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Plastic pollution is widely present in terrestrial and aquatic ecosystems, and microplastics (MPs) can be detected in organisms. In situ detection methods for MPs in organisms have attracted widespread attention. Traditional imaging characterization methods of MPs, including stereo microscopes and fluorescence microscopy, are typically used to image artificially added microsphere standards under laboratory conditions. However, they cannot specifically identify MPs in biological samples. Thus, there is a need for a detection technique that can provide spatial distribution information of MPs in biological samples as well as measure their quality and quantity. In this perspective, to obtain high-resolution images with chemical composition analysis, we compared ion sources for ionizing plastic macromolecules and mass analyzers for analyzing macromolecules. Matrix-assisted laser desorption/ionization (MALDI) is suitable for imaging characterization, while time-of-flight (TOF) and Orbitrap mass spectrometry are suitable for polymer mass spectrometry analysis. Furthermore, we propose a technique that combines MALDI with TOF or Orbitrap, which holds promise for the in situ imaging of MPs in biological samples.

Abstract The response of soil microorganisms and plants in soil ecosystems to biochar is well recognised. However, biochars’ impact on large soil animal, such as ants, is inadequately understood, with only limited studies focusing on the abundance and mortality rates of some specific ant species. In this study, soil physicochemical properties, and ant community diversity and functional characteristics were compared between experimental plots with and without biochar application. No significant differences in soil (soil physicochemical properties) or ants (ant community richness, species abundance, and morphological characteristics) were observed between the two plots before biochar application. However, the biochar-treated plot soil surface temperatures, pH, and soil water content were significantly higher after 48 weeks. Biochar application promoted Cardiocondyla nuda (by 426%) and Formica japonica abundance (by 93%), but decreased Solenopsis invicta invasive ant species richness (by 54%), consistent with the fact that changes in soil properties were more beneficial to the former two species. In addition, in biochar-treated plots, F. japonica and S. invicta generally showed larger body size (18% and 6.7%), larger eyes (2.7% and 4.0%), and longer femurs (6.3% and 7.9%), which enabled them to respond better to potential barriers, such as plants. Our results highlighted that, besides species abundance and community structure, certain ant functional morphological indicators were also informative in evaluating biochar ecological implications. Graphical abstract

Abstract The incomplete combustion of biomass and fossil fuels results in the formation of not only black carbon (BC) but also black nitrogen (BN), the dissolved fractions of which (i.e., DBC and DBN) are important components of dissolved organic matter pool. Relative to DBC, the activity and reactivity of DBN are much less understood. Here, we investigated the catalytic effect of DBN derived from N-enriched biomass in the abiotic transformation of chlorophenols by sulfides. The medium-temperature DBN (450 °C) exhibited 13–144% higher catalytic efficiency than other DBN samples and 9.3 times higher than its DBC counterpart. Both electron paramagnetic resonance spectra and fluorescent probe technique indicated that the attached sulfides contributed to the formation of reactive oxygen species (ROS) as the “primary” radicals by favoring electron transfer from DBN to chemisorbed oxygen, and then the generated ROS reacted with N-oxides in DBN to form reactive nitrogen species (RNS) as the “secondary” radicals. The contribution of RNS to the decay of 2-chlorophenol by DBN450 was up to 72%, much higher than that of ROS and non-radical mechanism. These findings suggest that the catalytic effect of DBN is distinct but no less significant than that of DBC to the abiotic transformation of micropollutants in water/soil systems. Graphical Abstract

Abstract Incomplete biomass burning produces considerable amounts of pyrogenic carbonaceous materials (PCMs), which are widely distributed in environmental matrices. Those PCMs undergo different environmental processes and consequently have non-negligible impacts on the global carbon cycle, ecological functions and environmental security. This review provided a comprehensive review of qualitative and quantitative methods, carbon sequestration capabilities and other ecosystem functions of PCMs. In addition, the generation mechanism and environmental health risks of emerging contaminants, especially persistent free radicals (EPFRs) and polycyclic aromatic hydrocarbons (PAHs) associated with PCMs were discussed. The results showed that the coexisting kerogen and coal may interfere with PCMs quantification, and that estimates of PCMs pools vary significantly due to methodological differences, natural variability and limited spatial coverage. The input of PCMs into soils increased soil carbon sequestration through direct carbon contribution and indirect negative priming effect on native SOC. In addition, PCMs can improve soil structure and properties and immobilize/degrade pollutants, which is conducive to the restoration of soil ecology. However, various contaminants associated with PCMs may threaten ecological safety, and thus their formation mechanisms and toxicological pathway to living organisms need to be further investigated. The development of standards for PCMs identification and quantification, application protocols of PCMs in pilot scale, and assessing the effects of PCMs on soil health deserve extended studies.

Abstract Hydrochars as carbonaceous amendments rich in porous structures and nutrients can be used as promising slow-release fertilizers and soil health amendments. Yet, the performance of hydrochars derived from different feedstocks in improving crop plant growth and soil phosphorus (P) availability is not well understood. Here, a batch of sewage sludge (SS) and chicken manure (CM) derived hydrochars (SSCs and CMCs) were produced at 125 and 225 °C (SS125/225 and CM125/225) to investigate their characteristics and performances in improving the seedling growth of two representative crops, soybean (Glycine max) and corn (Zea mays), as well as the P availability in an acidic agricultural soil in comparison with triple super phosphate (TSP), a conventional P fertilizer. Compared with CMCs, SSCs with more porous and rougher surfaces contained relatively lower contents of carbon (C; 32.3–33.3%), hydrogen (H; 3.9–4.69%), and potassium (K; 29.2–51 mg g−1), but higher contents of P (37.4–85.4%) and nitrogen (N; 2.26–4.9%), as well as more O-containing and N-containing functional groups. The impacts of hydrochars on soybean and corn growth showed distinct variations. The application of SSCs showed little effect on soybean growth (i.e., biomass, chlorophyl contents, and number of leaves), while CMCs significantly increased its total dry biomass by 23.2–66.2%. For corn, both SSCs and CMCs increased the total dry biomass by 32.8–92.4% and 21.8–69.7%, respectively, compared to those in the un-amended soils. In addition, compared with the higher temperature hydrochars (SS225 and CM225), the lower temperature ones (SS125 and CM125) increased the total dry biomass by 24.6% and 34.9% for soybean and 44.8% and 39.3% for corn, respectively. The significant improvement in crop growth by hydrochars was mainly due to the direct nutrient supply (particularly P) by the hydrochars, which was supported by the increased soil and shoot P concentrations. Moreover, hydrochar application led to a rise in soil water soluble P (WSP) levels. However, as time progressed, these levels fell due to the fixation and adsorption of P via precipitation, electrostatic attraction, and ion exchange on the hydrochars. Contrarily, TSP maintained persistently high soil WSP levels, increasing the leaching risk of P through the soil profile. Our results provide direct evidence for hydrochars as slow-release P fertilizers to enhance crop growth and production and give better insights for producing functionalized P-rich chars as an alternative to chemical P fertilizers to maintain sustainable agricultural production. Graphical Abstract

Abstract The artificial humic acids (AHA) approach contributes to achieving the carbon (C) emission peaking and neutrality goal through efficient recycling of waste biomasses and promotion of plant photosynthesis. However, the dependence of their production processes and photosynthetic promotion mechanisms on feedstocks remains unclear. In this study, waste biomasses including camphor leaves (CL), corn stalks (CS), peanut shells (PS), and mixed cyanobacteria (MC) have been respectively converted into artificial humic acids through an environmentally friendly hydrothermal humification approach. The dynamic humification process of different feedstocks and the composition, structural properties, and electron transfer capacity of AHA products were determined. Moreover, the different AHA products were applied to corn to explore their respective photosynthetic promotion mechanisms. High relative contents of lignin and C/N in feedstocks are not conducive to the formation of photodegradable substances and the redox property in AHA. The application of AHA increased the net photosynthetic rate and biomass C of corn by 70–118% and 22–39%, respectively. The AHA produced from higher H/C (0.19) and hemicellulose content (17.09%) in feedstocks (e.g., MC) increased corn photosynthesis by improving light energy capture and conversion efficiency in the PSII process. In contrast, the AHA produced from a higher content of lignin (19.81%) and C/N (7.67) in feedstocks (e.g., CS) increased corn photosynthesis by providing functional enzymes (proteins) and nutrients for leaves. This work provides new insights into the utilization of renewable resources, and the artificial humic acids approach sheds light on environmental sustainability by constructing a closed loop of C in environments. Graphical Abstract

Perfluoroalkyl acids (PFAAs) are considered forever chemicals, gaining increasing attention for their hazardous impacts. However, the ecological effects of PFAAs remain unclear. Environmental DNA (eDNA), as the environmental gene pool, is often collected for evaluating the ecotoxicological effects of pollutants. In this study, we found that all PFAAs investigated, including perfluorohexanoic acid, perfluorooctanoic acid, perfluorononanoic acid, and perfluorooctane sulfonate, even at low concentrations (0.02 and 0.05 mg/L), expedited the enzymatic degradation of DNA in a nonlinear dose–effect relationship, with DNA degradation fragment sizes being lower than 1,000 bp and 200 bp after 15 and 30 min of degradation, respectively. This phenomenon was attributed to the binding interaction between PFAAs and AT bases in DNA via groove binding. van der Waals force (especially dispersion force) and hydrogen bonding are the main binding forces. DNA binding with PFAAs led to decreased base stacking and right-handed helicity, resulting in loose DNA structure exposing more digestion sites for degrading enzymes, and accelerating the enzymatic degradation of DNA. The global ecological risk evaluation results indicated that PFAA contamination could cause medium and high molecular ecological risk in 497 samples from 11 contamination-hot countries (such as the USA, Canada, and China). The findings of this study show new insights into the influence of PFAAs on the environmental fates of biomacromolecules and reveal the hidden molecular ecological effects of PFAAs in the environment.

Abstract Salt-affected soils urgently need to be remediated to achieve the goals of carbon neutrality and food security. Limited reviews are available on biochar performance in remediating salt-affected soils in the context of carbon neutrality and climate change mitigation. This work summarized the two pathways to achieve carbon neutrality during remediating salt-affected soils using biochars, i.e., biochar production from sustainable feedstock using thermal technologies, application for promoting plant productivity and mitigating greenhouse gas (GHG) emission. Converting biomass wastes into biochars can reduce GHG emission and promote carbon dioxide removal (CDR), and collection of halophyte biomass as biochar feedstocks, development of biochar poly-generation production systems with carbon neutrality or negativity could be promising strategies. Biochar can effectively improve plant growth in salt-affected soils, showing that the grand mean of plant productivity response was 29.3%, via improving physicochemical characteristics, shifting microbial communities, and enhancing plant halotolerance. Moreover, biochar can mitigate GHG emission via inducing negative priming effect, improving soil properties, changing microbial communities associated with carbon and nitrogen cycle, direct adsorption of GHG. However, biochar also may pose negative effects on plant growth because of stress of toxic compounds and free radicals, and deterioration of soil properties. The promoted GHG emission is mainly ascribed to positive priming effect, and provision of labile carbon and inorganic nitrogen fractions as microbial substrates. Finally, this review pointed out the gaps in the current studies and the future perspectives. Particularly, the development of “carbon neutral” or “carbon negative” biochar production system, balancing the relationship of biochar effectiveness and functionality with its environmental risks and costs, and designing biochar-based GHG adsorbents would be important directions for remediating salt-affected soils to achieve carbon neutrality and abate climate change. Graphical Abstract

The presence of polycyclic aromatic hydrocarbons (PAHs) in soil negatively affects the environment and the degradation of these contaminants is influenced by nitrogen metabolism. However, the mechanisms underlying the interrelationships between the functional genes involved in nitrogen metabolism and phenanthrene (PHE) biodegradation, as well as the effects of biochar on these mechanisms, require further study. Therefore, this study utilised metabolomic and metagenomic analysis to investigate primary nitrogen processes, associated functional soil enzymes and functional genes, and differential soil metabolites in PHE-contaminated soil with and without biochar amendment over a 45-day incubation period. Results showed that dissimilatory nitrate reduction to ammonium (DNRA) and denitrification were the dominant nitrogen metabolism processes in PHE-contaminated soil. The addition of biochar enhanced nitrogen modules, exhibiting discernible temporal fluctuations in denitrification and DNRA proportions. Co-occurrence networks and correlation heatmap analysis revealed potential interactions among functional genes and enzymes responsible for PHE biodegradation and nitrogen metabolism. Notably, enzymes associated with denitrification and DNRA displayed significant positive correlation with enzymes involved in downstream phenanthrene degradation. Of particular interest was stronger correlation observed with the addition of biochar. However, biochar amendment inhibited the 9-phenanthrol degradation pathway, resulting in elevated levels of glutathione (GSH) in response to environmental stress. These findings provide new insights into the interactions between nitrogen metabolism and PHE biodegradation in soil and highlight the dual effects of biochar on these processes.

Abstract Biodegradable plastic is often perceived as a possible solution for microplastic (MP) pollution. Photodegradation is an important transformation pathway of biodegradable MPs in aquatic environments. However, the influence mechanisms of dissolved organic matter (DOM) from different sources on photodegradation of biodegradable MPs are poorly understood. This study explored the role of naturally and pyrogenically sourced DOM in the photodegradation of polylactic acid (PLA) MPs. The aromatics of natural DOM (NDOM) were higher than those of biochar-sourced DOM (BDOM) and showed a stronger improvement in PLA-MPs degradation, as evidenced by particle size reduction, crystallinity increase and polymerization decrease, breakage of surface morphology, and increase in oxygen-containing functional groups on MPs’ surface (O/C increase: 65.1% for NDOM; 34.9% for BDOM). Reactive oxygen species analysis showed that the excited triplet states of DOM (3DOM*) generated by NDOM produced more •OH and 1O2 than that of BDOM, accelerating PLA-MPs photodegradation. Such photodegradation processes were further enhanced through the sorption of DOM by PLA-MPs, in which non-aromatic components were preferentially sorbed, causing the enrichment of aromatics in the solution, leading to more 3DOM* formation. This study improves the understanding of the migration and transformation of biodegradable MPs with the presence of DOM. Graphical Abstract

Glyphosate is an herbicide extensively used worldwide that can remain in the soil. Phytoremediation to decontaminate polluted water or soil requires a plant that can accumulate the target compound. Vulpia myuros is an annual fescue that can be used as a heavy mental phytoremediation strategy. Recently, it has been used to intercrop with tea plant to prohibit the germination and growth of other weeds in tea garden. In order to know whether it can be used an decontaminating glyphosate’ plant in water or soil, in this study, glyphosate degradation behavior was investigated in Vulpia myuros cultivated in a hydroponic system. The results showed that the concentration of glyphosate in the nutrient solution decreased from 43.09 μg mL−1 to 0.45 μg mL−1 in 30 days and that 99% of the glyphosate molecules were absorbed by V. myuros. The contents of glyphosate in the roots reached the maximum (224.33 mg kg−1) on day 1 and then decreased. After 3 days, the content of glyphosate in the leaves reached the highest value (215.64 mg kg−1), while it decreased to 156.26 mg kg−1 in the roots. The dissipation dynamics of glyphosate in the whole hydroponic system fits the first-order kinetic model C = 455.76e−0.21 t, with a half-life of 5.08 days. Over 30 days, 80% of the glyphosate was degraded. The contents of the glyphosate metabolite amino methyl phosphoric acid (AMPA), ranged from 0.103 mg kg−1 on day 1–0.098 mg kg−1 on day 30, not changing significantly over time. The Croot/solution, Cleaf/solution and Cleaf/root were used to express the absorption, transfer, and distribution of glyphosate in V. myuros. These results indicated that glyphosate entered into the root system through free diffusion, which was influenced by both the log Kow and the concentration of glyphosate in the nutrient solution, and that glyphosate was either easily transferred to the leaves through the transpiration stream, accumulated, or degraded. The degradation of glyphosate in V. myuros indicated that it has potential as a remediating plant for environmental restoration.

Salt-affected soil has become one of the major threats to soil health. However, the evaluation of biochar amendment effects and the underlying mechanisms on the physical, chemical, and biological indicators used for assessing the health of salt-affected soils is lacking. This review summarized biochar performance and mechanisms in improving the health of salt-affected soils. Biochar addition significantly improved soil physico-chemical properties by enhancing aggregate stability (15.0–34.9%), porosity (8.9%), and water retention capacity (7.8–18.2%), increasing cation exchange capacity (21.1%), soil organic carbon (63.1%), and nutrient availability (31.3–39.9%), as well as decreasing bulk density (6.0%) and alleviating salt stress (4.1–40.0%). Following biochar incorporation, soil biological health can also be improved, particularly enhancing microbial biomass (7.1–25.8%), facilitating enzyme activity (20.2–68.9%), and ultimately increasing plant growth. To properly assess the health of salt-affected soils, it is important to select indicators related to ecological service functions including plant production, water quality, climate change, and human health. This will improve the evaluation of soil multifunctionality and enhance current soil health assessment methods. Finally, limitations and future needs of biochar research and biochar-based technologies for soil health assessment in salt-affected soils are discussed. Based on a global meta-analysis to illustrate biochar effects on salt-affected soil health indicators, this review offers valuable insights for developing sustainable biochar-based tools for remediating salt-affected soil.

Small microplastics are preferentially retained in Three Gorges Reservoir sediments and the dam likely substantially reduces the microplastic flux in the Yangtze River, according to sedimentary analyses from the upper and lower reaches of the Three Gorges Dam, China between 2008 and 2020.

Highlights A new type of biochar was prepared by co-pyrolysis of corn stalks and alkali-fused fly ash for Pb(II) removal from wastewater. The high surface area and Pb(II) adsorption capacity of adsorbents made them suitable for wastewater treatment. The main Pb(II) adsorption mechanisms were physisorption, precipitation, cation exchange, and complexation.

Research on the environmental health of emerging contaminants is critical to understand their risks before causing severe harm. However, the low environmental concentrations, complex behaviors, and toxicology of emerging contaminants present enormous challenges for researchers. Here, we reviewed the research on the environmental health of engineered nanomaterials (ENMs), one of the typical emerging contaminants, to enlighten pathways for future research on emerging contaminants at their initial exploratory stage. To date, some developed pretreatment methods and detection technologies have been established for the determination of ENMs in natural environments. The mechanisms underlying the transfer and transformation of ENMs have been systematically explored in laboratory studies. The mechanisms of ENMs-induced toxicity have also been preliminarily clarified at genetic, cellular, individual, and short food chain levels, providing not only a theoretical basis for revealing the risk change and environmental health effects of ENMs in natural environments but also a methodological guidance for studying environmental health of other emerging contaminants. Nonetheless, due to the interaction of multiple environmental factors and the high diversity of organisms in natural environments, health effects observed in laboratory studies likely differ from those in natural environments. We propose a holistic approach and mesocosmic model ecosystems to systematically carry out environmental health research on emerging contaminants, obtaining data that determine the objectivity and accuracy of risk assessment.

Summary: Microplastics (MPs) can accumulate in animal organs. Numerous studies have linked MPs with immune system. However, the impact of MPs on immune response remains unclear. This study examined the innate immune response of mice exposed to 5 μm MPs. In the lipopolysaccharide challenge, mice treated with MPs exhibited lower levels of serum immune factors and activated immune cells. MPs disrupted immune-related receptors and cause dysfunction in cell signal transduction within the liver and spleen. Proteomic analysis revealed that MPs impede the activation of serum immune-related signals. In addition, the tissue section imaging exhibited a significant enrichment of MPs in the extracellular matrix (ECM), consistent with the ECM dysfunction and immune receptor suppression. Therefore, our data suggest excessive MPs accumulation in ECM inhibits cell signaling pathways, thereby suppressing the activation of immune responses. We propose the biotoxicity of MPs is partly through the MP disruption of ECM (MPDEM).

Food security and sustainable development of agriculture has been a key challenge for decades. To support this, nanotechnology in the agricultural sectors increases productivity and food security, while leaving complex environmental negative impacts including pollution of the human food chains by nanoparticles. Here we model the effects of silver nanoparticles (Ag-NPs) in a food chain consisting of soil-grown lettuce Lactuca sativa and snail Achatina fulica. Soil-grown lettuce were exposed to sulfurized Ag-NPs via root or metallic Ag-NPs via leaves before fed to snails. We discover an important biomagnification of silver in snails sourced from plant root uptake, with trophic transfer factors of 2.0–5.9 in soft tissues. NPs shifts from original size (55–68 nm) toward much smaller size (17–26 nm) in snails. Trophic transfer of Ag-NPs reprograms the global metabolic profile by down-regulating or up-regulating metabolites for up to 0.25- or 4.20- fold, respectively, relative to the control. These metabolites control osmoregulation, phospholipid, energy, and amino acid metabolism in snails, reflecting molecular pathways of biomagnification and pontential adverse biological effects on lower trophic levels. Consumption of these Ag-NP contaminated snails causes non-carcinogenic effects on human health. Global public health risks decrease by 72% under foliar Ag-NP application in agriculture or through a reduction in the consumption of snails sourced from root application. The latter strategy is at the expense of domestic economic losses in food security of $177.3 and $58.3 million annually for countries such as Nigeria and Cameroon. Foliar Ag-NP application in nano-agriculture has lower hazard quotient risks on public health than root application to ensure global food safety, as brought forward by the United Nations Sustainable Development Goals.

Hematite, as an extensive natural mineral with multiple crystal facets, profoundly affects the migration and transformation of pollutants in the natural environment. However, little is known about the photochemical behavior of microplastics on different facets of hematite in the aquatic environment. In this work, the photoaging of polystyrene microplastics (PS-MPs) on different crystal planes ({001}, {100}, and {012} facets) and related mechanisms were studied. Two-dimensional correlation spectroscopy analysis illustrated that the reaction pathways of PS-MPs photoaging on hematite tended to preferential chemical oxidization. The stronger performance of PS-MPs photoaging, expressed by particle size reduction and surface oxidation, was observed on the {012} crystal facet. Under irradiation, {012} facet-dominated hematite with a narrower bandgap (1.93 eV) reinforced the photogenerated charge carrier separation, and the lower activation energy barrier (1.41 eV calculated from density functional theory) led to effective •OH formation from water oxidation. These findings elucidate the underlying photoaging mechanism of MPs on hematite with different mineralogical phases.

There are increasing concerns over the threat of nanoplastics to environmental and human health. However, multidisciplinary barriers persist between the communities assessing the risks to environmental and human health. As a result, the hazards and risks of nanoplastics remain uncertain. Here, we identify key knowledge gaps by evaluating the exposure of nanoplastics in the environment, assessing their bio-nano interactions, and examining their potential risks to humans and the environment. We suggest considering nanoplastics a complex and dynamic mixture of polymers, additives, and contaminants, with interconnected risks to environmental and human health. We call for comprehensive integration of One Health approach to produce robust multidisciplinary evidence to nanoplastics threats at the planetary level. Although there are many challenges, this holistic approach incorporates the relevance of environmental exposure and multi-sectoral responses, which provide the opportunity to identify the risk mitigation strategies of nanoplastics to build resilient health systems.

Few-layer black phosphorus (LBP) has been widely investigated for its unique optical and electronic properties. As degradation of LBP in ambient conditions largely limited its practical applications, numerous stabilization methods were developed. Understanding stabilization mechanism is essential to development of new protection technologies for LBP. Herein, protection mechanism of the most wildly used exfoliation solvent N,N-dimethylformamide (DMF) on LBP was investigated. DMF was found to accelerate color fading of LBP in aerobic water solution. Nevertheless, dissolvable phosphorus generated from degradation of LBP in the presence of DMF accounted for only 52%–57% of that generated in the absence of DMF. By measuring kinetics constants and activation energies of the degradation reactions, the protection mechanism of DMF was attributed to impede hydrolysis of phosphorus oxides. This was caused by occupation of oxidation sites on LBP by DMF through electrostatic interaction. Insoluble phosphorus oxides in addition to dissolvable phosphorus were observed in DMF exfoliated LBP aqueous solution, providing further evidence for hydrolysis impeding mechanism. This finding threw mechanism light on protection effects of DMF on LBP, providing new knowledge for development of effective stabilization technologies of LBP.

Abstract Background Airborne nanoparticles can be inhaled and deposit in human alveoli, where pulmonary surfactant (PS) molecules lining at the alveolar air–water interface act as the first barrier against inhaled nanoparticles entering the body. Although considerable efforts have been devoted 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-family materials (GFMs) with coexisting benzo[a]pyrene (BaP). Results Depending on the BaP concentration, molecular agglomeration, and graphene oxidation, different nanocomposite structures are formed via BaPs adsorption on GFMs. Upon deposition of GFMs carrying BaPs at the pulmonary surfactant (PS) layer, competition and cooperation of interactions between different components determines the interfacial processes including BaP solubilization, GFM translocation and PS perturbation. Importantly, BaPs adsorbed on GFMs are solubilized to increase BaP’s bioavailability. By contrast with graphene adhering on the PS layer to release part of adsorbed BaPs, more BaPs are released from graphene oxide, which induces a hydrophilic pore in the PS layer and shows adverse effect on 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 by BaP adsorption due to the increase of surface hydrophobicity. Graphene extracts PS molecules from the layer, and the resultant PS depletion declines with graphene oxidation and BaP adsorption. Conclusion GFMs showed high adsorption capacity towards BaPs to form nanocomposites. Upon deposition of GFMs carrying BaPs at the alveolar air–water interface covered by a thin PS layer, the interactions of GFM-PS, GFM-BaP and BaP-PS determined the interfacial processes of BaP solubilization, GFM translocation and PS perturbation.

In this study, the release of dissolved black carbon (DBC) from bulk-BC, its surface properties, colloidal stability, and oxidative stress to rice seedlings in the presence and absence of rice root exudates were compared. The bulk-BCs were prepared at 550 °C and derived from wood chips and pig manure, respectively. The release of DBC from bulk-BC was significantly enhanced (20.19–23.63%) by the introduction of root exudates, where low molecular weight organic acids played a dominating role in the dissociation of DBC from carbon skeleton. The surface properties of DBC were greatly modified by root exudates including decreases in the surface area (18.13%) and mineral contents (43.90–69.57%). The O-containing groups and graphitization were also enhanced by 11.46% and 18.65%, respectively. Meanwhile, the presence of root exudates not only reduced the colloidal stability of DBC but also lowered the intensity of free radicals (19.44–22.22%) in DBC. Consequently, the oxidative stress of DBC to rice seedlings was significantly (p

Abstract Previous studies in the long-term experiments at Pendleton, OR (USA), were focused on organic matter cycling, but the consequences of land management for nutrient status over time have received little attention. Soil and wheat (Triticum aestivum L.) tissue samples were analyzed to determine the macronutrient dynamics associated with residue management methods and fertilizer rate under a dryland winter wheat-fallow rotation. The treatments included: no burn residue incorporation with farmyard manure (FYM) or pea vines, no burn or spring burn with application of N fertilizer (0, 45, and 90 kg ha−1), and fall burn wheat residue incorporation. The results revealed no differences on the effect of residue burning on macronutrient concentration over time. After receiving the same treatments for 84 years, the concentrations of soil organic C, total N and S, and extractable Mg, K, P in the 0–10 cm depth significantly increased in FYM plots compared to the rest of the plots. The N fertilization rate of 90 kg ha−1 reduced the accumulations of P, K, and Ca in grain compared to the 0 and 45 kg N ha−1 applications. The results indicate that residue incorporation with FYM can play vital role in reducing the macronutrient decline over time.

Honeybees (Apis mellifera) can be exposed via numerous potential pathways to ambient nanoparticles (NPs), including rare earth oxide (REO) NPs that are increasingly used and released into the environment. Gut microorganisms are pivotal in mediating honeybee health, but how REO NPs may affect honeybee health and gut microbiota remains poorly understood. To address this knowledge gap, honeybees were fed pollen and sucrose syrup containing 0, 1, 10, 100, and 1000mgkg−1 of nano-La2O3 for 12days. Nano-La2O3 exerted detrimental effects on honeybee physiology, as reflected by dose-dependent adverse effects of nano-La2O3 on survival, pollen consumption, and body weight (p

Background: Rare earth elements (REEs) are gaining attention due to rapid rise of modern industries and technological developments in their usage and residual fingerprinting. Cryptic entry of REEs in the natural resources and environment is significant; therefore, life on earth is prone to their nasty effects. Scientific sectors have expressed concerns over the entry of REEs into food chains, which ultimately influences their intake and metabolism in the living organisms. Objectives: Extensive scientific collections and intensive look in to the latest explorations agglomerated in this document aim to depict the distribution of REEs in soil, sediments, surface waters and groundwater possibly around the globe. Furthermore, it draws attention towards potential risks of intensive industrialization and modern agriculture to the exposure of REEs, and their effects on living organisms. It also draws links of REEs usage and their footprints in natural resources with the major food chains involving plants, animals and humans. Methods: Scientific literature preferably spanning over the last five years was obtained online from the MEDLINE and other sources publishing the latest studies on REEs distribution, properties, usage, cycling and intrusion in the environment and food-chains. Distribution of REEs in agricultural soils, sediments, surface and ground water was drawn on the global map, together with transport pathways of REEs and their cycling in the natural resources. Results: Fourteen REEs (Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tb, Th and Yb) were plighted in this study. Wide range of their concentrations has been detected in agricultural soils (

The exposure of polycyclic aromatic hydrocarbons (PAHs) can cause wheat leaf chlorosis. Thus, we hypothesize that chloroplast inner structure damage is the reason for leaf chlorosis. This study was conducted with the wheat seedlings exposed to Hoagland nutrient solution containing 1.0 mg L−1 phenanthrene for 9 days. Subcellular observation showed that chloroplast turns round and loses its structural integrity. Herein, iTRAQ (isobaric tag for relative and absolute quantification) was applied to analyze the changes of protein profile in chloroplast exposed to phenanthrene. A total of 517 proteins are identified, 261 of which are up-regulated. Eight proteins related with thylakoid (the structural component of chloroplast) are down-regulated and the expression of related genes further confirms the proteomic results through real-time PCR under phenanthrene treatment, suggesting that the thylakoid destruction is the reason for chloroplast deformation. Four proteins related with envelope and stroma are up-regulated, and this is the reason why chloroplast remains round. This study is useful in discussing the carcinogenic and teratogenic effects of PAHs in plant cells in the environment, and provides necessary knowledge for improving crop resistance to PAH pollution. Keywords: Polycyclic aromatic hydrocarbons, Leaf cell, Proteomics, Chloroplast deformation, Toxicity, iTRAQ

Air pollution caused by acid gases (NO2, SO2) or greenhouse gases (CO2) is an urgent environmental problem. Two-dimensional nanomaterials exhibit exciting application potential in air pollution control, among which layered black phosphorus (LBP) has superior performance and is environmentally friendly. However, the current interaction mechanism of LBP with hazardous gases is contradictory to experimental observations, largely impeding development of LBP-based air pollution control nanotechnologies. Here, interaction mechanisms between LBP and hazardous gases are unveiled based on density functional theory and experiments. Results show that NO2 is different from other gases, as it can react with unsaturated defects of LBP, resulting in oxidation of LBP and reduction of NO2. Computational results indicate that the redox is initiated by p orbital hybridization between one oxygen atom of NO2 and the phosphorus atom carrying a dangling single electron in a defect’s center. For NO, the interaction mechanism is chemisorption on unsaturated LBP defects, whereas for SO2, NH3, CO2 or CO, the interaction is dominated by van der Waals forces (57–82% of the total interaction). Experiments confirmed that NO2 can oxidize LBP, yet other gases such as CO2 cannot. This study provides mechanistic understanding in advance for developing novel nanotechnologies for selectively monitoring or treating gas pollutants containing NO2.

Strategies to mitigate the spread of antibiotic resistance genes (ARGs) in soils are urgently needed. Therefore, a pristine pyroligneous acid (PA) from pyrolyzing blended woody waste at 450 °C and its three fractions distilled at 98, 130, and 220 °C (F1, F2, and F3) were used to evaluate their feasibility of reducing ARGs in soil. Application of PA, F2, and F3 effectively decreased the relative ARG abundance by 22.4–75.4% and 39.7–66.7% in the rhizosphere and bulk soil relative to control, respectively, and the removal efficiency followed an order of F3 > PA > F2. Contrarily, F1 increased the abundance of ARGs. The decreased abundance of two mobile genetic elements and impaired conjugative transfer of RP4 plasmid in the presence of PA, F2 and F3 demonstrated that the weakened horizontal gene transfer (HGT) contributed to the reduced ARG level. Variation partitioning analysis and structural equation models confirmed that ARG reduction was primarily driven by the weakened HGT, followed by the decreased co-selection of heavy metals and shifted bacterial community (e.g., reduced potential host bacteria of ARGs). Our findings provide practical and technical support for developing PA-based technology in remediating ARG-contaminated soil to ensure food safety and protect human health.

Flavonoids contribute to fruit sensorial and nutritional quality. They are also highly beneficial for human health and can effectively prevent several chronic diseases. There is increasing interest in developing alternative food sources rich in flavonoids, and nano-enabled agriculture provides the prospect for solving this action. In this study, triiron tetrairon phosphate (Fe7(PO4)6) nanomaterials (NMs) were synthesized and amended in soils to enhance flavonoids accumulation in tomato fruits. 50 mg kg−1 of Fe7(PO4)6 NMs was the optimal dose based on its outstanding performance on promoting tomato fruit flavonoids accumulation. After entering tomato roots, Fe7(PO4)6 NMs promoted auxin (IAA) level by 70.75 and 164.21% over Fe-EDTA and control, and then up-regulated the expression of genes related to PM H+ ATPase, leading to root proton ef-flux at 5.87 pmol cm−2 s−1 and rhizosphere acidification. More Mg, Fe, and Mn were thus taken up into plants. Subsequently, photosynthate was synthesized, and transported into fruits more rapidly to increase flavonoid synthesis potential. The metabolomic and transcriptomic profile in fruits further revealed that Fe7(PO4)6 NMs regulated sucrose metabolism, shi-kimic acid pathway, phenylalanine synthesis, and finally enhanced flavonoid biosynthesis. This study implies the potential of NMs to improve fruit quality by enhancing flavonoids synthesis and accumulation.

With the rising global population growth and limitation of traditional agricultural technology, global crop production could not provide enough nutrients to assure adequate intake for all people. Nano-fertilizers and nano-pesticides have 20–30% higher efficacy than conventional products, which offer an effective solution to the above-mentioned problem. Rhizosphere is where plant roots, soil, and soil biota interact, and is the portal of nutrients transporting from soil into plants. The rhizosphere processes could modify the bioavailability of all nutrients and nanomaterials (NMs) before entering the food plants. However, to date, the overall rhizosphere processes regulating the behaviors and bioavailability of NMs to enhance the nutritional quality are still uncertain. In this review, a meta-analysis is conducted to quantitatively assess NMs-mediated changes in nutritional quality from food plants. Furthermore, the current knowledge and related mechanisms of the behavior and bioavailability of NMs driven by rhizosphere processes, e.g., root secretions, microbial and earthworm activities, are summarized. A series of rhizosphere processes can influence how NMs enter plants and change the biological responses, including signal transduction and nutrient absorption and transport. Moreover, future perspectives are presented to maximize the potentials of NMs applications for the enhancement of food crop production and global food security.

Abstract Background Given the tremendous potential for graphene quantum dots (QDs) in biomedical applications, a thorough understanding of the interaction of these materials with macrophages is essential because macrophages are one of the most important barriers against exogenous particles. Although the cytotoxicity and cellular uptake of graphene QDs were reported in previous studies, the interaction between nuclei and the internalized graphene QDs is not well understood. We thus systematically studied the nuclear uptake and related nuclear response associated with aminated graphene QDs (AG-QDs) exposure. Results AG-QDs showed modest 24-h inhibition to rat alveolar macrophages (NR8383), with a minimum inhibitory concentration (MIC) of 200 μg/mL. Early apoptosis was significantly increased by AG-QDs (100 and 200 μg/mL) exposure and played a major role in cell death. The internalization of AG-QDs was mainly via energy-dependent endocytosis, phagocytosis and caveolae-mediated endocytosis. After a 48-h clearance period, more than half of the internalized AG-QDs remained in the cellular cytoplasm and nucleus. Moreover, AG-QDs were effectively accumulated in nucleus and were likely regulated by two nuclear pore complexes genes (Kapβ2 and Nup98). AG-QDs were shown to alter the morphology, area, viability and nuclear components of exposed cells. Significant cleavage and cross-linking of DNA chains after AG-QDs exposure were confirmed by atomic force microscopy investigation. Molecular docking simulations showed that H-bonding and π-π stacking were the dominant forces mediating the interactions between AG-QDs and DNA, and were the important mechanisms resulting in DNA chain cleavage. In addition, the generation of reactive oxygen species (ROS) (e.g., •OH), and the up-regulation of caspase genes also contributed to DNA cleavage. Conclusions AG-QDs were internalized by macrophages and accumulated in nuclei, which further resulted in nuclear damage and DNA cleavage. It is demonstrated that oxidative damage, direct contact via H-bonding and π-π stacking, and the up-regulation of caspase genes are the primary mechanisms for the observed DNA cleavage by AG-QDs.

China ranks the top in global annual rice output. However, extensive mining and smelting has led to elevated arsenic (As) in paddy soils, potentially imperiling local population health and sustainable rice production in the country. Under flooded condition, reductive As mobilization generally occurs, providing a unique advantage for soil As removal. In this study, we explore the depletion magnitude of labile As from paddy soils through cycling of flooding-drainage with three distinct co-strategies, i.e. (1) no soil disturbance with spontaneously established hygrophyte plants, (2) selective fertilization to enhance soil As release, and (3) soil ploughing following each drainage. After 151 days of flooding with periodic drainage, diffusive gradients in thin film (DGT)-labile As through 0–14 cm soil profile with hygrophyte plants growing decreased from initial 292 μg l−1 to well below the required threshold level (57–77 μg l−1) for safe rice production. Correspondingly, an average of 22.9% of total soil As was removed, with up to 76.7% of As bound to amorphous Fe hydroxides being stripped in this treatment. In the following rice cultivation, inorganic As in the polished rice from the naturally vegetated treatment (0.15 mg kg−1) fell successfully below the Chinese food safety standard (0.2 mg kg−1). The results highlight that As removal from paddy soils with native hygrophyte under shallow flooded condition can decrease soil bioavailable As specifically to safe levels within a relatively short period, and thus provides a novel and quite cost-effective pathway securing rice production. Keywords: Paddy soil, Arsenic, Flooding, Mobilization, Native hygrophyte

We developed the effect of titanium dioxide nanoparticles (nano-TiO2) on the bioaccumulation and biotransformation of arsenic (As), which remain largely unknown. We thus exposed two freshwater algae (Microcystis aeruginosa and Scenedesmus obliquus) to inorganic As with the aim of increasing our understanding on As bioaccumulation and methylation in the presence of nano-TiO2. Direct evidence of TEM and EDX image showed that nano-TiO2 (anatase) entered the exposed algae. Thus, nano-TiO2 as carriers boosted arsenic accumulation and methylation in these two algae species, which varied with both inorganic As speciation and algae species. Specifically, nano-TiO2 could enhance markedly arsenate accumulation in M. aerugginosa and arsenite accumulation in S. obliquus. Similarly, we found higher content of As methylation in M. aeruginosa of arsenite with 2 mg L−1 of nano-TiO2 treatment and in S. obliquus of arsenate treatment. Additionally, S. obliquus exhibited higher As methylation compared to M. aeruginosa, being more sensitive to As associated with nano-TiO2 than M. aeruginosa. Due to changes in pH levels inside these exposed algae, the As dissociation from nano-TiO2 inside algal cell enhanced As methylation. Accordingly, the potential influence of nanoparticles on the bioaccumulation and biotransformation of their co-contaminants deserves more attention. • Nano-TiO2 entry is assumed to promote As accumulation into exposed algae. • Nano-TiO2 had different carrying capacities for different forms of As and algae. • As dissociation from nano-TiO2 is assumed to enhance As methylation in algae. Method name: Association of inorganic As and nano-TiO2 in algae, Keywords: Bioaccumulation, Engineered Nanomaterials, Dissociation, Algae, Trojan horse

Abstract Background Nutrient-containing nanomaterials have been developed as fertilizers to foster plant growth and agricultural yield through root applications. However, if applied through leaves, how these nanomaterials, e.g. γ-Fe2O3 nanoparticles (NPs), influence the plant growth and health are largely unknown. This study is aimed to assess the effects of foliar-applied γ-Fe2O3 NPs and their ionic counterparts on plant physiology of Citrus maxima and the associated mechanisms. Results No significant changes of chlorophyll content and root activity were observed upon the exposure of 20–100 mg/L γ-Fe2O3 NPs and Fe3+. In C. maxima roots, no oxidative stress occurred under all Fe treatments. In the shoots, 20 and 50 mg/L γ-Fe2O3 NPs did not induce oxidative stress while 100 mg/L γ-Fe2O3 NPs did. Furthermore, there was a positive correlation between the dosages of γ-Fe2O3 NPs and Fe3+ and iron accumulation in shoots. However, the accumulated iron in shoots was not translocated down to roots. We observed down-regulation of ferric-chelate reductase (FRO2) gene expression exposed to γ-Fe2O3 NPs and Fe3+ treatments. The gene expression of a Fe2+ transporter, Nramp3, was down regulated as well under γ-Fe2O3 NPs exposure. Although 100 mg/L γ-Fe2O3 NPs and 20–100 mg/L Fe3+ led to higher wax content, genes associated with wax formation (WIN1) and transport (ABCG12) were downregulated or unchanged compared to the control. Conclusions Our results showed that both γ-Fe2O3 NPs and Fe3+ exposure via foliar spray had an inconsequential effect on plant growth, but γ-Fe2O3 NPs can reduce nutrient loss due to their the strong adsorption ability. C. maxima plants exposed to γ-Fe2O3 NPs and Fe3+ were in iron-replete status. Moreover, the biosynthesis and transport of wax is a collaborative and multigene controlled process. This study compared the various effects of γ-Fe2O3 NPs, Fe3+ and Fe chelate and exhibited the advantages of NPs as a foliar fertilizer, laying the foundation for the future applications of nutrient-containing nanomaterials in agriculture and horticulture. Graphical abstract γ-Fe2O3 NPs exposed on plants via foliar spray and genes associated with the absorption and transformation of iron, as well as wax synthesis and secretion in Citrus maxima leaves

The outstanding commercial application potential of graphene oxide (GO) will inevitably lead to its increasing release into the environment, and then affect the environmental behavior and toxicity of conventional pollutants. Interactions between arsenite [As (III)]/arsenate [As (V)] with GO and their combined toxicity to Chlorella pyrenoidosa were investigated. Under abiotic conditions, approximately 42% of the adsorbed As (III) was oxidized by GO with simulated sunlight illumination, which was induced by electron-hole pairs on the surface of GO. Co-exposure with GO greatly enhanced the toxicity of As (III, V) to alga. When adding 10 mg/L GO, the 72 h median effect concentration of As (III) and As (V) to C. pyrendoidosa decreased to 12.7 and 9.4 mg/L from 30.1 and 16.3 mg/L in the As alone treatment, respectively. One possible mechanism by which GO enhanced As toxicity could be that GO decreased the phosphate concentration in the algal medium, and then increased the accumulation of As (V) in algae. In addition, transmission electron microscope (TEM) images demonstrated that GO acted as a carrier for As (III) and As (V) transport into the algal cells. Also, GO induced severe oxidative stress, which could have subsequently compromised important detoxification pathways (e.g., As complexation with glutathione, As methylation, and intracellular As efflux) in the algal cells. Our findings highlight the significant impact of GO on the fate and toxicity of As in the aquatic environment. Keywords: Graphene oxide, Arsenite oxidation, Combined toxicity, Arsenic methylation, Arsenic efflux

The goal of this research work was to determine widespread impact kiln-produced hardwood biochar has upon temperate agricultural soil characteristics in a long-term field experiment. This dataset is supplementary to the submitted research by [1] and presents select physical and chemical characteristics of the biochar and field plots amended with hardwood biochar. Data on soil gravimetric moisture content (GMC), soil acidity and soil nitrate-N concentration at lower depth of soil under different biochar application rates is presented. Fourier Transform Infrared (FTIR) spectroscopy is provided to demonstrate the difference between fresh and aged biochar in terms of surface functional group content.

Nanoscale hydroxyapatite (nHA) was synthesized to investigate its potential as a phosphorus (P) ensembled nanofertilizer, using soybean (Glycine max L.) as a model plant. The conventional analogue phosphate (pi) was used for comparison with the synthesized nHA. Varied precipitation intensities (0%, 30%, 60%, and 100%) were simulated by adding selected volumes of the P fertilizers (nHA or pi) via foliar spray and soil amendment. The total amounts of added P were the same across all the treatments. The importance of a wash-off effect was investigated on foliar-treated seedlings by evaluating different watering heights (20, 120, and 240 cm above the seedlings). Fresh weight, pigment content, macro-, and micronutrient contents were measured in soybean tissues across all the treatments after 4 weeks of greenhouse cultivation. The synthesized nHA showed superior effects on plant nutrient content upon high precipitation intensities. For example, at 100% precipitation intensity, there was 32.6% more P and 33.2% more Ca in shoots, 40.6% more P and 45.4% more Ca in roots, and 37.9% more P and 82.3% more Ca in pods, as compared to those with pi treatment, respectively. No impact on soybean biomass was evident upon the application of nHA or pi. Further investigation into customizing nHA to enhance its affinity with crop leaves and to extend retention time on the leaf surface is warranted given that the present study did not show significant positive impacts of nHA on soybean growth under the effects of precipitation. Taken together, our findings increase understanding of the potential application of nHA as a nano-enabled fertilizer in sustainable agriculture.

The present study investigated the role of graphitic carbon nitride (C3N4) in alleviating cadmium (Cd)- and arsenic (As)-induced phytotoxicity to rice (Oryza sativa L.). A high-temperature pyrolysis was used to synthesize the C3N4, which was characterized by transmission electron microscopy, Fourier-transform infrared spectroscopy, and dynamic light scattering. Rice seedlings were exposed to C3N4 at 50 and 250 mg/L in half-strength Hoagland’s solution amended with or without 10 mg/L Cd or As for 14 days. Both Cd and As alone resulted in 26–38% and 49–56% decreases in rice root and shoot biomass, respectively. Exposure to 250 mg/L C3N4 alone increased the root and shoot fresh biomass by 17.5% and 25.9%, respectively. Upon coexposure, Cd + C3N4 and As + C3N4 alleviated the heavy metal-induced phytotoxicity and increased the fresh weight by 26–38% and 49–56%, respectively. Further, the addition of C3N4 decreased Cd and As accumulation in the roots by 32% and 25%, respectively, whereas the metal contents in the shoots were 30% lower in the presence of C3N4. Both As and Cd also significantly altered the macronutrient (K, P, Ca, S, and Mg) and micronutrient (Cu, Fe, Zn, and Mn) contents in rice, but these alterations were not evident in plants coexposed to C3N4. Random amplified polymorphic DNA analysis suggests that Cd significantly altered the genomic DNA of rice roots, while no difference was found in shoots. The presence of C3N4 controlled Cd and As uptake in rice by regulating transport-related genes. For example, the relative expression of the Cd transporter OsIRT1 in roots was upregulated by approximately threefold with metal exposure, but C3N4 coamendment lowered the expression. Similar results were evident in the expression of the As transporter OsNIP1;1 in roots. Overall, these findings facilitate the understanding of the underlying mechanisms by which carbon-based nanomaterials alleviate contaminant-induced phyto- and genotoxicity and may provide a new strategy for the reduction of heavy metal contamination in agriculture.

Nanoparticles (NPs) have great potential for use in the fields of biomedicine, building materials, and environmental protection because of their antibacterial properties. However, there are few reports regarding the antifungal activities of NPs on plants. In this study, we evaluated the antifungal roles of NPs against Botrytis cinerea, which is a notorious worldwide fungal pathogen. Three common carbon nanomaterials, multi-walled carbon nanotubes, fullerene, and reduced graphene oxide, and three commercial metal oxidant NPs, copper oxide (CuO) NPs, ferric oxide (Fe2O3) NPs, and titanium oxides (TiO2) NPs, were independently added to water-agar plates at 50 and 200-mg/L concentrations. Detached rose petals were inoculated with spores of B. cinerea and co-cultured with each of the six nanomaterials. The sizes of the lesions on infected rose petals were measured at 72 h after inoculation, and the growth of fungi on the rose petals was observed by scanning electron microscopy. The six NPs inhibited the growth of B. cinerea, but different concentrations had different effects: 50 mg/L of fullerene and CuO NPs showed the strongest antifungal properties among the treatments, while 200 mg/L of CuO and Fe2O3 showed no significant antifungal activities. Thus, NPs may have antifungal activities that prevent B. cinerea infections in plants, and they could be used as antifungal agents during the growth and post-harvesting of roses and other flowers.

Crop residues are an important source of plant nutrients. However, information on the various methods of residue management on micronutrients in soil and wheat (Triticum aestivum L.) over time is limited. A long-term (84-year) agroecosystem experiment was assessed to determine the impact of fertilizer type and methods of crop residue management on micronutrients over time under dryland winter wheat-fallow rotation. The treatments were: no N application with residue burning in fall (FB), spring (SB), and no residue burn (NB); 45 kg N ha−1 with SB and NB; 90 kg N ha−1 with SB and NB; pea vines; and farmyard manure (FYM) and a nearby undisturbed grass pasture (GP). Wheat grain, straw, and soil samples from 1995, 2005, and 2015 were used to determine tissue total and soil Mehlich III extractable Mn, Cu, B, Fe, and Zn, and soil pH. After 84 years, extractable Mn and B in the top 10 cm of soil decreased in all plots, except for B in FYM and SB. The FYM plots had the highest extractable Mn (114 mg kg−1) in the top 10 cm soil; however, it declined by 33% compared to the GP (171 mg kg−1). Extractable Zn in the top 10 cm of soil increased with FYM while it decreased with inorganic N application in 2015; however, total Zn in grain increased by 7% with inorganic N (90 kg ha−1) application compared to FYM application. The results suggest that residue management had similar impact on soil micronutrients. Inorganic N and FYM application can be integrated to reduce micronutrient losses from cultivation.

Tillage plays a major role in nutrient dynamics under dryland cropping systems, but there remains uncertainty regarding the long-term impacts of tillage on nutrient availability. The objective of this study was to examine the influence of tillage intensity and timing on micronutrient concentration of soils and winter wheat (Triticum aestivum L.) under dryland winter wheat−pea (Pisum sativum L.) or WW-P rotation. The treatments included moldboard tillage in fall (FT) and spring (ST), disk/chisel tillage (DT), and no-tillage (NT). The concentrations of Mehlich III extractable boron, manganese, zinc, copper, and iron in soil were unaffected by the tillage methods; however, a significant decline in extractable zinc in the top 10 cm soil was observed compared to an adjacent undisturbed grass pasture (GP) (NT: 2.3 mg kg−1 vs. GP: 6.0 mg kg−1). In the upper 10 cm soil surface, NT (123 mg kg−1) maintained the extractable manganese concentration with GP (175 mg kg−1) whereas FT (97 mg kg−1), ST (92 mg kg−1), and DT (113 mg kg−1) had lower manganese than GP. Soil pH declined in the upper 10 cm under NT more than in the rest of the WW-P treatments. The results suggest NT can play a vital role in sustaining micronutrient availability due to decreased soil pH and the greater amount of organic matter within the surface soil of NT compared to other tillage methods.

The insights gained from the long-term impacts of tillage and N fertilization on soil fertility are crucial for the development of sustainable cropping systems. The objectives of this study were to quantify the effects of 75 years of tillage and N fertilization on macronutrients in soil and wheat (Triticum aestivum L.) tissues grown in a winter wheat–summer fallow rotation. The experiment included three types of tillage (disc, DP; sweep, SW; and moldboard, MP) and five N application rates (0, 45, 90, 135, and 180 kg ha−1). Soil and tissue samples were analyzed for the concentration of total N, S, and C, Mehlich III extractable P, K, Mg, Ca in the soil, and the total concentration of the same nutrients in wheat tissue. Soil N concentration was significantly greater under DP (1.10 g kg−1) than under MP (1.03 g kg−1). The P concentration in upper 20 cm soil depth increased with increased N rates. Comparison of experiment plots to a nearby undisturbed pasture revealed a decline of P (32%), SOC (34%), Mg (77%), and Ca (86%) in the top 10 cm soil depth. The results suggest that DP with high N rates could reduce the macronutrient decline in soil and plant over time.

The aim of this study was to investigate the phytotoxicity of thin-walled carbon nanotubes (CNTs) to rice (Oryza sativa L.) seedlings. Three different CNTs, including hollow multi-walled carbon nanotubes (MWCNTs), Fe-filled carbon nanotubes (Fe-CNTs), and Fe-Co-filled carbon nanotubes (FeCo-CNTs), were evaluated. The CNTs significantly inhibited rice growth by decreasing the concentrations of endogenous plant hormones. The carbon to nitrogen ratio (C:N ratio) significantly increased in rice roots after treatments with CNTs, and all three types of CNTs had the same effects on the C:N ratio. Interestingly, the increase in the C:N ratio in roots was largely because of decreased N content, indicating that the CNTs significantly decreased N assimilation. Analyses of the Fe and Co contents in plant tissues, transmission electron microscope (TEM) observations and energy dispersive X-ray spectroscopy (EDS) analysis proved that the CNTs could penetrate the cell wall and the cell membrane, and then enter the root cells. According to the author's knowledge, this is the first time to study the relationship between carbon nanotubes and carbon nitrogen ratio and plant hormones.

Phytoextraction has emerged as a novel approach to clean up metal-polluted soils in which plants are used to transfer toxic metals from soils to shoots. This review provides a synthesis of current knowledge on phytoextraction of metals from soils and their accumulation in plants. The objective is to integrate soil-related (root exudates and chemical amendments) and biological advances to suggest research needs and future directions. As far as can be deduced from the literature, it will be some time before phytoextraction may be established as a commercial technology. For chemically-assisted phytoextraction, research has not shown easily biodegradable compounds to overcome the risks associated with the use of EDTA for poorly available metals in soils. On the other hand, significant progress has been made on the physiological and molecular aspects regarding tolerance and phytoaccumulation of metals in plants. A multidisciplinary approach is warranted to make phytoextraction a feasible commercial technology to remediate metal-polluted soils.A fitoextração é uma tecnologia emergente para despoluição de solos contaminados por metais pesados que usa plantas para transferir metais do solo para a parte aérea, a qual pode ser removida da área poluída. Esta revisão apresenta uma síntese do atual conhecimento sobre fitoextração de metais pesados do solo e sua acumulação em plantas. O objetivo é integrar em uma mesma discussão os avanços relacionados à química do solo (exsudação radicular e adição de agentes quelantes para aumentar a absorção) e à biologia (tolerância a metais e melhoramento genético) visando sugerir futuras pesquisas na área. Embora promissor, o atual estado de desenvolvimento da fitoextração ainda não permite estabelecê-la como uma tecnologia comercial. A pesquisa ainda não encontrou agentes quelantes facilmente biodegradáveis que possam substituir o EDTA na solubilização de metais pouco disponíveis em solos. Entretanto, significativos progressos têm sido feitos no entendimento dos mecanismos fisiológicos e moleculares de tolerância e acumulação de metais em plantas. Uma abordagem multidisciplinar dos vários aspectos que envolvem a fitoextração poderá tornar essa tecnologia econômica e ambientalmente viável a médio prazo.

Ternary blend films were prepared with different ratios of starch/polyvinyl alcohol (PVA)/citric acid. The films were characterized by field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis, as well as Fourier transform infrared (FTIR) analysis. The influence of different ratios of starch/polyvinyl alcohol (PVA)/citric acid and different drying times on the performance properties, transparency, tensile strength (TS), water vapor permeability (WVP), water solubility (WS), color difference (ΔE), and antimicrobial activity of the ternary blends films were investigated. The starch/polyvinyl alcohol/citric acid (S/P/C1:1:0, S/P/C3:1:0.08, and S/P/C3:3:0.08) films were all highly transparent. The S/P/C3:3:0.08 had a 54.31 times water-holding capacity of its own weight and its mechanical tensile strength was 46.45 MPa. In addition, its surface had good uniformity and compactness. The S/P/C3:1:0.08 and S/P/C3:3:0.08 showed strong antimicrobial activity to Listeria monocytogenes and Escherichia coli, which were the food-borne pathogenic bacteria used. The freshness test results of fresh figs showed that all of the blends prevented the formation of condensed water on the surface of the film, and the S/P/C3:1:0.08 and S/P/C3:3:0.08 prevented the deterioration of figs during storage. The films can be used as an active food packaging system due to their strong antibacterial effect.

In this paper, the biosynthesis process of phenolic compounds in plants is summarized, which includes the shikimate, pentose phosphate and phenylpropanoid pathways. Plant phenolic compounds can act as antioxidants, structural polymers (lignin), attractants (flavonoids and carotenoids), UV screens (flavonoids), signal compounds (salicylic acid and flavonoids) and defense response chemicals (tannins and phytoalexins). From a human physiological standpoint, phenolic compounds are vital in defense responses, such as anti-aging, anti-inflammatory, antioxidant and anti-proliferative activities. Therefore, it is beneficial to eat such plant foods that have a high antioxidant compound content, which will cut down the incidence of certain chronic diseases, for instance diabetes, cancers and cardiovascular diseases, through the management of oxidative stress. Furthermore, berries and other fruits with low-amylase and high-glucosidase inhibitory activities could be regarded as candidate food items in the control of the early stages of hyperglycemia associated with type 2 diabetes.