Typical Pesticides Research Articles

Comparison of Combined Dissipation Behaviors and Dietary Risk Assessments of Thiamethoxam, Bifenthrin, Dinotefuran, and Their Mixtures in Tea.

In the tea-planting process, insecticides are commonly combined, potentially prolonging the pre-harvest interval and heightening the risk of dietary exposure. This study focused on three frequently used insecticides in tea cultivation: thiamethoxam, bifenthrin, and dinotefuran, aiming to investigate their dissipation behaviors and associated dietary risks upon individual and simultaneous application. The dissipation kinetics of thiamethoxam, bifenthrin, and dinotefuran were successfully characterized by first-order kinetics, yielding respective half-lives of 5.44, 9.81, and 10.16 days. Upon joint application, the dissipation half-lives of thiamethoxam and bifenthrin were notably prolonged compared with their individual applications, resulting in final concentrations after 28 days that were correspondingly elevated by 1.41 and 1.29 times. Assessment of the dietary intake risk revealed that the chronic and acute risk quotients associated with thiamethoxam and bifenthrin escalated by 1.44-1.59 times following their combined application. Although dietary risks associated with Tianmuhu white tea, as determined by the exposure assessment model, were deemed acceptable, the cumulative risks stemming from pesticide mixtures across various dietary sources warrant attention. Molecular docking analyses further unveiled that thiamethoxam and bifenthrin competitively bound to glutathione S-transferase (GST) at amino acid residues, notably at the 76th GLU and the 25th PHE, pivotal in the metabolism and absorption of exogenous substances. Moreover, the interactions between P-glycoprotein and pesticides during transport and absorption were likely to influence dissipation behaviors post-joint application. This research offers valuable insights and data support for optimizing joint pesticide application strategies and assessing risks associated with typical pesticides used in tea cultivation.

Unveiling responses and mechanisms of spice crop chive exposure to three typical pesticides using metabolomics combined with transcriptomics, physiology and biochemistry

Pesticides are frequently used to control target pests in the production of spice crops such as chives (Allium ascalonicum). However, little information is available on the responses and underlying mechanisms of pesticide exposure in this crop. Our findings revealed that the uptake, transportation, and subcellular distribution of three typical pesticides—the fungicide pyraclostrobin (PAL), insecticide acetamiprid (ATP), and herbicide pendimethalin (PND) in chives, as well as their physiological, biochemical, metabolic, and transcriptomic responses—were dependent on pesticide properties, especially hydrophobicity. The distribution of PAL and PND in chives decreased in the order root > stem > leaf, but the distribution order of ATP was the opposite. The proportion of PAL and PND in the solid phase of the root cells gradually increased, but ATP mainly existed in the cell-soluble component, indicating that the latter had an upward translocation ability and thus mainly accumulated in the leaves. Malondialdehyde levels in chive leaves were not significantly affected by exposure to these pesticides; however, the activities of superoxide dismutase (SOD) and catalase (CAT) in chive leaves increased significantly. Moreover, these pesticides exhibited critical differences in chive responses through the interaction of metabolites and regulation of differentially expressed genes. PAL dramatically influenced five carbohydrate metabolic pathways (34.35 %), disturbing the starch-to-sucrose balance. ATP strongly affected five amino acid (AC) metabolic pathways (33.38 %), enhancing four free amino acid levels. PND notably affected eight fatty acid (FA) metabolic pathways (25.38 %), increasing two unsaturated and decreasing one saturated FA. Simultaneously, PND, ATP, and PND accumulated in the chives could be detoxified through metabolic pathways mediated by cytochrome P450 (P450) and glycosyltransferase (GT)/glutathione S-transferase (GST), producing phase I (7, 4, and 5) and II (11, 13, and 10) metabolites, respectively. This study provides important molecular insights into the responses and underlying mechanisms of spice crop exposure to pesticides.

Pollution characteristics, sources and ecological risks of typical pesticides in Dongting Lake Basin

Pollution characteristics, sources and ecological risks of typical pesticides in Dongting Lake Basin

Molluscicide screening and identification of novel targets against Pomacea canaliculata.

Owing to the nonavailability of any clear targets for molluscicides against Pomacea canaliculata, target-based screening strategy cannot be employed. In this study, the molluscicidal effects of typical pesticides on P. canaliculata were evaluated to obtain the molluscicide target. A series of arylpyrrole compounds were synthesized based on the discovered target, and their structure-activity relationships explored. A preliminary strategy for screening molluscicides based on specific targets was also developed. A laboratory colony of P. canaliculata was developed, which showed no difference in sensitivity to niclosamide compared with the wild group, while exhibiting a higher stability against pesticide response. Mitochondrial adenosine triphosphate (ATP) synthase inhibitors and mitochondrial membrane potential uncouplers were identified and validated as potential targets for molluscicide screening against P. canaliculata. A series of arylpyrrole compounds were designed and synthesized. The median lethal concentration of 4-bromo-2-(4-chlorophenyl)-5-(trifluoromethyl)-1H-pyrrole-3-carbonitrile (Compound 102) was 10-fold lower than that of niclosamide. New molluscicide targets were discovered and validated, and preliminary strategies were explored for pesticide screening based on these targets. Compound 102 exhibited a high molluscicidal activity and had a great potential value for exploring a molluscicide to control P. canaliculata. © 2024 Society of Chemical Industry.

Experimental study on photodegradation and leaching of typical pesticides in greenhouse soil from Shouguang, Shandong Province, East China

BackgroundPesticide use contributes to national food security. The dissipation pathways and degradation mechanisms of pesticides have been widely studied and pesticide residues have remained a focus of public concern. However, studies on the migration and transformation behaviors of pesticide residues in real-world greenhouse soils are insufficient. Therefore, in this study, we collected greenhouse soil from Shouguang, Shandong Province, and investigated the photodegradation and leaching of 17 common pesticides, which leave residues in the soil and are the most frequently used pesticides in Shouguang. The environmental behavior of pesticides in greenhouse soils will provide new information on pesticide residues in the real environment and provide a scientific basis for the prevention and control of pesticide pollution in greenhouse soils.ResultsThe photodegradation of trifloxystrobin followed a first-order kinetic equation, whereas those of emamectin benzoate, chlorantraniliprole, buprofezin, difenoconazole, pyraclostrobin, boscalid, tebuconazole, isoprothiolane, metalaxyl, and oxadixyl followed second-order kinetics. The half-lives of 17 pesticides under light and dark conditions ranged from 2.5–104 (mean: 36.2) and 2.6–110 (mean: 31.4) days, respectively. The half-lives of emamectin benzoate, pyraclostrobin, and metalaxyl in the light were 86.6%, 68.5%, and 94.5% of their half-lives in the dark, respectively. Chlorantraniliprole, metalaxyl, nitenpyram, diethofencarb, acetamiprid, carbendazim, and oxadixyl were leached to ≥ 90% in aqueous solution. Six pesticides, avermectin B1A, emamectin benzoate, trifloxystrobin, difenoconazole, pyraclostrobin, and buprofezin, were difficult to leach from aqueous solutions.ConclusionsThe degradation rate of some pesticides was higher in the light environment than in the dark. The leaching potential of the leachable pesticides was nitenpyram ≫ metalaxyl > acetamiprid > carbendazim > diethofencarb ≈ chlorantraniliprole > isoprothiolane > oxadixyl > boscalid ≈ tebuconazole > hexaconazole. Pesticides that are easy to leach but not easily degraded, such as chlorantraniliprole and metalaxyl, have a high potential risk of groundwater pollution, and additional degradation technologies should be used to reduce their pollution risk. The study of the photodegradation and vertical migration behavior of various pesticides is conducive to providing references for the agricultural use and pollution control of pesticides.

Combined toxicity and adverse outcome pathways of common pesticides on Chlorella pyrenoidosa.

Pesticides due to their extensive use have entered the soil and water environment through various pathways, causing great harm to the environment. Herbicides and insecticides are common pesticides with long-term biological toxicity and bioaccumulation, which can harm the human body. The concept of the adverse outcome pathway (AOP) involves systematically analyzing the response levels of chemical mixtures to health-related indicators at the molecular and cellular levels. The AOP correlates the structures of chemical pollutants, toxic molecular initiation events and adverse outcomes of biological toxicity, providing a new model for toxicity testing, prediction, and evaluation of pollutants. Therefore, typical pesticides including diquat (DIQ), cyanazine (CYA), dipterex (DIP), propoxur (PRO), and oxamyl (OXA) were selected as research objects to explore the combined toxicity of typical pesticides on Chlorella pyrenoidosa (C. pyrenoidosa) and their adverse outcome pathways (AOPs). The mixture systems of pesticides were designed by the direct equipartition ray (EquRay) method and uniform design ray (UD-Ray) method. The toxic effects of single pesticides and their mixtures were systematically investigated by the time-dependent microplate toxicity analysis (t-MTA) method. The interactions of their mixtures were analyzed by the concentration addition model (CA) and the deviation from the CA model (dCA). The toxicity data showed a good concentration-effect relationship; the toxicities of five pesticides were different and the order was CYA > DIQ > OXA > PRO > DIP. Binary, ternary and quaternary mixture systems exhibited antagonism, while quinary mixture systems exhibited an additive effect. The AOP of pesticides showed that an excessive accumulation of peroxide in green algae cells led to a decline in stress resistance, inhibition of the synthesis of chlorophyll and protein in algal cells, destruction of the cellular structure, and eventually led to algal cell death.

Towards accuracy recognition and content estimation of typical pesticides in groundwater via electronic nose

Accurate and rapid prediction of pesticides in groundwater during groundwater remediation is important to optimize remediation processes and increase remediation efficiency. In this paper, an electronic nose was employed to recognize the pesticides in groundwater. Four typical pesticide-polluted and unpolluted groundwater samples were prepared and their odor information was collected by e-nose. The odor signals collected by the e-nose combined with machine learning algorithms were used to predict pesticides in groundwater. Firstly, based on different feature extraction methods, random forest was used to distinguish whether groundwater was polluted by pesticides. The recognition rate of both the training set and the test set were 100%. Secondly, the random forest was applied to determine the type of pesticides in the polluted samples, with recognition rates of 100% and 99.29% for the training and test sets, respectively. Finally, the concentrations of the four typical pesticides were predicted by the support vector regression models. The correlation coefficient R2 of the training set model was 0.99, and that of the test set ranged from 0.94 to 0.99. From the case studied, the e-nose technique can be applied in the recognition of pesticide in groundwater, which will contribute to the targeted remediation of groundwater.

Comprehensive insights into the occurrence, distribution, risk assessment of typical pesticides and their environmental driving effects in a large drinking water reservoir

The problem of pesticide pollution in large drinking water reservoirs is becoming increasingly prominent due to agricultural production. To systematically evaluate the distribution characteristics, seasonal fluctuations, environmental behaviors, and ecological risks of pesticides in the Fengshuba Reservoir (China), we conducted a comprehensive investigation of the seasonal changes in the concentrations of 31 pesticides, including 8 organochlorine pesticides (OCPs), 16 organophosphates pesticides (OPPs), and 7 synthetic pyrethroids (SPs). The results showed the concentrations of OCPs, OPPs, and SPs in the water phase were 121.98–321.64 ng/L, 279.28–371.75 ng/L, and 118.96–186.65 ng/L, respectively. The concentrations in the porewater phase were 3363.34–7105.00 ng/L, 8648.98–14,265.95 ng/L, and 2740.83–7738.28 ng/L, respectively. The concentrations in the sediment phase were 47.92–88.28 μg/kg, 159.87–446.64 μg/kg, and 29.43–99.62 μg/kg, respectively. The concentrations in the soil phase were 23.62–50.76 μg/kg, 96.85–184.19 μg/kg, and 21.02–37.02 μg/kg, respectively. Seasonal hydrology, hydraulic retention time, precipitation, temperature, and biological metabolism all impacted the concentration and composition of pesticides, but no apparent environmental gradient effect was found within the reservoir. Redundancy analysis indicated that NO3-, Dissolved oxygen (DO), Dissolved organic carbon (DOC), Organic nitrogen (ON), and Inorganic carbon (IC) were the main environmental parameters affecting pesticide concentrations. The pseudo-partitioning values in water and porewater ranged from 1.2 to 3.3 × 104 and 22.0–61.7 L/kg, respectively. The ecological risk was low for OCPs, moderate for OPPs, and high for SPs in the water phase. SPs should be considered a priority indicator for risk assessment. Future conservation efforts for reservoir system should focus on pollution prevention in the soil phase.

Pesticide residues in rice planted in South and Southwest China

ABSTRACT In 2019 and 2020, 70 paddy and 70 brown rice samples were collected from South China and Southwest China, wherein the residues of 15 target pesticides were investigated. A gas chromatography-mass spectrometry (GC-MS) method was established for the simultaneous detection of 15 pesticides, which achieved good linear relationship with limits of detection (LODs) of 0.10–4.00 μg kg−1. The average recoveries and relative standard deviations (RSD) were satisfied for the pesticide residues detection. Analysis results showed that the detection rates of 15 typical pesticides in paddy and brown rice were 0%-12.9% and 0%-1.4%, respectively. None of the 15 pesticides exceed their maximum residue limit (MRL) stipulated by China. The pesticide with the highest detection rate and concentration was chlorpyrifos. This study can provide data support for the control of pesticide residues in rice and the realisation of the improving the efficiency of pesticide and fertiliser while reducing their application.

CuFe2O4/diatomite actuates peroxymonosulfate activation process: Mechanism for active species transformation and pesticide degradation

Peroxymonosulfate (PMS) activation is a promising technology for water purification, but the removal performance of multiple pollutant matrices and the mechanism for reactive species transformation in the heterogeneous catalytic system remain ambiguous. Herein, a novel CuFe2O4/diatomite was fabricated for PMS activation to achieve efficient removal of typical pesticides. Uniform distribution of CuFe2O4 on diatomite efficiently alleviated the agglomeration of CuFe2O4 and increased specific surface area (57.20 m2 g−1, 3.8-fold larger than CuFe2O4). CuFe2O4/5% diatomite (5-CFD)/PMS system showed nearly 100% removal efficiency for mixed pesticide solution within 10 min (0.10 g L−1 5-CFD and 0.40 g L−1 PMS) and excellent anti-interference performance towards various coexisting substances (≥90% removal efficiency). The electrochemical measurements confirmed that the lower charge transfer resistance of 5-CFD significantly enhanced the electron-transfer capacity between 5-CFD and PMS, accelerating the reactions among Fe(III)/Fe(II), Cu(II)/Cu(I), and PMS, further generating •OH (261.3 μM), 1O2 (138.8 μM), SO4•– (11.8 μM), and O2•–. The O in reactive oxygen species didn't originate from dissolved oxygen (DO) but PMS, independent of the low solubility of DO and slow diffusion rate of O2 in water. Furthermore, the production of 1O2 went through the process: PMS → O2•– → 1O2, and SO4•– could rapidly convert into •OH. The degradation pathways and the evolution of intermediates were proposed by HPLC-QTOF-MS/MS and DFT calculations. QSAR analysis illustrated that the toxicity became lower with the reaction process. This study provides novel insights into the mechanism for pesticide degradation and active species transformation and the anti-interference capability of systems.

Determination of 107 typical pesticides and metabolites in raw water and drinking water by online-solid phase extraction coupled with ultra performance liquid chromatography-triple quadrupole mass spectrometry

In order to monitor the risk of pesticide pollutants in drinking water, an analytical method based on online-solid phase extraction coupled with ultra performance liquid chromatography-triple quadrupole mass spectrometry (online-SPE-UPLC-MS/MS) was established for the simultaneous rapid screening and determination of 107 pesticides and metabolites (organophosphorus, organic nitrogen, organic heterocycle, carbamate, amide, benzoyl urea, neonicotinoid, etc.) in raw water and drinking water. Different injection volumes (5, 10, and 15 mL) were compared. The detection response increased with an increase in the injection volume, but the matrix effect also became more pronounced. Under the premise of ensuring the sensitivity of the method and meeting the detection requirements, the injection volume was selected as 5 mL. Accordingly, the samples were filtered through a 0.22-μm hydrophilic polytetrafluoroethylene filter, and then, 5 mL samples were injected into the online-SPE system by the automatic sampler. After adsorption on an X Bridge C18 online-SPE column, the samples were washed with pure water and eluted by gradient elution using acetonitrile and 0.1% formic acid aqueous solution as the mobile phases, with separation on an ACQUITY HSS T3 column. The samples were detected by multiple reaction monitoring with electrospray ionization in positive and negative ion modes, and quantified by an external standard method. Using raw water and drinking water as the sample matrices, the accuracy and precision of the method were verified. The 107 pesticides and metabolites showed good linear relationships in different ranges with correlation coefficients (r2)>0.995. The limits of detection (LODs, S/N=3) of the method were 0.03-1.5 ng/L, and the limits of quantification (LOQs, S/N=10) were 0.1-5.0 ng/L. The target pesticides were spiked at concentration levels of 1, 20, and 50 ng/L. The spiked recoveries of the 107 targets in raw water and drinking water samples were 60.6%-119.8% and 61.2%-119.0%, respectively. The corresponding relative standard deviations (RSDs, n=6) were 0.3%-18.6% and 0.4%-17.1%. The pesticide residues in raw water and drinking water were determined by this method. Amide herbicides, triazine herbicides, triazole insecticides, carbamate insecticides, and neonicotinoid insecticides had high detection rates. The detected concentrations ranged from 0.1 to 97.1 ng/L in raw water and from 0.1 to 93.6 ng/L in drinking water. The sample consumption of online-SPE method was lower than that in the traditional off-line SPE methods, which greatly improved the convenience of sample collection, storage, and transportation. The samples only need to be filtered before injection and analysis. The method is simple to operate and shows good reproducibility. With this online-SPE method, only 23 min were required from online enrichment to detection completion. The developed method has the advantages of high analytical speed and high sensitivity. The method is suitable for the trace analysis and determination of 107 typical pesticides in raw water and drinking water, which effectively improves the detection efficiency of pesticides in water and has high potential for practical application. It can extend technical support for the pollution-level analysis of typical pesticides and metabolites in drinking water and provide an objective basis for human health risk assessment.

Pesticide risk constraints to achieving Sustainable Development Goals in China based on national modeling

Pesticides applied worldwide to meet food demand is recognized as a key threat to the Sustainable Development Goals (SDGs) set by the United Nations. Studies on pesticide risks employ different ingredients, methods or specific environments, which makes it difficult to quantify the scale of the problem. Furthermore, the complex influences and hotspots of long-term pesticide usage remain unclear. Herein, we present a national-scale study of four typical pesticides in China, the world’s largest pesticide user. The spatiotemporal changes in legacy and risk of pesticides over 30 years were analyzed using a modified fugacity model approach coupled with comprehensive ingredient database. Pesticide risk in mainland China might last until 2075 due to the previous legacy, although the usage has declined since 2014. The use of target pesticides was estimated as 2.38 × 105 tonnes in 2017, and about 6.59 × 103 tonnes discharged into the ocean from major basins. Risk areas expanded from 47% in 1991 to 79% in 2017, with 30% at high risk. Of the risk areas, 31% were highly populated while 3% had high biodiversity. 7% of mainland China suffered from both limited water resource and high pesticide risk. It is shown that the improper substitution with lower toxicity pesticides would make the proportion of high-risk regions unexpectedly increased from 18% to 44% due to the longer half-lives of the alternatives. Pesticides pose risks to environmental and human health, and the tailored assessment tool will be vital in contributing towards future pesticide management and meeting sustainability targets in China.

Uptake kinetics and subcellular distribution of three classes of typical pesticides in rice plants

Food safety problems caused by pesticide residues have always been a concern for many people. In this study, we investigated the uptake, translocation and subcellular distribution of neonicotinoid insecticides, triazole fungicides, and sulfonylurea herbicides in rice plants (Oryza sativa L.). The time-dependent uptake kinetics of the three categories of pesticides with different molecular structures fit a first-order one-compartment kinetic model. The neonicotinoids (log Kow −0.66–0.8) were mainly concentrated in the leaves, and the triazoles (log Kow 3.72–4.4) were mainly concentrated in the roots. Neonicotinoid pesticides in the roots were preferentially transported across the membrane through the symplastic pathway; triazole pesticides except for triadimefon and myclobutanil preferentially passed through the symplastic pathway; and sulfonylurea pesticides (log Kow 0.034–2.89) were first transported upward through the apoplastic pathway. In the roots, neonicotinoids, triazoles, and sulfonylurea herbicides were mainly concentrated in the soluble fractions, cell wall and apoplast fractions, respectively. In addition, there was a high positive correlation between the subcellular distribution of pesticides in the roots, stems and leaves. Molecular weight and log Kow jointly affected the enrichment of triazole pesticides in the roots, stems and leaves and the transfer from stems to leaves, while water solubility and log Kow commonly affected neonicotinoids. There was a correlation between pesticide absorption and the molecular structures of pesticides. To develop pesticides with strong uptake and transport capabilities, it is necessary to consider that the electronegativity of some atoms is stronger, the sum of the topological indices of heteroatoms can be large, and the van der Waals volume increases accordingly.

Typical Pesticide Residues and Their Risk Assessment in Farmland Environment of Different Plant Types in Shaya County, Xinjiang

In order to investigate the characteristics of typical pesticide residues in farmland soil of different plant types in Shaya County and to evaluate the level of human health risk and ecological risk caused by pesticide residues, a total of 55 samples of plants, soil, and water from nine areas of Shaya county were collected on September 29, 2020. The occurrence levels of 47 typical pesticides in the samples were analyzed using gas chromatography-mass spectrometry (GC-MS). The results showed that a total of 23 pesticides were detected in three environmental media, and the maximum concentrations of pesticides in soil, plants, and water were 70.58 μg·kg-1, 1832.18 μg·kg-1, and 188.53 μg·L-1, respectively. The levels of pesticide residues in the three environmental media in Shaya county were characterized as plants>water>soil. From the detection of pesticides in different plant types, P1, P2, P6, and P8 in the center of the county were the most seriously polluted. The plants with a high pesticide load level in the corresponding areas were cotton, walnut, red jujube, and poplar, and the pesticides with a high concentration contribution were hexachlorocyclohexanes, chlorpyrifos, cyhalothrin, fluvalinate, metalaxyl, difenoconazole, and procymidone. The human health risks of adults and children caused by oral intake, skin contact, and respiratory inhalation were evaluated. The results showed that oral intake was the main exposure route, and the risk level of children was significantly higher than that of adults but was within the acceptable range. The ecological risk level of earthworms in soil was subsequently evaluated. The results showed that the potential ecological risk level of a single pesticide was low, and the potential ecological risk level of bifenthrin was the largest. The calculation of the total ecological risk of mixed pesticides showed that areas P1, P4, P7, and P9 were at moderate risk, whereas other areas were at low risk. Therefore, the use of some pesticides in Shaya County should be restricted.

Residue level, occurrence characteristics and ecological risk of pesticides in typical farmland-river interlaced area of Baiyang Lake upstream, China

Baiyang Lake is the largest freshwater lake in North China, playing an important role in aquatic products production and eco-environment improvement. Traditional organochlorine pesticides were not enough to reflect ecological risk. We performed the high-throughput and non-targeted screening to identify the high-residue and wide-distribution pesticides at farmland-river interlaced area. We firstly reported the residue level and spatio-temporal distribution of typical pesticides in soils and waters (SP1–SP13) near Fuhe river in 2020–2021. The mean recoveries of eight pesticides ranged from 79.4 to 129%. The residues were 0.250–3530 ng/L (water) and 2.79 × 10−3–647 μg/kg dw (soil), respectively. Thiamethoxam was dominant with the high-residue proportion (HRP) of 53–95% (water, HRP > 50%) and 63–97% (soil, HRP > 60%), respectively. Most of pesticides almost have no significant season-change. The risk quotient (RQ) model results showed that although most pesticides have no aquatic risk (RQ < 0.01), carbendazim and propionazole deserved attention. The individual thiamethoxam at nearly half of the sites exhibited high terrestrial risk (RQ, 1.070–1.682), while propiconazole was at medium risk (SP1, SP2, SP8, and SP9) and high risk (SP12). The RQall were in the range of 0.4541–3.327 (earthworm), 0.0239–0.4552 (algae), 0.1094–1.103 (aquatic invertabrates), and 0.1657–1.923 (fish), respectively, so co-residue caused joint toxic effect to aquatic invertebrates.

Cu/Fe Bimetallic Treatment Performance on Organophosphorus Pesticides

Typical organophosphorus pesticides, such as glyphosate, trichlorfon, and ethephon, are widely used nowadays, and the treatment of their production wastewater is difficult to achieve by conventional water treatment methods. A Cu/Fe bimetallic system has been proposed as a viable technology to treat toxic and refractory pollutants. The performance of the system with different pH, Cu/Fe molar ratios, Cu/Fe dosages, and initial glyphosate concentrations was analyzed to investigate the operational factors affecting glyphosate removal by the Cu/Fe bimetallic system. Acidic pH (2.0), 250 g/L Cu/Fe dosage, 0.25% Cu/Fe, and 60 mg/L initial glyphosate concentration were the appropriate conditions for glyphosate removal, in which the efficiency of the system was in accordance with the pseudo–second-order kinetic model. Under this condition, the removal efficiencies of total phosphorus and total organic carbon reached 99 and 65%, respectively. The Fe/Cu bimetal surface was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The optimal conditions for glyphosate decomposition were applied to the treatment of trichlorfon and ethephon. The removal efficiency of the system was poor, but its toxicity to luminescent bacteria Q67 was remarkably reduced.

The dissipation, processing factors, metabolites, and risk assessment of pesticides in honeysuckle from field to table

Globally, honeysuckle is consumed as a food and administered as a medicinal agent. However, pesticide residues in honeysuckle limit its application and development of the honeysuckle industry, affecting food safety and endangering human health. Here, the degradation kinetics of 11 typical pesticides, including insecticides, fungicides, and an acaricide, in honeysuckle were investigated. The half-lives of pesticides in Henan and Liaoning fields were 1.90–4.33 and 2.05–4.62 d, respectively. The processing factors (PFs) of these pesticides after oven, sun, and shade drying ranged from 3.52 to 11.2. After decocting, the PFs of the pesticides were <1. Twenty degradation products were identified using ultra high performance liquid chromatography-quadrupole time-of-flight mass spectrometry, and pathways were proposed based on drying and decoction. The ecotoxicities of the degradation products were evaluated using the Toxicity Estimation Software Tool. Finally, the acute hazard indices of these pesticides, as determined via dietary exposure assessment combined with the PFs, were 0.227 and 0.911 for adults and children, respectively. Thus, special populations, such as children, require particularly careful risk control in terms of dietary exposure.

Smartphone-coupled three-layered paper-based microfluidic chips demonstrating stereoscopic capillary-driven fluid transport towards colorimetric detection of pesticides.

The existence of pesticide residues in the hydrosphere, biosphere, and anthroposphere can cause acute or chronic diseases and deteriorate the environment. Therefore, efficient detection of pesticide residues is of great significance to prevent food poisoning, control food pollution, and protect human lives by recognizing their distribution and concentration. Herein, a novel smartphone-coupled three-layered paper-based microfluidic chip is proposed as a facile platform to detect the pesticides. The stereoscopic capillary-driven fluid transport is enabled by the three-layered microfluidic chip configuration. The detection mechanism is based on the enzyme inhibition reaction and the chromatic reaction. The detection results are obtained by a smartphone and figured out by colorimetric quantitative analysis. Taking advantages of the above merits, we demonstrate the utilization of this smartphone-coupled three-layered paper-based microfluidic chip for the effective analysis of typical pesticides (profenofo and methomyl). The linear ranges of profenofo and methomyl are 0.27-2.1μmol L-1 and 0.14-1.85μmol L-1, respectively. The corresponding limits of detection in the chips are 55nM and 34nM, respectively. The paper-based chips are also highly cost-effective with a total cost of 0.082 ¥ per piece. It can be anticipated that this technique will open new avenues for the mass fabrication of paper-based microfluidic chips and provide state-of-the-art methods in the field of analytical chemistry.

Removal of pesticide residues from fresh vegetables by the coupled free chlorine/ultrasound process

Pesticide residue in vegetables has been considered as a serious food safety problem across the whole world. This study investigates a novel advanced oxidation process (AOP), namely the coupled free chlorine/ultrasound (FC/US) process for the removal of three typical pesticides from lettuce. The removal efficiencies of dimethoate (DMT), trichlorfon (TCF) and carbofuran (CBF) from lettuce reached 86.7%, 79.8% and 71.3%, respectively by the FC/US process. There existed a synergistic effect in the coupled FC/US process for pesticide removal and the synergistic factors reached 22.3%, 19.0% and 36.4% for DMT, TCF and CBF, respectively. Based on the analysis of mass balance of pesticides, the synergistic effect was probably attributed to the efficient oxidation of pesticides both in vegetables and in water by the generated free radicals and FC. The surface area and surface structure of vegetables strongly affected the removal of pesticides by FC/US. The removal efficiency of DMT increased from 80.9% to 88.1% as solution pH increased from 5.0 to 8.0, and then decreased to 84.1% when solution pH further increased to 9.0. When the ultrasonic frequency changed from 20 to 40 kHz, a remarkable improvement in pesticide removal by FC/US was observed. As the FC concentration increased from 0 to 15 mg L–l, the removal efficiencies of pesticides increased firstly, and then became stagnant when the FC concentration further increased to 25 mg L–l. The pesticide degradation pathways based on the identified intermediates were proposed. The total chlorophyll content was reduced by less than 5% after the FC/US process, indicating a negligible damage to the quality of vegetables. It suggests that the FC/US process is a promising AOP for pesticides removal from vegetables.

Synthesis of a synthetic analogue for the Sitophilus weevil aggregation pheromone and study on its hygienic and toxicological indexes

The work was initiated to study hygienic and toxicological indices of a synthetic analogue for the Sitophilus weevil aggregation pheromone. The toxicity testing of 5-hydroxy-4-methyl-3-heptanone demonstrated its extremely low toxicity for the warm-blood animals, as compared to the one of the typical pesticides. The average lethal dose of the product per orally administered to the white mice was established to be 4375.0 mg kg-1 LD16 and LD84 being 2225.0 mg kg-1 and 6550.0 mg kg-1, respectively. The average lethal dose for rabbits was 5900.0 mg kg-1 5-hydroxy-4-methyl-3-heptanone proved to have a mild skin and conjunctival irritant action, and equally mild functional cumulation. As to chronic toxicity, the acceptable daily dose of 4.3 mg/person/d was calculated and scientifically substantiated. The odor threshold was determined at the dose ranging from 0.35 to 0.7 mg l-1 with the practical limit ranging from 0.35 to 1.5 mg l-1, taste sensation threshold was found at the dose ranging from 1.0 to 3.0 mg l-1 with the practical limit ranging from 3.0 to 7.0 mg l-1