Identifying the bioavailability and release-desorption mechanism of heavy metals (HMs) in soil is critical to understand the release risk of HMs. Simultaneously, the mechanistic investigation of affecting the bioavailability of HMs in soil is necessary, such as the grain-size distribution and soil mineralogy. Herein, the bioavailability of HMs (Cu, Cd, Ni, Pb, and Zn) in different area soils near a typical copper-smelter was evaluated by the sequential extraction technique (BCR), diffusive gradients in thin-films (DGT), and DGT-induced fluxes in sediments (DIFS) model. Results showed that the HMs proportion of the residual fraction in all soils was the highest. The average bioavailability concentration (CDGT) of Cu and Cd in industrial soil was the highest, with 45.12 μg· L⁻¹ and 9.06 μg· L⁻¹. The result of DIFS model revealed that the decreased order of the mean value of desorption rate constant (K₋₁) was Cd > Zn > Ni > Cu > Pb, 5.91 × 10⁻⁵, 4.96 × 10⁻⁵, 2.89 × 10⁻⁵, 9.64 × 10⁻⁶, and 8.69 × 10⁻⁶, respectively. According to the spatial distribution of release potential (R-value), the release potential of labile-Cu in agricultural soil was the highest, which was mainly attributed to fertilizer application in farmland. Simultaneously, the reduced hydroxyl was also related to the agricultural activities, resulting in the weakened adsorption capacity of HMs by soil. Redundancy analysis (RDA) results showed that the bioavailability of Cd, Ni, and Zn was mainly driven by soil pH, while the bioavailability of Cu and Pb was primarily driven by dissolved organic carbon (DOC). Meanwhile, carbonate minerals had a positive correlation with the bioavailability of Cd, Ni, and Zn, which could promote the release of HMs in mining soil as chemical weathering progresses. In conclusion, this study provides a structured method which can be used as a standard approach for similar scenarios to determine the geochemical fractionation, bioavailability, and release kinetics of heavy metals in soils.

Particulate matter with aerodynamic diameter not larger than 2.5 μm (PM₂.₅) escalated the risk of respiratory diseases. Mitochondrial dysfunction may play a pivotal role in PM₂.₅-induced airway injury. However, the potential effect of PM₂.₅ on mitochondrial permeability transition pore (mPTP)-related airway injury is still unknown. This study aimed to investigate the role of mPTP in PM₂.₅-induced mitochondrial dysfunction in airway epithelial cells in vitro. PM₂.₅ significantly reduced cell viability and caused apoptosis in BEAS-2B cells. We also found PM₂.₅ caused cellular and mitochondrial morphological alterations, evidenced by the disappearance of mitochondrial cristae, mitochondrial swelling, and the rupture of the outer mitochondrial membrane. PM₂.₅ induced mPTP opening via upregulation of voltage-dependent anion-selective channel (VDAC), leading to deprivation of mitochondrial membrane potential, increased mitochondrial reactive oxygen species (ROS) generation and intracellular calcium level. PM₂.₅ suppressed mitochondrial respiratory function by reducing basal and maximal respiration, and ATP production. The mPTP targeting compounds cyclosporin A [CsA; a potent inhibitor of cyclophilin D (CypD)] and VBIT-12 (a selective VDAC1 inhibitor) significantly inhibited PM₂.₅-induced mPTP opening and apoptosis, and preserved mitochondrial function by restoring mitochondrial membrane potential, reducing mitochondrial ROS generation and intracellular calcium content, and maintaining mitochondrial respiration function. Our data further demonstrated that PM₂.₅ caused reduction in nuclear expressions of PPARγ and PGC-1α, which were reversed in the presence of CsA. These findings suggest that mPTP might be a potential therapeutic target in the treatment of PM₂.₅-induced airway injury.

Herein, polyethylenimine (PEI)-grafted nitrogen (N)-doping magnetic biochar (PEIMW@MNBCBM) was synthesized, and characterization results showed that the microwave-assisted PEI grafting and ball milling-assisted N doping introduced abundant amino, pyridine N and pyrrole N structures onto biochar, which possessed high affinity to Cr(VI) in the anion form. The as-prepared PEIMW@MNBCBM displayed pH-dependence adsorption performance and high tolerance to co-existing ions with maximum uptake capacity of Cr(VI) identified as 183.02 mg/g. Furthermore, PEIMW@MNBCBM could bind Cr(VI) through electrostatic attraction, complexion, precipitation, reduction and pore filling. Especially, effective reduction of Cr(VI) was ascribed to cooperative electron transfer of partial oxygen-containing functional groups, intramolecular pyridine/pyrrole N, protonated amino and Fe²⁺ on the adsorbent, while oxygen-containing and amino functional groups from N-doping biochar and PEI synergistically complexed Cr(III) via providing lone pair electrons to form coordinate bonds. Furthermore, the stable precipitation was formed between Fe³⁺ and Cr(III). Additionally, the Cr(VI) elimination efficiency could maintain 95.83% even after four adsorption-desorption cycles, suggesting PEIMW@MNBCBM as a high-performance adsorbent for Cr(VI) contaminated water remediation.

Wastewater treatment plant (WWTP) effluents are pointed as hotspots for the introduction of both commensal and pathogenic bacteria as well as their antibiotic resistance genes (ARGs) in receiving water bodies. For the first time, the effect of partially treated submarine effluents was explored at the bottom and surface of the water column to provide a comprehensive overview of the structure of the microbiome and associated AR, and to assess environmental factors leading to their alteration. Seawater samples were collected over a 5-month period from submarine outfalls in central Adriatic Sea, Croatia. 16S rRNA amplicon sequencing was used to establish taxonomic and resistome profiles of the bacterial communities. The community differences observed between the two discharge areas, especially in the abundance of Proteobacteria and Firmicutes, could be due to the origin of wastewaters treated in WWTPs and the limiting environmental conditions such as temperature and nutrients. PICRUSt2 analysis inferred the total content of ARGs in the studied microbiomes and showed the highest abundance of resistance genes encoding multidrug efflux pumps, such as MexAB-OprM, AcrEF-TolC and MdtEF-TolC, followed by the modified peptidoglycan precursors, transporter genes encoding tetracycline, macrolide and phenicol resistance, and the bla operon conferring β-lactam resistance. A number of pathogenic genera introduced by effluents, including Acinetobacter, Arcobacter, Bacteroides, Escherichia-Shigella, Klebsiella, Pseudomonas, and Salmonella, were predicted to account for the majority of efflux pump-driven multidrug resistance, while Acinetobacter, Salmonella, Bacteroides and Pseudomonas were also shown to be the predominant carriers of non-efflux ARGs conferring resistance to most of nine antibiotic classes. Taken together, we evidenced the negative impact of submarine discharges of treated effluents via alteration of physico-chemical characteristics of the water column and enrichment of bacterial community with nonindigenous taxa carrying an arsenal of ARGs, which could contribute to the further propagation of the AR in the natural environment.

Cadmium (Cd) contamination in soil has posed a great threat to crop safety and yield as well as soil quality. Biochar blended with nitrogen fertilizer have been reported to be effective in remediating Cd-contaminated soil. However, the influence of co-application of biochar and nitrogen fertilizer on the Cd bioavailability, rice yield and soil microbiome remains unclear. In this study, eight different treatments including control (CK), 5% biochar (B), 2.6, 3.5, 4.4 g/pot nitrogen fertilizers (N1, N2 and N3), and co-application of biochar and nitrogen fertilizers (BN1, BN2, BN3) were performed in a pot experiment with paddy soil for observations in an entire rice cycle growth period. Results showed single N increased soil available Cd content and Cd uptake in edible part of rice, while the soil available Cd content significantly decreased by 14.8% and 7.4%–11.1% under the B, BN treatments, and the Cd content in edible part of rice was significantly reduced by 35.1% and 18.5%–26.5%, respectively. Besides, B, N and BN treatments significantly increased the yield of rice by 14.3%–86.6% compared with CK, and the highest yield was gained under BN3 treatment. Soil bacterial diversity indices (Shannon, Chao1, observed species and PD whole tree index) under N2, N3 were generally improved. Cluster analysis indicated that bacterial community structures under BN treatments differed from those of CK and single N treatments. BN treatments enhanced the abundances of key bacterial phylum such as Acidobacteria, positively associated with yield, and increased the abundance of Spirochaetes, negatively correlated to soil available Cd and Cd uptake of rice. Furthermore, the regression path analysis (RPA) revealed that pH, organic matter (OM), alkaline hydrolysis of nitrogen (AHN) and available Cd were the major properties influencing Cd content in edible part of rice. Redundancy analysis (RDA) revealed that pH and available Cd played key role in shaping soil bacterial community. Thus, BN is a feasible practice for the improvements of rice growth and remediation of Cd-polluted soil.

A large amount of disposable plastic face masks (DPFs) is produced and used during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, which results in an inevitable consequence of the dramatic increase of DPFs waste. However, the impact of DPFs exposure to the environment on their toxicity is rarely considered. In this study, a range of 76–276 items/L microplastics (MPs) was detected in the DPFs leachates, and fibrous (> 80.3%) and polypropylene (PP, > 89.2%) MPs were dominant. Co, Cu, Ni, Sr, Ti and Zn, were commonly detected in all leachates of the tested DPFs. Organics, such as acetophenone, 2,4-Di-tert-butylphenol, benzothiazole, bisphenol-A and phthalide, were found in the DPFs leachate, which were including organic solvents and plasticizer. Besides, we first found an emerging environmental risk substance, namely environmentally persistent free radicals (EPFRs), was generated in the DPFs leachates. The characteristic g-factors of the EPFRs was in a range of 2.003–2.004, identified as mixture of carbon- and oxygen-centered radicals. By means of in vitro toxicity assay, the DPFs leachate were confirmed to cause cytotoxicity and oxidative stress. Significantly, it is found that the formed EPFRs could contribute more toxic effects. Furthermore, when compared to N95 respirators, the tested surgical masks tend to release more MPs, leach more metals and organics, and generate more EPFRs. Surgical masks were thus showed higher risk than N95 respirators after exposure to water. This work highlights the importance of understanding the chemical complexity and possible toxicity of DPFs for their risk assessment.

The widespread use of disposable face masks as a preventative strategy to address transmission of the SARS-CoV-2 virus has been a key environmental concern since the pandemic began. This has led to an unprecedented new form of contamination from improperly disposed masks, which liberates significant amounts of heavy metals and toxic chemicals in addition to volatile organic compounds (VOCs). Therefore, this study monitored the liberation of heavy metals, VOCs, and microfibers from submerged disposable face masks at different pH (4, 7 and 12), to simulate distinct environmental conditions. Lead (3.238% ppb), cadmium (0.672 ppb) and chromium (0.786 ppb) were found in the analyzed leachates. By pyrolysis, 2,4-dimethylhept-1-ene and 4-methylheptane were identified as the VOCs produced by the samples. The chemically degraded morphology in the FESEM images provided further evidence that toxic heavy metals and volatile organic compounds had been leached from the submerged face masks, with greater degradation observed in samples submerged at pH 7 and higher. The results are seen to communicate the comparable danger of passively degrading disposable face masks and the release of micro- or nanofibers into the marine environment. The toxicity of certain heavy metals and chemicals released from discarded face masks warrants better, more robust manufacturing protocols and increased public awareness for responsible disposal to reduce the adverse impact on ecology and human health.

To examine the potential role of acetate in conferring cadmium (Cd) stress tolerance in lentil (Lens culinaris), several phenotypical and physio-biochemical properties have been examined in Cd-stressed lentil seedlings following acetate applications. Acetate treatment inhibited the translocation of Cd from roots to shoots, which resulted in a minimal reduction in photosynthetic pigment contents. Additionally, acetate-treated lentil showed higher shoot (1.1 and 11.72%) and root (4.98 and 30.64%) dry weights compared with acetate-non-treated plants under low-Cd and high-Cd concentrations, respectively. Concurrently, acetate treatments increase osmoprotection under low-Cd stress through proline accumulation (24.69%), as well as enhancement of antioxidant defense by increasing ascorbic acid content (239.13%) and catalase activity (148.51%) under high-Cd stress. Acetate-induced antioxidant defense resulted in a significant diminution in hydrogen peroxide, malondialdehyde and electrolyte leakage in Cd-stressed lentil seedlings. Our results indicated that acetate application mitigated oxidative stress-induced damage by modulating antioxidant defense and osmoprotection, and reducing root-to-shoot Cd transport. These findings indicate an important contribution of acetate in mitigating the Cd toxicity during growth and development of lentil seedlings, and suggest that the exogenous applications of acetate could be an economical and new avenue for controlling heavy metal-caused damage in lentil, and potentially in many other crops.

Engine start-stop (S&S) technology has been substantially incorporated into modern vehicles to save fuel during idling in congested urban areas because fuel economy regulations have become more stringent. However, the potential for increasing particle emissions after engine restarts, especially in cold environments, is of great concern. To investigate the effects of S&S systems on fuel consumption and tailpipe emissions, a chassis dynamometer was employed to measure the fuel consumption, particulate matter (PM), solid particle number (PN), particle number size distribution and black carbon (BC) for a typical gasoline direct injection vehicle when the S&S was on (S&S-on) and when the S&S was off (S&S-off) according to the worldwide harmonized light-duty test cycle in both hot (28 °C) and cold (5 °C) environments. S&S operation resulted in 3.1–4.3% fuel-savings at 28 °C but had a tendency to increase particulate emissions, especially of BC (21.8–31.8%) and PM (19.2–32.8%). Although PN emissions with S&S-on over the entire cycle were slightly lower than those with S&S-off, more particles were emitted during the engine restart moments. In a cold environment, the fuel-savings advantage of the S&S system was weakened, and the negative impacts on the particle emissions during the restart moment worsened. The S&S system resulted in higher abundances of accumulation mode particles, especially under cold ambient conditions. The relationship between the PN reduction rates and idling segments was determining to be exponential. Our results indicate that the S&S system, which may increase particle emissions during restarts, does save fuel, and that a comprehensive evaluation of the system in cold environments is needed to determine the serviceability of new engine technologies and after-treatments.