Adsorption of acetamiprid, chlorantraniliprole and flubendiamide on different type of microplastics present in alluvial soil

Investigating the impact of microplastics on triphenyl phosphate adsorption in soil: Insights into environmental factors and soil properties

Microplastics (MPs) pose significant environmental pollution problems owing to their diverse properties such as various shapes, sizes, compositions, surface features, and levels of degradation. Moreover, their interactions with toxic chemicals and aging processes add complexity to environmental research. This study investigated the adsorption of triphenyl phosphate (TPhP) in soil-only, MP-only, and soil-MP simulated environments under different conditions. The experiment involved three phases: initial exposure to a pH of 5.5 under fluorescent light, subsequent introduction of ultraviolet (UV) radiation, and pH adjustment to 4.0 and 7.0, while maintaining UV exposure, each lasting 7 days. The study found that environmental factors affected TPhP sorption capacity, with higher adsorption observed under UV radiation and acidic conditions. In contrast, the MP-only systems showed no clear trend for TPhP adsorption, suggesting kinetic limitations. When MPs were added to the soil, the adsorption dynamics were altered, with varying adsorption capacities observed for different MP polymers under different aging conditions. ATR-FTIR spectroscopy, micro-Raman spectroscopy, and water contact angle measurements suggested potential photooxidation processes and changes in the surface hydrophobicity of the MPs subjected to simulated environmental conditions. This study provides valuable insights into the interplay between soil properties, MP characteristics, and environmental factors in determining TPhP sorption dynamics in soil-MP environments.

Interactions of traditional and biodegradable microplastics with neonicotinoid pesticides

Neonicotinoid pesticides (NNPs) and microplastics (MPs) are two emerging contaminants in agricultural environment. However, the interaction between MPs (especially biodegradable plastics) and NNPs is currently unclear. Therefore, taking thiacloprid (THI) as an example of NNPs, this study explores the adsorption-desorption process and mechanism of NNPs on MPs (traditional and biodegradable plastics), and analyzed the main factors affecting the adsorption (pH, salinity and dissolved organic matter). In addition, by using diffusive gradients in thin-films device, this study assessed the impact of MPs on the bioavailability of NNPs in soil. The results showed that the maximum adsorption capacity of polyamide 6 (96.49 μg g-1) for THI was greater than that of poly (butylene adipate co-terephthalate) (88.78 μg g-1). Aging increased the adsorption amount of THI (5.53 %-15.8 %) due to the higher specific surface area and reduced contact angle of MPs, but the adsorption mechanism remained unchanged. The desorption amount of THI from MPs in simulated intestinal fluid is 1.30-1.36 times. The MPs in soil alter the distribution of THI in the soil, increasing the bioavailability of THI while inhibiting its degradation. The results highlighted the significance of examining the combined pollution caused by MPs and NNPs.

Microplastics in agroecosystems: Soil-plant dynamics and effective remediation approaches

Increasing microplastic (MP) pollution, primarily from anthropogenic sources such as plastic film mulching, waste degradation, and agricultural practices, has emerged as a pressing global environmental concern. This review examines the direct and indirect effects of MPs on crops, both in isolation and in conjunction with other contaminants, to elucidate their combined toxicological impacts. Organic fertilizers predominantly contain 78.6% blue, 9.5% black, and 8.3% red MPs, while irrigation water in agroecosystems contains 66.2% white, 15.4% blue, and 8.1% black MPs, ranging from 0-1 mm to 4-5 mm in size. We elucidate five pivotal insights: Firstly, soil MPs exhibit affinity towards crop roots, seeds, and vascular systems, impeding water and nutrient uptake. Secondly, MPs induce oxidative stress in crops, disrupting vital metabolic processes. Thirdly, leachates from MPs elicit cytotoxic and genotoxic responses in crops. Fourthly, MPs disrupt soil biotic and abiotic dynamics, influencing water and nutrient availability for crops. Lastly, the cumulative effects of MPs and co-existing contaminants in agricultural soils detrimentally affect crop yield. Thus, we advocate agronomic interventions as practical remedies. These include biochar input, application of growth regulators, substitution of plastic mulch with crop residues, promotion of biological degradation, and encouragement of crop diversification. However, the efficacy of these measures varies based on MP type and dosage. As MP volumes increase, exploring alternative mitigation strategies such as bio-based plastics and environmentally friendly biotechnological solutions is imperative. Recognizing the persistence of plastics, policymakers should enact legislation favoring the mitigation and substitution of non-degradable materials with bio-derived or compostable alternatives. This review demonstrates the urgent need for collective efforts to alleviate MP pollution and emphasizes sustainable interventions for agricultural ecosystems.

Mechanistic interpretation of the sorption of terbuthylazine pesticide onto aged microplastics

Microplastics (MPs) pose a global concern due to their ubiquitous distribution. Once in the environment, they are subject to aging, which changes their chemical-physical properties and ability to interact with organic pollutants, such as pesticides. Therefore, this study investigated the interaction of the hydrophobic herbicide terbuthylazine (TBA), which is widely used in agriculture, with artificially aged polyethylene (PE) MP (PE-MP) to understand how aging affects its sorption. PE was aged by an accelerated weathering process including UV irradiation, hydrogen peroxide, and ultrasonic treatment, and aged particles were characterized in comparison to pristine particles. Sorption kinetics were performed for aged and pristine materials, while further sorption studies with aged PE-MP included determining environmental factors such as pH, temperature, and TBA concentration. Sorption of TBA was found to be significantly lower on aged PE-MP compared to pristine particles because aging led to the formation of oxygen-containing functional groups, resulting in a reduction in hydrophobicity and the formation of negatively charged sites on oxidized surfaces. For pristine PE-MP, sorption kinetics were best described by the pseudo-second-order model, while it was intra-particle diffusion for aged PE-MP as a result of crack and pore formation. Sorption followed a decreasing trend with increasing pH, while it became less favorable at higher temperatures. The isotherm data revealed a complex sorption process on altered, heterogeneous surfaces involving hydrophobic interactions, hydrogen bonding, and π-π interactions, and the process was best described by the Sips adsorption isotherm model. Desorption was found to be low, confirming a strong interaction. However, thermodynamic results imply that increased temperatures, such as those resulting from climate change, could promote the re-release of TBA from aged PE-MP into the environment. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) confirmed TBA sorption onto PE.

Combined effects of mulch film-derived microplastics and pesticides on soil microbial communities and element cycling

Pesticides and microplastics (MPs) derived from mulch film in agricultural soil can independently impact soil ecology, yet the consequences of their combined exposure remain unclear. Therefore, the effects of simultaneous exposure to commonly used pesticides (imidacloprid and flumioxazin) and aged mulch film-derived MPs on soil microorganisms and element cycles in cotton fields were investigated. The combined exposure influenced soil microorganisms, alongside processes related to carbon, nitrogen, and phosphorus cycles, exhibiting effects that were either neutralized or enhanced compared to individual exposures. The impact of pesticides in combined exposure was notably more significant and played a dominant role than that of MPs. Specifically, combined exposure intensified changes in soil bacterial community and symbiotic networks. The combined exposure neutralized NH4+, NO3-, DOC, and A-P contents, shifting from 0.33 % and 40.23 % increase in MPs and pesticides individually to a 40.24 % increase. Moreover, combined exposure resulted in the neutralization or amplification of the nitrogen-fixing gene nifH, nitrifying genes (amoA and amoB), and denitrifying genes (nirS and nirK), the carbon cycle gene cbbLG and the phosphorus cycle gene phoD from 0.48 and 2.57-fold increase to a 2.99-fold increase. The combined exposure also led to the neutralization or enhancement of carbon and nitrogen cycle functional microorganisms, shifting from a 1.53-fold inhibition and 10.52-fold increase to a 6.39-fold increase. These findings provide additional insights into the potential risks associated with combined pesticide exposure and MPs, particularly concerning soil microbial communities and elemental cycling processes.

A bibliometric analysis of global research hotspots and progress on microplastics in soil‒plant systems

Plastic pollution has become a global and persistent challenge, posing threats to ecosystems and organisms. In recent years, there has been a rapid increase in scientific research focused on understanding microplastics in the soil‒plant system. This surge is primarily driven by the direct impact of microplastics on agricultural productivity and their association with human activities. In this study, we conducted a comprehensive bibliometric analysis to provide an overview of the current research on microplastics in soil‒plant systems. We systematically analysed 192 articles and observed a significant rise in research interests since 2017. Notably, China has emerged as a leading contributor in terms of published papers, closely followed by Germany and the Netherlands. Through co-authorship network analysis, we identified 634 different institutions that participated in publishing papers in this field, with the Chinese Academy of Sciences having the most collaborations. In the co-occurrence keyword network, we identified four clusters focusing on the diversity of microplastics within the agroecosystem, transportation, and quantification of microplastics in soil, analysis of plastic contamination type and impact, and investigation of microplastic phytotoxicity. Furthermore, we identified ten research priorities, categorized into the effects of microplastics in "soil" and "plant". The research hotspots were found to be the effect of microplastics on soil physicochemical properties and the synergistic phytotoxicity of microplastics with other pollutants. Overall, this bibliometric analysis holds significant value, serving as an important reference point and offering valuable suggestions for future researchers in this rapidly advancing field.

Adaptation of the metolachlor-degrading fungus Trichoderma harzianum to the simultaneous presence of low-density polyethylene (LDPE) microplastics

Although it is known that microplastics (MPs) in soils cause a threat to this complex environment, the actual effects of MPs on soil microorganisms and their catabolic activities, particularly with the biodegradation of herbicides, remain unclear. Hence, the objective of this study was to investigate the effects of a simultaneous presence of metolachlor and low-density polyethylene (LDPE) microplastics on growth inhibition and adaptive responses of Trichoderma harzianum in soil microcosms. Using ergosterol content as an indicator of fungal biomass, it was observed that MPs alone had a marginal inhibitory effect on the growth of the fungus, whereas MET exhibited a dose-dependent inhibitory effect on T. harzianum. However, the presence of MPs did not influence the fungal transforming activity toward the herbicide. Conversely, analysis of lipid profiles in the presence of MPs and herbicides revealed a reduction in the overall fluidity of phospholipid fatty acids, primarily attributed to an increase in lysophospholipids. The activities of six extracellular enzymes in the soil, measured using methylumbelliferone-linked substrates, were significantly enhanced in the presence of MET. These findings contribute to a broader understanding of the alterations in fungal activity in soil resulting from the influence of MPs and MET.

Sorption of ionic liquids in soil enriched with polystyrene microplastic reveals independent behavior of cations and anions

Recently, much attention has been focused on the application of the Ionic Liquids (ILs) with herbicidal activity in agriculture. It has been suggested that through the appropriate selection of cations and anions, one can adjust the properties of ILs, particularly the hydrophobicity, solubility, bioavailability, toxicity. In practical agricultural conditions, it will be beneficial to reduce the mobility of herbicidal anions, such as the commonly applied 2,4-dichlorophenoxyacetic acid [2,4-D] in the soil. Furthermore, microplastics are becoming increasingly prevalent in the soil, potentially stimulating herbicidal sorption. Therefore, we investigated whether cations in ILs influence the mobility of anions in OECD soil supplemented with polystyrene microplastic (PS). For this purpose, we used the 2,4-D based ILs consisting of: a hydrophilic choline cation [Chol][2,4-D] and a hydrophobic choline cation with a C12chain [C12Chol][2,4-D]. Characterization of selected micropolystyrene was carried out using the BET sorption-desorption isotherm, particle size distribution and changes in soil sorption parameters such as soil sorption capacity and cation exchange capacity. Based on the batch sorption experiment, the effect of microplastic on the sorption of individual cations and anions in soil contaminated with micropolystyrene was evaluated. The results obtained indicate that the introduction of a 1-10% (w/w) PS resulted in an 18-23% increase of the soil sorption capacity. However, the sorption of both ILs' cations increased only by 3-5%. No sorption of the [2,4-D] anion was noted. This suggests that cations and anions forming ILs, behave independently of each other in the environment. The results indicate the fact that ILs upon introduction into the environment are not a new type of emerging contaminant, but rather a typical mixture of ions. It is worth noting that when analyzing the behavior of ILs in the environment, it is necessary to follow the fate of both cations and anions.

Quantification and characterization of microplastics (MPs) pollution in peri-uburban agricultural lands of Lahore, Pakistan

Microplastics (MPs) contaminate every conceivable terrestrial and aquatic environment including high peaks and deep marine trenches. Agricultural lands alone are expected to receive plastic up to 23 times more than ocean basins. In this study, soil samples were collected from peri-urban agricultural lands of Lahore on four sides including Kala Shah Kaku (KSK), Punjab University (PU), Dera Gujran (DG), and Sagian (SG). National Oceanic and Atmospheric Administration (NOAA) protocol was used for MPs extraction and analysis. Extracted MPs were analyzed under microscope at 40X magnification and their composition was analyzed using Fourier Transform Infrared (FTIR) spectroscopy. A considerable concentration of MPs was recorded at all sites. The highest contamination was found at SG with 876 ±194 MPs/kg of soil, and the lowest contamination was recorded at PU with 672 ±235 MPs/kg of soil. However, these differences among the sites were not statistically significant (p = 0.29). The overall predominant shape of MPs was fibers (613±71, 79.73%) followed by sheets (125±55, 16.28%), fragments (30±5, 3.9%) and foam particles (1±2, .09%). The differences in the distribution of MPs in various types were statistically significant (p = 0), while differences between sites were insignificant (p = 0.13). About 95% of MPs were less than 2 mm and 85% were less than 1 mm size. The distribution of MPs in various sizes (p = 0) and differences of this distribution between sites (p = 0.037) were both statistically significant. A good diversity of nine colored MPs was recorded, however majority of the MPs were transparent (89.57%). Six polymer including Polyethylene (PE), Polyethylene terephthalate (PET), Polypropylene (PP), Polystyrene (PS), Polycarbonate (PC), and Polyvinyl Chloride (PVC) were identified by FTIR. The current levels of MPs pollution are higher than in many other parts of the world. Composition of MPs (types, colors, sizes, and polymer types) indicates the diversity of their sources and their possible implications on agricultural ecosystem.

The Microplastics Iceberg: Filling Gaps in Our Understanding

Plastic is an indispensable material in modern society; however, high production rates combined with inadequate waste management and disposal have resulted in enormous stress on ecosystems. In addition, plastics can become smaller particles known as microplastics (MPs) due to physical, chemical, and biological drivers. MP pollution has become a significant environmental problem affecting terrestrial and aquatic ecosystems worldwide. Although the topic is not entirely new, it is of great importance to the field of polymers, drawing attention to specific gaps in the existing literature, identifying future areas of research, and improving the understanding of MP pollution and its environmental impacts. Despite progress in this field, problems remain. The lack of standardized methods for MP sampling, separation, extraction, and detection makes it difficult to collect information and establish links between studies. In addition, the distribution and pathways of MPs in ecosystems remain unknown because of their heterogeneous nature and the complex matrices in which they occur. Second, toxicological tests showed that MPs can be ingested by a wide range of organisms, such as Danio rerio and Eisenia fetida, resulting in gut obstruction, physical damage, histological changes, and oxidative stress. The uptake of MP and their toxicological effects depend on their shape, size, concentration, and polymer composition. Furthermore, MPs can enter the food chain, raising concerns regarding potential contaminations for human and environmental health. This review paper sheds light on the pressing issue of MP pollution and highlights the need for interdisciplinary collaboration between scientists, policymakers, and industry leaders.

Photo-aged non-biodegradable and biodegradable mulching film microplastics alter the interfacial behaviors between agricultural soil and inorganic arsenic

The impacts of microplastics (MPs) prevalent in soil on the transport of pollutants were urged to be addressed, which has important implications for ecological risk assessment. Therefore, we investigated the influence of virgin/photo-aged biodegradable polylactic acid (PLA) and non-biodegradable black polyethylene (BPE) mulching films MPs on arsenic (As) transport behaviors in agricultural soil. Results showed that both virgin PLA (VPLA) and aged PLA (APLA) enhanced the adsorption of As(Ⅲ) (9.5%, 13.3%) and As(Ⅴ) (22.0%, 6.8%) due to the formation of abundant H-bonds. Conversely, virgin BPE (VBPE) reduced the adsorption of As(Ⅲ) (11.0%) and As(Ⅴ) (7.4%) in soil owing to the "dilution effect", while aged BPE (ABPE) improved arsenic adsorption amount to the level of pure soil due to newly generated O-containing functional groups being feasible to form H-bonds with arsenic. Site energy distribution analysis indicated that the dominant adsorption mechanism of arsenic, chemisorption, was not impacted by MPs. The occurrence of biodegradable VPLA/APLA MPs rather than non-biodegradable VBPE/ABPE MPs resulted in an increased risk of soil accumulating As(Ⅲ) (moderate) and As(Ⅴ) (considerable). This work uncovers the role of biodegradable/non-biodegradable mulching film MPs in arsenic migration and potential risks in the soil ecosystem, depending on the types and aging of MPs.

A critical review on interaction of microplastics with organic contaminants in soil and their ecological risks on soil organisms

The pollution of microplastics (MPs) in soil has become a global environmental problem. Due to high sorption capacity and persistence in environment, the MPs exhibit combined effects with organic pollutants in soil, thereby posing a potential risk to soil ecology and human health. However, limited reviews are available on this subject. Therefore, in response to this issue, this review provides an in-depth account of interaction of MPs with organic contaminants in soil and the combined risks to soil environment. The sorption of organic contaminants onto MPs is mainly through hydrophobic and π-π interactions, hydrogen bonding, pore filling and electrostatic and van der Waals forces. The intrinsic characteristics of MPs, organic contaminants and soil are the key factors influencing the sorption of organic pollutants onto MPs. Importantly, the presence of MPs changes the sorption, degradation and transport behaviors of organic contaminants in soil, and affects the toxic effects of organic contaminants on soil organisms including animals, plants and soil microorganisms through synergistic or antagonistic effects. Source control, policy implementation and plastic removal are the main preventive and control measures to reduce soil MPs pollution. Finally, priorities for future research are proposed, such as field investigations of co-pollution, contribution of plastisphere to organic contaminant degradation, and mechanisms of MPs effects on organic contaminant toxicity.

Microplastics mulch film affects the environmental behavior of adsorption and degradation of pesticide residues in soil

Plastic pollution in the soil ecosystem is currently receiving worldwide attention. However, little is known whether the presence of microplastics (MPs) in soil will affect the environmental behavior of pesticide residues in soil. Here, the effect of the addition of new mulch MPs (New-MPs), aged mulch MPs (Aged-MPs) and biodegradable mulch MPs (BioD-MPs) on the adsorption and degradation behaviors of two pesticides (imidacloprid and flumioxazin) in soil was investigated. Three MPs slowed down rapid adsorption stage of pesticides in soil and delayed the time to reach adsorption equilibrium. Adsorption rates: Soil > Soil + New-MPs > Soil + Aged-MPs > Soil + BioD-MPs. Three MPs enhanced the adsorption strength of the soil system for the two pesticides, and the aging treatment of the MPs enhanced this effect. Three MPs affected the degradation process of the two pesticides. New-MPs promoted the degradation of two pesticides imidacloprid and flumioxazin, and the degradation half-lives were shortened to 0.93 and 0.85 times, respectively; while Aged-Mps and BioD-MPs delayed the degradation process of two pesticides, and the degradation half-lives were extended to 1.64 times and 1.21 times, respectively. The effect was more significant with the increase of MPs and pesticides concentration. Pesticide polarity, surface structure and functional groups of MPs are potentially important reasons for the differences in adsorption and degradation of MPs-soil systems. Our findings provide a deep insight into understanding the mechanism of interaction between MPs and pesticide residues in soil environment.

Pesticide soil microbial toxicity: setting the scene for a new pesticide risk assessment for soil microorganisms (IUPAC Technical Report)

Pesticides constitute an integral part of modern agriculture. However, there are still concerns about their effects on non-target organisms. To address this the European Commission has imposed a stringent regulatory scheme for new pesticide compounds. Assessment of the aquatic toxicity of pesticides is based on a range of advanced tests. This does not apply to terrestrial ecosystems, where the toxicity of pesticides on soil microorganisms, is based on an outdated and crude test (N mineralization). This regulatory gap is reinforced by the recent methodological and standardization advances in soil microbial ecology. The inclusion of such standardized tools in a revised risk assessment scheme will enable the accurate estimation of the toxicity of pesticides on soil microorganisms and on associated ecosystem services. In this review we (i) summarize recent work in the assessment of the soil microbial toxicity of pesticides and point to ammonia-oxidizing microorganisms (AOM) and arbuscular mycorrhizal fungi (AMF) as most relevant bioindicator groups (ii) identify limitations in the experimental approaches used and propose mitigation solutions, (iii) identify scientific gaps and (iv) propose a new risk assessment procedure to assess the effects of pesticides on soil microorganisms.

Accumulation of chiral pharmaceuticals (ofloxacin or levofloxacin) onto polyethylene microplastics from aqueous solutions

Drug chirality is attracting increasing attention because the enantiomers of the same chiral pharmaceutical usually exhibit different biological activities, metabolic pathways, and toxicities. The ubiquitous presence of microplastics (MPs) can enrich organic pollutants commonly found in the environment. However, knowledge about the enrichment of pharmaceutical enantiomers to MPs is relatively limited. We investigated the occurrence of enantioselectivity of ofloxacin (OFL) and levofloxacin (LEV) in the adsorption processes on polyethylene (PE) and the interactions influenced by environmental factors. The results showed that the adsorption efficiency of OFL was generally 3-5% (p < 0.05) higher than that of LEV, indicating the different affinities of the enantiomers to PE, but the adsorption process of OFL and LEV on PE was both well described by pseudo-first-order kinetics and liner isotherm models. The chirality of OFL and LEV was not affected by sizes of PE particles and solution salinity due to the identical physicochemical properties. An examination of pH effect indicated that OFL showed better acid-base adaptability than LEV. Moreover, the differences in enantiomeric enrichment between OFL and LEV on PE were promoted with increasing UV light exposure time and natural organic matter (NOM) concentrations. Using Fourier transform infrared spectroscopy (FTIR), we demonstrated that the constituents of the functional groups in chiral NOM were greatly related to the enantiomer stereoselectivity of OFL, subsequently affecting their adsorption in a chiral environment. The excitation-emission matrix (EEM) spectra confirmed the enantioselective behaviors of chiral pharmaceuticals under UV light due to the different optical activity and humic acid-like and fulvic acid-like molecular structure of the enantiomers. These findings imply that the enantioselectivity of drug enantiomers should be considered in presence of microplastics, leading to a more accurate environmental fate and risks assessments of chiral pharmaceuticals.

Detection of trizole contaminated waste water using biocatalyst and effective biodegradation potential of flubendiamide

Flubendiamide is a new class of chemical pesticide with broad spectrum activity against lepidopteran pests. Due to limited approach and high specificity towards various non targeted organisms, the unrestricted application of this pesticide as a prominent alternate for organochlorine and organophosphate pesticides, causing serious environmental pollution. In this study, wastewater was used for the determination of microbial strains and pesticide degrading fungi. Microbial population and flubendiamide resistant fungal strains were characterized using enriched medium. Aerobic bacteria (6.38 ± 0.23 log CFU/mL), nitrifying bacteria (2.73 ± 0.31 CFU/mL), Lactobaillus (0.72 ± 0.03 log CFU/mL), actinomycetes (5.36 ± 0.27 log CFU/mL) and fungi (4.79 ± 0.22 log CFU/mL) were detected. The prominent fungi genera were, Fusarium, Trichoderma, Cladophialophora, Paecilomyces, Talaromyces, Penicillium, Aspergillus, Candida, Phyllosticta, Mycosphaerella, Ochroconis, and Mucor. Minimum inhibitory concentration of the rapidly growing organism (FR04) revealed its ability to tolerate up to 1250 mg/L flubendiamide concentration. Morphological, biochemical and molecular analysis revealed that the strain was Aspergillus terreus FR04. The residual pesticide was detected using a High Performance Liquid Chromatography (HPLC). High performance liquid chromatography analysis revealed that 89 ± 1.9% pesticide removal efficiency was observed in strain FR04 at optimized culture conditions (96 h, pH 6.5, 30 °C and 300 mg/L pesticide concentration). The strain FR04 degraded pollutants from the wastewater and improved water quality. A. terreu sFR04 is an indigenous fungus and has the ability to degrade trizole pesticides from the wastewater significantly.

MFI, BEA and FAU zeolite scavenging role in neonicotinoids and radical species elimination

Ecotoxicity caused by neonicotinoid pesticides is largely due to oxidative stress on non-target species. Due to the fact that reactive radical species reach the environment, materials intended for pesticide removal should be applicable for the simultaneous removal of reactive radicals, as well. This work uses the spectroscopic, adsorptive and antioxidant responses from MFI, FAU and BEA zeolites as descriptors of their potential environmental importance. Different network structures and Si/Al ratios were correlated with excellent zeolite adsorption properties, as over 200 mg g^-1 of investigated neonicotinoids, acetamiprid and imidacloprid, was achieved in one cycle. Additionally, after two regeneration steps, over 450 mg g^-1 adsorbed pesticides were retained, in three adsorption cycles. Overall the best results were detected for the FAU zeotype in both tested applications, insecticide adsorption and radical-scavenging performance, with and without insecticides present. The proposed mechanism for adsorption relies on kinetic investigation, isotherm modelling and spectroscopic post-adsorption analysis and targets zeolite hydroxyl/siloxane groups as active sites for insecticide adsorption via hydrogen bonding. Neat, well-defined zeolite structures enable their prospective application in ecotoxic species removal.

Microplastics in Asian freshwater ecosystems: Current knowledge and perspectives

Plastic pollution in freshwater ecosystems, including microplastics (MPs) smaller than 5 mm, has become an emerging global concern. Asia is considered a "hot spot" for plastic pollution due to rapid economic and demographic growth, together with rapid urbanization. Here, we provide an overview of the current knowledge on MP abundance, sources, fate, and transfer in Asian freshwater ecosystems based on publications from January 2014 to May 2021. MP contamination in freshwater compartments, including water, sediment, and biota, was found to vary strongly. In water, it ranged from 0.004 items m^-3 in a moderately urbanized region to more than 500,000 items m^-3 in a dumping river in a highly populated watershed. In the sediment, MP abundance ranged from 1 to more than 30,000 items kg^-1 dry weight. Polyethylene (PE) and polypropylene (PP) were predominant in both water and sediment compartments. MP was detected in biota samples from all the studied species, but their abundance depended on the locations and species studied. Overall, MP characteristics (form, size, color, and polymer type) depended on sources and natural constraints (mainly hydrodynamics). This study also revealed that MP in Asian freshwater ecosystems mainly originated from domestic wastewater/runoff, followed by industrial emissions, fisheries and aquaculture wastewater. Plastic waste is not efficiently recycled or incinerated in Asia, leading to MP transfer and accumulation in the aquatic environment, and, more importantly, to ingestion by low to high trophic level organisms. This work highlights several knowledge gaps to guides future research to improve MP pollution management for the sustainable development of highly populated regions such as Asia.

Adsorption behaviors and mechanisms of antibiotic norfloxacin on degradable and nondegradable microplastics

The misuse of both antibiotics and plastics significantly increases the environmental pollution problems associated with these contaminants. Moreover, microplastics can adsorb other pollutants in the environment. However, the mechanisms of antibiotic adsorption by degradable and nondegradable microplastics are not completely understood. In this study, we investigated the environmental behavior of norfloxacin (NOR) using polybutylene succinate (PBS), which is a degradable microplastic, and compared it with conventional microplastics, polystyrene (PS) and polyethylene (PE). The order of adsorption capacity was PS > PBS ≫ PE. The adsorption behavior fitted well with the pseudo-second-order kinetic and Langmuir isotherm models, indicating monolayer adsorption. The process is thermodynamically endothermic and non-spontaneous and is controlled by chemical and physical mechanisms, including π-π conjugation, hydrogen bonds, ion exchange, and electrostatic interactions. The adsorption capacity of microplastics was higher when the solution pH was around the pKa value of NOR than at other pH values. Ionic strength and dissolved organic matter inhibited the adsorption process. For PS and PBS, the amount of NOR adsorbed onto MPs initially decreased and then increased with the increase of coexisting heavy metal ions. Zn²⁺ and Pb²⁺ could promote the adsorption of NOR by PE. This study reveals the interaction mechanisms between microplastics and antibiotics and provides a more comprehensive theoretical basis for an ecological environmental risk assessment of different microplastics.

Revisiting pesticide pollution: The case of fluorinated pesticides

Fluorinated pesticides acquired a significant market share in the agrochemical sector due to the surge of new fluoroorganic ingredients approved in the last two decades. This growing trend has not been accompanied by a comprehensive scientific and regulatory framework entailing all their potential negative impacts for the environment, especially when considering the hazardous properties that may result from the incorporation of fluorine into organic molecules. This review aims to address the safe/hazardous dichotomy associated with fluorinated pesticides by providing an updated outlook on their relevancy in the agrochemical sector and how it leads to their role as environmental pollutants. Specifically, the environmental fate and distribution of these pesticides in the ecosystems is discussed, while also analysing their potential to act as toxic substances for non-target organisms.

Do microplastics mediate the effects of chemicals on aquatic organisms?

Microplastics are ubiquitous in both marine and freshwater ecosystems, where they can act as a physical contaminant, as well as interact with chemicals present in the environment. It has been suggested that chemical contaminants can sorb to microplastics, such that microplastics act as a vector for chemicals into aquatic biota and enhance their negative effects. It has been repeatedly suggested that the main factors underpinning the binding of chemicals to microplastics are hydrophobic partitioning and the size of microplastic particles. Therefore, we used the hydrophobicity of chemicals, as log K_ow, as well as the size of microplastic particles to conduct a quantitative analysis of published results to evaluate the influence of microplastics on chemical toxicity. We collated data from 39 laboratory studies that assessed the effects of microplastics, chemicals and their combination on several ecotoxicological responses of freshwater and marine organisms. Each chemical was assigned the relevant octanol / water partition coefficient (log K_OW) as a measure of its hydrophobicity, and the mean size of microplastics particles used in each study was recorded. We found no effect of log K_OW or the size of microplastic particles on the interaction between microplastics and chemicals with regards to any of the relevant ecotoxicological responses (behaviour, growth, survival and cellular) considered in this study. These findings are significant in showing that the effect of microplastics on the toxicity of chemicals is more complex than just considering hydrophobicity of chemicals and size of microplastics. We call for more mechanistic experiments to motivate a robust risk assessment and mitigation of microplastic toxicity in the environment.

Simply Applicable Method for Microplastics Determination in Environmental Samples

Microplastics (MPs) have gained significant attention in the last two decades and have been widely researched in the marine environment. There are, however, less studies on their presence, routes of entry, and impacts on the biota in the soil environment. One of the main issues in the study of MPs is a lack of standardized methods for their identification in environmental samples. Currently the most commonly used techniques are thermal desorption gas chromatography–mass spectrometry (GC–MS) methods and pyrolysis followed by GC–MS. In this study, headspace-solid phase microextraction followed by GC–MS is proposed as a simple and widely applicable method for the determination of commonly present polymer MPs (polyethylene terephthalate, polystyrene, polyvinyl chloride, polyethylene, and polypropylene) in environmental samples, for analytical laboratories with basic equipment worldwide. The proposed method is based on the identification of compounds, which are formed during the well-controlled melting process of specific coarse (1–5 mm) and fine fraction (1 mm–100 μm) MPs. The method was upgraded for the identification of individual polymer type in blends and in complex environmental matrices (soil and algae biomass). The successful application of the method in complex matrices makes it especially suitable for widescale use.

Sorption of chemical contaminants on degradable and non-degradable microplastics: Recent progress and research trends

Microplastics (<5 mm) are ubiquitous contaminants of growing concern. These have been found in multiple environmental compartments, including remote sites where anthropogenic activity is null. Once released, microplastics interact with multiple chemicals in the environment, many of which are classified as organic contaminants or heavy metals. Some contaminants have an affinity for microplastics, attributed to certain sorption mechanisms, and thus become vectors of hazardous chemicals. Here, we focused on the sorption behavior of degradable and non-degradable microplastics, including field and laboratory experiments. We reviewed the sorption mechanisms, namely hydrophobic interactions, electrostatic interactions, pore-filling, Van der Waals forces, hydrogen bonding, and π-π interactions, and the factors strengthening or weakening these mechanisms. Then, we analyzed the literature investigating the sorption behavior of a wide range of chemicals contaminants on microplastics, and the current knowledge regarding the occurrence of organic contaminants and heavy metals on microplastics extracted from the environment. The future perspectives and research priorities were discussed. It is apparent that degradable microplastics, such as polylactic acid or polybutylene succinate, have a greater affinity for hydrophobic contaminants than conventional synthetic non-degradable microplastics according to recent studies. However, studies assessing degradable microplastics are scarce and much research is required to further prove this point. We stated several knowledge gaps in this new line of research and suggest the future studies to follow an integrative approach, allowing to comprehend the multiple factors involved, such as ecotoxicity, bioaccumulation, and fate of the chemical contaminants.