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Dissolved organic matter (DOM) exists widely in natural water, which inevitably influences microplastic (MP) photoaging. Nevertheless, the impacts of DOM fractions with diverse molecular structures on MP photoaging remain to be elucidated. This study explored the photoaging mechanisms of polylactic acid (PLA)-MPs and polystyrene (PS)-MPs in the presence of DOM and its subfractions (hydrophobic acid (HPOA), hydrophobic neutral (HPON), and hydrophilic (HPI)). Across DOM fractions, HPI exhibited the highest electron accepting capacity (23 μmol e–(mg C)−1) due to its abundant tannin-like species (36.8%) with carboxylic groups, which facilitated more reactive oxygen species generation (particularly hydroxyl radical), leading to the strongest photoaging rate of two MPs by HPI. However, the sequences of bond cleavage during photoaging of each MPs were not clearly shifted as revealed by two-dimensional infrared correlation spectra. Inconspicuous effects on the extent of PS- and PLA-MPs photoaging were observed for HPOA and HPON, respectively. This was mainly ascribed to the occurrence of inhibitory mechanisms (e.g., light-shielding and quenching effect) counteracting the reactive oxygen species-promoting effects. The findings identified the HPI fraction of DOM for promoting PS- and PLA-MPs photoaging rate and first constructed a link among DOM molecular structures, redox properties, and effects on MP photoaging.

To investigate the mechanisms by which g-C3N4alleviates metal(loid)-induced phytotoxicity, rice seedlings were exposed to 100 and 250 mg/kg graphitic carbon nitride (g-C3N4) with or without coexposure to 10 mg/kg Cd and 50 mg/kg As for 30 days. Treatment with 250 mg/kg g-C3N4significantly increased shoot and root fresh weight by 22.4–29.9%, reduced Cd and As accumulations in rice tissues by 20.6–26.6%, and elevated the content of essential nutrients (e.g., K, S, Mg, Cu, and Zn) compared to untreated controls. High-throughput sequencing showed that g-C3N4treatment increased the proportion of plant-growth-promoting endophytic bacteria, including Streptomyces, Saccharimonadales, and Thermosporothrix, by 0.5–3.30-fold; these groups are known to be important to plant nutrient assimilation, as well as metal(loid) resistance and bioremediation. In addition, the population of Deinococcuswas decreased by 72.3%; this genus is known to induce biotransformation As(V) to As(III). Metabolomics analyses highlighted differentially expressed metabolites (DEMs) involved in the metabolism of tyrosine metabolism, pyrimidines, and purines, as well as phenylpropanoid biosynthesis related to Cd/As-induced phytotoxicity. In the phenylpropanoid biosynthesis pathway, the increased expression of 4-coumarate (1.13-fold) and sinapyl alcohol (1.26-fold) triggered by g-C3N4coexposure with Cd or As played a critical role in promoting plant growth and enhancing rice resistance against metal(loid) stresses. Our findings demonstrate the potential of g-C3N4to enhance plant growth and minimize the Cd/As-induced toxicity in rice and provide a promising nanoenabled strategy for remediating heavy metal(loid)-contaminated soil.

With the widespread use of nanoenabled agrochemicals, it is essential to evaluate the food safety of nanomaterials (NMs)-treated vegetable crops in full life cycle studies as well as their potential impacts on human health. Tomato seedlings were foliarly sprayed with 50 mg/L ZnO NMs, including ZnO quantum dots (QDs) and ZnO nanoparticles once per week over 11 weeks. The foliar sprayed ZnO QDs increased fruit dry weight and yield per plant by 39.1% and 24.9, respectively. It also significantly increased the lycopene, amino acids, Zn, B, and Fe in tomato fruits by 40.5%, 15.1%, 44.5%, 76.2%, and 12.8%, respectively. The tomato fruit metabolome of tomatoes showed that ZnO NMs upregulated the biosynthesis of unsaturated fatty acids and sphingolipid metabolism and elevated the levels of linoleic and arachidonic acids. The ZnO NMs-treated tomato fruits were then digested in a human gastrointestinal tract model. The results of essential mineral release suggested that the ZnO QDs treatment increased the bioaccessibility of K, Zn, and Cu by 14.8–35.1% relative to the control. Additionally, both types of ZnO NMs had no negative impact on the α-amylase, pepsin, and trypsin activities. The digested fruit metabolome in the intestinal fluid demonstrated that ZnO NMs did not interfere with the normal process of human digestion. Importantly, ZnO NMs treatments increased the glycerophospholipids, carbohydrates, amino acids, and peptides in the intestinal fluids of tomato fruits. This study suggests that nanoscale Zn can be potentially used to increase the nutritional value of vegetable crops and can be an important tool to sustainably increase food quality and security.

The use of nanotechnology to suppress crop diseases has attracted significant attention in agriculture. The present study investigated the antifungal mechanism by which aloe vera extract gel-biosynthesized (AVGE) selenium nanoparticles (Se NPs) suppressed Fusarium-induced wilt disease in lettuce (Lactuca sativa). AVGE Se NPs were synthesized by utilizing sodium selenite as a Se source and AVGE as a biocompatible capping and reducing agent. Over 21 d, 2.75% of total AVGE Se NPs was dissolved into Se ions, which was more than 8-fold greater than that of bare Se NPs (0.34%). Upon exposure to soil applied AVGE Se NPs at 50 mg/kg, fresh shoot biomass was significantly increased by 61.6 and 27.8% over the infected control and bare Se NPs, respectively. As compared to the infected control, the shoot levels of citrate, isocitrate, succinate, malate, and 2-oxo-glutarate were significantly upregulated by 0.5–3-fold as affected by both Se NPs. In addition, AVGE Se NPs significantly increased the shoot level of khelmarin D, a type of coumarin, by 4.40- and 0.71-fold over infected controls and bare Se NPs, respectively. Additionally, AVGE Se NPs showed greater upregulation of jasmonic acid and downregulation of abscisic acid content relative to bare Se NPs in diseased shoots. Moreover, the diversity of bacterial endophytes was significantly increased by AVGE Se NPs, with the values of Shannon index 40.2 and 9.16% greater over the infected control and bare Se NPs. Collectively, these findings highlight the significant potential of AVGE Se NPs as an effective and biocompatible strategy for nanoenabled sustainable crop protection.

Soil aggregation is one of the crucial processes that facilitate carbon sequestration and maintain soil fertility. So far, the effect of biochar amendment on soil aggregation remains inconclusive. Here, we tested the hypothesis that the response of soil aggregation to biochar addition varied with incubation duration and biochar chemistry. A one year microcosm experiment of soil with biochar was conducted that included biochar produced at three different temperatures (300, 450, and 600 °C), and three biochar application rates, i.e., 0, 1, and 3 wt%. It was observed that after one and three months, biochar mainly (> 90%) distributed in the micro-aggregates, and slightly reduced aggregate stability and increased proportion of micro-aggregates, which was demonstrated to result from the mechanical mixture of amended biochar with soil. Contrastingly, when the duration was prolonged to six months and one year, a significant increase in macro-aggregates (6.6–38.5%) and aggregate stability (7.3–29.4%) was detected, with the increasing extent being apparently higher for low-temperature biochar. This was related to the comparatively strong interaction of biochar particles with soil minerals or microbes after long-time incubation. The strong interaction was directly supported by the significant increase in H/C, O/C ratios of isolated biochar from treated soils, the detection of typical soil mineral elements on the surface of isolated biochar, and the increase in microbial biomass carbon of treated soils. The findings of this study highlighted the role of biochar type and amendment duration in mediating the effect of biochar application on soil aggregation.

The benefits and disadvantages of hydrochar incorporation into soil have been heavily researched. However, the effect of hydrochar application on the soil microbial communities and the molecular structure of native soil organic carbon (SOC) has not been thoroughly elucidated. This study conducted an incubation experiment at 25 °C for 135 days using a soil column with 0.5 and 1.5% hydrochar-amended paddy soil to explore the interconnections between changes in soil properties and microbial communities and shifts in native SOC structure using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) and NMR after hydrochar application. Hydrochar addition decreased the labile SOC fraction by 15.6–33.6% and increased the stable SOC fraction by 10.3–27.0%. These effects were significantly stronger for 1.5% hydrochar-treated soil. Additionally, hydrochar addition induced the native SOC with 1.0–3.0% more carbon and 6.0–13.0% higher molecular weight. The SOC in hydrochar-amended soil contained more aromatic compounds but fewer carbohydrates and lower polarity. This was resulted by a statistically significant reduction in Sphingobacterium, which was active in polycyclic aromatic hydrocarbon degradation, and an increase in Flavobacterium, Anaerolinea, Penicillium, and Acremonium, which were the efficient decomposers of labile SOC. These findings will help elucidate the potential influence of hydrochar on the carbon biogeochemical cycle in the soil.

Nanotechnology has demonstrated significant potential to improve agricultural production and increase crop tolerance to abiotic stress including exposure to heavy metals. The present study investigated the mechanisms by which aloe vera extract gel-biosynthesized (AVGE) selenium nanoparticles (Se NPs) alleviated cadmium (Cd)-induced toxicity to rice (Oryza sativaL.). AVGE Se NPs, chemically synthesized bare Se NPs, and NaSeO3as an ionic control were applied to Cd-stressed rice seedlings via root exposure in both hydroponic and soil systems. Upon exposure to AVGE Se NPs at 15 mg Se/L, the fresh root biomass was significantly increased by 100.7% and 19.5% as compared to Cd control and conventional bare Se NPs. Transcriptional analyses highlighted that AVGE Se NPs activated stress signaling and defense related pathways, including glutathione metabolism, phenylpropanoid biosynthesis and plant hormone signal transduction. Specifically, exposure to AVGE Se NPs upregulated the expression of genes associated with the gibberellic acid (GA) biosynthesis by and 4.79- and 3.29-fold as compared to the Cd-alone treatment and the untreated control, respectively. Importantly, AVGE Se NPs restored the composition of the endophyte community and recruit of beneficial species under Cd exposure; the relative abundance of Azospirillumwas significantly increased in roots, shoots, and the rhizosphere soil by 0.73-, 4.58- and 0.37-fold, respectively, relative to the Cd-alone treatment. Collectively, these findings highlight the significant potential of AVGE Se NPs to enhance plant growth and to minimize the Cd-induced toxicity in rice and provide a promising nanoenabled strategy to enhance food safety upon crop cultivation in contaminated agricultural soils.

Microplastics (MPs) were considered as emerging pollutants in soil. Cadmium (Cd) is the typical heavy metal contaminant in paddy soil in China. It was not unraveled that the effects of the existence of MPs on soil properties and Cd adsorption after rice growth in paddy soil, one of the most important soil types in China. In this study, several typical MPs in dosage of 0.5% (w/w) with different particle sizes, including polyethylene (PE, 200μm), polyacrylonitrile (PAN, 200μm), and polyethylene terephthalate (PET, 200 and 10μm), were selected and aged for a rice season (∼6 months) in paddy soil by column experiments. Some essential physicochemical properties of paddy soil collected from different treatments and the adsorption performance of typical metal contaminants (cadmium, Cd) in paddy soil with MPs coexisting were compared. The results indicated that the 6-month existence of 200μmMPs increased water content (15.94% to 26.08-30.30%), pH value (7.05 to 7.16–7.33), organic matter (OM) content (15.1 gkg −1to 18.2–22.9 gkg −1), the percentage of soil sand and Cd adsorption capacity of paddy soil, whereas decreased soil cation exchange capacity (CEC), the percentage of soil clay and silt. The adsorption experiments of Cd in soil showed that the adsorption behavior was consistent with the pseudo-second order and Langmuir isotherm model, and the addition of MPs would increase the adsorption capacity of Cd in soil. Besides, the particle size of MPs was found to be one of the dominant factors, in which MPs with smaller particle size (10μm) favored the increase of water content, pH, OM content, CEC, and adsorption performance with Cd. The results of this study could provide a supplemental understanding of the effect of MPs input on the paddy soil ecosystem, including the soil properties and the bioavailability and transport of metal in paddy soil.

The growing food delivery service market has boosted the consumption of packaging materials, and this trend is projected to continue in the following years. The gap between industrial supply and consumer demand from a sustainable viewpoint leads to a need for agricultural cellulosic waste-based materials that bring the idea of trash-to-treasure to fruition. In this paper, we review up-to-date advancements surrounding the food delivery packaging that are derived from agricultural cellulosic waste. Two scenarios in which agricultural feedstock is used as a host or guest material are summarized, and sketch on the individual processing routine is depicted. We further evaluate how the chemical compositions and processing parameters influence the properties of the final products. Current challenges and gaps in developing sustainable packaging materials are identified, with perspectives on these important issues highlighting the importance of process innovation as well as economic and environmental-impact assessment for agricultural cellulosic waste to food delivery packaging.