Black carbon (BC) exerts a large impact on climate radiative forcing and public health, and such impacts depend strongly on chemical composition and mixing state. Here a single particle aerosol mass spectrometry (SPA-MS) along with an aerosol chemical speciation monitor was employed to characterize the composition and mixing state of BC-containing particles in summer and winter in Beijing. Approximately 2 million BC-containing particles were chemically analyzed, and the particles were classified into nine and eight different types in summer and winter, respectively, according to mass spectral signatures and composition. The BC-containing particles in summer were dominated by the type of nitrate-related BC (BC-N, 56.7%), while in winter the BC mixed with organic carbon (OC) and sulfate (BCOC-S), and OC and nitrate (BCOC-N) were two dominant types accounting for 44.9% and 16.6%, respectively. The number fractions of BC-N in summer, and BCOC-N and BC-SN in winter increased largely during periods with severe air pollution, suggesting the enhanced secondary formation on BC-containing particles. We also found that the primary emissions of the biomass burning and coal combustion can affect BC mixing state substaintially as indicated by the considerable fraction of BC mixed with levoglucosan and polycyclic aromatic hydrocarbons in winter. Bivariate polar plots and back trajectory analysis indicated that the sulfate-associated BC-containing particles were mostly from regional transport while the nitrate-related type was more from local production. The optical parameter of absorbing Ångström exponents (AAE) of BC was 1.2 and 1.5 in summer and winter, respectively, and the AAE dependence of BC mixing state was also different in the two seasons. While higher fractions of BC-N were observed during lower AAE periods in summer, the variations of dominant OC-related BC-containing particles in winter were fairly stable as a function of AAE.

Organic carbon is an essential element for sustainable soil management. While the effects of microplastics on soil physical and biological properties are presenting, it remains unclear whether the organic carbon dynamics of soil are altered by increased microplastic accumulation. The objectives of this study were to evaluate the influences of different polyester microfiber (PMF 0, 0.1% and 0.3% of soil dry weight) and organic material (OM 0, 1%, 2% and 3% of soil dry weight) addition levels on soil organic carbon and to determine the PMF distribution in aggregates from a pot experiment. After 75 days of incubation under 6 wet-dry cycles, the concentrations of soil total organic carbon did not differ significantly between the PMF (9.7 ± 6.6 g kg⁻¹) and control (9.7 ± 6.9 g kg⁻¹) treatments. However, PMF addition significantly reduced the organic carbon concentration in the large (>2 mm) macro-aggregates compared to the control treatment (10.6 ± 4.8 g kg⁻¹ vs. 11.7 ± 4.4 g kg⁻¹), but the results were opposite in the small (2–0.25 mm)macro-aggregates (10.2 ± 4.9 g kg⁻¹ vs. 8.4 ± 3.8 g kg⁻¹). In this study, less than 30% of added PMFs were incorporated into soil aggregates. In addition, the abundance and average length of aggregate-associated PMF in the large (2210 ± 180 particles per g aggregate and 2.08 ± 0.17 mm) and small (1820 ± 150 particles per g aggregate and 1.68 ± 0.11 mm) macro-aggregates were significantly greater than those in the micro-aggregates (1010 ± 70 particles per g aggregate and 0.72 ± 0.05 mm). Our results demonstrate that the distribution of organic carbon in soil macro-aggregates is affected by PMFs addition. Thus, we propose that the behavior of microplastics inside soil aggregates should be further explored to clarify their effects on the physical protection of soil organic carbon.

Different pH conditions have been demonstrated to affect the activities of dechlorinating populations participating in the successive dechlorination of trichloroethylene to ethylene. However, the mechanism of the effect of pH conditions on the assembly of dechlorinating populations and their relations to the structure, function, and dynamics of the microbiome are unclear. In this study, we evaluated the effects of pH on microbiomes assembled in anaerobic trichloroethylene-dechlorinating reactors under neutral (pH 7.2), acidic (pH 6.2), and alkaline (pH 8.2) conditions. The results revealed that among the reactors, the acidic reactor had the highest efficiency for dechlorination without accumulation of dechlorinated metabolites, even at high loading rates. The results of high-throughput sequencing of the 16S rRNA gene indicated that the microbiomes in the 3 reactors underwent varied dynamic succession. The acidic reactor harbored a higher degree of complex microbes, dechlorinator diversity, and abundance of the Victoria subgroup of Dehalococcoides (1.2 ± 0.1 × 10⁶ cell/mL), which were approximately 10–10²-fold higher than those at neutral and alkaline conditions. The pH settings altered species–species connectivity and complexity of microbial interaction networks, with more commensal interactions in the dechlorinators of the acidic reactor. As predicted, abundances of several functional gene categories were in strong linearity with pH values, and the microbiome possessed significantly more abundant functions in the acidic reactor (P < 0.001), such as potentially stimulating hydrogen production, cobalamin synthesis, cobalt transport, transport and metabolism of amino acids and secondary metabolites, cell motility, and transcription. All results of microbiomic analyses consistently revealed the observed superior dechlorination process and suggested an association of the reductive dechlorination process with the pH-dependent microbiome. The results of this study provide a new insight into the trichloroethylene dechlorination with regards to pH, and they will be useful for improving bioremediation and management of trichloroethylene-contaminated sites.

The main purpose of current study is accurate prediction of NOx emissions from diesel engines considering in-cylinder ion current. To reach this goal, a validated thermodynamic multi-zone model was used. A modified chemical kinetics mechanism of diesel fuel oxidation was used too. A chemical kinetics mechanism of NOX formation including 103 reactions was added to the main mechanism. A set of ions and ionic reactions was added to the developed chemical kinetics mechanism and finally a modified chemical kinetics mechanism with 445 reactions and 100 species was formed. The developed mechanism was coupled to the multi-zone model and a diesel engine was simulated. The importance of Zeldovich mechanism, prompt mechanism, N₂O mechanism and NNH mechanism were investigated. The progress rates of reactions were calculated and important reactions were identified. The results show that the oxygenated ions, NO⁺, O⁺ and O₂⁺, has more effects on NO production than other ions. The prompt mechanism plays an important role in predicting the ion current inside the chamber. Because this mechanism has reactions that can lead to CH production. The CH radicals produced by this mechanism can be employed by basic ionic reactions and lead to ion production. The results show that using NOx related ionic reactions results in accurate prediction of engine exhaust NOx.

Removal of dissolved sulfide contaminants from aqueous model solution using bio-derived porous graphitic carbon (PGC) impregnated with δ-MnO₂ was investigated. The composite adsorbent was synthesized using the chemical wet deposition method wherein MnO₂ was deposited on carbon walls through an in-situ reaction between permanganate and ethanol. Formation of transition metal oxide of manganese in the form of birnessite nanoparticles on interconnected PGC cell structure was confirmed by transmission electron microscopy, scanning electron microscopy, elemental analysis, and X-Ray diffraction characterization studies. The composite nanomaterial was tested for sulfide removal from aqueous solution at various conditions, including the pH, adsorbent dosage, initial solution concentration, and contact time. Adsorption results demonstrated an excellent adsorption capacity of ca. 90% within 20 min of contact time at 298 K. Equilibrium data collected from batch adsorption experiments fitted well with the Langmuir isotherm model (KL = 190 L/mg; R² = 0.99). The maximum adsorption capacity of the composite was estimated as 526.3 mg S²⁻/g at highly alkaline conditions compared to ca. 340 mg/g for a δ-MnO₂ adsorbent. Adsorptive oxidation of sulfides on composite MnO₂-PGC adsorbent was found to be controlled by the chemisorption process in accordance with the pseudo-second-order reaction model. Characterization of spent adsorbents revealed that sulfide was removed through adsorptive oxidation resulting in the formation of agglomerated particles of metal sulfate complexes and elemental sulfur. Analysis of reaction mechanism revealed that both MnO₂ and PGC played a role in the adsorptive oxidation of sulfides to CaSO₄ and elemental sulfur.

Heat stress (HS) during gestation has been associated with negative outcomes, such as preterm birth or postnatal metabolic syndromes. The intestinal microbiota is a unique ecosystem playing an essential role in mediating the metabolism and health of mammals. Here we hypothesize late gestational HS alters maternal microbial transmission and structures offspring’s intestinal microbiota and serum metabolic profiles. Our results show maternal HS alters bacterial β-diversity and composition in sows and their piglets. In the maternal intestine, genera Ruminococcaceae UCG-005, [Eubacterium] coprostanoligenes group and Halomonas are higher by HS (q < 0.05), whereas the populations of Streptococcus, Bacteroidales RF16 group_norank and Roseburia are decreased (q < 0.05). In the maternal vagina, HS mainly elevates the proportions of phylum Bacteroidetes and Fusobacteria (q < 0.05), whereas reduces the population of Clostridiales Family XI (q < 0.05). In the neonatal intestine, maternal HS promotes the population of Proteobacteria but reduces the relative abundance of Firmicutes (q < 0.05). Moreover, the core Operational taxonomic units (OTU) analysis indicates the proportions of Clostridium sensu stricto 1, Romboutsia and Turicibacter are decreased by maternal HS in the intestinal and vaginal co-transmission, whereas that of phylum Proteobacteria and Epsilonbacteraeota, such as Escherichia-Shigella, Klebsiella, Acinetobacter, and Comamonas are increased in both the intestinal and vaginal co-transmission and the vagina. Additionally, Aeromonas is the only genus that is transmitted from environmental sources. Lastly, we evaluate the importance of neonatal differential OTU for the differential serum metabolites. The results indicate Acinetobacter significantly contributes to the differences in the adrenocorticotropic hormone (ACTH) and glucose levels due to HS (P < 0.05). Further, Stenotrophomonas is the most important variable for Cholesterol, low-density lipoprotein (LDL), diamine oxidase (DAO), blood urea nitrogen (BUN) and 5-hydroxytryptamine (5-HT) (P < 0.10). Overall, our data provides evidence for the maternal HS in establishing the neonatal microbiota via affecting maternal transmission, which in turn affects the maintenance of metabolic health.

The biodegradable S,S-ethylenediaminedisuccinic acid (EDDS) is a promising chelant for chelant-assisted phytoextraction of trace metals in polluted soil. The interactions between EDDS and trace metals/major elements in the soil affect the metal bioavailability and their subsequent phytoextraction efficiency. This study aimed to investigate the macroscopic and molecular-level interactions of EDDS with Cu in the rhizosphere and non-rhizosphere of a Cu-polluted agricultural soil. A multi-interlayer rhizobox planted with ryegrass was used to simulate the transport of EDDS and Cu from the non-rhizosphere to rhizosphere soils. The results showed that EDDS (5 mM kg⁻¹) significantly dissociated Cu (285–690 fold), Fe (by 3.47–60.2 fold), and Al (2.43–5.31 fold) from the soil in comparison with a control group. A combination of micro-X-ray fluorescence, X-ray absorption near-edge structure spectroscopy, and sequential extraction analysis revealed that EDDS primarily chelated the adsorbed fraction of Cu by facilitating the dissolution of goethite. Moreover, as facilitated by ryegrass transpiration, CuEDDS was moved from the non-rhizosphere to rhizosphere and accumulated in ryegrass. In situ processes of Cu extraction and transport by EDDS in the rhizosphere were further elucidated with chemical speciation analysis and geochemical modeling methods.

The combined contamination of brominated flame retardants (BFRs) and heavy metals in electronic waste (e-waste) recycling and disposal areas has been a serious concern owing to their environmental persistence and chronic toxicities. Ammonia oxidizers, e.g., ammonia-oxidizing archaea (AOA) and bacteria (AOB) play essential roles in nitrogen cycling and can serve as ideal indicators that reflect the changes in sediment health in response to environmental variables. There is currently very little information available on the combined toxic effects of BFRs and heavy metals on AOA and AOB communities. In this study, two typical e-waste pollutants, tetrabromobisphenol A (TBBPA) and copper (Cu), were selected as target contaminants to investigate the individual and combined effects of both pollutants on AOA and AOB communities in river sediments. Respective treatments of TBBPA (1, 10, and 20 mg/kg wet weight), Cu (100 mg/kg wet weight) and their combined treatments (weight ratios of 1:100, 1:10, and 1:5) were performed in laboratory experiments. High-throughput sequencing was applied to explore the response of ammonia oxidizers to TBBPA and Cu. The interaction types of TBBPA and Cu were calculated by the directional classification system to reveal the individual and combined toxicities of both contaminants to the ammonia oxidizers. On days 15 and 30, the dominant interaction type of TBBPA and Cu was synergistic (62.50%), and the combined contamination exacted selective pressure and inhibition on the AOB and AOA communities. On days 45 and 90, the interaction type shifted to be antagonistic (83.33%), with both the AOB and AOA communities gradually reaching stable population equilibria. The alteration of the interaction type is attributed to the elevated TBBPA/Cu tolerance as the incubation time increased. This study disclosed the interaction types of TBBPA and Cu in contaminated river sediments, and revealed that the combined effect could potentially manipulate AOB and AOA communities.

The occurrence of emergent contaminants, 24 polybrominated diphenyl ethers (PBDEs), di(2-ethylhexyl)phthalate (DEHP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), diethyl phthalate (DEP), dimethyl phthalate (DMP), di-n-octyl phthalate (DnOP), bisphenol A (BPA) and nonylphenol (NP), was investigated in sediments and fishes collected from the Tamsui River system to determine the factors that influence their distribution and their risk to aquatic ecosystems and human health. The concentrations of total PBDEs, DEHP, DBP, BBP, DEP, DMP, DnOP, BPA and NP in sediments were 1–955, ND-23570, <50–411, <50–430, ND-80, ND-<50, ND-<50, 1–144, 3–19624 μg/kg dw, respectively. The spatial-temporal distribution trends of these compounds in sediments could be attributed to urbanization, industrial discharge and effluents from wastewater treatment plants. The PBDE congener distribution patterns (BDE-209 was the dominant congener) in sediments reflected the occurrence of debromination of BDE-209 and the elution of penta-BDE from the treated products. The concentrations of total PBDEs, DEHP, DBP, BBP, DEP, DMP, DnOP, BPA and NP in fish muscles were 2–66, 17–1046, <10–231, <10–66, <30, ND-<30, ND-<30, 0.4–7 and 3–440 μg/kg ww, respectively. The species-specific bioaccumulation of these compounds by fish was found and four species particularly showed high bioaccumulation potential. BDE-47 was the predominant BDE congener in fish muscles, suggesting high bioavailability and bioaccumulation of this compound. The results of biota–sediment accumulation factors showed that BDE-47, 99, 100, 153 and 154 had relatively high bioavailability and bioaccumulation potential for some fish species. The ecological risk assessment showed that the concentrations of BPA and NP in sediments were likely to have adverse effects on aquatic organisms (risk quotients > 1). The human health risk assessment according to hazard quotients (HQs) and carcinogenic risks (CRs) revealed no remarkable risk to human health through consumption of fish contaminated with BDE-47, 99, 100, 154, 209, DEHP, BPA and NP.

China has been seriously affected by particulate matter (PM) and gaseous pollutants in the atmosphere. In this study, we systematically analyse the spatio-temporal patterns of PM₂.₅, PM₁₀, SO₂, CO, NO₂, and O₃ and the associated health risks, using data collected from 1498 national air quality monitoring sites. An analysis of the averaged data from all the sites indicated that, from 2015 to 2018, annual mean concentrations of PM₂.₅, PM₁₀, SO₂ and CO declined by 3.2 μg m⁻³, 3.7 μg m⁻³, 3.9 μg m⁻³, and 0.1 mg m⁻³, respectively. In contrast, those of NO₂ and O₃ increased at rates of 0.4 and 3.1 μg m⁻³, respectively. Except for O₃, the annual mean concentrations of all pollutants were generally the highest in North China and lowest in the Tibetan Plateau. The concentrations were generally higher in the north of the country than in the south. In all regions of China, the pollutant concentrations were the highest in winter and lowest in summer, except for O₃, which showed an opposite seasonal pattern. Overall, the seasonal mean concentrations of all the pollutants (except for O₃) significantly decreased between the same seasons in 2018 and 2015, whereas the seasonal mean O₃ concentrations generally significantly increased, and/or remained at stable levels in all four seasons except for winter. Diurnal variations of all pollutants (except for O₃) exhibited a bimodal pattern with peaks between 8:00 and 11:00 a.m. and 9:00 and 12:00 p.m., whereas O₃ exhibited a unimodal pattern with maximum values between 5:00 and 7:00 p.m. No significant differences in the daily mean concentrations of all pollutants were found between weekdays and weekends in all regions, except for PM₂.₅ and PM₁₀ in Northeast China. In Northwest China and Southeast China, PM₂.₅ showed stronger correlations with NO₂ relative to SO₂, suggesting that NOₓ emission control may be more effective than SO₂ emission control for alleviating PM₂.₅ formation. Compared with 2015, the total PM₂.₅-attributable mortality, number of respiratory and cardiovascular diseases, and incidence of chronic bronchitis decreased overall by 23.4%–26.9% in 2018. In contrast, for O₃-attributable deaths, there was an increase of 18.9%. Our study not only improves the understanding of the spatial and temporal patterns of air pollutants in China, but also highlights that synchronous control of PM₂.₅ and O₃ pollution should be implemented to achieve dual benefits in protecting human health.