Vehicle emissions are an important source of nitrated aromatic compounds (NACs) in particulate size smaller 2.5 μm (PM₂.₅), which adversely affect human health and biodiversity, especially in urban areas. In this study, filter-based PM₂.₅ samples were collected during October 14–19, 2019, in a busy urban tunnel (approximately 35,000 vehicles per day) in south China to identify PM₂.₅-bound NACs. Among them, 2,8-dinitrodibenzothiophene, 3-nitrodibenzofuran and 2-nitrodibenzothiophene were the most abundant nitrated polycyclic aromatic hydrocarbons (NPAHs), while 2-methyl-4-nitrophenol, 2,4-dinitrophenol, 3-methyl-4-nitrophenol and 4-nitrophenol were the most abundant nitrophenols (NPs). The observed mean fleet emission factors (EFs) of NPAHs and NPs were 2.2 ± 2.1 and 7.7 ± 4.1 μg km⁻¹, and were 2.9 ± 2.7 and 10.2 ± 5.4 μg km⁻¹ if excluding electric and liquefied petroleum gas vehicles, respectively. Regression analysis revealed that diesel vehicles (DVs) had NPAH-EFs (55.3 ± 5.3 μg km⁻¹) approximately 180 times higher than gasoline vehicles (GVs) (0.3 ± 0.2 μg km⁻¹), and NP-EFs (120.6 ± 25.8 μg km⁻¹) approximately 30 times higher than GVs (4.1 ± 0.2 μg km⁻¹), and thus 89% NPAH emissions and 56% NP emissions from the onroad fleets were contributed by DVs although DVs only accounted for 3.3% in the fleets. Methanol solution-based light absorption measurements demonstrated that the mean incremental light absorption for methanol-soluble brown carbon at 365 nm was 6.8 ± 2.2 Mm⁻¹, of which the 44 detected NACs only contributed about 1%. The mean EF of the 7 toxic NACs was approximately 3% that of the 16 priority PAHs; However, their benzo(a)pyrene toxic equivalence quotients (TEQBₐP) could reach over 25% that of the PAHs. Moreover, 6-nitrochrysene mainly from DVs contributed 93% of the total TEQBₐP of the NACs. This study demonstrated that enhancing DV emission control in urban areas could benefit the reduction of exposure to air toxins such as 6-nitrochrysene.

The extensive application of nanomaterials has increased their levels in soil environments. Therefore, clarifying the process of environmental migration is important for environmental safety and human health. In this study, alfalfa was used to determine the effects of different doses of ZnO nanoparticles (NPs) on the growth of alfalfa and the soil environment. Results showed that the alfalfa biomass was inversely proportional to the exposure concentration of ZnO NPs. The Zn concentration in the alfalfa tissue and the exposure dose presented a significant positive correlation. A high concentration of ZnO NPs decreased the nitrogen-fixing area of root nodules while the number of bacteroids and root nodules, which in turn affected the nitrogen-fixing ability of alfalfa. At the same time, it caused different degrees of damage to the root nodules and root tip cells of alfalfa. A high dose of ZnO NPs decreased the relative abundance and diversity of the soil microorganisms. Therefore, short-term and high-dose exposure of ZnO NPs causes multiple toxicities in plants and soil environments.

China is the largest beekeeping and honey consumption country globally. Neonicotinoids in honey can pose adverse effects on honey bees and human, but data on neonicotinoids residues in honey and its health risk remain limited in China. A total of 94 honey samples were selected from Chinese market based on production region and sale volume in 2020. Eight neonicotinoids and four metabolites were determined by liquid chromatography coupled to mass spectrometry. Health risk of neonicotinoids in honey on honey bees and human was assessed by hazard quotient (HQ) and hazard index (HI). Neonicotinoids and their metabolites were overall detected in 97.9% of honey samples. Acetamiprid, thiamethoxam, and imidacloprid were top three dominant neonicotinoids in honey with the detection frequencies of 92.6%, 90.4%, and 73.4%, respectively. For honey bees, 78.7% of honey samples had a HI larger than one based on the safety threshold value of sublethal effects. Top three neonicotinoids with the highest percent proportion of HQ larger than one for honey bees were acetamiprid (43.6%), imidacloprid (31.9%), and thiamethoxam (24.5%) and their maximum HQs were 420, 210, and 41, respectively. Based on oral median lethal doses for honey bees, both HQ and HI were lower than one in all honey samples. For human, both HQ and HI were lower than one based on acceptable daily intakes in all honey samples. Neonicotinoids concentrations and detection frequencies in honey samples and its health risk varied with production region, commercial value of nectariferous plants, number of nectariferous plants, and sale price. The results suggested extensive residues of neonicotinoids in honey in Chinese market with a variation by the characteristics of honey. The residues were likely to affect the health of honey bees, but showed no detectable effect on human health.

In this work, we report a facile receptor OMB [N′,N”’-(3-((4-oxochroman-3-yl)methylene)pentane-2,4- diylidene)bis(4-methoxybenzohydrazide)] for the simultaneous detection of toxic analytes (Hg²⁺ and Cd²⁺ ions) in environment and biological samples. The receptor OMB exhibits an excellent selectivity and sensitivity which was determined using absorption and emission spectra. The receptor OMB shows rapid detection with lowest LOD (0.62 nM for Hg²⁺ ions and 0.77 nM for Cd²⁺ ions) and LOQ (2.08 nM for Hg²⁺ ions and 2.57 nM for Cd²⁺ ions) values. In addition, the receptor OMB exhibits 1:1 binding stoichiometry towards Hg²⁺ and Cd²⁺ ions with binding constant values of 5.5 × 10⁶ M⁻¹ and 4.6 × 10⁶ M⁻¹. Moreover, the synthesized receptor OMB possess ability to detect these analytes (Hg²⁺ and Cd²⁺ ions) in realistic samples (food and water) which was recognized using photoluminescence spectroscopy technique. In addition, the receptor OMB is also utilized to detect both the analytes in live HeLa cells. Thus, the overall results indicate that the receptor OMB was more suitable to detect the toxic analytes (Hg²⁺ and Cd²⁺ ions) present in the environment.

European natural peatlands have undergone long-term anthropogenic drainage activities that have severely decreased their functions, such as carbon sequestration. Recent rewetting has been conducted to restore the ecosystem services of peatlands and mitigate the emissions of potent greenhouse gases such as nitrous oxide (N₂O). However, the magnitudes and spatial patterns of annual N₂O fluxes and their mitigation potentials across European peatlands remain unknown. Here, we synthesized 492 annual N₂O flux data points from 77 in situ studies across European peatlands and found that the soil annual N₂O fluxes varied extensively from −1.08 to 33.40 kg N₂O–N ha⁻¹ yr⁻¹; these results were significantly and interactively (P < 0.05) affected by the peatland status, climatic regime and nutrient supply type. Drainage significantly (P < 0.05) stimulated soil N₂O emissions from natural minerotrophic rather than ombrotrophic peatlands, regardless of the climatic regime. Similarly, rewetting significantly (P < 0.05) reduced soil N₂O emissions from drained minerotrophic rather than ombrotrophic peatlands, demonstrating that the high N₂O emissions were driven by a simultaneous decline in the water table depth and increase in the soil nitrogen (N) availability. Magnitudes of the increases or decreases in N₂O emissions due to drainage or rewetting were also significantly influenced by the land-use and drainage history before rewetting and in the years following drainage/rewetting, respectively. The estimated annual mean N₂O emission total was found to be 90.42 (95% confidence interval: 64.49–122.57) Gg N₂O–N in 2020 from European peatlands. Scenario analysis showed that drained peatlands should be rewetted expeditiously; postponing rewetting would cause larger emissions from continued N₂O emissions from drained peatlands. Fully rewetting the drained peatlands used for forestry and peat extraction and partially rewetting those used for agriculture and grassland comprise a strategy for mitigating drained peatland N₂O emissions without compromising food security.

Nowadays, the accumulation of toxic heavy metals in soil and water streams is considered a serious environmental problem that causes various harmful effects on plants and animals. Phytoremediation is an effective, green, and economical bioremediation approach by which the harmful heavy metals in the contaminated ecosystem can be detoxified and accumulated in the plant. Hyperaccumulators exude molecules called transporters that carry and translocate the heavy metals present in the soil to different plant parts. The hyperaccumulator plant genes can confine higher concentrations of toxic heavy metals in their tissues. The efficiency of phytoremediation relies on various parameters such as soil properties (pH and soil type), organic matters in soil, heavy metal type, nature of rhizosphere, characteristics of rhizosphere microflora, etc. The present review comprehensively discusses the toxicity effect of heavy metals on the environment and different phytoremediation mechanisms for the transport and accumulation of heavy metals from polluted soil. This review gave comprehensive insights into plants tolerance for the higher heavy metal concentration their responses for heavy metal accumulation and the different mechanisms involved for heavy metal tolerance. The current status and the characteristic features that need to be improved in the phytoremediation process are also reviewed in detail.

The synthesis of clay-biochar composite has been recognized as an effective way to enhance the removal of pollutants. The interaction between clay mineral and biomass during thermal pyrolysis and the sorption capacity for ionic/nonionic organic containments have not been elaborated. In this study, two types of biochar were obtained from pyrolytic carbonization of the cellulosic-rich corn straw (C) and lignin-rich pine wood (P) at 500 or 700 °C. Typical clay minerals kaolinite and montmorillonite were selected to prepare clay-biochar composite. The results showed that the addition of clay mineral could strengthen dehydration reaction of corn straw biomass and reinforce its carbon structure. Montmorillonite-biochar composite owned more CC functional groups and porous structure than kaolinite-biochar composite. The addition of clay minerals could promote electrostatic attraction of ionic formed norfloxacin (NOR) on clay-pine wood biochar. However, the sorption capacity of nonionic diethyl phthalate (DEP) adsorption on clay-corn straw biochar decreased, owing to that clay increased the compactness of the biochar carbon structure, thus inhabited hydrophobic partition of nonionic organic compounds on disordered carbon fraction. The results from this study provide insights into the suitable contaminated site remediation by clay-biochar composite.

Nitroguanidine (NQ) is an emerging contaminant being used by the military as a constituent of new insensitive munitions. NQ is also used in rocket propellants, smokeless pyrotechnics, and vehicle restraint systems. Its uncontrolled transformation in the environment can generate toxic and potentially mutagenic products, posing hazards that need to be remediated. NQ transformation has only been investigated to a limited extent. Thus, it is crucial to expand the narrow spectrum of NQ remediation strategies and understand its transformation pathways and end products. Iron-based reactive minerals should be investigated for NQ treatment because they are successfully used in existing technologies, such as permeable reactive barriers, for treating a wide range of organic pollutants. This study tested the ability of micron-sized zero-valent iron (m-ZVI), mackinawite, and commercial FeS, to transform NQ under anoxic conditions. NQ transformation followed pseudo-first-order kinetics. The reaction rate constants decreased as follows: commercial FeS > mackinawite > m-ZVI. For the assessed minerals, the NQ transformation started with the reduction of the nitro group forming nitrosoguanidine (NsoQ). Then, aminoguanidine (AQ) was accumulated during the reaction of NQ with m-ZVI, accounting for 86% of the nitrogen mass recovery. When NQ was reacted with commercial FeS, 45% and 20% of nitrogen were recovered as AQ and guanidine, respectively, after 24 h. Nonetheless, NsoQ persisted, contributing to the N-balance. When mackinawite was present, NsoQ disappeared, but AQ was not detected, and guanidine accounted for 11% of the nitrogen recovery. AQ was ultimately transformed into cyanamide, whose dimerization triggered the formation of cyanoguanidine. Alternatively, NsoQ was transformed into guanidine, which reacted with cyanamide to form biguanide. This is the first report systematically investigating the NQ transformation by different iron-based reactive minerals. The evidence indicates that these minerals are attractive alternatives for developing NQ remediation strategies.

Contracting Parties to the OSPAR Convention for the Protection of the Maine Environment of the North-East Atlantic are required to undertake monitoring and assessment of both inorganic and organic contaminants. There is a requirement to assess contaminants across different trophic levels on an ecosystem-specific basis. However, this is currently constrained by the availability of relevant samples to cover the full range of trophic levels. This study investigates the variability (inter- and intra-species variation) of the concentrations and distributions of thirty-two polychlorinated biphenyl (PCB) congeners and nine polybrominated diphenyl ether (PBDE) congeners in twenty-six species covering four trophic levels from different geographic locations around Scotland. Trophic magnification factors (TMFs) were calculated using a traditional method and a balanced method for both the ICES-7 PCBs and BDE47, to refine and improve the application of TMFs to assess and predict biomagnification risk to biota in the marine environment. There were clear differences in congener percentage distribution between sample categories and species, with differences influenced by physiological processes and eco-biological parameters. Trophic magnification was found to occur for the ICES-7 PCBs and BDE47 using the traditional method, with the highest degree of trophic magnification reported for CB52. An unbalanced dataset was found to influence the calculated TMF and in some cases, the overall conclusion of the trophic transfer of PCB and PBDE congeners. The balanced method is highly recommended for calculating TMFs to ensure that the TMF is a true indication of the biomagnification potential, particularly when conducting regional comparisons for which sampling requirements are difficult to achieve.