Interactions between Iron Minerals and Dissolved Organic Matter Derived from Microplastics Inhibited the Ferrihydrite Transformation as Revealed at the Molecular Scale.

Microplastic-derived dissolved organic matter (MP-DOM) is an emerging carbon source in the environment. Interactions between MP-DOM and iron minerals alter the transformation of ferrihydrite (Fh) as well as the distribution and fate of MP-DOM. However, these interactions and their effects on both two components are not fully elucidated. In this study, we selected three types of MP-DOM as model substances and utilized Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and extended X-ray absorption fine structure (EXAFS) spectroscopy to characterize the structural features of DOMs and DOM-mineral complexes at the molecular and atomic levels. Our results suggest that carboxyl and hydroxyl groups in MP-DOM increased the Fe-O bond length by 0.02-0.03 Å through interacting with Fe atoms in the first shell, thereby inhibiting the transformation of Fh to hematite (Hm). The most significant inhibition of Fh transformation was found in PS-DOM, followed by PBAT-DOM and PE-DOM. MP-DOM components, such as phenolic compounds and condensed polycyclic aromatics (MW > 360 Da) with high oxygen content and high unsaturation, exhibited stronger mineral adsorption affinity. These findings provide a profound theoretical basis for accurately predicting the behavior and fate of iron minerals as well as MP-DOM in complex natural environments.

High-Resolution Mass Spectrometry Combined with Reactive Oxygen Species Reveals Differences in Photoreactivity of Dissolved Organic Matter from Microplastic Sources in Aqueous Environments.

Microplastics (MPs)-derived dissolved organic matter (MPs-DOM) is becoming a non-negligible source of DOM pools in aquatic systems, but there is limited understanding about the photoreactivity of different MPs-DOM. Herein, MPs-DOM from polystyrene (PS), polyethylene terephthalate (PET), poly(butylene adipate-co-terephthalate) (PBAT), PE, and polypropylene (PP), representing aromatic, biodegradable, and aliphatic plastics, were prepared to examine their photoreactivity. Spectral and high-resolution mass spectrometry analyses revealed that PS/PET/PBAT-DOM contained more unsaturated aromatic components, whereas PE/PP-DOM was richer in saturated aliphatic components. Photodegradation experiments observed that unsaturated aromatic molecules were prone to be degraded compared to saturated aliphatic molecules, leading to a higher degradation of PS/PET/PBAT-DOM than PE/PP-DOM. PS/PET/PBAT-DOM was mainly degraded by hydroxyl (•OH) via attacking unsaturated aromatic structures, whereas PE/PP-DOM by singlet oxygen (1O2) through oxidizing aliphatic side chains. The [•OH]ss was 1.21-1.60 × 10-4 M in PS/PET/PBAT-DOM and 0.97-1.14 × 10-4 M in PE/PP-DOM, while the [1O2]ss was 0.90-1.35 × 10-12 and 0.33-0.44 × 10-12 M, respectively. This contributes to the stronger photoreactivity of PS/PET/PBAT-DOM with a higher unsaturated aromatic degree than PE/PP-DOM. The photodegradation of MPs-DOM reflected a decreasing tendency from aromatic-unsaturated molecules to aliphatic-saturated molecules. Special attention should be paid to the photoreactivity and environmental impacts associated with MPs-DOM containing highly unsaturated aromatic compounds.

Microplastics in Qinghai-Tibet Plateau and Yunnan-Guizhou Plateau lakes, China.

As an emerging environmental pollutant, microplastics (MPs) have received widespread attention. Recently, studies examining microplastic pollution in plateau lakes have been increasing, but few have examined the distributions, sources, and fates of MPs in different plateau areas. In this work, the abundances and characteristics of MPs in surface waters and sediments in lakes of the Qinghai-Tibet Plateau (QTP) and Yunnan-Guizhou Plateau (YGP) were systematically investigated. The abundances of MPs in the lakes of the QTP ranges within 0.05-1.8 n/L in surface waters and 10-2643.7 n/kg in sediments. In the lakes of the YGP, the abundances of MPs ranged within 1.3-10.1 n/L in surface waters and 171.7-4260 n/kg in sediments. The dominant shape, color, and size class of MPs were fiber, transparent, and 0-0.5 mm in plateau lakes, respectively. MPs were mainly composed of polypropylene, polyethylene, and polyethylene terephthalate polymers. The different sources of MPs in the QTP and YGP lakes were mainly due to differences in human activities. The primary sources of microplastic pollution in the lakes of the QTP were tourism and atmospheric transport, while sewage discharge, agriculture, and fishing activities were the main sources of MPs in urban lakes of the YGP. Although the level of microplastic pollution in plateau lakes was relatively low, the sources should be identified and monitored so that the effects and extent of microplastic pollution in these fragile environments can be fully understood. This study provides a valuable dataset and theoretical basis for subsequent research on microplastic pollution in plateau lakes.

Insight into interactions between microplastics and fulvic acid: Mechanisms affected by microplastics type.

Microplastics (MPs) can interact with dissolved organic matter (DOM), a common component found in the environment. However, the effect of MPs type on its interaction with DOM has not been systematically studied. Therefore, the binding properties of different MPs with fulvic acid (FA) were explored in this study. The results showed that polypropylene (PP) and polyethylene (PE) had higher adsorption affinity for FA than polystyrene (PS) and polyvinyl chloride (PVC). The interaction between MPs and FA conformed to the pseudo-first-order model and Freundlich model (except PS). The interaction mechanisms between various MPs tested in this paper and FA are considered to be different. PP, PE and PS interacted with the aromatic structure of FA and were entrapped in the FA polymers by the carboxyl groups and CO bonds, resulting in a highly conjugated co-polymer, suggesting that oxygen-containing functional groups played a key role. However, it was assumed that the interaction between PVC and FA was more likely to be caused by hydrophobic interaction. This research will help to enhance our comprehension of the environmental behavior of MPs and their interaction with the DOM specifically.

Identification and visualization of environmental microplastics by Raman imaging based on hyperspectral unmixing coupled machine learning.

Microplastics (MPs) are ubiquitous contaminants that have become an emerging pollutant of concern, potentially threatening human health and ecosystem environments. Although current detection methods can accurately identify various types of MPs, it remains necessary to develop non-destructive and rapid methods to meet growing demands for detection. Herein, we combine a hyperspectral unmixing method and machine learning to analyse Raman imaging data of environmental MPs. Five MPs types including poly(butylene adipate-co-terephthalate) (PBAT), poly(butylene succinate) (PBS), p-polyethylene (PE), polystyrene (PS) and polypropylene (PP) were visualized and identified. Individual or mixed pure or aged MPs along with environmental samples were analysed by Raman imaging. Alternating volume maximization (AVmax) combined with unconstrained least squares (UCLS) method estimated end members and abundance maps of each of the MPs in the samples. Pearson correlation coefficients (r) were used as the evaluation index; the results showed that there is a high similarity between the raw spectra and the average spectra calculated by AVmax. This indicates that Raman imaging based on machine learning and hyperspectral unmixing is a novel imaging analysis method that can directly identify and visualize MPs in the environment.

Different microbial assemblage colonized on microplastics and clay particles in aerobic sludge treatment.

In this study, a combination of property analysis and high-throughput sequencing was used to investigate the microbial colonization ability and their community structures and functions in polypropylene microplastics (PPMPs), polystyrene microplastics (PSMPs) and montmorillonite (MMT), respectively as the representatives of artificial and natural substrates in aerobic sludge treatment. After 45 d of incubation, the surface properties of substrates were altered with the increased oxygen functional groups and surface roughness, indicating microbial settlement. Moreover, MPs had different microbial structures from that of MMT, and PSMPs exhibited higher microbial diversity and abundance than PPMPs and MMT. Also, these substrates changed the inherent ecological niche in sludge. Especially, the abundance of some pathogens (e.g., Pseudomonas, Klebsiella and Flavobacterium) was increased in MPs, and the disease risk of Kyoto Encyclopedia of Genes and Genomes metabolic pathway (e.g., Infectious diseases: Bacterial, Infectious diseases: Parasitic and Immune diseases) was higher. Also, the presence of MPs inhibited the decomposition of organic matter including soluble chemical oxygen demand and protein compared to natural substrates. The findings revealed the crucial vector role of MPs for microbes and the effect on aerobic sludge treatment, highlighting the necessity of MP removal in sludge.

Microplastics exhibit lower carrying effects on the bioaccessibility and cytotoxicity of lead than montmorillonite clay particles.

Microplastics (MPs) in the environment are always colonized by microbes, which may have implications for carrying effect of pollutants and exposure risk in organisms. We present the crucial impacts and mechanisms of microbial colonization on the bioaccessibility and toxicity of Pb(II) loaded in disposable box-derived polypropylene (PP) and polystyrene (PS) MPs and montmorillonite (MMT) clay particles. After 45 d incubation, higher biomass measured by crystal violet staining were detected in MMT (1.23) than in PP and PS (0.400 and 0.721) indicating preferential colonization of microbes in clay particles. Microbial colonization further enhanced the sorption ability toward Pb(II), but inhibited the desorption and bioaccessibility of enriched Pb(II) in zebrafish and decreased the toxicity to gastric epithelial cells in an order of MMT > PS ≈ PP. The crucial effects were mainly because microbe-colonized substrates possessed higher oxygen functional groups and specific surface area and exhibited stronger interactions with Pb(II) and digestive component (i.e., pepsin) than pure substrates. This decreased the available soluble pepsin for complexing with sorbed Pb(II). The findings highlight the role of microbial colonization in modulating the exposure risks of artificial and natural substrate-associated pollutants and suggest that the risks of MPs may be overestimated compared to clay particles.

Corn stalk pith-based hydrophobic aerogel for efficient oil sorption.

Bio-based aerogel has become an attractive sorbent for spilled oil and organic pollutants because of its light weight, high porosity and strong sorption capacity. However, the current fabrication process is mainly "bottom-up" technology, which is cost-expensive, time-consuming, and energy-intensive. Herein, we report a top-down, green, efficient and selective sorbent prepared from corn stalk pith (CSP) using the deep eutectic solvent (DES) treatment, followed by TEMPO/NaClO/NaClO2 oxidization and microfibrillation, and then hexamethyldisilazane coating. Such chemical treatments selectively removed lignin and hemicellulose, broke the thin cell walls of natural CSP, forming an aligned porous structure with capillary channels. The resultant aerogels had a density of 29.3 mg/g, a porosity of 98.13%, and a water contact angle of 130.5◦, exhibiting excellent oil/organic solvents sorption performance, with a high sorption capacity in the range of 25.4-36.5 g/g, approximately 5-16-fold higher than CSP, and with fast absorption speed and good reusability.

Enzymatic preparation of hydrophobic biomass with one-pot synthesis and the oil removal performance.

Oil pollution is causing deleterious damage to aquatic ecosystems and human health. The utilization of agricultural waste such as corn stalk (CS) to produce biosorbents has been considered an ecofriendly and efficient approach for removing oil. However, most previous studies focused on the modification of the whole CS, which is inefficient due to the heterogeneity of CS. In this study, corn stalk pith (CP), which has excellent amphipathic characteristics, was selected to prepare a high-efficiency oil sorbent by grafting dodecyl gallate (DG, a long-chain alkyl) onto CP surface lignin via laccase mediation. The modified biomass (DGCP) shows high hydrophobicity (water contact angle = 140.2°) and superoleophilicity (oil contact angle = 0°) and exhibits a high oil sorption capacity (46.43 g/g). In addition, DGCP has good stability and reusability for adsorbing oil from the aqueous phase. Kinetic and isotherm models and two-dimensional correlation spectroscopy integrated with FTIR analyses revealed that the main sorption mechanism involves the H-bond effect, hydrophobic effect and van der Waals force. This work provides an ecofriendly method to prepare oil sorbents and new insights into the mechanisms underlying the removal of spilled oil from wastewater.

Release of millions of micro(nano)plastic fragments from photooxidation of disposable plastic boxes.

The widespread use of disposable plastic boxes is exacerbating the dangers of microplastics (MPs); however, little is known about the fragmentation behavior of MPs during aging. In this study, the dynamic evolution on the release of micro(nano)plastics and photoaging properties of two disposable plastic boxes (polypropylene (PP) and polystyrene (PS)) were investigated under light irradiation and mechanical abrasion. Results showed that the weight of PP and PS was decreased by 53 % and 100 %, respectively after 60 d of ultraviolet irradiation (UV60). Moreover, a large number of fragmented particles were produced from the combined light irradiation and abrasion, with 0.142 ± 0.006 and 0.141 ± 0.013 million micro(nano)plastics/mL particles from PP and PS boxes, respectively, and the nanometer range (<100 nm) accounted for 70.8 % and 46.8 %. The correlation model of the average size or alteration time versus carbonyl index (CI) was developed, which indicated that the fragmentation behavior was mainly related to the photooxidation, though mechanical abrasion also played a certain enhancing role. Additionally, PS was susceptible to the fragmentation and photooxidation compared to PP possibly since the phenyl ring of PS was more vulnerable to UV attack than the methyl of PP. The findings of this study clarify the dynamic fragmentation process of micro(nano)plastics of disposable plastic boxes and provide useful information to access environmental fate of MPs more holistically.

Insight into the Photodegradation of Microplastics Boosted by Iron (Hydr)oxides.

Iron (hydr)oxides as a kind of natural mineral actively participate in the transformation of organic pollutants, but there is a large knowledge gap in their impacts on photochemical processes of microplastics (MPs). This study is the first to examine the degradation of two ordinary plastic materials, polyethylene (PE) and polypropylene (PP), mediated by iron (hydr)oxides (goethite and hematite) under simulated solar light irradiation. Both iron (hydr)oxides significantly promoted the degradation of MPs (particularly PP) with a greater effect by goethite than hematite, related to hydroxyl radical (•OH) produced by iron (hydr)oxides. Under light irradiation, the surface Fe(II) phase catalyzed the production of H2O2 and promoted the release of Fe2+, leading to the subsequent light-driven Fenton reaction which produced a large amount of •OH. As the iron (hydr)oxides were modified with NaF at various concentrations, the activity of the surface Fe(II) as well as the release of Fe2+ were greatly reduced, and thus the •OH formation and MP degradation were depressed remarkably. It is worth noting that the surface hydroxyl groups (especially ≡FeOH) affected the reaction kinetics of •OH by regulating the activity of Fe species. These findings unveil the distinct impacts and intrinsic mechanisms of iron (hydr)oxides in influencing the photodegradation of MPs.

Exposed facets mediated interaction of polystyrene nanoplastics (PSNPs) with iron oxides nanocrystal.

Nanoplastics (NPs), which are often detected in the natural environment, are regarded as a group of emerging pollutants. Hematite is a substance that exists widely in the surface environment and has an important impact on the environmental behavior of pollutants. Clarifying the migration of NPs requires an in-depth understanding of intrinsic interaction mechanisms of NPs with iron-containing minerals. The interaction process of polystyrene nanoplastics (PSNPs) on the hematite exposed facets was systematically studied by experiments under different conditions, adsorption isotherm curves, Fourier Transform infrared (FTIR) spectroscopy and two-dimensional correlation spectroscopy (2D-COS) analyses. We found that PSNPs were adsorbed on the three exposed faces of hematite ({001}, {012}, and {100}) by electrostatic interaction, respectively, but the capacities for PSNPs were different. Adsorption models were established to explore the preferred interaction surface dependent on the exposed facets, and it was found that {012} surfaces were more favorable for PSNPs adsorption, while {001} surface has better adsorption capacity for PSNPs than {100} surface, which is due to the different density and proportion of hydroxyl groups on the exposed facets of hematite. These findings elucidated the dependence of PSNPs adsorption on the hematite facets, and illustrated t the effect of hematite on the migration of PSNPs in the environment.

Photochlorination-induced degradation of microplastics and interaction with Cr(VI) and amlodipine.

Wastewater treatment plants (WWTPs) are the important source of microplastics (MPs) in the environment, and disinfection processes bear high potential to degrade MPs. This study investigated the physicochemical degradation, dissolved organic products and interaction with co-existed pollutants (heavy metal and pharmaceutical) on polyethylene (PE), polypropylene (PP) and polystyrene (PS) MPs during simulated disinfection processes. Compared to photo or chlorination, photochlorination significantly resulted in the physicochemical degradation, including morphology alteration, fragmentation, and chemical oxidation on PP and PS MPs, but showed relatively low effect on PE, indicating the different resistance among polymers to disinfected treatment. Photochlorination also caused the formation of chain-scission organic compounds and even chlorinated products from MPs (e.g. C11H19O4Cl for PP and monochlorophenol, dichlorophenol, chloroacetophenone and chlorobenzoic acid for PS), which may form disinfection byproducts to induce healthy risk. The adsorption potentials of MPs for Cr(VI) or amlodipine were enhanced by photochlorination since the cracking and formed oxygen functional groups enhanced the pore filling and surface precipitation of Cr(VI), and the electrostatic attraction and hydrogen bonding with amlodipine. The findings indicated the physicochemical degradation of MPs and the combined pollution with co-existed pollutants, highlighting the health risks of MP-derived organic products during the disinfection treatments (even in normal dosage) in WWTPs.

The characteristics of dissolved organic matter release from UV-aged microplastics and its cytotoxicity on human colonic adenocarcinoma cells.

There are a large number of microplastic (MPs) in the sea or on land, most of which undergo physical, chemical or biological processes leading to the release of dissolved organic matter (DOM). In this study, we analyzed the change of Polyurethane microplastic (PU-MPs) valence bond under different aging conditions thanks to Fourier transform infrared spectroscopy (FTIR) and its surface characteristics using scanning electron microscopy (SEM) and also described the characteristics of DOM dissolved from PU (PU-DOM) under UV aging process in two different medium (water and air), based on Dissolved organic carbon (DOC) measurements, UV-visible spectrometer and Three-dimensional excitation emission matrices (3D-EEMs). The DOC data both showed that Under UV aging of different systems, PU-DOM concentration increases with the extension of aging time, and correspondingly, its toxicity to human colon adenocarcinoma cells also increases, but the release amount of PU-DOM under air aging is higher than that of PU-DOM in water. We speculate that it may be the refraction and scattering of water, which leads to the reduction of the intensity of UV radiation. 3D-EEMs identified tryptophan-like fluorescent component and tyrosine-like component, meanwhile, the liquid chromatography-mass spectrometer (LC-MS) data further confirmed the formation of acid substances. The results further confirmed that the composition of PU-DOM in different systems is the same, but the release amount is different. The contents of the produced conjugated carbonyls and Reactive oxygen species (ROS) because of light irradiation increased likewise. The cytotoxicity of PU-DOM was consistent with the changing trend of ROS level in PU-MPs, suggesting that the produced ROS induced the in vitro toxicities. The results not only highlight the adverse health effects of photoaged PU-MPs, but also provide new perspectives for the environmental risks of MPs.

Polystyrene microplastics accelerated photodegradation of co-existed polypropylene via photosensitization of polymer itself and released organic compounds.

Combined pollution consisted of various types of microplastics (MPs) was extensively detected in the environment; however, little is known about their interaction on degradation behavior during exposure in sunlight. This study investigated the effects of polystyrene (PS) MPs and mechanisms on photodegradation of pure and commercial polypropylene (PP) MPs co-existed in aquatic environment. Results showed that PS MPs significantly accelerated photodegradation of co-existed PP, including faster oxidation and fragmentation. Photodegradation route of PP MPs such as the reaction priority of partial chemical bindings was even altered with the presence of PS MPs, highlighting the important role of PS in photodegradation process of PP. Analysis of leachate and free radical indicated that the critical effects were derived from photosensitization of PS polymer itself and its released dissolved organic matter (PS-DOM); here, more important role of PS itself in initial period and that of PS-DOM in later period. Among generated ROS, OH· was the key species for accelerating photodegradation of PP by PS itself and its released DOM, which were generated from the reaction of polymer radical with dissolved oxygen. The findings firstly reveal the important role of PS in photodegradation of co-existed MPs and suggested the shorter duration of (micro)plastics in combined system than that in the single, which provide useful information to assess environmental behavior and fate of MPs more holistically.

Pollution characteristics and health risk assessment of potentially toxic elements in soils around China's gold mines: a meta-analysis.

Since toxic element pollution is widespread in soils near gold mines due to increasing mining activities, the adverse effects of potentially toxic elements (PTEs) in the soils on ecological systems and human health cannot be ignored. However, assessments of PTE pollution in soils and their ecological-health risks on a national scale are still limited. Here, the concentrations of eight PTEs in soils near gold mines throughout China were obtained from published articles. Based on these data, the pollution levels and ecological-health risks of the eight PTEs in soils were comprehensively estimated. The results showed that the average contents of As, Cr, Cd, Pb, Hg, Cu, Ni, and Zn were 81.62, 79.82, 1.04, 206.03, 2.05, 40.82, 71.82, and 130.42 mg kg-1, respectively, which exceeded the corresponding background values for soils. Most of the examined soils were heavily polluted by Hg and Cd, and higher pollution levels were found in the Henan and Shaanxi Provinces than in other regions. The average potential ecological risk value of all PTEs was 2534.71, indicating the presence of very high risks. Contribution of Hg to the potential ecological risk was more than 80%. For adults, all hazard index (HI) values of noncarcinogenic risks were below the safe level of 1.00. For children, none of the HI values exceeded the safe level, with the exception of As (HI = 1.81); nevertheless, four PTEs (As, Cr, Cu, and Ni) presented unacceptable carcinogenic risks. This study provides scientific basis for controlling PTE contamination and reducing the health risks in soils near gold mines worldwide.

Environmental and health risk assessment of potentially toxic trace elements in soils near uranium (U) mines: A global meta-analysis.

Soil pollution by potentially toxic trace elements (PTEs) near uranium (U) mines arouses a growing interest worldwide. However, nearly all studies have focused on a single site or only a few sites, which may not fully represent the soil pollution status at the global scale. In this study, data of U, Cd, Cr, Pb, Cu, Zn, As, Mn, and Ni contents in U mine-associated soils were collected and screened from published articles (2006-2021). Assessments of pollution levels, distributions, ecological, and human health risks of the nine PTEs were analysed. The results revealed that the average contents of the U, Cd, Cr, Pb, Cu, Zn, As, Mn, and Ni were 39.88-, 55.33-, 0.88-, 3.81-, 3.12-, 3.07-, 9.26-, 1.83-, and 1.17-fold greater than those in the upper continental crust, respectively. The pollution assessment showed that most of the studied soils were heavily polluted by U and Cd. Among them, the U mine-associated soils in France, Portugal, and Bulgaria exhibited significantly higher pollution levels of U and Cd when compared to other regions. The average potential ecological risk value for all PTEs was 3358.83, which indicated the presence of remarkably high risks. Among the PTEs, Cd and U contributed more to the potential ecological risk than the other elements. The health risk assessment showed that oral ingestion was the main exposure route for soil PTEs; and the hazard index (HI) values for children were higher than those for adult males and females. For adult males and females, all hazard index values for the noncarcinogenic risks were below the safe level of 1.00. For children, none of the HI values exceeded the safe level, with the exception of U (HI = 3.56) and As (HI = 1.83), but Cu presented unacceptable carcinogenic risks. This study provides a comprehensive analysis that demonstrates the urgent necessity for treating PTE pollution in U mine-associated soils worldwide.

Abundance and characteristics of microplastics in the surface water and sediment of parks in Xi'an city, Northwest China.

Microplastics (MPs), as a new type of pollutants, have attracted wide attention especially in recent years, but there was insufficient research on the distribution and characteristics of MPs in urban park water body. In this study, the pollution of MPs in water and sediment of Xi'an, the largest city in northwest China, was investigated. The MPs concentration in the surface water and sediment was 2900-6970 items/m3 and 940-3560 items/kg, respectively. According to the urban functions, the parks were divided into residential areas, commercial areas, tourism areas and industrial areas, and the highest abundance of MPs was observed in the tourism and residential areas, suggesting the impacts of human activities. MPs in these parks were mainly in four kinds of shapes, namely fiber, pellet, fragment and film, and dominated by fibers and fragments. Most of the extracted MPs were small in size, and 63-92% of them were smaller than 0.5 mm. Polypropylene and polyethylene terephthalate were the main polymer types in surface water and sediments, respectively. This study showed that the park water and sediment can be used as an important "sink" in MPs, which is of great significance for monitoring and alleviating the pollution of urban MPs. This study provided important reference for better understanding MPs levels in inland freshwaters.

Effect of cadmium on the sorption of tylosin by polystyrene microplastics.

Microplastics are widespread in the environment and might transport readily by ocean currents, wind and atmospheric deposition. Simultaneously, antibiotics and heavy metals could often be detected in the environment. They are both positively charged, it is necessary to clarify the interactions of these pollutants with microplastics when they were coexist. In this study, the most commonly used polystyrene (PS) was selected as a representative microplastic. This study investigated the effect of Cd(II) on the sorption of TYL by PS in different coexistence systems. The results showed that: in the composite system, when TYL and Cd(II) coexist, the presence of Cd(II) could inhibit the sorption of TYL by PS, and the inhibitory effect increases with the increase of the concentration of Cd(II), indicating that competitive sorption dominates the sorption. When PS adsorbed Cd(II) first and then adsorbed TYL, the presence of Cd(II) was conducive to the sorption of TYL, and the sorption strengthened with the increase of Cd(II) concentration, indicating that the complexation between TYL and Cd(II) enhanced the sorption of TYL. In addition, initial pH values and ionic strength were essential in the sorption process. Therefore, this study could provide an important basis for evaluating the environmental behavior and ecological risk of microplastics in the process of compound pollution.

The occurrence and abundance of microplastics in surface water and sediment of the West River downstream, in the south of China.

Microplastic pollution has aroused great concern in inland waters. Freshwater is the transport routes and potential sources for plastic fragments to the oceans. However, information especially about the occurrence of microplastics in freshwater systems is unclear in certain key areas. This work studied the distribution and characteristics for microplastics in the downstream area of West River. Both sediment and surface water detected microplastics with abundance ranging from 2560 to 10,240 items/kg and 2.99 to 9.87 items/L, respectively. Small size (<0.5 mm) and fiber were the main size and type in both surface waters and sediments. Polypropylene, polyethylene, polyethylene, polyvinyl chloride and polyethylene terephthalate were the polymer types of microplastics, as identified using a Fourier transform infrared spectrometer. In addition, findings here might be in consideration of studying about the distribution of microplastics and the degree to which they were influenced by the use of land. In descending order, the highest microplastics abundance was observed in commercial/public/recreational > residential > industrial > natural areas. Our results indicate the occurrence of high abundance microplastics in river impacted by human activities, and suggest that spatial distribution of microplastics varies between different land use areas.