Fate Of Pesticides Research Articles

Rapid prediction of atrazine sorption in soil using visible near-infrared spectroscopy.

Sorption is an important process for determining the fate, effects, and ecological risks of pesticides in terrestrial and aquatic environments. Within a watershed, soil properties vary greatly because of landscape and management practices, leading to spatial variation of pesticide sorption coefficients (Kd). A method for the rapid determination of the sorption variability of atrazine in soils of the Baima river catchment using visible near-infrared (Vis-NIR) spectroscopy is studied in this work. Partial least square regression (PLS) was used to build calibration models. To achieve optimum models, several methods of spectral preprocessing and variable selection were investigated. The results show that the combination of standard normal variant transform (SNV) and Monte Carlo uninformative variable elimination (MC-UVE) can significantly improve the model. For validation samples, the correlation coefficient between the predicted value and the reference value determined by high-performance liquid chromatography (HPLC) analysis is 0.8090. Moreover, positive correlations are observed between the pesticide adsorption coefficient and the organic carbon (OC) and total nitrogen (TN) contents, respectively. Prediction models for OC and TN were built. The correlation coefficients of OC and TN between the predicted values and the reference values are 0.9285 and 0.6599, respectively. The results show that Vis-NIR can be used as a rapid and simple method to predict soil composition and pesticide sorption.

Comparative analysis on the sorption kinetics and isotherms of fipronil on nondegradable and biodegradable microplastics

Biodegradable plastics have been introduced and widely used as a promising alternative to traditional nondegradable plastics. However, the differences in sorption behavior of pesticides on nondegradable and biodegradable microplastics has been insufficiently studied. Here, four types of nondegradable [polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polypropylene (PP)] and two types of biodegradable [polylactic acid (PLA), polybutylene succinate (PBS)] microplastics were selected to investigate the sorption mechanism of fipronil based on their sorption kinetics and isotherms. The results indicated that the sorption rates of PLA and PBS were much higher than those of PE, PP, PVC and PS and that the sorption capacities of fipronil on microplastics followed the order of PBS > PLA > PP > PE > PS > PVC. The sorption kinetics followed a pseudo-second-order kinetics model (R2 = 0.953–0.998) for all tested microplastics. External mass transport and intraparticle diffusion were the main rate controlling steps of the sorption of fipronil on microplastics. Furthermore, isotherm results indicated that a Langmuir model provided the best fit for fipronil sorption on PE, PS, PVC and PP (R2 = 0.997–0.999), while a Freundlich model was the most appropriate model for PLA and PBS (R2 = 0.998–0.999). The presence of surface O-containing functional groups and the spatial arrangement of rubbery domains are likely to affect the sorption process. The results from this work suggest that microplastics, especially biodegradable ones, may play an important role in the fate and transport of pesticides, and their effects on soil organisms (e.g., earthworms) require further investigation.

Assessment of pesticides in soil from obsolete pesticides stores: a Caribbean case study.

The fate of highly hazardous or persistent pesticides in soils and their potential for environmental and health risks depends on the physical and chemical properties of the pesticide, soil properties including biological health and climatic conditions. Assessing the fate and impact of pesticides in soil is complicated in the Caribbean due to the high diversity of soils and duality of climate. The FAO supported national competent authorities from 11 countries in the Caribbean in the assessment of obsolete stocks and potentially contaminated soil. The Environmental Management Tool Kit (EMKT) prioritised Fond Cole and Camden Base as the only critical sites. Preliminary site investigations that utilised the rapid environmental assessment (REA) methodology identified that contamination was restricted to an impervious layer at the Camden site. Pesticide properties varied across groups, with the organochlorides exhibiting greater sorptive capacity and lower leaching potential relative to the organophosphates. All tested soils were non-saline with alkaline pH and notably sandy in texture with low adsorptive capacity. Analysis of pesticide levels revealed low to undetected quantities across contaminated sites. Traces of Endrin and Dieldrin were found in Marienburg, Suriname. Overall, assessment of soil contamination from stored obsolete pesticides revealed minimal contamination, however, detailed assessment considering contamination gradients should be performed where pesticides were identified.

Degradation and Mobility of Pesticides in Norwegian Soils

Degradation and Mobility of Pesticides in Norwegian Soils

From field to food II – will pesticide-contaminated pollen diet lead to a contamination of worker jelly?

Residues of pesticides have been found in bee collected pollen and stored beebread. Pollen is the protein source for bees and hence important for nurse bees to produce larval food. However, the fate of pesticides in the pollen used for larval food production is not clarified. We conducted a feeding experiment with free-flying mini-hives of the honey bee, Apis mellifera. A mixture of 13 different substances in high concentrations (156 - 9,021 µg/kg) was offered inside the hive. During the time of feeding, worker larvae of known age were reared. At larval age three to six days, worker jelly (WJ) was harvested and subjected to a multi-pesticide residue analysis. Concentrations of the detected pesticides in the WJ increased with larval age and ranged from 2.9 - 871 µg/kg for three- to six-day-old larvae, depending on the pesticide. The amount of pesticides significantly correlates with the amount of pollen grains in the worker jelly with increasing larval age from 41 - 4,654 pollen/mg WJ. Thus, we hypothesize the addition of pollen to the WJ to be responsible for the pesticide residues in the WJ. For the first time, this study shows the real pesticide exposure of honey bee larvae to pesticides by larval food. Our results should help to better evaluate the concentrations found in the field and to conduct field realistic feeding experiments, which may be used for risk assessments or pesticide approval.

Heterogeneous atmospheric degradation of current-use pesticides by nitrate radicals

In the atmosphere, pesticides are distributed between gaseous and particulate phases according to their physicochemical properties. In these two phases, they can react with atmospheric oxidants such as ozone, hydroxyl radical and nitrate radicals. Heterogeneous kinetics of the degradation by nighttime nitrate radicals are not well described. In this study, the heterogeneous reactivity with nitrate radicals of eight current-use pesticides (i.e., difenoconazole, tetraconazole, cyprodinil, fipronil, oxadiazon, pendimethalin, deltamethrin, and permethrin) adsorbed on silica model particles was investigated using laboratory experiments with in-situ nitrate radicals generation and concentration measurement. Under these experimental conditions, all pesticides were degraded. Atmospheric half-lives calculated with a Langmuir-Rideal model ranged between 8 days and 16 days and between 2 days and 11 days according to a Langmuir-Hinshelwood model for an atmospheric nitrate radicals concentration of 20 ppt. Results obtained can contribute to a better understanding of the atmospheric fate of pesticides in the particulate phase and show the importance of their degradation by nitrate radical compared to their degradation by other oxidants such as ozone and hydroxyl radicals.

Influence of pesticide concentration on their heterogeneous atmospheric degradation by ozone

A fraction of the atmospheric pesticides can be adsorbed on particles surface according to their physicochemical properties. After adsorption, pesticides can undergo heterogeneous reactivity with atmospheric oxidants such as ozone, but the influence of the pesticide surface coating (i.e., the percentage of the particle surface covered by pesticide molecules) on the degradation kinetics is not well-understood. To estimate the importance of this phenomenon, the influence of the surface coating level in pesticides on the heterogeneous ozonolysis of cyprodinil, deltamethrin, permethrin, and pendimethalin adsorbed on hydrophobic and hydrophilic silicas was investigated. Surface coating level varied from 0.3% to 15% of a monolayer. Generally, the increase of the surface coating level induced a slower degradation of the pesticides above 1%–3% of a monolayer. This decrease was attributed to a shielding effect. More aggregates of pesticides form with increasing surface coating leading to lower accessibility for ozone to the adsorbed pesticide molecules. Moreover, it was observed that the particle type could play a role in the influence of the surface coating level on the degradation rates. Results obtained will contribute to a better understanding of the atmospheric fate of pesticides and semi-volatile organic compounds in the particulate phase and show the importance of working with consistent surface coating level in order to compare the obtained degradation constants.

Influence of different redox conditions and dissolved organic matter on pesticide biodegradation in simulated groundwater systems

Insights into the influence of redox conditions, that is the availability of electron acceptors, and dissolved organic matter (DOM) on pesticide biodegradation in groundwater are key to understanding the environmental fate of pesticides in natural groundwater systems. Here, the influence of redox conditions and supplemental DOM addition on biodegradation of pesticides, 2,4-dichlorophenoxyacetic acid (2,4-D), 2,6-dichlorobenzamide (BAM), mecoprop-p (MCPP) and bentazone, was tested in microcosm and subsequent column experiments. Pesticide degradation, functional genes and changes in specific fractions and quantity of DOM were systematically quantified. In aerobic microcosm experiments, the highest 2,4-D degradation rate was obtained with the presence of more assimilable DOM. In column experiments, minimal pesticide degradation (≤33.77%) in any anaerobic redox conditions was observed in the absence of DOM. However, in the presence of DOM, 2,4-D biodegradation was considerably enhanced under nitrate-reducing conditions (from 23.5 ± 10.2% to 82.3 ± 11.6%) and in a column without external electron acceptor amendment (from −6.3 ± 12.6% to 31.1 ± 36.3%). Observed preferential depletion of the fulvic acid fraction of DOM provides indications for specific functional DOM properties. The qPCR results show an increase in microbial biomass and functional genes (tfdA) in liquid phase after DOM addition. The results of this work provide insights into the interplays among DOM, redox geochemistry, and pesticide biodegradation, and show the potential of a novel approach – DOM addition to groundwater systems – for in situ biostimulation technology to remove pesticides from groundwater systems.

Organofosfatlı Pestisitlerin Pilot Ölçekli Sulak Alan Reaktörlerinde Gideriminin İncelenmesi

Modern tarımın yaygınlaşmasıyla birlikte dünyada pestisit kullanımı artmıştır. Birçok ülkede olduğu gibi ülkemizde de aşırı ve bilinçsizce pestisit kullanımı sonucunda su ve toprak ortamında giderek artan miktarlarda pestisit kirlenmesi görülmektedir. Meriç- Ergene Havzası’nda bulunan ve etrafında yoğun bir şekilde çeltik tarımı yapılan Meriç Deltası sulak alanları da bu kirlenmenin görüldüğü bölgelerden biridir. Bu çalışma kapsamında, Meriç Deltası sulak alanlarından numuneler alınarak organofosfatlı pestisitlerin akıbeti incelenmiştir. Sulak alanları temsil etmesi amacıyla pilot ölçekli reaktörle çalışılmış, seçilen 4 organofosfatlı pestisit (Chlorpyrifos, Dichlorvos, Fenthion, Diazinon) için biyolojik ayrışma ve adsorpsiyon deneyleri yapılmıştır. Pilot ölçekli sistemde, seçilen pestisitlerin yarı ömürleri belirlenmiş ve bitki ve sediment üzerine adsorpsiyon miktarları ölçülmüştür. Aynı zamanda pestisitlerin yeraltı suyuna sızma potansiyelleri GUS (“Groundwater Ubiquity Score” / “Yeraltı Suyunda Mevcudiyet Katsayısı”) kullanılarak hesaplanmıştır. Elde edilen sonuçlar serbest yüzey akışlı yapay sulak alan sistemlerinin organofosfatlı pestisitlerin giderimindeki etkinliğini ortaya koymuştur. Bu çalışmadan elde edilen sonuçlar, organofosfatlı pestisitlerin giderimi için önerilen yapay sulak alanların tasarımı için yol gösterici niteliktedir.

From agricultural catchment to management scenarios: A modular tool to assess effects of landscape features on water and pesticide behavior

Pesticide transfers and fate are highly influenced by the presence of discontinuities such as grass strips, slopes, hedgerows or roads that can accelerate or slow down and dissipate water and contaminant fluxes. That is why those landscape elements must be integrated into watershed management plans. It implies taking them into account when modeling water and contaminant fluxes at the small catchment scale. However, if the influence of landscape elements has already been widely explored at field scale, models generally do not reach the catchment scale. The project PESHMELBA aims at developing a new modeling tool of water and contaminants circulation and fate at the scale of small catchments in order to optimize landscape organization. The model explicitly takes into account spatial organization of landscape by representing existing elements, their locations and shapes. The final aim of this modeling tool is to efficiently test and rank different development scenarios in order to assess the influence of agricultural practices, land uses and landscape management strategies on water quality. In PESHMELBA, dominating processes ruling water and contaminants circulation and dissipation for each element type are mainly represented by existing and validated models. New components have also been developed when no suitable model was found in the literature. All these models present different levels of conceptualization and are used as modeling units ensuring a modular structure. Then, the different units are gathered and connected in the OpenPALM coupler (Fouilloux and Piacentini, 1999) in order to implement the spatial and temporal couplings. This innovative approach leads to a spatialized model of the whole catchment. Applications cases are tested with an increasing complexity, from a case with two plots to the hillslope scale with several plots, ditches and rivers. They show that PESHMELBA is a promising tool to compare scenarios considering water and pesticide fate in different complex landscapes.

In situ localization of micropollutants and associated stress response in Populus nigra leaves

Micropollutants and emerging organic contaminants (EOCs) have been widely studied in terms of persistance, removal, human risk assessment, toxicology, etc. Mass spectrometry imaging (MSI) offers the possibility of following the fate of a single pesticide in a plant leaf or a drug in the whole body of an animal, organ by organ. However, the admissibility of chronic low doses of complex mixtures for the ecosystem has not been assessed. How do micropollutants diffuse in the environment? How do living organisms cope with chronic exposure to a low dose of diverse micropollutants? Is there a cocktail effect or a chance for hormesis? Combining mass spectrometry imaging (MSI) and targeted and nontargeted liquid chromatography coupled to mass spectrometry (LC-MS), we attempt to answer these questions. We investigate the diversity of micropollutants at the exit of a water treatment facility, their diffusion in sludge and black poplar (Populus nigra), and their impact on a living organism. We reveal a specific tissue localization of micropollutants in peripheral leaf tissues, and an associated stress response from the plant, with stress hormones and tissue degradation markers induced in the plant growing near the water efflux.

Heterogeneous degradation of pesticides by OH radicals in the atmosphere: Influence of humidity and particle type on the kinetics

Pesticides can be adsorbed on the surface of atmospheric aerosol, depending on their physicochemical properties. They can be degraded by atmospheric oxidants such as OH radicals but the influence of some environmental parameters on the degradation kinetics, especially relative humidity and particle surface type, is not well understood. Heterogeneous degradation by OH radicals of eight commonly used pesticides (i.e., difenoconazole, tetraconazole, cyprodinil, fipronil, oxadiazon, pendimethalin, deltamethrin, and permethrin) adsorbed on hydrophobic and hydrophilic silicas at a relative humidity ranging from 0% to 70% was studied. Under experimental conditions, only cyprodinil, deltamethrin, permethrin, and pendimethalin were degraded by OH radical in atmospheric relevant concentration. Second-order kinetic constants calculated for the pesticides degraded by OH radicals ranged from (1.93 ± 0.61) × 10−13 cm3 molecule−1 s−1 (permethrin, hydrophobic silica, 30% RH) to (4.08 ± 0.27) × 10−12 cm3 molecule−1 s−1 (pendimethalin, hydrophilic silica, 0% RH). Results obtained can contribute to improve the understanding of the atmospheric fate of pesticides and other semi-volatile organic compounds in the particulate phase and they highlight the importance of taking humidity and particle type into account for the determination of pesticides atmospheric half-lives.

A conceptual model of organochlorine fate from a combined analysis of spatial and mid- to long-term trends of surface and ground water contamination in tropical areas (FWI)

Abstract. In this study, we investigated the management of long-term environmental pollution by organic pollutants such as organochlorine pesticides. We set out to identify conditions that are conducive to reducing pollution levels for these persistent molecules and then propose a conceptual model of organochlorine fate in water. Our approach looked at spatio-temporal changes in pollutant contents in surface water (SW) and groundwater (GW) on a large scale, in order to decipher the respective roles of soil, geology, hydrology and past treatment practices. The case of chlordecone (CLD) on the island of Martinique (1100 km2) was selected given the sampling campaigns carried out since 2007 over more than 150 sites. CLD, its metabolite chlordecone-5b-hydro (5bCLD) and the metabolite-to-parent-compound ratio were compared. As regards the spatial variability of water contamination, our results showed that banana cropping areas explained the location of contaminated SW and GW, whereas the combination of soil and geology factors explained the main spatial variability in the 5bCLD∕CLD ratio. For temporal variability, these conditions defined a high diversity of situations in terms of the duration of pollution, highlighting two groups: water draining old geological formations and ferralsols or vertisols vs. recent geology and andosols. A conceptual leaching model provided some key information to help interpret downward trends in CLD and 5bCLD observed in water. Lastly, a conceptual model of organochlorine fate is proposed to explain the diversity of the 5bCLD∕CLD ratio in water. Our conclusions highlight the combined role of soil and groundwater residence time for differentiating between conditions that are more conducive, or not, to the disappearance of CLD from the environment. This paper presents a model that provides an overall perception of organochlorine pesticide fate in the environment.

Environmental Fate of RNA Interference Pesticides: Adsorption and Degradation of Double-Stranded RNA Molecules in Agricultural Soils.

Double-stranded RNA (dsRNA) pesticides are a new generation of crop protectants that interfere with protein expression in targeted pest insects by a cellular mechanism called RNA interference (RNAi). The ecological risk assessment of these emerging pesticides necessitates an understanding of the fate of dsRNA molecules in receiving environments, among which agricultural soils are most important. We herein present an experimental approach using phosphorus-32 (32P)-radiolabeled dsRNA that allows studying key fate processes of dsRNA in soils with unprecedented sensitivity. This approach resolves previous analytical challenges in quantifying unlabeled dsRNA and its degradation products in soils. We demonstrate that 32P-dsRNA and its degradation products are quantifiable at concentrations as low as a few nanograms of dsRNA per gram of soil by both Cerenkov counting (to quantify total 32P-activity) and by polyacrylamide gel electrophoresis followed by phosphorimaging (to detect intact 32P-dsRNA and its 32P-containing degradation products). We show that dsRNA molecules added to soil suspensions undergo adsorption to soil particle surfaces, degradation in solution, and potential uptake by soil microorganisms. The results of this work on dsRNA adsorption and degradation advance a process-based understanding of the fate of dsRNA in soils and will inform ecological risk assessments of emerging dsRNA pesticides.

A New Approach for Investigating the Impact of Pesticides and Nutrient Flux from Agricultural Holdings and Land-Use Structures on Baltic Sea Coastal Waters

Knowledge related to land-use management impacts on the Baltic Sea ecosystem is limited. The constant release of pollutants into water bodies has resulted in water quality degradation. Therefore, only the innovative approaches integrated with research will provide accurate solutions and methods for proper environment management and will enable understanding and prediction of the impacts of land-use in the Baltic Sea region. Modelling approaches have become essential to address water issues and to evaluate ecosystem management. There are many water quality models, but only a few work in the operational mode and only some of them can be used as an interactive tool for environmental management to assess the impact of pollution on water quality. This study presents a new approach for investigating the influence of pesticides and nutrient fluxes from agricultural holdings and land-use structures on coastal waters of the Baltic Sea. Called WaterPUCK, this method will enable calculation of the sufficient amount of fertilizers, investigation nutrients, and pesticide sources and model: the fate and distribution of nutrients and pesticides in the surface water and groundwater; loads of pollution to surface water and groundwater; fluxes of nutrients via submarine groundwater discharge (SGD) to the Baltic Sea coastal environment; the processes and mechanisms influencing the persistence of nutrients in the environment; and predict the changes in land use and climate change influence on the Bay of Puck ecosystem.

Nanoformulations can significantly affect pesticide degradation and uptake by earthworms and plants

Environmental contextNanopesticides are increasingly being developed for agricultural use, but knowledge concerning their environmental fate and effects is limited. This microcosm study brings new results about soil fate and bioaccumulation of polymeric or lipid nanoparticles carrying chlorpyrifos or tebuconazole. The nanoformulations significantly altered the fate and bioavailability of the pesticides in soil even under the real-world and complex conditions of microcosms. AbstractAn increasing number of nanoformulated pesticides (nanopesticides) have been developed in recent years with the aim to improve pesticide efficiencies and reduce their impact on the environment and human health. However, knowledge about their environmental fate and effects is still very limited. This study compares the soil fate and bioaccumulation of four model nanopesticides (chlorpyrifos and tebuconazole loaded on polymeric and lipid nanocarriers) relative to the conventional formulations and pure active ingredients (all added at 0.5mgkg−1) in microcosms containing earthworms Eisenia fetida and lettuce Lactuca sativa in two soils (LUFA 2.1 and 2.4) over a period of four months. The nanoformulations increased the soil half-life of the pesticides by up to 2 times (e.g. chlorpyrifos with lipid nanocarrier and tebuconazole with polymeric nanocarrier in LUFA 2.1), probably as a direct consequence of the slow release of the pesticide from the nanocarriers. Pesticide bioaccumulation in earthworms was often increased for the nanopesticides probably as a result of their enhanced bioavailability. The nanoformulations were also shown to affect the pesticide bioaccumulation in plants, but trends were inconsistent. Overall, the microcosm results demonstrated that nanoformulations can significantly alter the fate and bioavailability of pesticides. However, generalisations were difficult to make as the impacts depended on the type of nanocarrier, pesticide, soil used and time scale. We believe that our study contributes towards the critical mass of case studies needed to enable a judging of the benefits versus risks of nanopesticides.

Soil properties of sugarcane fields controlling triazine leaching potential

Atrazine and ametryn are pre- and post-emergence herbicides widely used in sugarcane fields. Both are characterised by moderate to high mobility in soil and are regarded as a threat to hydrologic systems. Physical and chemical soil properties are highlighted as one of the factors governing the fate of pesticides in hydrologic systems. The aim of our study was to estimate the leaching potential of atrazine and ametryn in soils of the saline alluvial plain of Tucumán cultivated with sugarcane. Miscible displacement experiments were carried out in triplicate using undisturbed topsoil cores from four farm fields. Field 1 was in plant, fields 2 and 3 were in second ratoon, and field 4 was in third ratoon. Experimental breakthrough curves were fitted to the convection–dispersion equation; results showed that hydraulic transport was in equilibrium conditions, meaning that all soil water was involved in solute convective transport. Atrazine had asymmetric breakthrough curves, revealing chemical non-equilibrium conditions, with at least two sorption–desorption sites participating in the process. In contrast, ametryn concentrations in leached samples were low and inconsistent; therefore, no breakthrough curves could be described. Of the total applied, recoveries reached 10% and 2% for leached atrazine and ametryn respectively. For an estimated annual recharge of 100 mm, these leached amounts would exceed international reference values for drinking water.

Global evaluation and sensitivity analysis of a physically based flow and reactive transport model on a laboratory experiment

Spatialized physically based models are necessary tools for assessing the fate of pesticides in natural environments transferred by diffuse pollution. In this study the CATHY (CATchment HYdrology) model is coupled with reactive processes (adsorption and degradation). The resulting reactive subsurface component is evaluated on laboratory data by (i) comparing the model performance on experimental data using a combination of statistical criteria, (ii) conducting a Morris sensitivity analysis on both hydrological and solute transfer variables, and (iii) improving the CATHY model parameter settings based on the sensitivity analysis results. The sensitivity analysis produces a ranking of the factors wherein those that are particularly influential on water flow and reactive solute transfer emerge. These are found to be the saturated hydraulic conductivity, the retention curve parameters, and the sorption coefficient. After a calibration of influential parameters based on Morris sensitivity analysis, the results obtained are largely consistent with laboratory data.

Characteristics and mechanisms of chlorpyrifos and chlorpyrifos-methyl adsorption onto biochars: Influence of deashing and low molecular weight organic acid (LMWOA) aging and co-existence

The effects of inherent minerals in biochars and low molecular weight organic acids (LMWOAs) on chlorpyrifos and chlorpyrifos-methyl adsorption by biochars are unclear. We examined the sorption of chlorpyrifos and chlorpyrifos-methyl onto giant reed-derived biochars before and after deashing or LMWOA aging. The effect of citric acid (CA) as a co-solute on the sorption of chlorpyrifos and chlorpyrifos-methyl was also investigated. With increasing temperature (300–600 °C), the adsorption capacity of biochars increased from 4.32 to 14.8 mg/g for chlorpyrifos and from 15.0 to 50.5 mg/g for chlorpyrifos-methyl. This can be explained by the fact that higher temperature biochar had more aromatic units and pores for capturing more sorbates. The deashing and LMWOA aging treatments exposed more carbon surfaces and improved the porosity of biochar, thus favoring sorption. Further, the deashing treatment resulted in greater sorption enhancement, when compared with the LMWOA aging treatment. At pH 6.5, CA2− and CA3− chelated Ca2+ via bridging at CA concentration below 10 mmol/L, thus reducing the competition of Ca2+ for aromatic surfaces and COO−/OH groups. When the CA concentration was above 20 mmol/L, CA2−, CA3−, and [Ca(CA)2]x− inhibited the sorption of chlorpyrifos and chlorpyrifos-methyl by competing for carbon sites and pores of biochar. These findings will help guide the practical application of biochar in pesticide-contaminated water and soil, and to better understand the role of biochar in the transport, fate, and bioavailability of organophosphorus pesticides in the rhizosphere.

Antibiotics may increase triazine herbicide exposure risk via disturbing gut microbiota

BackgroundAntibiotics are commonly used worldwide, and pesticide is a kind of xenobiotic to which humans are frequently exposed. The interactive impact of antibiotics on pesticides has rarely been studied. We aim to investigate the effects of antibiotics on the pesticide exposure risk and whether gut microbiota altered by antibiotics has an influence on pesticide bioavailability. Furthermore, we explored the mechanisms of gut microbiota affecting the fate of pesticides in the host.ResultsThe oral bioavailability of triazine herbicides significantly increased in the rats treated with ampicillin or antibiotic cocktails. The antibiotic-altered gut microbiota directly influenced the increased pesticide bioavailability through downregulating hepatic metabolic enzyme gene expression and upregulating intestinal absorption-related proteins.ConclusionsAntibiotics could increase the pesticide bioavailability and thereby may increase the pesticide exposure risk. The antibiotic-altered gut microbiota that could alter the hepatic metabolic enzyme gene expression and intestinal absorption-related proteome was a critical cause of the increased bioavailability. This study revealed an undiscovered potential health impact of antibiotics and reminded people to consider the co-exposed xenobiotics when taking antibiotics.