Pesticides In Soil Research Articles

Occurrences, Possible Sources, and Risk Impacts of Organochlorine Pesticides in Soil of Changchun Central Urban Area, Northeast China

Eighteen organochlorine pesticides (OCPs) in soil samples from the Changchun central urban area, Northeast China were analyzed using accelerated solvent extraction combined with gas chromatography/mass spectrometry (ASE-GC/MS) for the purpose of elucidating their contamination status, distribution characteristics, influencing factors, and feasible dangers in this city region. The complete concentrations of OCPs ranged from 15.63 to 92.79 ng/g, with a geomean of 36.46 ng/g. Hexachlorocyclohexane(HCHs), dichlorodiphenyltrichoroethane (DDTs), and chlordanes were the most dominant OCPs, with γ-HCH and p,p′-DDT being the predominant isomers. Higher concentrations of OCPs often centered to the northeast and southwest of the Changchun metropolis, and these artificial influences contributed to the destiny of OCPs in the soils. The residues of OCPs were derived from the historic utility of the technological DDT, dicofol, and lindane. A Pearson’s correlation evaluation indicated that TOC was once a key factor controlling OCP accumulation. The ecological risk evaluation based on the soil quality guidelines (SQGs) advises that the presence of DDTs, lindane, and heptachlor may additionally pose a poisonous ecological danger to soil organisms. The contrast outcomes of the incremental lifetime cancer risk (ILCR) confirmed that the highest cancer risk of OCPs to the posed populace was once low, whilst some unique areas with excessive OCP residues ought to be given attention. The research results provide basic information for evaluating the extent of OCP pollution in the soil of major cities in Northeast China and can help authorities establish environmental protection regulations and soil remediation techniques.

First surveillance of pesticides in soils of the perimeter of Tadla, a Moroccan sugar beet intensive area.

With the long-term application of pesticides on sugar beet farms in the irrigated perimeter of Tadla in Morocco for over 50years, pesticide monitoring is necessary to assess soil health. The objective of our study was to monitor multiple pesticide residues in topsoil samples collected from post-harvest sugar beet fields and verify their migration to deep soil layers. Topsoil and deep soil samples were collected from arbitrarily selected sugar beet fields in the IPT. In this study, a target-screening method was applied. All target pesticides were detected in soil samples, with tefluthrin being the most frequently detected pesticide. The residue with the highest concentration in soil samples was DDE. All the soil samples contained a mixture of pesticide residues, with a maximum of 13 residues per sample. The total pesticide content decreased toward more profound layers of soil, except in one field where it reached a concentration of 348µg/kg at the deeper soil layer. For pesticides detected at the three soil depths, only tefluthrin concentration increased in the deep soil layer. The results provide comprehensive and precise information on the pesticide residue status in sugar beet soils warning against the multiple risks that this contamination can cause. This study indicates the need of regular monitoring of pesticides over a large area of the perimeter to enable decision-makers to pronounce the impacts of the extension and intensification of sugar beet cultivation at the irrigated perimeter of Tadla.

Mixing bamboo charcoal with vinasse fertilizer to remediate the phytotoxicity of quinclorac to tobacco

ABSTRACT Modern agriculture has caused extensive soil pesticide contamination, which is a global concern. This study explored the potential of bamboo charcoal (BC) to alleviate quinclorac-induced stress in tobacco plants. A pot experiment was conducted to investigate the effects of BC and vinasse fertilizer (VF) on the growth and physiological parameters of tobacco plants subjected to quinclorac stress. At 30, 60, and 90 d after transplantation, BC and VF exhibited pronounced restorative effects on quinclorac-stressed tobacco plants. The treatments improved plant height, leaf length, and leaf width, and enhanced leaf quality and various biochemical indicators. Treatment with 500 g VF + 4% BC resulted in the lowest residual quinclorac levels in both the soil and leaves. Treatment with 500 g VF + 2% BC resulted in the most significant recovery of agronomic traits, whereas 500 g VF + 0.5% BC was the most effective in enhancing leaf quality. However, the effectiveness of BC decreased with time following application, and furthermore, quinclorac may be released from the BC. In conclusion, BC shows promise in alleviating the adverse effects of quinclorac stress in tobacco plants.

Establishment of a GC-HRMS-IDMS-based modified QuEChERS approach for rapid, reliable, and simultaneous determination of organochlorine pesticides in soil

Organochlorine pesticides (OCPs), a class of organic pollutants, are highly toxic and persistent in soil and can have harmful effects on humans, organisms, and agricultural environments when bioaccumulated through the food chain. The existing methods for OCP analysis are complex and time consuming; thus, developing a rapid and reliable method for quantifying and monitoring soil-bound OCPs is essential. This study demonstrates the feasibility of replacing the existing official method for OCP analysis with a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method based on GC-HRMS-IDMS. In this modified QuEChERS method, acetonitrile was replaced with ethyl acetate as the extraction solvent. We also assessed the optimal extraction salt (Original, AOAC, and EN) and dispersive solid-phase extraction clean-up sorbent. The limits of detection (LODs) and quantification (LOQs) of the modified QuEChERS method for 24 OCPs ranged from 0.02 to 0.24 ng/g and from 0.06 to 0.3 ng/g, respectively. The recovery rates at the LOQ level were 59.6–115.9 % for the Original method, 60.5–112.5 % for the AOAC method, and 59.6–115.9 % for the EN method. Furthermore, soil samples contaminated with endosulfan were analyzed using the three QuEChERS methods to compare their contents and deviation. EN exhibited more accurate results than Original and AOAC. Thus, the sample processing method using QuECHERS can replace the existing method.

Organochlorine Pesticides in Soil–Groundwater–Plant System in a Famous Agricultural Production Area in China: Spatial Distribution, Source Identification and Migration Prediction

Being a famous hometown of vegetables in China, Shouguang City has a long history of vegetable cultivation and is a comprehensive national commodity base for vegetables and fruits. In recent decades, with the expansion of agricultural production, the use of pesticides is increasing. Although organochlorine pesticides (OCPs) have been banned, there are still some residues in soil, groundwater and other media. The study on the migration of the OCPs in soil and groundwater is of great importance for the maintenance of food security. Using methods of hydrogeological survey, laboratory testing and numerical simulation, the spatial distribution characteristics, sources and pollution degree of OCPs in soil and groundwater were analyzed, and the migration and transformation of OCPs in soil–groundwater was dynamically simulated and predicted. The study showed that there were many kinds of OCPs residual in the soil environment. The hexachlorocyclohexane (HCHs) in the topsoil of the study area were mainly due to the use of lindane, and the main source of dichlorodiphenyltrichloroethane (DDTs) in soil was the use of DDTs in history. The contents of HCHs, DDTs and hexachlorobenzene in the topsoil of the study area were at a low level, while the content of endosulfan metabolite endosulfan sulfate was comparatively higher. In recent years, the content of organochlorine pesticides in soil has generally decreased. The indexes of OCPs in groundwater can meet the Standards for Drinking Water quality of China. It was predicted that the HCH pollutants would mainly be distributed in Gucheng Street, Shangkou Town, and its south area where the concentration exceeds 3 ng/L exceeds that of 240 km2. DDT pollutants would mainly be distributed in the east and north of Shouguang City, where the concentration beyond 0.6 ng/L exceeds that of 200 km2. Endosulfan sulfate pollutants would mainly be distributed in the Gucheng Street Office, Shangkou Town, and its south area where the concentration exceeds 1.5 ng/L will exceed that of 150 km2. Hexachlorobenzene (HCB) pollutants would mainly be distributed in Fengcheng in the west of Shouguang City and Nancha River in the northeast, where the concentration exceeds 0.2 ng/L will exceed that of 200 km2. The study enriched the monitoring data of OCPs in agricultural planting areas and provided reference for source analysis, migration prediction, and pollution prevention of OCPs.

Pesticides in Agricultural Soils: Major Findings from Various Monitoring Campaigns in Switzerland.

Synthetic pesticides are widely applied in modern agriculture, where they are used against diseases, pests, and weeds to secure crop yield and quality. However, their intensive application has led to widespread contamination of the environment, including soils. Due to their inherent toxicity, they might pose a risk to soil health by causing harm to non-target organisms and disrupting ecosystem services in both agricultural and other exposed soils. Following the Swiss National Action Plan on the reduction of pesticide risks, Agroscope has conducted several soil monitoring studies that are briefly presented here. All of them resort to different multi-residue trace analytical approaches to simultaneously quantify up to about 150 modern pesticides by either accelerated solvent, or Quick, Easy, Cheap, Efficient, Rugged, Safe (QuEChERS) extraction, followed by separation and detection with liquid chromatography-triple quadrupole mass spectrometry. While partly still in progress, our investigations led to the following major findings this far: Multiple pesticides are commonly present in soils, with individual concentrations in agricultural soils often reaching up to a few tens of µg/kg. Pesticide occurrence and concentrations in agricultural soils primarily depend on land use, land use history and cultivated crops. Pesticides can prevail much longer than predicted by their half-lives, and were found in soils even decades after conversion from conventional to organic farming. Corresponding residual fractions can be in the order of a few percent of the originally applied amounts. We further found negative associations of pesticide residues with the abundance of beneficial soil life, underpinning their potential risk to the fertility of agricultural soils. Traces of pesticides are also detected in soils to which they were never applied, indicating contamination, e.g., via spray drift or atmospheric deposition. These results confirm the general notion of both scientists and legislators that prospective risk assessments (RA; as executed during registration and use authorization) should be confirmed and adjusted by retrospective RA (e.g., by environmental monitoring studies of currently used compounds) to jointly lead to an overall reduced environmental risk of pesticides.

Liquid chromatography - high-resolution quadrupole time-of-flight mass spectrometry analysis of pesticides in French agricultural soils

ABSTRACT Agricultural soils are not controlled in France for the massive use of pesticides. The quadrupole mass spectrometer is used for targeted analysis of a few dozen pesticides, while the high-resolution time-of-flight quadrupole mass spectrometer (QTOF-MS) allows both targeted and non-targeted analysis of hundreds of pesticides. In this study, a targeted method was developed in soils using pressurised-liquid extraction (PLE) and liquid chromatography (LC) coupled with a QTOF-MS. This method development was necessary to carry out next suspect and non-target screening in soils and has been validated for triazines, phenylureas and emerging pesticides in soils. The internal calibration of pesticides was validated for low levels (0.5 to 12.5 µg L−1) and high levels (12.5 to 400 µg L−1) using labelled internal standards. The determination coefficient (R2) of calibration curve of each pesticide was greater than 0.99. Excepted DCPU and IPPU, the mean recoveries of pesticides in five reference soils spiked at 40 µg kg−1 and 10 µg kg−1 were greater than 93.5% and 106.2%, and the variation coefficients lower than 14.7% and 22.5%, respectively. So, multiplier factors were applied to the quantification results of DCPU and IPPU, respectively, 2.5 and 1.7 for correction. This validated method has been applied to a selection of 40 French soils of Centre-Val de Loire region. The limit of quantification (LOQ) of pesticides varied between 0.005 and 0.175 µg kg−1 in soils. Seven pesticides were the most detected in soils. Seventeen pesticides were detected between 10 and 50% of cases and very low detection frequencies (<10%) were found for 10 pesticides in soils. The mean concentrations were 0.730 µg kg−1 dw for triazines, 1.367 µg kg−1 dw for phenylureas and 7.638 µg kg−1 dw for emerging pesticides. DCPMU and epoxiconazole were detected in all the 40 soils.

Algae-derived biochar nanozyme array for discrimination and detection of multiple pesticides in soil, water and food

Despite the potential of nanozymes combined with sensor arrays for discriminating multiple pesticides simultaneously, they have few practical pesticide sensing uses due to the limited performance of existing nanozymes and the complexity of their preparation. Here, agricultural waste is utilized for the facile synthesis of high-performance biochar nanozymes and the fabrication of biochar nanozyme sensor arrays. The production of autogenous N-doped biochars with abundant surface functional groups and good peroxidase-like activities is achieved with different types of algae. High-performance biochar nanozyme sensor arrays can discriminate pesticides in a concentration range from 1 to 500 μM and in real samples from soil, lake water, seawater, apples, cucumbers, peaches, tomatoes and cabbages. Furthermore, pesticides can be quantified down to 1 μM. The development of high-performance nanozyme sensor arrays based on waste conversion could be a step toward pesticide discrimination and detection, which would improve human and environmental safety.

Environmental carrying capacity and ecological risk assessment of pesticides under different soil use types in the Central Plains Urban Agglomeration (CPUA), China

Soil environmental safety has received much attention during the past few decades due to its significance in agricultural production and human health. Special attention is required for soil pesticide residues and ecological risks. This study examined 197 soil samples from industrial, residential and agricultural areas for the presence of 12 organophosphorus pesticides (OPPs) and 8 synthetic pyrethroids (SYPs) in the 16 cities in Henan Province, and the center of CPUA, based on the Central Plains Urban Agglomeration (CPUA) concept proposed by China. The total average concentrations of ∑12OPPs in industrial, residential and agricultural soils were 194, 217, 267 ng/g dry weight, and those of ∑8SYPs were 26.8, 35.7, 25.5 ng/g dry weight, respectively. The two pollutants with the greatest concentrations in the soils were malathion and fenpropathrin, respectively, the dominant components of OPPs and SYPs. The soil environmental carrying capacity (SECC) analysis, representing the maximum residual load that can be supported, shows that acephate and cyhalothrin were overloaded, with a predicted period of over 500 years. Among the 16 cities of CPUA, a higher frequency of high ecological risk could be observed only in Shangqiu. The OPPs in children had total non-carcinogenic risk values of more than 1.0. Similarly, the non-carcinogenic risks of SYPs in adults and children in the residential areas were more than 1.0. The study provides knowledge on how to effectively manage soil safety in Henan Province, which is the center of the CPUA, with a large population and grain province to protect ecosystems and reduce the risks of soil pesticide residues in humans.

Terahertz determination of imidacloprid in soil based on a metasurface sensor.

Pesticides in soil are continuously one of the most studied analytes due to their environmental and human health effects. Thus the detection of pesticides in soil is an important means to control and assess soil quality. Here, we theoretically and experimentally present a novel method for the determination of imidacloprid in soil by using a metasurface sensor operating at terahertz frequencies. The metasurface shows a resonance peak at 880 GHz and the electric field at the peak is strongly localized and concentrated in the gap of split I-shaped resonator. The detection of complex refractive index shows that the position and the transmittance of resonance peak are depend on the change in the complex refractive index. The measurement of imidacloprid concentration in soil demonstrates that both the frequency shift and the transmittance change at peak increase almost linearly with the increasing of imidacloprid concentration ranging from 0.25% to 2%. In this case, the frequency shift reaches 97 GHz and the transmittance change at peak is as high as 30.9%. Our work enables the determination of imidacloprid in soil at terahertz frequencies with good reliability and high sensitivity, showing the potential application of terahertz spectroscopy in environmental monitoring.

The status of organochlorine pesticide contamination in Greek agricultural soils: the ghost of traditional agricultural history.

Inadequate information regarding pesticide contamination in Greek agricultural soils is currently available, while national soil monitoring programs have not been initiated yet. The aim of the present study was to assess the levels, compositions, and distribution of thirty three organochlorine pesticides (OCPs) in Greek agricultural soils, due to the environmental threat posed by these compounds, even after decades from their abrogation from the market. Determination of the organochlorine pesticides was achieved using gas-chromatography-mass spectrometry, following a QuEChERS sample preparation method. A total of 60 soil samples, from two soil horizons (up to 60 cm), were obtained from agricultural lands in Greece throughout 2019-2020. The major findings presented DDTs, γ-HCH, alachlor, and 4,4- DCBP in the examined soil samples, with DDTs being the major compounds with their maximum cumulative concentration (ΣDDTs) reaching 1273.4 μg kg-1 d.w. Compositional profile and diagnostic ratios suggested that the occurrence of DDT residues was due to historical inputs. Most of the samples did not exceed the target values set by the Netherlands and Canadian guidelines for DDTs in soil; however, there was one exception in the case of Aegina Island. Finally, based on the environmental exposure assessment conducted, the vast majority of the analytes presented lower concentrations compared to the predicted environmental concentrations, with an exemption for DDE metabolite where the measured and predicted concentrations were almost equal.

Assessing potential soil pollution from plant waste disposal: A modeling analysis of pesticide contamination

Pesticide residues can be taken up by plants after pesticide application, potentially resulting in soil pollution following the disposal of plant wastes at harvest. Currently, there is a lack of simple and efficient methods that can conduct high-throughput simulations to explore this problem across various chemicals and plant species. We present a modeling approach to simulating pesticide residue concentrations in soil as a result of plant waste disposal to assess the impact of plant wastes on agricultural soil pollution with respect to pesticide residues. This modeling approach employs well-established plant uptake models, providing versatility in evaluating different chemicals and plant species. The simulation process was tabulated in the spreadsheet interface, providing users with the flexibility to adjust input values for specific chemicals, plant species, and regions. The simulation results revealed that pesticides with relatively low lipophilicity (i.e., log KOW < 2) had low simulated residue concentrations in the soil as a result of plant waste disposal at harvest, whereas soil concentrations for lipophilic pesticides dramatically rose. This indicated that disposal of plant waste in agricultural soils will not pose significant ecological concerns to pesticides with low lipophilicity. The variability analysis showed that for certain pesticides, environmental factors (such as temperature and humidity) had a significant impact on the simulated residue concentrations in the soil as a result of plant waste disposal, which aided in the assessment of regional ecological risk as well as plant disposal management. Although some modeling aspects such as plant decomposition process, advanced plant uptake models, heterological distribution of residue concentrations in the soil, and plant waste stacking patterns require further research, the proposed approach can be used to assist in managing soil pesticides from plant waste disposal in preliminary stages.

Environmental fate and metabolic transformation of two non-ionic pesticides in soil: Effect of biochar, moisture, and soil sterilization

Soil moisture, organic matter, and soil microbes are the key considering factors that control the persistence, degradation, and transformation of applied pesticides under varied soil conditions. In this study, underlying influence of these factors was assessed through the fates and metabolic transformation of two non-ionic pesticides (e.g., Phorate and Terbufos) in soils. Concisely, two distinct experiments including a customized batch equilibrium (sorption study), and a lab incubation trial (degradation study) were performed, following the OECD guidelines. As per study findings, biochar (BC) amendment was found to be the most influential factors during sorption study, particularly, 1% BC amendment contributed to achieve the best results. In addition, the non-linearity of sorption isotherm (1/n < 1.0) was revealed through Freundlich isotherm, indicating the strong adsorption of studied pesticides onto the soils. On the other hand, during degradation study, soil moisture initiates the enhanced degradation of parent pesticides and subsequent metabolism. In the presence of 40% water holding capacity (WHC), 1% BC amendment enhances the metabolic transformation, while H2O2 treatment could hinder the process. Additionally, the half-life degradation (t1/2) of phorate and terbufos was controlled by biochar amendment, moisture, and soil sterilization, respectively. Finally, BC can accelerate the metabolic transformation, whereas, phorate underwent a metabolic change into sulfoxide and sulfone while terbufos turned into solely sulfoxide. This pioneering study gathered crucial data for understanding the persistence and metabolic transition of non-ionic pesticides in soils and their patterns of degradation.

Biosensors Technological Advancement and Their Biomedical, Agricultural, Environmental and Food Industrial Applications: A Review

The biosensors are devices that receive the biological message and convert it into a sensible electrical signal. The biosensing involves a combination of biological entities like DNA, RNA, and proteins/enzymes to the electrochemical transducers. Biosensors comprise a biorecognition element (enzyme, antigen, antibody or nucleic) that mediates selective biocatalysis or specific binding of analyte and transducers that able to measure the signal. There are several types of biosensors being employed today, such as optical, surface plasmon resonance, enzymes, DNA, Phage, and microbial biosensors. Now days biosensor technologies have been employed in biomedicine, food safety standards, defense and environmental monitoring. Detection of the lower or higher limits of glucose in the body, microbial invasion in the body and food, heavy metal detection in soil, water and airborne microbes, pesticides in water and soil and various harmful chemicals produced by body, can be easily and timely monitored with high precision using the different types of biosensors. Biosensors can overcome all the limitation of the traditional methods of chemical and microbiological analyses by offering rapid, non-destructive and affordable methods for quality control. Thus, this review paper highlights biosensor and its components, types of biosensors and its application in different disciplines.

Fermented biochar has a markedly different effect on fate of pesticides in soil than compost, straw, and a mixed biochar-product

Current knowledge about how biochars affect the fate of pesticides in soil is based on studies that used pure biochars. After finding that an additional biological post-pyrolysis treatment, such as co-composting or lactic fermentation, is required for biochars for superior performance in temperate arable soils, a knowledge gap formed of how such further processed biochar products would affect the fate of pesticides in soil. This study compared the effects of a novel fermented biochar alone or mixed with biogas residues on the fate of two pesticides, 4-chloro-2-methylphenoxyacetic acid (MCPA) and metalaxyl-M, in a temperate arable soil to the traditional organic amendments wheat straw and compost. The fate of 14C-labeled MCPA was markedly affected in different ways. Fermented biochar effectively reduced the water-extractability and mineralization due to adsorption that was comparable to adsorption strengths reported for pure biochars. However, this effect was weak for the biochar mixed with biogas residues. Straw reduced water-extractable amounts due to increased biodegradation and formation of likely biogenic non-extractable residues of MCPA. In contrast, compost decelerated mineralization and increased the water solubility of the MCPA residues due to released dissolved organic matter. The amendments' effects were minor regarding 14C-metalaxyl-M, except for the fermented biochar which again reduced water-extractability and delayed degradation due to adsorption. Thus, the effects of the organic amendments differed for the two pesticide compounds with only the fermented biochar's effect being similar for both. However, this effect was no longer present in the mixed product containing 20% biochar. Our findings clearly show that biologically treated biochar-containing products can affect the fate of pesticides in soil very differently, also when compared to traditional organic amendments. Such impacts and their desirable and undesirable ecotoxicological implications need to be considered before the large-scale application of biochars to temperate arable soils.

Pesticide Soil Pollution: An Overview about Advantages and Disadvantages of Different Remediation Technologies

The use of pesticides presents a looming danger to the living elements of our ecological system, crops, and the well-being of our species. As an outcome, various organic contaminants pollute the soil. Different physical, chemical, and biological remediation techniques have been employed for the decontamination of pesticide-polluted soils. Remediation technology should always be affordable, on-site or in-situ, and capable of restoring the soil's natural functionality. The presence of multiple pesticides can pose challenges in effectively remediating them from the soil. The present work examines the scientific literature on the benefits and drawbacks of various existing and emerging soil remediation techniques. Customized technology choices and designs for specific site conditions enhance the effective cleanup of polluted areas. The present study, which evaluates and contrasts various technological approaches, shall serve as an invaluable tool for determining the optimal soil remediation method for a given contamination dilemma.

Effects of mixed application of avermectin, imidacloprid and carbendazim on soil degradation and toxicity toward earthworms

The application of pesticides in mixtures often exerts multiple pressures on agricultural soils in the short term. Therefore, it is necessary to assess the effects of mixed application on the environmental behavior and ecotoxicity of pesticides in soil. In this study, we assessed the effects of three common pesticides through mixed application on soil degradation and toxicity toward the earthworm Eisenia fetida. Compared with the degradation half-lives (DT50) the single pesticide, the DT50 values of avermectin, imidacloprid and carbendazim in the binary mixtures were similar. However, their DT50 values in the ternary mixtures were approximately 1.5 times longer than those in the individual applications, enhancing their stable in soil after two or three applications. The ternary mixtures of the pesticides showed significantly synergistic toxicity toward E. fetida, while their binary mixtures exhibited a changing interaction throughout the entire effect level range. The ternary mixtures activated higher SOD and CAT activities in E. fetida than the individual treatments, confirming their synergistic effects. By conducting avoidance tests with E. fetida, ternary toxic interactions were effectively assessed within a relatively short testing period. In summary, the three pesticides in ternary mixtures exhibited longer degradation half-lives and synergistic toxicity toward earthworms compared to individual or binary mixtures.

In Vitro Biofilm-Mediated Biodegradation of Pesticides and Dye-Contaminated Effluents Using Bacterial Biofilms.

Overuse of pesticides in agricultural soil and dye-polluted effluents severely contaminates the environment and is toxic to animals and humans making their removal from the environment essential. The present study aimed to assess the biodegradation of pesticides (cypermethrin (CYP) and imidacloprid (IMI)), and dyes (malachite green (MG) and Congo red (CR)) using biofilms of bacteria isolated from pesticide-contaminated soil and dye effluents. Biofilms of indigenous bacteria, i.e., Bacillus thuringiensis 2A (OP554568), Enterobacter hormaechei 4A (OP723332), Bacillus sp. 5A (OP586601), and Bacillus cereus 6B (OP586602) individually and in mixed culture were tested against CYP and IMI. Biofilms of indigenous bacteria i.e., Lysinibacillus sphaericus AF1 (OP589134), Bacillus sp. CF3 (OP589135) and Bacillus sp. DF4 (OP589136) individually and in mixed culture were tested for their ability to degrade dyes. The biofilm of a mixed culture of B. thuringiensis + Bacillus sp. (P7) showed 46.2% degradation of CYP compared to the biofilm of a mixed culture of B. thuringiensis + E. hormaechei + Bacillus sp. + B. cereus (P11), which showed significantly high degradation (70.0%) of IMI. Regarding dye biodegradation, a mixed culture biofilm of Bacillus sp. + Bacillus sp. (D6) showed 86.76% degradation of MG, which was significantly high compared to a mixed culture biofilm of L. sphaericus + Bacillus sp. (D4) that degraded only 30.78% of CR. UV-VIS spectroscopy revealed major peaks at 224 nm, 263 nm, 581 nm and 436 nm for CYP, IMI, MG and CR, respectively, which completely disappeared after treatment with bacterial biofilms. Fourier transform infrared (FTIR) analysis showed the appearance of new peaks in degraded metabolites and disappearance of a peak in the control spectrum after biofilm treatment. Thin layer chromatography (TLC) analysis also confirmed the degradation of CYP, IMI, MG and CR into several metabolites compared to the control. The present study demonstrates the biodegradation potential of biofilm-forming bacteria isolated from pesticide-polluted soil and dye effluents against pesticides and dyes. This is the first report demonstrating biofilm-mediated bio-degradation of CYP, IMI, MG and CR utilizing soil and effluent bacterial flora from Multan and Sheikhupura, Punjab, Pakistan.

Integrating environmental carry capacity based on pesticide risk assessment in soil management: A case study for China

Pesticides are widely used in agriculture and can pose risks to soil health and environmental quality. This study assessed the occurrence, distribution, ecological risk, and environmental carrying capacity of 56 currently used pesticides and three metabolites in agricultural soils of Horqin Left Middle Banner, a typical Northeast China agricultural area. 29 pesticides were detected, with atrazine, clothianidin, and propiconazole the most common. Clothianidin and difenoconazole were high-risk to non-target organisms according to risk-toxicity exposure ratio and risk quotient approaches. This study provides a comprehensive and improvement framework for pesticide soil environmental carrying capacity (SECC) assessment and soil quality protection early warning. The SECC model showed no pesticides surpassed the soil carrying capacity threshold under the current application pattern. Five pesticides (clothianidin, difenoconazole, propiconazole, atrazine, and imidacloprid) may reach the threshold within 10 years, requiring pesticide reduction and soil quality monitoring. An early warning system based on SECC values and cumulative amounts of pesticides predicted that clothianidin may exceed the threshold within 0.1 years. These pesticides should be prioritized for management and regulation to prevent soil environmental degradation. The findings can help inform policymakers and stakeholders on pesticide management and sustainable agricultural development in Horqin Left Middle Banner and similar regions.

Empirical model to assess leaching of pesticides in soil under a steady-state flow and tropical conditions

An empirical model of leaching of pesticides was developed to simulate the concentration of fungicides throughout unsaturated soil. The model was based on chemical reactions and the travel time of a conservative tracer to represent the travel time required for water to flow between soil layers. The model’s performance was then tested using experimental data from dimethomorph and pyrimethanil applied to the soil under field and laboratory conditions. The empirical model simulated fungicide concentration on soil solids and in soil solution at different depths over time (mean square error between 2.9 mg2 kg−2 and 61mg2 kg−2) using sorption percentages and degradation rates under laboratory conditions. The sorption process was affected by the organic carbon, clay, and the effective cation exchange capacity of the soil. The degradation rate values of dimethomorph (0.039 d−1–0.009 d−1) and pyrimethanil (0.053 d−1–0.004 d−1) decreased from 0 to 40 cm and then remained constant in deeper soil layers (60–80 cm). Fungicide degradation was a critical input in the model at subsurface layers. The model was determined to be a reliable mathematical tool to estimate the leachability of pesticides in tropical soil under a steady-state flow. It may be extended to other substances and soils for environmental risk assessment projects.Graphical abstract