Transport of polyethylene and polypropylene microplastics under the action of agricultural chemicals: Role of pesticide adjuvants and neonicotinoid active ingredients.

Understanding the impact of various agricultural chemical components on the fate and transport of microplastics (MPs) in the subsurface is essential. In this study, column experiments on saturated porous media were conducted to explore the influence of the coexistence environment of pesticide adjuvants (surfactants) and active ingredients (neonicotinoids) on the transport of polyethylene (PE) and polypropylene (PP) MPs. An anionic surfactant (sodium dodecyl sulfate (SDS)), a nonionic surfactant (nonylphenol ethoxylate (NP-40)), and three neonicotinoid insecticides (acetamiprid, dinotefuran, and nitenpyram) could independently increase MP migration by 9.31%-61.01% by improving the hydrophilicity. Acetamiprid or dinotefuran reduced the adhesion work of the binary system by competing with SDS for adsorption sites, thereby inhibiting PE mobility. However, nitenpyram in the mixture was not easily adsorbed on the surface of PE MPs together with SDS because of nitenpyram's high hydrophilicity. Neonicotinoid molecules could not reduce the hydrophilic modification of SDS on PP MPs by competing for adsorption sites. Owing to their weak charge and adhesion work of nonionic surfactants (-4.80 mV and 28.45 kT for PE and -8.21 mV and 17.64 kT for PP), neonicotinoids tended to occupy the adsorption sites originally belonging to NP-40. The long molecular chain of NP-40 made it difficult for high-concentration neonicotinoids to affect the adhesion on MPs. In addition, NP-40 was harder to peel off from the MP surface than SDS, leading to a larger MP transport ability in the sand column.

Photocatalytic reduction of Cr(VI) via surface modified g-C3N4 by acid-base regulation.

Cr(VI) is a class of highly toxic heavy metals. In this study, alkali-modified g-C3N4 (cOH-CN) and acid-modified g-C3N4 (cH-CN) materials were successfully synthesized, and their photocatalytic activities for Cr(VI) reduction under visible light irradiation were tested. Owing to defect structures by cH-CN and -OH group introduction by cOH-CN, the modified materials exhibited a larger surface area, more abundant pore structures, a wider visible light absorption range, higher energy gap values, and a stronger capacity for electron-hole pair separation. As a result, satisfactory Cr(VI) reduction performance was gained by these two photocatalysts. Almost all Cr(VI) was converted to Cr(III) after 60 min of treatment in the presence of these two catalysts, while it was only 30% for the pristine g-C3N4 materials. Relatively higher dosages of cH-CN and cOH-CN and acidic conditions both improved Cr(VI) reduction in the cH-CN and cOH-CN photocatalytic systems. Cr(VI) reduction was mainly initiated by free electrons in the photocatalytic system of the modified materials. Finally, Cr(VI) in the photocatalytic system was almost completely converted to Cr(III). Furthermore, the stability and recycling of the cH-CN and cOH-CN catalysts were evaluated.

Effect of nZVI/biochar nanocomposites on Cd transport in clay mineral-coated quartz sand: Facilitation and rerelease.

The development and application of nano-biochar synthesized by ball milling technology is still challenging in the field of environmental remediation because of its higher activity with pollutants. The purpose of this study was to investigate the transport behavior of two kinds of biochar nanoparticles (nanobiochar (NBC) and nZVI-modified nanobiochar (nZVI-NBC)) and Cd2+ in clay mineral (kaolinite, illite, and montmorillonite)-coated quartz sand columns. The interaction between biochar nanoparticles and Cd2+ in saturated porous media was studied in cotransport experiments. Then, the effect of biochar nanoparticles on the release of Cd2+ in contaminated media was explored by elution experiments. The cotransport experiments showed that the mobility of Cd2+ was enhanced by two kinds of biochar nanoparticles, while the transport of biochar was limited due to the presence of Cd2+. The elution experiments showed that the transport of biochar nanoparticles can be inhibited by Cd2+ previously immobilized in the sand column, and Cd2+ can be rereleased by biochar nanoparticles. The rerelease ability of nZVI-NBC to Cd2+ is weaker than that of NBC because nZVI is more easily retained in the sand column after oxidation, thus strengthening the immobilization of Cd2+. In general, the recoveries of NBC, nZVI-NBC and Cd2+ in saturated porous media were reduced by the presence of clay minerals. The experimental results describing the stability of biochar nanoparticles in sand columns are consistent with those predicted by the Derjaguin-Landau-Verwey-Overbeek theory. The transport behavior of Cd2+ and biochar nanoparticles in sand columns can be well simulated by advection-dispersion-reaction. These findings reveal the interaction between biochar nanoparticles and heavy metals in the soil environment and provide new insights into the transport and fate of environmental remediation materials and pollutants in the underground environment.

Scavenging effect of oxidized biochar against the phytotoxicity of lead ions on hydroponically grown chicory: An anatomical and ultrastructural investigation.

To evaluate the scavenging effect of functionalized biochar against the phytotoxicity of Pb2+, original biochar (O-B) was chemically oxidized with either HNO3 or KMnO4 to serve as biofilters (O-BF, HNO3-BF and KMnO4-BF) to hydroponically grown chicory (Cichorium intybus L. var. intybus). Plants subjected to Pb-stress showed various deteriorations in cell organelles including visible alterations in chloroplasts, malformations in plant cells, abnormalities in the mitochondrial system, inward invagination of cell walls, distortions in the plasma membrane, oversized vacuoles and irregular increase in plastoglobuli formation. In addition, disorganization in xylem and phloem tissues and numerous variations in the stomatal number, density and dimensions as well as stomata movement were noticeable in the abaxial leaf surface. Pb-stressed plants showed increments in root diameter, vascular cylinder and metaxylem vessels as well as an obvious increase in the thickness of cortex, intercellular aerenchyma and endodermis layer. Furthermore, a noticeable disturbance in macro-and micronutrient concentrations was recorded in Pb-stressed plants due to the defect in their water status. O-BF showed a limited scavenging effect against the phytotoxicity of Pb2+. However, oxidized biochar filters (particularly KMnO4-BF) recorded a noticeable safeguard effect due to their high affinity to Pb2+ ions. The higher sorption capacity of KMnO4-BF reduced the concentration of Pb in leaf tissues compared to the unequipped filtration treatment (117 vs. 19 µg g-1). In conclusion, data of this hydroponic study provides baseline information regarding the detoxification mechanisms of functionalized biochar against the phytotoxicity of trace elements.

Removal of V (V) and Pb (II) by nanosized TiO2 and ZnO from aqueous solution.

The removal of V (V) and Pb (II) by TiO2 and ZnO nanoparticles from aqueous solution was studied with batch experiments. Atomic force microscopy (AFM), fourier Transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface properties including functional groups of the adsorbent as well as to explore adsorption mechanisms. Factors influencing V (V) and Pb (II) removal such as initial metal ion concentration and contact time were investigated. The kinetics of V (V) and Pb (II) removal occurred quickly and > 90% of the metals was removed within 30 min for both nanoparticles. Maximum adsorption of V (V) and Pb (II) onto TiO2 and ZnO nanoparticles was observed at temperature of 298 K and pH 6.5 ±â€¯0.1. The removal characteristics of the metals by the two nanoparticles were similar. A comparison of the kinetic models against experimental data showed that the kinetics react system was best described by the pseudo-second-order model. V (V) and Pb (II) reacted with functional groups, which led to the formation of polytype Pb-O bond and hydroxyl-vanadium complexes. The experimental data also confirmed the formation of heavy metal-OH sorption complexes on the adsorbent surfaces. This research enhanced current understanding of the removal of V (V) and Pb (II) by nanosized TiO2 and ZnO from contaminated water.

Effect of water-soluble polymers on the transport of functional group-modified polystyrene nanoplastics in goethite-coated saturated porous media.

The research on the impact of water-soluble polymers (WSPs) on the migration and fate of plastic particles is extremely limited. This article explored the effects of polyacrylic acid (PAA, a common WSP) and physicochemical factors on the transport of polystyrene nanoparticles (PSNPs-NH2/COOH) with different functional groups in QS (quartz sand) and FOS (goethite-modified quartz sand, simulates mineral colloids). Research has shown that PAA can selectively adsorb onto the surface of PSNPs-NH2, forming ecological corona heterogeneous aggregates. This process increased the spatial hindrance and elastic repulsion, resulting in the recovery of PSNPs-NH2 always exceeding that of PSNPs-COOH. Overall, PAA can hinder the migration of PSNPs in QS but can promote their migration in FOS. When multivalent cations coexist with PAA, the transport of PSNPs in the media is primarily affected by cation bridging and CH-cation-π interaction. The presence of oxyanions and PAA prevents PSNPs from following the Hofmeister rule and promotes their migration (PO43-: 82.34 ± 0.16% to 94.63 ± 2.82%>SO42-: 81.38 ± 2.73% to 91.15 ± 0.93%>NO3-: 55.85 ± 0.70%-87.16 ± 3.80%). The findings of this study contribute significantly to a better understanding of the migration of WSPs and group-modified NPs in complex saturated porous media.

Stereoselective transport of 2-aryl propionic acid enantiomers in porous media subjected to chiral organic acids.

The study examined the transport behavior of the 2-aryl propionic acid (2-APA) chiral pharmaceutical enantiomers by means of a laboratory-scale saturated quartz sand column experiment. Four typical of 2-APA and their enantiomers were selected for the study under different types of chiral organic acids (COAs)-mediated effects. Differences in the transport of the 2-APA enantiomeric pairs have been identified in response to various pH, types of COAs, and enantiomeric structures of COAs. Redundancy analysis identified the factors responsible for the largest differences in transport of 2-APA enantiomeric pairs, while spectroscopic characterization and density function theory (DFT) studies elucidated the underlying mechanisms contributing to the differences in transport of enantiomeric pairs. Obvious correlations among homochirality or heterochirality between COAs and 2-APA enantiomeric pairs were observed for changes in the mobility of 2-APA. The results indicate widespread COAs significantly affect the transport behavior of chiral man-made chemicals, suggesting more attention is needed to fill the gap in the perception of the transport behavior of chiral compounds.

Dynamic ion exchange engineering bismuth ferrite-derived Bi2O2CO3 for rapid piezo-photocatalytic degradation of tetracycline.

Piezoelectric materials can generate the built-in electric field under ultrasound assistance, which is beneficial to the separation of the photogenerated electron-hole pairs in photocatalysis. Meanwhile, the ultrasound stress usually leads to accelerate electron transfer and enhance catalytic activity. Thus, piezo-photocatalysis technique is believed to be one of the effective techniques for organic pollutant degradation. In this work, a binary piezoelectric integrated piezo-photocatalytic Z-Scheme heterojunction with bismuth ferrite (BFO) and bismuth oxycarbonate (Bi2O2CO3, BOC) based on the in situ production of Bi2O2CO3 on Bi25FeO40 surface in dichloromethane, where Bi25FeO40 was employed as piezoelectric materials and Bi source, CO2 dissolved in dichloromethane was used as carbon source. Under 60 min ultrasound and visible light irradiation, the optimal BFO/BOC presented a higher piezo-photocatalytic tetracycline (TC) degradation rate (95 %) than Bi25FeO40 (30 %) and Bi2O2CO3 (17 %). Moreover, the optimal BFO/BOC illustrated higher piezo-photocatalytic TC degradation rate under ultrasound and visible light irradiation than that under visible light condition and ultrasound condition, respectively. These results strongly demonstrated the synergistically piezo-photocatalytic degradation of TC by BFO and BOC. This work not only provides a novel piezo-photocatalyst for pollutant degradation, but also provides a novel method to prepare Bi2O2CO3-based piezo-photocatalytic composite catalyst.

The synergistic effect of typical chiral organic acids and solution chemistry conditions on the transport of 2-arylpropionic acid chiral derivatives in porous media.

The hazards of man-made chiral compounds are of great public concern, with reports of worrying stereoselective compounds and an urgent need to assess their transport. This study evaluated the transport of 2-arylpropionic acid derivatives enantiomers (2-APA) in porous media under a variety of solution chemistry conditions via column packing assays. The results revealed the introduction of Malic acid (MA) enantiomers enhanced the mobility of 2-APA enantiomers, but the enhancement effect was different for different 2-APA enantiomers. Batch sorption experiments confirmed that the MA enantiomers occupied the sorption site of the quartz sand, thus reducing the deposition of the 2-APA enantiomer. Homo- or heterochirality between 2-APA and MA dominates the transport of 2-APA enantiomers, with homochirality between them triggering stronger retention and vice versa. Further evaluating the effect of solution chemistry conditions on the transport of 2-APA enantiomers, increased ionic strength attenuated the mobility of 2-APA enantiomers, whereas introduced coexisting cations enhanced the retention of 2-APA enantiomers in the column. The redundancy analyses corroborated these solution chemistry conditions were negatively correlated with the transport of 2-APA enantiomers. The coupling of pH and these conditions reveals electrostatic forces dominate the transport behavior and stereoselective interactions of 2-APA enantiomers. Distinguishing the transport of enantiomeric pair helps to understand the difference in stereoselectivity of enantiomers and promises to remove the more hazardous one.

Synchronous removal of oxytetracycline and Cr(â ¥) in Fenton-like photocatalysis process driven by MnFe2O4/g-C3N4: Performance and mechanisms.

Complex wastewater has more complicated toxicity and potential harm to organisms, and synchronous REDOX of complex pollutants in wastewater has always been a bottleneck in the development of advanced oxidation technology. Herein, a Fenton-like photocatalytic system (MnFe2O4/g-C3N4 heterojunction composites) was established to simultaneously remove oxytetracycline (OTC) and Cr(Ⅵ) in this study. The MnFe2O4/g-C3N4 heterojunction composites exhibited outstanding catalytic performances for OTC and Cr(Ⅵ) removal, and more than 90% of OTC and nearly 100% of Cr(Ⅵ) were simultaneously removed within 1 min photocatalysis. The photo-generared electrons and holes played significant roles in Cr(Ⅵ) reduction and OTC degradation, respectively. Moreover, the heterojunction formed between g-C3N4 and MnFe2O4 effectively accelerated the separation and migration of photogenerated carriers. The OTC degradation was mainly initiated by cracking of benzene rings, degradation of substituents, and removal of groups such as -OH, -NH2, -CH3, and -CONH2, resulting in generation of small molecular substances; Cr(Ⅲ) was the main reduction product of Cr(Ⅵ). Meanwhile, the MnFe2O4/g-C3N4 heterojunction composites also exhibited excellent stability and reusability in removal of OTC and Cr(Ⅵ).

Effects of neonicotinoid insecticides on transport of non-degradable agricultural film microplastics.

Mulch film microplastics (MPs) could act as a vector for agricultural chemicals due to their long-term presence in farmland environments. As a result, this study focuses on the adsorption mechanism of three neonicotinoids on two typical agricultural film MPs, polyethylene (PE) and polypropylene (PP), as well as the effects of neonicotinoids on the MPs transport in quartz sand saturated porous media. The findings revealed that the adsorption of neonicotinoids on PE and PP was a combination of physical and chemical processes, including hydrophobic, electrostatic and hydrogen bonding. Acidity and appropriate ionic strength (IS) were favorable conditions for neonicotinoid adsorption of on MPs. The results of column experiments showed that the presence of neonicotinoids, particularly at low concentrations (0.5 mmol L-1), could promote the transport of PE and PP in the column by improving the electrostatic interaction and hydrophilic repulsion of particles. The neonicotinoids would be adsorbed on MPs through hydrophobic action preferentially, whereas excessive neonicotinoids could cover the hydrophilic functional groups on the surface of MPs. Neonicotinoids reduced the response of PE and PP transport behavior to pH changes. 0.005 mol L-1 NaCl ameliorated the migration of MPs by increasing their stability. Because of its highest hydration ability and the bridging effect of Mg2+, Na+ had the most prominent transport promoting effect on PE and PP in MPs-neonicotinoid. This study shows that the increased environmental risk caused by the coexistence of microplastic particles and agricultural chemicals is unneglectable.

Transport of functional group modified polystyrene nanoplastics in binary metal oxide saturated porous media.

Metal oxides exist in porous media in the form of composite metal oxides, which can significantly affect the transport and transformation of pollutants in the soil environment. In this study, binary metal oxide porous media were prepared to explore the effects of solution chemistry, and the presence of binary metal oxides on the transport of functional group modified polystyrene nanoplastics (PSNPs) in saturated porous media. The results show that the existence of binary metal oxides significantly affects the migration ability of PSNPs in saturated porous media. The increase of ionic strength and the presence of multivalent cations affect the transport capacity of PSNPs in porous media. The types of binary metal oxides affect the migration of PSNPs in saturated porous media. The surface roughness and electrostatic interaction are important factors affecting the retention of PSNPs on the surface of binary metal oxide saturated porous media. The surface morphology has a more far-reaching impact. In addition, DLVO theory cannot fully explain the interaction between PSNPs and saturated porous media in the presence of Al3+. This study's results help provide some theoretical support for the migration of microplastics in the soil environment.

Oxidative stress and gene expression induced by biodegradable microplastics and imidacloprid in earthworms (Eisenia fetida) at environmentally relevant concentrations.

The environmental issues caused by biodegradable microplastics (BMPs) from polylactic acid (PLA) as well as pesticides are of increasing concern nowadays. In this study, the toxicological effects of the single and combined exposure of PLA BMPs and imidacloprid (IMI), a neonicotinoid insecticide, on earthworms (Eisenia fetida) were investigated in terms of oxidative stress, DNA damage, and gene expression, respectively. The results showed that compared with the control, SOD, CAT and AChE activities in the single and combined treatments decreased significantly, and POD activity showed an "inhibition-activation" trend. SOD and CAT activities of combined treatments on day 28 and AChE activity of combined treatment on day 21 were significantly higher than those of the single treatments. For the rest of the exposure period, SOD, CAT and AChE activities in the combined treatments were lower than those in the single treatments. POD activity in the combined treatment was significantly lower than those of single treatments at day 7 and higher than that of single treatments at day 28. MDA content showed an "inhibition-activation-inhibition" trend, and the ROS level and 8-OHdG content increased significantly in both the single and combined treatments. This shows that both single and combined treatments led to oxidative stress and DNA damage. ANN and HSP70 were expressed abnormally, while the SOD and CAT mRNA expression changes were generally consistent with the corresponding enzyme activities. The integrated biomarker response (IBR) values were higher under combined exposures than single exposures at both biochemical and molecular levels, indicating that combined treatment exacerbated the toxicity. However, the IBR value of the combined treatment decreased consistently at the time axis. Overall, our results suggest that PLA BMPs and IMI induce oxidative stress and gene expression in earthworms at environmentally relevant concentrations, thereby increasing the risk of earthworms.

Exploring the toxicity of biodegradable microplastics and imidacloprid to earthworms (Eisenia fetida) from morphological and gut microbial perspectives.

Biodegradable microplastics (BMPs) pose serious environmental problems to soil organisms, and their adsorption capacity might make pesticides more dangerous for soil organisms. Therefore, in this study, polylactic acid (PLA) BMPs and imidacloprid (IMI) were used as a representative of BMPs and pesticides, respectively. Eisenia fetida was used as a test animal to investigate the effects of environmentally relevant concentrations of single and compound contaminated PLA BMPs and IMI on mortality, growth, number of offspring, tissue damage, and gut microorganisms of E.fetida. Exposure to PLA BMPs treatment and PLA BMPs + IMI treatment resulted in a sustained increase in E.fetida mortality, reaching 16.7% and 26.7%, respectively. The growth inhibition rate of single treatments was significantly increased. The compound contamination had the greatest effect on E.fetida offspring compared to the control. PLA BMPs and IMI cause histological damage to E.fetida, with the compound treatment causing the most severe damage. Based on the results of 16S sequencing, the bacterial communities in E.fetida gut and soil treated to PLA BMPs and IMI were significantly different. PLA BMPs + IMI treatment suppresses the abundance and diversity of E.fetida gut microorganisms, disrupting the homeostasis of bacterial communities and causing immune and metabolic dysfunction. These findings highlight the more severe damage of combined PLA BMPs and IMI pollution to E.fetida, and help to assess the risk of earthworm exposure to environmentally relevant concentrations of PLA BMPs and IMI.

Co-transport of degradable microplastics with Cd(â ¡) in saturated porous media: Synergistic effects of strong adsorption affinity and high mobility.

With the utilization of degradable plastics in the agricultural film and packaging industries, degradable microplastics (MPs) with strong mobility distributed in the underground environment may serve as carriers for heavy metals. It is essential to explore the interaction of (aged) degradable MPs with Cd(Ⅱ). The adsorption and co-transport behavior of different types of (aged) MPs (polylactic acid (PLA), polyvinyl chloride (PVC)) with Cd(Ⅱ) were investigated through batch adsorption experiments and column experiments under different conditions, respectively. The adsorption results showed that the adsorptive capacity of (aged) PLA with O-functional groups, polarity, and more negative charges was stronger than that of PVC and aged PVC, which was attributed to the binding of (aged) PLA to Cd(Ⅱ) through complexation and electrostatic attraction. The co-transport results indicated that the promotion of Cd(Ⅱ) transport by MPs followed the order of aged PLA > PLA > aged PVC > PVC. This facilitation was more pronounced under conditions of stronger transport of MPs and favorable attachment of Cd(Ⅱ) to MPs. Overall, the combination of strong adsorption affinity and high mobility helped (aged) PLA act as effective carriers for Cd(Ⅱ). The DLVO theory well explains the transport behavior of Cd(Ⅱ)-MPs. These findings provide new insights into the co-transport of degradable MPs and heavy metals in the subsurface environment.

Ecological risk assessment of environmentally relevant concentrations of propofol on zebrafish (Danio rerio) at early life stage: Insight into physiological, biochemical, and molecular aspects.

Propofol is an intravenous anesthetic injection extensively used in clinic, which has been proved to be neurotoxic in humans. Improper use and disposal of propofol may lead to its release into the aquatic environment, but the potential ecological risk of propofol to aquatic organisms remains poorly understood. For this study, we comprehensively explored the ecotoxicological effects and potential mechanisms of propofol (0.04, 0.2 and 2 mg L-1) on 120 hpf zebrafish (Danio rerio) embryos from physiological, biochemical, and molecular perspectives. The results showed that propofol has moderate toxicity on zebrafish embryos (96 h LC50 = 4.260 mg L-1), which could significantly reduce the hatchability and delay the development. Propofol can trigger reactive oxygen species (ROS) generation, lipid peroxidation (Malondialdehyde, MDA) and DNA damage (8-hydroxy-2-deoxyguanosine, 8-OHdG). The glutathione peroxidase (GPX) activity of zebrafish embryos in 0.04 and 0.2 mg L-1 propofol treatment group was activated in response to oxidative damage, while activities of superoxide dismutase (SOD), catalase (CAT) and GPX in zebrafish treated with 2 mg L-1 was significant inhibited compared with the control group (p＜0.05). Moreover, the expression of antioxidant genes and related pathways was inhibited. Apoptosis was investigated at genes level and histochemistry. Molecular docking confirmed that propofol could change in the secondary structure of acetylcholinesterase (AChE) and competitively inhibited acetylcholine (ACh) binding to AChE, which may disturb the nervous system. These results described toxic response and molecular mechanism in zebrafish embryos, providing multiple aspects about ecological risk assessment of propofol in water environment.

Evaluation of the biological response of propofol in zebrafish (Danio rerio): Focusing on biochemical, transcriptional, and molecular level.

Propofol, one of the most widely used intravenous anesthetic in clinical practice, has been reported to impair cognitive and memory function. However, the toxicological effects of propofol on aquatic organisms are still poorly understood. This study explored the toxic effects of chronic propofol exposure (0.008, 0.04, and 0.2 mg L-1) on adult zebrafish from biochemical, transcriptional, and molecular level after 7, 14, 21 and 28 days of exposure. Results indicated that the reactive oxygen species (ROS) levels were significantly upregulated during the 28 days exposure period, and excessive ROS caused lipid peroxidation, resulting in increased malondialdehyde (MDA) contents in the zebrafish brain. In order to relieve the oxidative damage induced by the excessive ROS, the activities of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT)) were significantly activated, and detoxification enzyme (glutathione S-transferase, GST) activities showed an "activation-inhibition" trend. However, the antioxidant enzymes and detoxification enzyme system could not eliminate the excessive ROS in time and thus caused DNA damage in zebrafish brain. The olive tail moment (OTM) values displayed a "dose-response" relationship with propofol concentrations. Meanwhile, the transcription of related genes of Nrf2-Keap1 pathway was activated. Further molecular simulation experiments suggested that propofol could directly combine with SOD/CAT to change the activity of its biological enzyme. These findings indicated that zebrafish could regulate antioxidant capacity to combat oxidative stress at the early exposure stage, but the activity of antioxidant enzymes were significantly inhibited with the increase of propofol exposure time. Our results are of great importance for understanding toxicological effects of propofol on aquatic organisms.

Effect of different aging treatments on the transport of nano-biochar in saturated porous media.

Widely used for soil amendment, carbon sequestration, and remediation of contaminated soils, biochars (BCs) inevitably produce a large number of nanoparticles with relatively high mobility. Geochemical aging alters chemical structure of these nanoparticles and thus affect their colloidal aggregation and transport behavior. In this study, the transport of ramie derived nano-BCs (after ball-milling) was investigated by different aging treatments (i.e., photo (PBC) and chemical aging (NBC)) as well as the managing BC under different physicochemical factors (i.e., flow rates, ionic strengths (IS), pH, and coexisting cations). Consequences of the column experiments indicated aging promoted the mobility of the nano-BCs. Compared to the nonaging BC, consequences of spectroscopic analysis demonstrated the aging BCs exhibited a number of tiny corrosion pores. Both of these aging treatments contribute to a more negative zeta potential and a higher dispersion stability of the nano-BCs, which is caused by the abundance of O-functional groups. Also the specific surface area and mesoporous volume of both aging BCs increased significantly, with the increase being more pronounced for NBC. The breakthrough curves (BTCs) obtained for the three nano-BCs were modelled by the advection-dispersion equation (ADE), which included first-order deposition and release terms. The ADE revealed high mobility of aging BCs, which meant their retention in saturated porous media was reduced. This work contributes to a comprehensive understanding of the transport of aging nano-BCs in the environment.

Novel Zn-Fe engineered kiwi branch biochar for the removal of Pb(II) from aqueous solution.

In this study, a novel adsorbent made from kiwi branch biochar modified with Zn-Fe (KB/Zn-Fe) was compared with original biochar to the Pb(II)'s adsorptivity from waste water. The adsorbent was synthetized by liquid-phase deposition. Batches of sorption tests were performed, and the biochars' representative properties were tested. Characterizations revealed the physicochemical properties of biochars and showed that the KB/Zn-Fe composites were successfully synthesized. The Langmuir model and pseudo-second-order kinetic model were proven to satisfactorily fit the original biochar and KB/Zn-Fe. The KB/Zn-Fe showed Langmuir maximum adsorption ability to Pb (II) in aqueous solution of 161.29 mg g-1, compared with 36.76 mg g-1 for original biochar. The adsorption ability of Pb(II) decreased and the Pb(II) removal efficiency increased with increasing biochar dose. The effect of co-existence of NO3- to the absorptive capacity of KB/Zn-Fe on Pb(II) was unremarkable, but Cl- could increase the absorptive capacity. Multiple Pb(II) adsorption mechanisms by KB/Zn-Fe include surface precipitation of metal hydroxides, complexation with active functional groups and ion-exchange. This work provides guidance for future production of biochar with efficient adsorption ability, which could be used to remove Pb(II) ions from wastewater.

Dibutyl phthalate induced oxidative stress and genotoxicity on adult zebrafish (Danio rerio) brain.

Dibutyl phthalate (DBP) is one of the most widely used plasticizers with a high concentration in the water. Although the toxicity of DBP on aquatic organisms has become a significant concern in recent years, the effects of DBP on zebrafish (Danio rerio) brain is poorly understood. This study investigated the toxic effects of DBP exposure for 7, 14, 21 and 28 days on zebrafish brain. The results showed that DBP significantly stimulated SOD and CAT activities, increasing MDA and 8-OHdG contents. On the 28th day, the AChE inhibition rates in 0.08, 0.4, 2 mg·L-1 treatment were 13.4%, 11.9%, 14.7%. The trend of Cu/Zn-sod gene variation was consistent with SOD activity, showing "inhibition-activation-inhibition". The expression of apoptotic genes (caspase-3, p53) showed "inhibition-activation-inhibition". The integrated biomarker response (IBR) results showed that the IBR values were 4.37, 7.18 and 9.63 in 0.08, 0.4 and 2 mg·L-1 group on the 28th day, presenting a "dose-response" relationship. These findings confirmed that low concentration of DBP induced oxidative damage and genotoxicity in zebrafish brain, which provided an effective toxicological basis for phthalate pollution. Based on above studies, it is of great significance for assessing the harmful effects of DBP with low concentration on aquatic organisms.