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Molecular simulations identify distinctive behaviors of nanoplastics at the cell membrane surface and reveal interfacial processes of translocation, transformation and membrane perturbation governed by the polymer type and aging properties.

Metal-organic frameworks (MOFs) are composed by metal ions (or metal clusters) and bridging organic ligands, which have shown great application potential in biomedicine and environment fields. However, MOFs would inevitably be transformed or degraded in the environment and/or organisms during applications, which could change their structures and limit the applications. At the same time, MOFs could bring potential risks to human and environmental health. Therefore, the effects of simulated biological physiological conditions (such as pH, ions, protein/enzyme, microorganism) and environmental conditions (such as moisture, redox substances, light, temperature) on the degradation of MOFs are systematically summarized in this review, and the related degradation mechanisms are discussed. In the human digestive system and blood, pH and PO43− are the main factors that affect the degradation of MOFs, respectively, which could lead to the degradation of MOFs by directly destroying coordination bonds in MOFs and acting on metal centers in MOFs. While in the environment, water molecules are the key factors that affect the stability of MOFs, which could replace the organic ligands in MOFs through substitution reaction or destroy the coordination bonds in MOFs through hydrolysis, resulting in the degradation of MOFs. This review provides support for clarifying the degradation behaviors of MOFs and the impact of degradation products on human health and environmental fate. Finally, combining with existing issues, this article highlights the prospects and suggestions for future research perspectives of MOFs degradation, providing a theoretical basis for the green and sustainable application of MOFs.

Due to excellent properties such as ease of processing, transportation and storage, as well as outstanding chemical stability, plastics are widely used in daily production and life, which induce the possibility of plastics entering the natural environment and long-term staying in the environment. Plastics could release into different environmental compartments such as sea, lake, soil and sediment through various ways, and have toxicity to organisms through ingestion and bioaccumulation. In particular, the physical and chemical properties of plastics can be changed by biotic and abiotic factors in the environments. Biodegradation is one of the inevitable environmental processes of plastics, and it is also an eco-friendly treatment for plastic waste. Therefore, exploring the biodegradation of plastics has great practical and ecological significances. In this review, the biodegradation process of plastics by animals, plants, microorganisms and enzymes were summarized and analyzed, and the biodegradation mechanisms of plastics were revealed. Animals (e.g., insects) could physically crush plastics by gastric grinding and chewing, and also change the chemical properties of the ingested plastics under the complex biochemical reactions in their bodies. Current researches on the biodegradation of plastics by animals mainly focus on insects and their intestinal microorganisms. Limited investigations focused on plants, in which the colonization of plants (e.g., algae) on the plastics surface was observed. The biodegradation by plants could be attributed to the enzymes existing on the surface of stems and leaves or secreting by roots. Therefore, it can be concluded that the biodegradation of plastics by animals and plants is closely related to microorganisms and enzymes. It is noted that the microorganisms from animals, plants and external environments showed similar pathways on plastics biodegradation. The microorganisms could first colonize on the plastics surface to form a biofilm, and then secrete extracellular or intracellular enzymes to contact with the plastics and decompose the plastics into low molecular weight oligomers, dimers or monomers through catalysis of their binding sites. These generated oligomers, dimers and monomers can be absorbed by microorganisms as a carbon source through in vivo metabolic mechanism (e.g., the assimilation of organisms). Finally, plastics can be mineralized to CO2, CH4 and/or H2O. In addition, this review deeply analyzes the factors that affect the efficiency of plastic biodegradation, including plastic properties (e.g., plastics types, glass transition temperature, surface hydrophobicity, types of additives), organism species (e.g., insects, marine animals, plants, bacteria, fungi) and abiotic environmental factors (e.g., temperature, oxygen content, solar radiation, physical abrasion). In addition, the environmental behavior of the products after plastics biodegradation was discussed. The small-sized fragments, oligomers and plasticizers released after the biodegradation of plastics could further show different effects on organisms and ecosystems. In conclusion, challenges and future research perspectives for the plastic biodegradation were suggested at the end of this review. Further investigation on the biodegradation mechanisms of plastics and the degradation and fate of plastics additives are suggested. More efforts are recommended on the environmental behaviors and possible biological impacts of the degraded microplastics and nanoplastics. The unified measurement standards and characterization methods should be explored. This review will provide forceful scientific supports for better understanding the environmental fate of plastics.

Microplastics (MPs) are recognized as vectors for the transport of organic contaminants in aquatic environments in addition to their own adverse effects on aquatic organisms. Per- and polyfluoroalkyl substances (PFASs) are widely present in aquatic environments due to their widespread applications, and thus coexist with MPs. Therefore, we focus on the interaction of MPs and PFASs and related combined toxicity in aquatic environments in this work. The adsorption of PFASs on MPs is critically reviewed, and new mechanisms such as halogen bonding, π-π interaction, cation-π interactions, and micelle formation are proposed. Moreover, the effect of MPs on the transport and transformation of PFASs in aquatic environments is discussed. Based on four typical aquatic organisms (shellfish, Daphnia, algae, and fish), the toxicity of MPs and/or PFASs at the organismal or molecular levels is also evaluated and summarized. Finally, challenges and research perspectives are proposed, and the roles of the shapes and aging process of MPs on PFAS biogeochemical processes and toxicity, especially on PFAS substitutes, are recommended for further investigation. This review provides a better understanding of the interactions and toxic effects of coexisting MPs and PFASs in aquatic environments.

With the rapid development of nanotechnology, the environmental impact assessment of nanoparticles (NPs) becomes a pressing problem to ensure the environmental safety and human health. However, the roles of CeO

Nanoplastics adsorb pollutants and organic matter to aggravate or alleviate impact to the eco-environment and human health. However, the interaction mechanisms remain unclear and difficult to study using current experimental techniques. By means of molecular dynamics simulation, here we investigate adsorption of benzo[a]pyrene (BaP) and heavy metal ions (Cu2+) on nanoplastics of different materials and surface charges regulated by humic acid (HA). Among considered materials, polystyrene shows the highest capacity of adsorbing BaPs via forming sandwiched π-stacking structures with benzene rings. Driven by hydrophobic, electrostatic and hydrogen bonding interactions, HAs spontaneously aggregate into micelle-like structures with hydrophobic core and charged exterior accessible to BaPs and Cu2+, respectively. Cationic and neutral nanoplastics adsorb more HAs to form eco-coronas, which modulate BaP and Cu2+ adsorption via following cooperation/competition mechanisms. On one hand, the direct binding of BaPs to nanoplastics is hindered by HAs through BaP encapsulation plus competitive adsorption. On the other hand, adsorbed HAs expose carboxyl groups to offer rich binding sites to promote Cu2+ adsorption on neutral and cationic nanoplastics, while unbound HAs compete with anionic nanoplastics to inhibit Cu2+ adsorption. These results provide molecular level insights into transport, transformation and accessibility of nanoplastics with coexisting contaminants in the aqueous environment.

Enclosure fisheries have accommodated the widespread expansion of aquaculture in many lakes throughout the Yangtze Plain (YP), China, for over four decades. Such practices have increased food provision but have also triggered various detrimental environmental consequences. To restore ecosystem functions, the Chinese government recently implemented specific regulations to remove enclosure fences from lakes throughout the YP. However, little information is available on the spatial and temporal distributions of the enclosure fences, particularly in relation to the enforcement of recent policy changes. Using synthetic aperture radar (SAR) satellite images taken between 2002 and 2018, we conducted the first comprehensive assessment of the interannual changes in enclosure fences in 17 large lakes throughout the YP. Consistent decreases in fence density were found in most lakes after 2015; 15 lakes had >50% of their fences removed, while 9 lakes had >90% removed. The timing and implementation of the development and destruction of enclosure fisheries were related to government policy; before 2015, regional dynamics in enclosure fisheries were attributed to provincial policies, whereas the nearly ubiquitous fence demolition after 2015 was likely a response to national policy. This study represents remotely sensed evidence that demonstrates the importance of both local and national environmental policies and their effectiveness in mitigating ongoing human impacts on vulnerable and valuable natural resources. These findings provide valuable baseline information for future lake environmental monitoring and restoration in the YP region, and the methods used here could be applied to other lacustrine and coastal regions experiencing similar aquaculture activities.

Background: Airborne nanoparticles can be inhaled and deposit in human alveoli, where pulmonary surfactant (PS) molecules line at the alveolar air-water interface to act as the first barrier against inhaled nanoparticles entering the body. Although considerable efforts have been made to elucidate the mechanisms underlying nanoparticle-PS interactions, our understanding on this important issue is limited due to the high complexity of the atmosphere, in which nanoparticles are believed to experience transformations that remarkably change the nanoparticles’ surface properties and states. By contrast with bare nanoparticles that have been extensively studied, relatively little is known about the interactions between PS and inhaled nanoparticles which already adsorb contaminants. In this combined experimental and computational effort, we investigate the joint interactions between PS and graphene with coexisting benzo[a]pyrene (BaP).Results: Depending on the BaP concentration and molecular agglomeration, different nanocomposite structures are formed via BaPs adsorption on graphene. Upon deposition of graphene carrying BaPs at the pulmonary surfactant (PS) layer, competition of interactions between different components determines the interfacial processes including BaP solubilization, graphene translocation and PS perturbation. Importantly, BaP adsorbed on graphene is solubilized to increase its bioavailability and inhibit the PS biophysical function. Translocation of graphene across the PS layer is facilitated by BaP adsorption through segregating it from contact with PS, while translocation of graphene oxide is suppressed due to increase of the surface hydrophobicity. Graphene extracts PS molecules from the layer, and the resultant PS depletion declines with graphene oxidation and BaP adsorption.Conclusion: Graphene showed high capacity of adsorbing BaPs to form nanocomposites, which were inhaled and deposit in alveoli, where competition of interactions between different components determined the interfacial processes of BaP solubilization, graphene translocation and PS perturbation.

The transformation of CuO nanoparticles (NPs) during interaction with Nicotiana tabacum L. cv. bright yellow-2 (BY-2) cells was investigated in this study. CuO NPs were taken up, and transformed into Cu2O, Cu2S and Cu acetate after incubation with plant cells for 12 h based on high resolution transmission electron microscopy and X-ray absorption near-edge spectroscopy analysis. The transformation of CuO NPs initially occurred on cell walls with Cu2O and Cu2S being the main transformation products. Galacturonic acid as an important component of cell walls was mainly responsible for reducing CuO to Cu2O and cysteine for the formation of Cu2S. Cu2+ ions could not be transformed into any Cu-based particles (CuO, Cu2O, or Cu2S) on cell walls. After internalization, CuO NPs could also be transformed into Cu2O and Cu2S through interacting with protoplasts as well as mitochondria, confirming that CuO NPs were able to transform intracellularly. Moreover, Cu2O NPs showed higher toxicity to plant cells as compared to CuO NPs with similar individual sizes, indicating that the transformation of CuO NPs enhanced their toxicity to plant cells. These findings could provide new insights into better understanding the transformation and fate of metal-based NPs in living organisms and environments.

Airborne nanoplastics can be inhaled to threaten human health, but research on the inhaled nanoplastic toxicity is in its infancy, and interaction mechanisms are largely unknown. By means of molecular dynamics simulation, we employed spherical nanoplastics of different materials and aging properties to predict and elucidate nanoplastic transformations in alveolar fluid and impacts on the lung surfactant (LS) film at the alveolar air-water interface. Results showed spontaneous adsorption of LS molecules on nanoplastics of 10 nm in diameter, and the adsorption layer can be defined as coronas, which increased the particle size, reduced and equalized the surface hydrophobicity, and endowed nanoplastics with negative surface charges. Nanoplastics of polypropylene and polyvinylchloride materials were dissolved by LS, which could increase bioavailability of polymers and toxic additives. Aging properties represented by the nanoplastic size, polymer’s molecular weight and surface chemistry altered nanoplastic transformations through modulating competition between polymer-LS and polymer-polymer interactions. Upon transferred to the alveolar air-water interface through vesicle fusion, nanoplastics could interfere with the normal biophysical function of LS through disrupting the LS ultrastructure and fluidity, and prompting collapse of the LS film. These results provide new molecular level insights into fate and toxicity of airborne nanoplastics in human respiratory system.

The roles of Al2O3 particles with different morphologies in altering graphene oxide (GO) toxicity to Chlorella pyrenoidosa were investigated. Algal growth inhibition by GO with coexisting Al2O3 particles was much lower than the sum of inhibitions from the individual materials for all the three Al2O3, showing the toxicity mitigation by Al2O3. The lowest GO toxicity was observed at the concentrations of 300, 150, and 100 mg/L for Al2O3 nanoparticles (NPs, 8-10 nm), bulk particles (BPs, 100-300 nm), and fibers (diameter: 10 nm; length: 400 nm), respectively. GO-Al2O3 heteroaggregation was responsible for the observed toxicity reduction. GO-induced algal membrane damage was suppressed by the three types of Al2O3 due to GO-Al2O3 heteroaggregation, and the reduction in intracellular reactive oxygen species generation and physical contact were confirmed as two main mechanisms. Moreover, the exposure sequence of GO and Al2O3 could highly influence the toxicity, and the simultaneous exposure of individual GO and Al2O3 showed the lowest toxicity due to minimum direct contact with algal cells. Humic acid further decreased GO-Al2O3 toxicity due to enhanced steric hindrance through surface coating of GO-Al2O3 heteroaggregates. This work provides new insights into the role of natural mineral particles in altering the environmental risk of GO.

With wide applications, the production of carbon nanomaterials (CNMs) is rapidly increased, and the CNMs in nanoproducts during consumption are inevitably released into the environment. CNMs in the environment can interact with co-existing pollutants (e.g., organic pollutants, heavy metals and other nanoparticles), thus affecting their fate and toxicity. Therefore, the joint toxicity of CNMs and co-existing pollutants cannot be neglected during the environmental risk assessment of CNMs. In this review, we firstly summarized the mechanisms of direct and indirect toxicity of CNMs; then the joint toxicity of CNMs with other pollutants was emphatically discussed to elaborate the difference with single toxicity; finally, the evaluation methods, research level and challenges of the joint toxicity of CNMs with co-existing pollutants were analyzed and prospected. This review will provide a theoretical basis for the accurate assessment and better understanding of the environmental risks of CNMs.

Nanotechnology is developing rapidly and has been widely applied in chemical engineering, electronic engineering, energy sources, environmental protection and other fields. Engineered nanoparticles (ENPs) are inevitably releasing into the aquatic environment during the entire life cycle of nano-products, thus exposing to aquatic organisms, which has been well investigated in the past decade. ENPs could be internalized by different types of aquatic organisms including algae, plants, and fish. Therefore, the possible transfer of ENPs between different aquatic organisms has attracted attentions, and many important publications reported the trophic transfer of ENPs through aquatic food chains. This review first provided the internalization and distribution of ENPs in different aquatic organisms including microorganism, aquatic plants, invertebrate and fish: (1) For microorganisms, ENPs are mainly adsorbed on the cellular surface, and then be internalized, and the internalization could lead to subsequent toxicity; (2) ENPs could be taken up by the roots of aquatic plants, and then be migrated to stem and leaves by evapotranspiration; (3) ENPs were mainly located in the hepatopancreas and gut of invertebrates; (4) ENPs could be accumulated in the gill and digestive tract of fish, and then distributed into other tissues such as liver and spleen. Secondly, the research status of ENPs in aquatic food chain were summarized and analyzed. The transfer of ENPs was observed in both freshwater and marine food chains, and current investigations on freshwater food chains contributed a larger proportion than in the marine. Most of the researches proved that ENPs can transfer along the food chain, but the biomagnification was only reported in a few publications. Thirdly, the influence of water chemistry factors and ENPs properties on the transfer of ENPs via aquatic food chains was discussed. For the water chemistry factors, like light illumination, solution pH, co-existing compounds such as natural organic matter, ionic strength, and oxidation–reduction potential all altered the bioavailability of ENPs and played important roles in the trophic transfer of ENPs. For the properties of ENPs, it is observed that: (1) the metal ions which were released from metal-containing ENPs can improve the bioavailability of ENPs in aquatic organisms; (2) different coatings of ENPs brought different or opposite surface charge on the surface, thus changing the internalization and bioavailability of ENPs. For example, ENPs with positively charged surface could be easily adsorbed on the surface of aquatic organisms than the negatively charged particles; (3) different size and shape influenced the contacting area between the ENPs and organisms, and ENPs with smaller size were usually more readily enter aquatic organisms, which were deeply discussed in this review. Finally, the current researches, prospects and challenges on ENPs transfer in the aquatic food chains are addressed.

Since industrial revolution, anthropogenic carbon dioxides releasing into the atmosphere are absorbed by the global oceans, which leads to measurable decrease of surface seawater pH and carbonate ion concentration ([CO32−]), thus causing the acidification of global ocean. Besides direct threatening the stability of marine ecosystems, ocean acidification (OA) could also change the environmental processes of marine pollutants, thus indirectly influencing their toxicity to marine organisms. By selecting heavy metals and metallic nanoparticles (MNPs) as the model marine pollutants, this review deeply summarizes the dominant mechanisms on species changes of heavy metals, and the dissolution, dispersion and transport of MNPs based on the causes of OA. The effects of OA-induced environmental process alteration on the toxicity of heavy metal and MNPs to marine organisms at different levels are explored. The differences among the observed toxicological data are analyzed. Finally, the key research challenges and future directions on the toxicity of OA and coexisting pollutants are provided.

This study investigated the toxicity of CuO nanoparticles (NPs) to Nicotiana tabacum L. cv. Bright Yellow-2 (BY-2) cells. CuO NPs with concentrations higher than 2 mg L−1 began to exhibit significant inhibition of the growth of plant cells, and the 24 h median effective concentration was calculated to be 12 mg L−1. CuO NPs (12 mg L−1) showed much higher toxicity than the released Cu2+ (0.8 mg L−1) and bulk particles (BPs, 12 mg L−1) during all the exposure times (0–24 h). CuO NPs were internalized by plant cells through endocytosis, and then located in the cytoplasm, mitochondria and vacuoles. Under CuO NP exposure, the generation of total reactive oxygen species increased by 38.3% and 40.9% compared with CuO BPs and Cu2+ treatments, respectively. The main radical species were identified as H2O2 and OH˙. CuO NPs significantly reduced the activities of complexes I and III on the mitochondrial electron transport chain, blocked the electron transfer from NADH to ubiquinone, and from ubisemiquinone to ubiquinol, induced oxidative stress, and finally led to membrane damage as indicated by an increase in the contents of malondialdehyde and lactate dehydrogenase. Global gene expression analysis from RNA-sequencing showed that CuO NPs (12 mg L−1) significantly induced the expression of 2692 differentially expressed genes (P-value 2) including 1132 up-regulated and 1560 down-regulated genes in BY-2 cells. The differentially expressed genes related to oxidative stress and mitochondria were identified according to gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. This work provides insights into the molecular mechanism of nanotoxicity toward plants.

Biochar application in agricultural soils can be highly beneficial to plant productivity. However, how plant productivity response (PPR) [% change of plant yield from control (without biochar application)] to biochar application is affected by biochar properties, soil conditions, and their combinations is still unclear. Therefore, a meta-analysis based on 1254 paired comparisons from 153 published studies was conducted. The grand mean of PPR was estimated to be 16.0 ± 1.3%, regardless of biochar/soil conditions. Meanwhile, a large variation of PPR from −31.8% to 974% was also observed under different biochar or/and soil conditions. Specifically, biochar properties including pH, cation exchange capacity (CEC), contents of carbon and ash, bulk density, and soil conditions including texture, pH, CEC, nitrogen content, and C/N ratio significantly affected the results of PPR to biochar addition. Furthermore, the liming effect, improvement in soil physical structure, and increased nutrient use efficiency were suggested as the key mechanisms for the positive PPR in biochar-amended soils. Moreover, PPR could be significantly affected (strengthened or weakened) by the combined effect of biochar properties and soil conditions. Overall, the application of biochars with high ash content (or low carbon content) into sandy soils or acidic soils is highly recommended for increasing plant productivity. This meta-analysis will provide helpful information to elucidate the combined effect of biochar properties and soil conditions on plant growth, which is critical for developing engineered biochar with specific functionality to promote plant production and food security.

The methods of life cycle assessment and cost-effectiveness analysis were employed to compare the energetic, environmental, and economic performances of three household-based modern bioenergy (MBE) utilization systems: biogas utilization (BGs), biomass briquette utilization for energy only (BBs), and biomass briquette utilization for energy and biochar (BCs). The results showed that all the three MBEs performed positive results in net energy output, which ranged from 0.86 to 3.75 MJ (kg crop residues)−1. The positive greenhouse gas reductions also can be acquired when using these three MBEs to substitute for traditional energy, respectively. The cost-effectiveness values of three MBE systems ranged from 343 RMB (tCO2e)−1 for BGs to 598 RMB (tCO2e)−1 for BCs (the CO2e indicates the CO2 equivalent). Considering the supply index analysis results furtherly, the BGs is regarded as the best strategy for the development of MBE in rural households. However, BG leakage during BG digester operations should be received much greater attention to avoid adverse impacts on GHG mitigation.

We systematically investigated the reduction mechanisms and reduction kinetics of silver ions (Ag ions) by graphene oxide (GO) under ambient condition. UV–vis spectroscopy, transmission electron microscopy, and electron diffraction results revealed that silver nanoparticles (Ag NPs) could be formed from aqueous Ag ions in the presence of GO at pH 8 under light. Formation of Ag NPs increased with increasing pH (7.4, 8, and 9) and temperature (from 30 to 90); however, the increasing ionic strength and dissolved oxygen reduced the Ag NPs yield. The Ag ions reduction by GO followed pseudo-first-order kinetics under both dark and light, and light irradiation significantly accelerated the Ag NPs formation induced by GO. The phenolic-OH on GO was the dominating electron donator for Ag ion reduction in dark. Exposure to light increased the concentration of phenolic-OH on the GO surface, thereby stimulating the reduction rate of Ag ions by GO. In addition, the light induced electron-hole pairs on GO surface and light activated oxygen-centered radicals on GO surface promoted the reduction of adsorbed Ag ions by GO. Our findings provide important information for the role of GO in reducing Ag ions to Ag NPs in aquatic environments, and shed light on understanding the environmental fate and risk of both Ag ions and GO materials.

Submerged aquatic vegetation (SAV) is one of the main producers in inland lakes. Tracking the temporal and spatial changes in SAV is crucial for the identification of state changes in lacustrine ecosystems, such as changes in light, nutrients, and temperature. However, the available SAV classification algorithms based on remote sensing are highly dependent on field survey data and/or human interventions, prohibiting the extraction of large-scale and/or long-term patterns. Here, we developed an automatic SAV classification algorithm using Landsat imagery, where the thresholds of two key parameters (the floating algae index (FAI) and reflectance in the shortwave-infrared (SWIR) band) are automatically determined. The algorithm was applied to eight Landsat images of four Yangtze Plain lakes and obtained a mean producer accuracy of 82.9% when gauged against field-surveyed datasets. The algorithm was further employed to obtain long-term SAV areal data from Changdang Lake on the Yangtze Plain from 1984 to 2018, and the result was highly consistent with lake transparency data. Numerical simulations indicated that our developed algorithm is insensitive to the Chl-a concentration of the water column. Yet, it has a detection limit of ~0.35 m below the water surface, and such a limit changes with different fractions of vegetation coverage within a pixel. The automatic classification algorithm proposed in this study has the potential to obtain the temporal and spatial distribution patterns of SAV in other shallow lakes where SAV grows in lakes sharing similar hydrological characteristics as the lakes in the Yangtze Plain.

The status and changes of the rural household energy consumption (RHEC) and its pollutants emission in Shandong province, China, from 1995 to 2010 were assessed, as well as the reductions of the air pollutants by developing modern bioenergy (MBE). The results indicated that the RHEC significantly increased with annual growth rate of 1.04% during the study period, and significantly changed from the traditional energy use pattern to the commercial energy use pattern. The income effect ( ∆ RE ri t ) was identified as the critical factor responsible for the increased RHEC, while the energy intensity effect ( ∆ RE ei t ) and the population effect ( ∆ RE rp t ) were the dominant factors responsible for the decreased RHEC. Correspondingly, total emissions of the majority pollutants including CO2, particulate matters (PMs), NOx and SO2 significantly increased with increasing RHEC, and positively correlated with the proportion of commercial energy (PCE) used in RHEC (r=0.821–0.992, P

Over the past half century, the Yangtze Plain of China has experienced rapid economic development. Lake reclamation (i.e., conversion of natural lake/wetland areas to agricultural/urban land or aquaculture, thereby reducing the area of natural waters) in particular has greatly contributed to meeting the increasing demands for food and urban development. However, until now, a comprehensive quantification and understanding of historical anthropogenic lacustrine exploitation in this region has been lacking, prohibiting assessment of the impacts of these activities. We used Landsat observations from 1973 to 2018 to track reclamation-induced changes in 112 large lakes (97.8% of the total lake area) in the Yangtze Plain. We show that 41.6% (6056.9 km2) of the total lake area has been reclaimed since the 1970s. The expansion of agricultural and built-up lands dominated the reclamation activities in the 1970s, while the increase of aquaculture zones has prevailed since the mid-1980s. Reclamation activities were closely connected to government policies and major socio-economic events and had strong impacts on lake hydrology, flood risk mitigation capacity, and water quality as revealed by satellite and in situ observations. This new quantitative understanding of anthropogenic reclamation and its associated impacts on Yangtze Plain freshwater lakes can underpin the development of strategies to reduce the impacts of lake reclamation on environmental quality. The study has also demonstrated the unique strength of using long-term series satellite images in tracking historical environmental changes in a substantial region of the world, and the methods used here are potentially extendable to other inland and coastal areas to understand similar human-environment interaction problems.

Crop residue (CR) based-technology has several benefits, including renewable energy production and improvement in the environment and waste biomass management. However, the quantitative assessment of different CR based-technologies in terms of these benefits is limited. In this study, three typical CR-based technologies, CR biochar (CR-BC), CR direct-fired power (CR-DFP), and CR briquette biofuel (CR-BB), were assessed in terms of energy- and environment-related performances using a mixed-unit input-output life cycle assessment method. The results indicated that CR-BB performed better in energy production and air pollution mitigation than the other two technologies. Energy conversion efficiency was suggested as a key factor in determining the potentials of bioenergy production and environmental improvement. Furthermore, based on the energy demand from the Chinese agricultural sector and CR supply in 2012, the energy supply capacity (ESI) of CR-BC, CR-DFP, and CR-BB was estimated to be 24.3, 2.89, and 53.0, respectively, and their total greenhouse gas (GHG) reduction potential (TRGHG) was estimated to be 1.41 × 106, 4.81 × 106, and 1.68 × 106 t CO2e (CO2 equivalent), respectively. Overall, the CR-DFP and CR-BC are recommended for the high-value utilization of CR resources. The findings of this study could provide a basis for the development of CR-based technologies and CR management policy.

The roles of Al

Figure S1. Physicochemical characterization of AG-QDs. Figure S2. The hydrodynamic diameter of AG-QDs in DI water and cell culture medium. Figure S3. Cell viability of macrophages after exposure to AG-QDs at different concentrations. Figure S4. Viability of MC3T3-E1 cells after exposure to AG-QDs at different concentrations. Figure S5. Apoptosis of NR8383 cells during 24- and 48-h AG-QDs exposure. Figure S6. Export of AG-QDs by macrophages after AG-QDs internalization. Figure S7. Distribution of internalized AG-QDs in macrophages after exocytosis for 24 and 48 h. Figure S8. Confocal images of AG-QDs distributed in mitochondria, endo-lysosomes, and endoplasmic reticulum after incubation for 24 h. Figure S9. The effect of AG-QDs on the membrane stability of endo-lysosomes. Figure S10. Uptake of GO-QDs by NR8383 cells under confocal imaging. Figure S11. Confocal images of AG-QDs distributed in the cellular cytoplasm under 438 nm fluorescence emission. Figure S12. Distribution of AG-QDs in the cellular cytoplasm after incubation for 12 h. Figure S13. Relative expression of Kapβ2 and Nup98 after exposure to AG-QDs (200 μg/mL) for 12 and 24 h. Figure S14. The high content screening (HCS) images of NR8383 cells after AG-QDs (200 μg/mL) exposure in absence and presence of Hoechst33342 at 347 nm excitation and 483 nm emission. Figure S15. Raman images of cells after exposure to AG-QDs (200 μg/mL) for 24 and 48 h. Figure S16. ROS levels of AG-QDs (200 μg/mL) alone and NR8383 cells after AG-QDs exposure. Figure S17. AFM image of DNA chains that were directly exposed to AG-QDs-FBS (200 μg/mL) for 24 h. Figure S18. Ten representative structural models of AG-QDs. Figure S19. π-π Interactions between the AG-QDs (Structures 7–10) and DNA. Table S1. The number of π bonds between AG-QDs (Structures 1–10) and DNA as obtained by molecular docking. Table S2. The expression of genes in the caspase family after AG-QDs exposure. The macrophages were exposed to AG-QDs for 24 h prior to analysis. Table S3. Sequences of the gene-specific primers used in the quantitative real-time PCR (qRT-PCR) experiment. (DOCX 2467 kb)

Engineered nanoparticles (NPs) are being released into aquatic environments with their increasing applications. In this work, we investigated the interaction of CuO NPs with a floating plant, water hyacinth (Eichhornia crassipes). CuO NPs (50 mg/L) showed significant growth inhibition on both roots and shoots of E. crassipes after 8-day exposure, much higher than that of the bulk CuO particles (50 mg/L) and their corresponding dissolved Cu2+ ions (0.30 mg/L). Scanning electron and light microscopic observations showed that the root caps and meristematic zone of E. Crassipes were severely damaged after CuO NP exposure, with disordered cell arrangement and a destroyed elongation zone of root tips. It is confirmed that CuO NPs could be translocated to shoot from both roots and submerged leaves. As detected by X-ray absorption near-edge spectroscopy analysis (XANES), CuO NPs were observed in roots, submerged leaves, and emerged leaves. Cu2S and other Cu species were also detected in these tissues, providing s...

The aging of biochar by low molecular weight organic acids (LMWOAs), which are typical root-derived exudates, is not well understood. Three LMWOAs (ethanoic, malic, and citric acids) were employed to investigate their aging impacts on the biochars from furfural production residues at 300-600°C (BC300-600). The LMWOAs created abundant macropores in BC300, whereas they significantly increased the mesoporosity and surface area of BC600 by 13.5-27.0% and 44.6-61.5%, respectively. After LMWOA aging, the content of C and H of the biochars increased from 51.3-60.2% and 1.87-3.45% to 56.8-69.9% and 2.06-4.45%, respectively, but the O content decreased from 13.8-24.8% to 7.82-19.4% (except BC300). For carbon fraction in the biochars, the LMWOAs barely altered the bulk and surface functional properties during short-term aging. The LMWOAs facilitated the dissolution of minerals (e.g., K2Mg(PO3)4, AlPO4, and Pb2P2O7) and correspondingly promoted the release of not only plant nutrients (K+, Ca2+, Mg2+, Fe3+, PO43-, and SO42-) but also toxic metals (Al3+ and Pb2+). This research provided systematic insights on the responses of biochar properties to LMWOAs and presented direct evidence for acid activation of inorganic minerals in the biochars by LMWOAs, which could enhance the understanding of environmental behaviors of biochars in rhizosphere soils.

Copper element was employed to achieve the interlayer doping and intralayer doping in g-C3N4 (CN). Univalent Cu single atom prefer to dope into the interlayer site of CN to form a steady bridged bond structure. Further increasing the doping amount of Cu, except for the univalent Cu at the interlayer, some divalent Cu single atoms can be doped on the intralayer site of CN to form an unstable but active-catalysis structure. Electrochemical and theoretical calculation results reveal that Cu-interlayer doping can form an energy gradient between the different CN layers to decrease the charge transfer energy barrier between them. More importantly, these interlayer photogenerated electrons will converge on the divalent Cu, a catalysis active site for the photogenerated electrons, inducing more superoxide radicals and high activity. This two-sites modified CN, can mineralize a refractory antibiotic Norfloxacin (NOR) to CO2 and H2O completely under visible light stimulation, and the two-sites co-doping method provides a reference for CN photocatalyst modification to solve the questions of insufficient redox energy and low photons quantum efficiency of CN.

Biochar has been suggested as a potential tailored technology for mediating soil conditions and improving crop yields. However, the efficacies of biochar and biochar-based amendments (e.g., composted biochar) in agricultural soils under a rotation system remain uncertain. In this study, an arable soil was subjected to peanut shell biochar (PBC) and biochar-based amendment (PAD) combined with or without nitrogen (N) fertilizer to evaluate their effects on vegetable yield, N bioavailability, and their relative contribution to vegetable biomass in four consecutive planting seasons. PBC alone or in co-application with N fertilizer had little effect on vegetable yield, while PAD co-application with N fertilizer decreased vegetable biomass because of the inhibition of root morphology by excessive nutrient supply. PBC and PAD applications increased rhizosphere soil pH due to OH– and HCO3– release and NO3−-N uptake. Although the addition of PAD increased soil N contents due to its high contents in PAD, it had little effects on N utilization efficiency (NUE) in the four seasons. The relative contribution of PBC, PAD, and their interaction with N fertilizer to biomass yield was maintained at a low level. Our results indicated that a biochar-based amendment (e.g., PAD) was a potential alternative to N fertilizer, but the ratio of biochar to additives should be managed carefully to generate optimal benefits. Notably, the efficacy of PAD on plant growth was closely associated with plant species, and further related research on different plants is encouraged.

We systematically investigated the toxicity mechanism of three graphene-family materials (GFMs), graphene oxide (GO), reduced graphene oxide (rGO) and multi-layer graphene (MG), to algae (Chlorella pyrenoidosa). GFMs exhibited much higher toxicity than other carbon materials (carbon nanotube and graphite), with the 96 h median effective concentration (EC50) values of 37.3 (GO), 34.0 (rGO), and 62.2 (MG) mg/L. Shading effect contributed approximately 16.4% of growth inhibition by GO due to its higher dispersibility and transformation while the other GFMs did not show any shading effect. Hydrophobic rGO and MG more readily heteroagglomerated with algae than GO, thus likely leading to more direct contacts with algae. Flow cytometry results showed significant decrease of membrane integrity after GFM exposure, and rGO caused the highest membrane damage, which was confirmed by the increased DNA and K+ efflux. The observed membrane damage was caused by a combination of oxidative stress and physical penetration/extraction. Moreover, all the three GFMs could adsorb macronutrients (N, P, Mg, and Ca) from the algal medium, thus leading to nutrient depletion-induced indirect toxicity. GO showed the highest nutrient depletion (53% of total toxicity) due to its abundant functional groups. The information provided in this work will be useful for understanding toxicity mechanism and environmental risk of different GFMs in aquatic environments.

This study investigated the adsorption of cadmium (Cd(II)) by cerium oxide nanoparticles (CeO2 NPs) and oyster shells in seawater. The results showed that the addition of Cd(II) significantly inhibited the agglomeration of CeO2 NPs both in DI water and seawater, increased the positive charges of CeO2 NPs in DI water and neutralized the negative charges of CeO2 NPs in seawater. Additionally, CeO2 NPs could adsorb Cd and the bioavailability of Cd was reduced in the presence of oyster shells. This study demonstrated that the adsorption of metals on shells should not be neglected for the accumulation of metals by shellfish.

This work investigated the toxicity of CuO nanoparticles (NPs) to Escherichia coli in the presence of dissolved organic matter (DOM). CuO NPs (2, 6 and 10 mg/L) exhibited high bacteria toxicity in distilled water prepared medium, with a 2 h median inhibitory concentration of 10 mg/L. The toxicity was significantly reduced by the presence of fulvic acid (FA, 5 and 40 mg/L) which is an important fraction of DOM. Bacteria membranes were highly damaged by CuO NPs, but FA mitigated this damage. Disruption of the bacteria wall and membrane was directly observed using transmission/scanning electron microscopy. Moreover, CuO NPs significantly caused the leakage of K(+) ions from bacteria cells to extracellular medium, while this leakage was reduced by FA. The reduced toxicity was due to enhanced electrostatic repulsion and surface coating by FA, therefore, the physical contact between CuO NPs and bacteria membrane was hindered. These findings indicate that DOM is of importance for antibacterial activity of NPs, and more attention should be paid to the effect of DOM when assessing the environmental risk of NPs.