-adsorbent to remove imidacloprid from the aqueous environment. Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), transient electron microscopy (TEM), and Field-scattering scanning electron microscopy (FE-SEM) techniques were used to analyse physicochemical characteristics of produced MDANP and MOFs. Kinetic data have been fitted with pseudo-second-order models; according to the obtained correlation coefficients (R2 = 0.9993). Adsorption isotherm models suggested that except imidacloprid adsorption on MDANP, which was best explained by the Freundlich model (R2 = 0.9018), pesticide adsorption from MOFs was well explained by the Langmuir model (R2 = 0.9473). The removal efficiency of imidacloprid onto MDANP and MOFs decreased from 65.28% to 40.25% and from 61.56% to 36.89%, respectively, as the initial concentration of imidacloprid increased from 25 to 400 mg/L. The results showed that the highest adsorption of imidacloprid happens within 120 min for 150 mg of adsorbent. Under optimum conditions, a maximum adsorption capacity of 97.4 mg/g occurred. Thus, MDANP and MOFs have medium potential for environmental implications and can be exploited as nano-adsorbents of imidacloprid pesticides in aquatic environments.

Co-exposure of carbon nanotubes with carbofuran pesticide affects metabolic rate in Palaemon pandaliformis (shrimp)

Palaemon pandalirformis (shrimp) is a species widely distributed in the Brazilian coastal region and with an important economic role. In addition, this organism is considered an indicator of environmental pollution in estuaries; however, its physiological responses to toxic environmental pollutants, including pesticides and nanomaterials, are not well known, mainly, the effects of co-exposure. Thus, the purpose of this study was to evaluate the ecotoxicological effects of co-exposure between oxidized multiwalled carbon nanotubes (HNO3-MWCNT) and carbofuran pesticide on the routine metabolism of P. pandalirformis. The shrimps were exposed to different concentrations of HNO3-MWCNT (0; 10; 100; 500; 1000 μg L−1), carbofuran (0; 0.1; 1.0; 5.0; 10 μg L−1) and to co-exposure with 100 μg L−1 of HNO3-MWCNT + carbofuran (0; 0.1; 1.0; 5.0; 10 μg L−1), to evaluate the effects on metabolic rate (O2 consumption) and excretion of ammonia (NH4+NH3). Our results showed that the shrimps exposed to HNO3-MWCNT (10 μg L−1) increased the metabolic rate by 292% and the excretion of ammonia by 275%; those exposed to carbofuran (10 μg L−1) increased their metabolic rate by 162% and the excretion of ammonia by 425%; and with the co-exposure of HNO3-MWCNT + carbofuran there was also an increase in the metabolic rate by 317% and an excretion of ammonia by 433% when compared to control. These findings provides useful information toward better understanding the physiological responses of shrimps after combined exposure to nanomaterials and pesticides in aquatic environments.

Trends in metaldehyde concentrations and fluxes in a lowland, semi-agricultural catchment in the UK (2008–2018)

Metaldehyde, a widely used molluscicide, is one of the most commonly detected pesticides in aquatic environments in the UK. In this study, metaldehyde concentrations and fluxes in stream water over a ten-year period (2008–2018) are reported for the River Colne catchment (Essex, southeast England), and the influence of hydrological conditions and application regimes are assessed.In general, peaks in metaldehyde concentration in river water occasionally exceeded 0.25 μg L−1, and concentrations did not typically exceed the European Union Drinking Water Directive (EU DWD) regulatory limit of 0.1 μg L−1. Metaldehyde concentration peaks displayed a seasonal pattern. Metaldehyde concentrations during periods when the molluscicide was not applied to agricultural land (January, July) and during the spring-summer application period (February to June) were generally low (0.01–0.03 μg L−1). Peaks in metaldehyde concentration mainly occurred during the autumn-winter application season (August to December), and were typically associated with high intensity hydrological regimes (daily rainfall ≥10 mm; stream flow up to 18 m3 s−1). Where metaldehyde concentrations exceeded the EU DWD regulatory limit, this was short-lived.The annual flux at the top of the Colne catchment (0.2–0.6 kg a−1) tended to be lower than in the middle of the catchment (0.3–1.4 kg a−1), with maximum flux values observed at the bottom of the catchment (0.5–25.8 kg a−1). Metaldehyde losses from point of application to surface water varied between 0.01 and 0.25%, with a maximum of 1.18% (2012). Annual flux was primarily controlled by the annual precipitation and stream flow (R2 = 0.9) rather than annual metaldehyde use (kg active applied). Precipitation explained 37% and 81% of variability in metaldehyde concentration and flux, respectively.Annual ranges in metaldehyde concentration were greater in the years 2012 and 2014 with an overall reduction in the range of metaldehyde concentrations evident over the period 2015–2018. It is the expectation that metaldehyde concentrations in stream water will continue to decrease following the withdrawal of metaldehyde for outdoor use in the UK from March 2022.

Role of Pond Sediments for Trapping Pesticides in an Agricultural Catchment (Auradé, SW France): Distribution and Controlling Factors

In agricultural areas, ponds are suitable wetland environments to dissipate and reduce the occurrence of pesticides in aquatic environments. However, their impact at a catchment scale is still poorly understood. This study aims to determine how these organic contaminants were trapped in a pond located in an agricultural critical zone from SW France (Auradé catchment). The spatial distribution of pesticide concentrations and their different controlling factors were investigated in waters and sediments collected during two distinct seasons. The results highlighted (i) the link between the presence of the molecules and the agricultural practices upstream, (ii) the influence of hydrological/seasonal conditions, especially on hydrophobic molecule accumulation such as tebuconazole, (iii) the key role of clay content in sediments on the control of moderately hydrophilic pesticides (metolachlor and boscalid), but also the unexpected role of coarse particles for boscalid; and (iv) the influence of sediment depth on pesticide storage. Nevertheless, other physico-chemical parameters, such as mineralogical composition of sediment, needed to be considered to explain the pesticide patterns. This study brings a new hypothesis to be investigated in the future about pesticide behaviour in such pond environments.

Development of a high-throughput multi-residue method for analysis of common pesticides in aquatic environments by automated online solid phase extraction coupled with LC-MS/MS

A reliable method based on fully automated online solid phase extraction coupled with LC-MS/MS was developed for the high throughput analysis of 111 common pesticides or metabolites in three aquatic matrices.

Influence of multi-walled carbon nanotubes on enantioselective bioaccumulation and oxidative stress toxicity of indoxacarb in zebrafish(Danio rerio)

Carbon nanotubes (CNTs) have been widely used in various fields with the rapid development of nanotechnology. Pesticides have an irreplaceable role in agricultural production, which leads to their massive utilization and their inevitably penetrate into the aquatic environment. However, limited information is available regarding the impact of CNTs on the toxicity and enrichment of chiral compounds to organisms. Using zebrafish as a model to study whether the enantioselective bioaccumulation and oxidative stress of chiral pollutants may be altered in the presence of MWCNTs. Significant enantioselective bioaccumulation was observed in zebrafish with the preferential accumulation of R-(−)-indoxacarb during the 28-day bioaccumulation. The combined exposure of MWCNTs does not affect the enantioselectivity of zebrafish bioaccumulation, but increase the bioaccumulation amount of R-(−)-indoxacarb by 65%. Moreover, the average degradation half-life of indoxacarb enantiomers was 1.30 days. The indoxacarb causes oxidative stress toxicity in zebrafish liver and exhibited enantioselectivity, while the addition of MWCNTs did not significantly change the enantioselectivity of oxidative stress toxicity of indoxacarb, but enhanced the toxicity 20% with increased MWCNTs concentrations. This study suggests that the risk of the co-presence of nanomaterials and chiral pesticides in aquatic environments should be taken into consideration.

PHOTOCATALYTIC DEGRADATION OF CHLORPYRIFOS BY USING SYNTHESIZED NANO TITANIUM

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