Quantifying the Nitrogen Sources and Secondary Formation of Ambient HONO with a Stable Isotopic Method.

Nitrous acid (HONO) is a reactive gas that plays an important role in atmospheric chemistry. However, accurately quantifying its direct emissions and secondary formation in the atmosphere as well as attributing it to specific nitrogen sources remains a significant challenge. In this study, we developed a novel method using stable nitrogen and oxygen isotopes (δ15N; δ18O) for apportioning ambient HONO in an urban area in North China. The results show that secondary formation was the dominant HONO formation processes during both day and night, with the NO2 heterogeneous reaction contributing 59.0 ± 14.6% in daytime and 64.4 ± 10.8% at nighttime. A Bayesian simulation demonstrated that the average contributions of coal combustion, biomass burning, vehicle exhaust, and soil emissions to HONO were 22.2 ± 13.1, 26.0 ± 5.7, 28.6 ± 6.7, and 23.2 ± 8.1%, respectively. We propose that the isotopic method presents a promising approach for identifying nitrogen sources and the secondary formation of HONO, which could contribute to mitigating HONO and its adverse effects on air quality.

New Insights into Unexpected Severe PM2.5 Pollution during the SARS and COVID-19 Pandemic Periods in Beijing.

During the SARS period in 2003 and COVID-19 pandemic period in 2020, unexpected severe particulate matter pollution occurred in northern China, although the anthropogenic activities and associated emissions have assumed to be reduced dramatically. This anomalistic increase in PM2.5 pollution raises a question about how source emissions impact the air quality during these pandemic periods. In this study, we investigated the stable Cu and Si isotopic compositions and typical source-specific fingerprints of PM2.5 and its sources. We show that the primary PM2.5 emissions (PM2.5 emitted directly from sources) actually had no reduction but redistribution during these pandemic periods, rather than the previous thought of being greatly reduced. This finding provided critical evidence to interpret the anomalistic PM2.5 increase during the pandemic periods in north China. Our results also suggested that both the energy structure adjustment and stringent regulations on primary emissions should be synergistically implemented in a regional scale for clean air actions in China.

Feeling and Calculation: The Impact of Lay Rationalism Thinking Mode on Mental Budgeting.

Mental budgeting is a cognitive process that helps individuals control consumption expenditures. Previous literature has shown that mental budgeting is influenced by people's cognitive capabilities and emotions, which indicates a potential influence of thinking modes on mental budgeting. Under the view of lay rationalism, the present three studies investigated the relationship between thinking modes (i.e., calculation-based thinking and feeling-based thinking) and mental budgeting, as well as the moderating effect of product types that participants consume. It was found that, first, the scores of lay rationalism, which indicate calculation-based thinking, were positively correlated with the mental budgeting levels of college students (Study 1a) and newcomers in the workplace (Study 1b); second, the activation of calculation-based thinking (vs. feeling-based thinking) decreased participants' consumption willingness (Study 2); and third, the calculation-based thinking exhibited a stronger binding effect in participants who consumed only hedonic products than in participants who consumed only utilitarian products (Study 2). The results demonstrated the effects of lay rationalism thinking mode and product types on mental budgeting, which highlighted different implications for consumers and merchants. Supplementary Information: The online version contains supplementary material available at 10.1007/s12144-022-03689-5.

Assessing the emission sources and reduction potential of atmospheric ammonia at an urban site in Northeast China.

Atmospheric ammonium and ammonia have brought negative environmental impacts and adverse health effects. However, ammonia emissions are generally less regulated worldwide. This study analyzed ammonium pollution character, quantified the dominant ammonia emission sources, and assessed ammonia reduction potential in urban Harbin (China). The results showed that ammonium recorded low concentration in the non-heating season (1.34 ± 1.57 µg/m3), and recorded sharply increased concentration (6.50 ± 7.02 µg/m3) and relative abundance in the heating season. It was closely correlated with vehicle-related pollutants (CO) in non-heating season, while with biomass burning-related pollutants (K+, Cl-) in the heating season. Bayesian Mixing Model emphasized the increasing contribution of biomass burning and decreasing contribution of fertilizer as the pollution levels escalate. The results from the thermodynamic equilibrium model showed that a 50%-60% ammonium decrease could bring marketable decrements of the aerosol pH, aerosol water content, ammonium nitrate concentration, and inorganic ion mass. The results of this study would provide scientific bases for ammonia emission reduction and haze pollution control in urban Harbin.

Insight into the Variability of the Nitrogen Isotope Composition of Vehicular NOx in China.

Nitrogen isotope (δ15N) monitoring is a potentially powerful tool in tracing atmospheric nitrogen oxides (NOx); however, the isotopic fingerprint of vehicle exhaust remains poorly interpreted. This deficiency limits our understanding of the origin of atmospheric haze pollution, especially in China. In this study, we systemically explored the δ15N-NOx fingerprints of various vehicle exhausts (n = 137) in China. The δ15N-NOx values of vehicle exhausts ranged from -18.8‰ to +6.4‰, presenting a significant correlation with NOx concentrations (p < 0.01). The highest δ15N-NOx values were observed for liquefied petroleum gas vehicles (-0.1 ± 1.8‰), followed by gasoline vehicles (-7.0 ± 4.8‰) and diesel vehicles (-12.7 ± 3.4‰), all of which displayed a rising trend as emissions standards were continuously updated. The δ15N-NOx values under working conditions followed the trend warm start (-5.9 ± 5.0‰) > driving (-7.3 ± 5.9‰) > cold start (-9.2 ± 2.7‰). By establishing a suitable model for assessing representative δ15N-NOx values, the δ15N-NOx values of various vehicles, including different fuel types with different emission standards, were evaluated. A model of δ15N-NOx associated with motor vehicle data was developed, which estimated the national δ15N-NOx value of vehicle emissions to be -12.6 ± 2.2‰, but there was considerable variation among different target areas in China.

Isotopic Interpretation of Particulate Nitrate in the Metropolitan City of Karachi, Pakistan: Insight into the Oceanic Contribution to NOx.

Nitrogen oxide (NOx) abatement has become the focus of air quality management strategies. In this study, we examined NOx sources and the atmospheric conversion of NOx in Karachi, Pakistan, a megacity in South Asia with serious particulate pollution problems. Oceanic contributions to NOx were quantified for the first time based on a novel approach using nitrogen/oxygen isotopic analysis in nitrate (δ15N-NO3-; δ18O-NO3-) and a Bayesian model. Our results showed that δ15N-NO3- in Karachi varied between -10.2‰ and +12.4‰. As indicated by the δ18O-NO3- findings (+66.2 ± 7.8‰), the •OH pathway dominated NOx conversion throughout the nearly two-year observation, but high NO3- events were attributed to the O3 pathway. Coal combustion was the most significant source (32.0 ± 9.8%) of NOx in Karachi, with higher contributions in the autumn and winter; a similar situation occurred for biomass burning + lightning (30.3 ± 6.5%). However, mobile sources (25.2 ± 6.4%) and microbial processes (12.5 ± 7.5%) exhibited opposite seasonal trends. The oceanic contributions to NOx in Karachi were estimated to be 16.8%, of which lightning, shipping emissions, and microbial processes accounted for 20.3%, 46.3%, and 33.4%, respectively, emphasizing the dominance of shipping emissions as an oceanic NOx source.

First Assessment of NOx Sources at a Regional Background Site in North China Using Isotopic Analysis Linked with Modeling.

Nitrogen oxides (NOx, including NO and NO2) play an important role in the formation of atmospheric particles. Thus, NOx emission reduction is critical for improving air quality, especially in severely air-polluted regions (e.g., North China). In this study, the source of NOx was investigated by the isotopic composition (δ15N) of particulate nitrate (p-NO3-) at Beihuangcheng Island (BH), a regional background site in North China. It was found that the δ15N-NO3- (n = 120) values varied between -1.7‰ and +24.0‰ and the δ18O-NO3- values ranged from 49.4‰ to 103.9‰. On the basis of the Bayesian mixing model, 27.78 ± 8.89%, 36.53 ± 6.66%, 22.01 ± 6.92%, and 13.68 ± 3.16% of annual NOx could be attributed to biomass burning, coal combustion, mobile sources, and biogenic soil emissions, respectively. Seasonally, the four sources were similar in spring and fall. Biogenic soil emissions were augmented in summer in association with the hot and rainy weather. Coal combustion increased significantly in winter with other sources showing an obvious decline. This study confirmed that isotope-modeling by δ15N-NO3- is a promising tool for partitioning NOx sources and provides guidance to policymakers with regard to options for NOx reduction in North China.

Biodegradation of 5-chloro-2-picolinic acid by novel identified co-metabolizing degrader Achromobacter sp. f1.

Several bacteria have been isolated to degrade 4-chloronitrobenzene. Degradation of 4-chloronitrobenzene by Cupriavidus sp. D4 produces 5-chloro-2-picolinic acid as a dead-end by-product, a potential pollutant. To date, no bacterium that degrades 5-chloro-2-picolinic acid has been reported. Strain f1, isolated from a soil polluted by 4-chloronitrobenzene, was able to co-metabolize 5-chloro-2-picolinic acid in the presence of ethanol or other appropriate carbon sources. The strain was identified as Achromobacter sp. based on its physiological, biochemical characteristics, and 16S rRNA gene sequence analysis. The organism completely degraded 50, 100 and 200 mg L-1 of 5-chloro-2-picolinic acid within 48, 60, and 72 h, respectively. During the degradation of 5-chloro-2-picolinic acid, Cl- was released. The initial metabolic product of 5-chloro-2-picolinic acid was identified as 6-hydroxy-5-chloro-2-picolinic acid by LC-MS and NMR. Using a mixed culture of Achromobacter sp. f1 and Cupriavidus sp. D4 for degradation of 4-chloronitrobenzen, 5-chloro-2-picolinic acid did not accumulate. Results infer that Achromobacter sp. f1 can be used for complete biodegradation of 4-chloronitrobenzene in remedial applications.

Aquamicrobium terrae sp. nov., isolated from the polluted soil near a chemical factory.

A Gram-negative, aerobic, non-motile bacterial strain hun6(T) isolated from the polluted soil near a chemical factory in northern Nanjing, China was investigated to clarify its taxonomic position. Growth of strain hun6(T) occurred between 10 and 45 °C (optimum, 30 °C) and between pH 6.0 and 8.0 (optimum, pH 7.0). No growth occurred at NaCl concentrations greater than 5 % (w/v). The 16S rRNA gene sequence analysis indicated that strain hun6(T) belongs to the genus Aquamicrobium. The sequence similarities of strain hun6(T) to other type strains of Aquamicrobium genus were all below 98.5 %. The presence of ubiquinone-10, the predominant fatty acid summed feature 8 (C18:1 ω7c and/or C18:1 ω6c) and C19:0 cyclo ω8c, a polar lipid pattern with phosphatidylglycerol, phosphatidylcholine, diphosphatidylglycerol, phosphatidylethanolamine and phophatidylmonomethylethanoamine were in accord with the characteristics of the genus Aquamicrobium. The G+C content of the genomic DNA was determined to be 63.5 mol%. The results of DNA-DNA hybridization, physiological and biochemical tests and chemotaxonomic properties allowed genotypic and phenotypic differentiation of strain hun6(T) from all known Aquamicrobium species. Therefore, strain hun6(T) can be assigned to a new species of this genus for which the name Aquamicrobium terrae sp. nov. is proposed. The type strain is hun6(T) (= CICC 10733(T) = DSM 27865(T)).

USP31 Activates the Wnt/ß-catenin Signaling Pathway and Promotes Gastric Cancer Cell Proliferation, Invasion and Migration.

BACKGROUND: Gastric cancer (GC) has a poor prognosis because it is highly aggressive, yet there are currently few effective therapies available. Although protein ubiquitination has been shown to play a complex role in the development of gastric cancer, to date, no efficient ubiquitinating enzymes have been identified as treatment targets for GC. METHODS: The TCGA database was used for bioinformatic investigation of ubiquitin-specific protease 31 (USP31) expression in GC, and experimental techniques, including Western blotting, qRT-PCR, and immunohistochemistry, were used to confirm the findings. We also analyzed the relationship between USP31 expression and clinical prognosis in patients with GC. We further investigated the effects of USP31 on the proliferation, invasion, migration, and glycolysis of GC cells in vitro and in vivo by using colony formation, CCK-8 assays, Transwell chamber assays, cell scratch assays, and cell-derived xenograft. Furthermore, we examined the molecular processes by which USP31 influences the biological development of GC. RESULTS: Patients with high USP31 expression have a poor prognosis because USP31 is abundantly expressed in GC. Therefore, USP31 reduces the level of ubiquitination of the Wnt/ß-catenin pathway by binding to ß-catenin, thereby activating glycolysis, which ultimately promotes GC proliferation and aggressive metastasis. CONCLUSION: USP31 inhibits ubiquitination of ß-catenin by binding to it, stimulates the Wnt/ß-- catenin pathway, activates glycolysis, and accelerates the biology of GCs, which are all demonstrated in this work.

Efficiency and Stability of Transarterial Chemoembolization Combined With or Without Lenvatinib for Unresectable Hepatocellular Carcinoma.

BACKGROUND/AIMS:  At present, there are relatively few reports on the treatment consisting of transarterial chemoembolization (TACE) combined with lenvatinib, and there is no unified conclusion on the curative effect. The objective of this research was to assess the efficacy and safety of combining TACE with lenvatinib for the treatment of unresectable hepatocellular carcinoma (uHCC). MATERIALS AND METHODS:  This study was a retrospective analysis of the patient's medical records. In this study, 249 patients (uHCC) in our hospital from 2020 to 2021 were divided into 2 groups, including the TACE-alone group (198 patients received TACE alone) and the TACE-LEN group (51 patients were treated with TACE combined with lenvatinib). According to the propensity score matching method, there were TACE-LEN group (51 patients) and TACE-alone group (51 patients). With the help of surgical experts, the overall survival (OS), progression-free survival (PFS), and tumor response (according to mRECIST) of the 2 groups were sorted and recorded, and then analyzed. Survival curves were established, the prognostic factors of OS and PFS were analyzed by univariate and multivariate analyses, and the independent prognostic factors were recorded. The adverse reactions of patients after treatment were recorded. RESULTS:  The 1-year and 2-year OS rates were 50.98% and 19.48% for the TACE-LEN group, 27.45% and 8.55% for the TACE-alone group (P = .042), respectively. The PFS of patients in the TACE-LEN group was also longer (1-year PFS rate: 25.49% vs. 11.76%, 2-year PFS rate: 19.17% vs. 5.88%; P = .0069). The disease control rate (68.63% vs. 49.10%, P = .044) of the TACE-LEN group was significantly higher. In the subgroup analysis, the OS of the TACE-LEN group was better than TACE-alone group in patients with Barcelona Clinic Liver Cancer stage C (1-year OS rate: 44.44% vs. 17.14%, 2-year OS rate: 8.67% vs. 0%; P = .009). Factor analysis concluded that serum alkaline phosphatase and treatment protocol (TACE-LEN vs. TACE) were independent influencing factors of OS. The most common treatment-related AEs included decreased albumin (n = 28, 54.9%), hypertension (n = 23, 45.1%), elevated aspartate transaminase (n = 21, 41.2%) and elevated total bilirubin (n = 18, 35.2%) in TACE-LEN group. CONCLUSION:  Compared with TACE monotherapy, TACE combined with lenvatinib effectively prolonged the OS time with a controllable safety profile for patients with uHCC.

Raman-Activated Cell Ejection for Validating the Reliability of the Raman Fingerprint Database of Foodborne Pathogens.

Raman spectroscopy for rapid identification of foodborne pathogens based on phenotype has attracted increasing attention, and the reliability of the Raman fingerprint database through genotypic determination is crucial. In the research, the classification model of four foodborne pathogens was established based on t-distributed stochastic neighbor embedding (t-SNE) and support vector machine (SVM); the recognition accuracy was 97.04%. The target bacteria named by the model were ejected through Raman-activated cell ejection (RACE), and then single-cell genomic DNA was amplified for species analysis. The accuracy of correct matches between the predicted phenotype and the actual genotype of the target cells was at least 83.3%. Furthermore, all anticipant sequencing results brought into correspondence with the species were predicted through the model. In sum, the Raman fingerprint database based on Raman spectroscopy combined with machine learning was reliable and promising in the field of rapid detection of foodborne pathogens.

Sources and formation characteristics of particulate nitrate in the Pearl River Delta region of China: Insights from three-year online observations.

Nitrate (NO3-) has been identified as a key component of particulate matter (PM2.5) in China. However, there is still a lack of understanding regarding its sources and how it forms, especially in the context of high-frequency and long-term data. In this study, NO3- levels were observed on an hourly basis over an almost three-year period at an urban site in the Pearl River Delta (PRD) region, China, from January 2019 to December 2021. The results reveal an average daily NO3- concentration ranging from 0.08 µg m-3 to 61.69 µg m-3, constituting 11.9 ± 12.5 % of PM2.5. This percentage rose to as high as 57 % during pollution episodes, highlighting NO3-'s significant role in pollution formation. The ammonia-rich environment was found to be the most important factor in promoting NO3- formation. Positive Matrix Factorization (PMF) analysis indicates that the primary sources of NO3- in the PRD region were vehicle emissions (43.8 ± 21.2 %) and coal combustion (39.1 ± 21.5 %), with shipping emissions, sea salt, soil dust and industrial emissions + biomass burning following in importance. Regarding source areas, the primary contributor of vehicle emissions was predominantly from the PRD region, whereas the coal combustion, aside from local contributions, also originates from the northern region. From a long-term perspective, NO3- pollution has remained relatively stable since the summer of 2020. Concurrently, coal combustion source has shown a localization trend. These insights derived from the extensive, high-frequency observation presented in this study serve as a valuable reference for devising strategies to control NO3- and PM2.5 in the PRD region and China.

Machine Learning-Enabled Optical Architecture Design of Perovskite Solar Cells.

Perovskite solar cells, emerging as a cutting-edge solar energy technology, have demonstrated a power conversion efficiency (PCE) of >26%, which is below the theoretical limit of 33%. This study, employing a combination of neural network models and high-throughput simulation calculations, taking the single-junction FAPbI3 cell as an illustrative example, indicates that a pyramid structure, in comparison of a planar one, can increase the highest Jsc to 27.4 mA/cm2 and the PCE to 28.4%. Both Jsc and PCE surpass the currently reported experimental results. The optimized periodicity and tilt angle of the pyramid structure align with the textured structure of crystalline silicon solar cells. These results underscore the substantial development potential of neural network inverse design based on high-throughput calculations in the field of optoelectronic devices and provide theoretical guidance for the design of monolithic perovskite-silicon tandem solar cells.

Molecular signatures and formation mechanisms of water-soluble chromophores in particulate matter from Karachi in Pakistan.

Excitation-emission matrix (EEM) fluorescence spectroscopy is a widely-used method for characterizing the chemical components of brown carbon (BrC). However, the molecular basics and formation mechanisms of chromophores, which are decomposed by parallel factor (PARAFAC) analysis, are not yet fully understood. In this study, we characterized the water-soluble organic carbon (WSOC) in aerosols collected from Karachi, Pakistan, using EEM spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). We identified three PARAFAC components, including two humic-like components (C1 and C2) and one phenolic-like species (C3). We determined the molecular families associated with each component by performing Spearman correlation analysis between FT-ICR MS peaks and PARAFAC component intensities. We found that the C1 and C2 components were associated with nitrogen-enriched compounds, where C2 with the longest emission wavelength exhibited a higher level of aromaticity, N content, and oxygenation than C1. The C3 associated formulas have fewer nitrogen-containing species, a lower unsaturation degree, and a lower oxidation state. An oxidation pathway was identified as an important process in the formation of C1 and C2 components at the molecular level, particularly for the assigned CHON compounds associated with the gas-phase oxidation process, despite their diverse precursor types. Numerous C2 formulas were found in the "potential BrC" region and overlapped with the BrC-associated formulas. It can be inferred that the compounds that fluoresce C2 contributed considerably to the light absorption of BrC. These findings are essential for future studies utilizing the EEM-PARAFAC method to explore the sources, processes, and compositions of atmospheric BrC.

The effects of allogeneic and autologous blood transfusion on immune function in patients receiving total hip replacement.

OBJECTIVE: To evaluate the effects of allogeneic and autologous blood transfusion on immune function and postoperative inflammation in patients after total hip replacement. METHODS: In this retrospective study, the clinical data of 60 patients undergoing total hip arthroplasty through a posterolateral approach were analyzed. The patients were grouped into an autologous blood transfusion group (allo group) (n = 30) and an autologous blood transfusion group (auto-group) (n = 30) according to the treatment they received. All patients did not receive preoperative and intraoperative blood transfusion. The blood collected in the operation area was transfused to the patients in the auto-group with the autotransfusion device and the allogeneic blood was transfused to the patients in the allo-group after the operation. The average amount of blood transfusion was 400 ml. The immune function after blood transfusion was mainly evaluated by natural killer cell cytotoxicity (NKCC) and interleukin-2 (IL-2) using ELISA kits, meanwhile the changes of cellular immune factor levels (differentiation cluster of differentiation, CD) (CD3+, CD4+) and humoral immune factor levels (Immunoglobulin E, IgE) after blood transfusion were determined by flow cytometry. The secondary outcome was postoperative inflammatory response measured by white blood cell (WBC) count, neutrophil percentage (NP) and C-reactive protein (CRP). RESULTS: The parameters of both groups of patients were comparable. The auto-group significantly outperformed the Allo-group in the following laboratory parameters: NKCC (%, E:T = 10:1) at day 2 [26.1 (Auto) vs 19.3 (Allo); P = 0.0025], NKCC (%, E:T = 5:1) at day 2 [20.0 (Auto) vs 17.3 (Allo); P = 0.0094], CD3+ (%) at day 2 [50.5 (Auto) vs 40.8 (Allo); P = 0.0233], CD4+ (%) at day 2 [41.2 (Auto) vs 26.3 (Allo); P = 0.0122], IgE (U/mL) at day 2 [157.8 (Auto) vs 319.8 (Allo); P = 0.0064]. CONCLUSION: Autotransfusion can safely replace allogeneic blood transfusion and reduce the damage of postoperative immune function after total hip arthroplasty.

Isotopic comparison of ammonium between two summertime field campaigns in 2013 and 2021 at a background site of North China.

Ammonia (NH3) is the primary atmospheric alkaline gas, playing a crucial role in the atmospheric chemistry. Recently, non-agricultural emissions have been identified as the dominant sources of NH3 in urban areas. However, few studies have quantified the contributions of different sources to regional NH3. This study conducted two summertime field observations in 2013 and 2021 at a background site of North China to comprehensively explore the regional variations in concentration, nitrogen isotope composition (δ15N), and sources of ammonium (NH4+). The results indicate that NHx (NHx = NH3 + NH4+) concentration has increased in 2021, but the fNH4+ (NH4+/ NHx) has decreased significantly. The δ15N-NH4+ values show a significant increase, ranging from -4.7 ± 8.1 ‰ to +12.0 ± 2.4 ‰. The increase can be attributed to two primary factors: changes in fNH4+ resulting from the reduction of atmospheric acid gases and alterations in the sources of NH3. Bayesian simulation analysis reveals substantial variations in NH3 sources between 2013 and 2021 observations. Non-agricultural sources have significantly increased their contribution to NHx concentration, with vehicle exhaust and NH3 slip experiencing growth rates of 187 % and 104 %, respectively. Our results confirm the dominate contribution of non-agricultural sources to regional NH3 at the present stage and propose relevant mitigation strategies, which would provide essential insights for reducing NH3 emissions in North China.

[Changes in Health Risks and Pollution Sources of Atmospheric PM2.5-bound Metals in a Background Site in North China].

To explore the change features of PM2.5-bound metals in a background site of North China in the past ten years, 71 and 160 samples were collected from December 2011 to January 2013 (period Ⅰ) and from September 2019 to November 2021 (period Ⅱ) in Tuoji Island National Atmospheric Monitoring Station, respectively.The concentration of metals sampled was determined using ICP-MS, and the concentrations, sources, and health risks of heavy metals were compared. The results revealed that the average concentration of PM2.5 was (54.06±39.71) µg·m-3during period Ⅱ, which was 3.53 ng·m-3 lower than that during period Ⅰ. The concentrations of Zn, Mn, As, Pb, and V in stage Ⅱ decreased by 54.53, 172.63, 0.8, 79.06, and 3.81 ng·m-3, respectively, whereas the concentrations of Cr, Cu, Cd, and Ni increased by 2.01, 5.42, 3.03, and 3.55 ng·m-3, respectively. The PMF model results indicated that the biggest contributor to PM2.5-bound metal was industrial emissions (32.32%), followed by coal combustion (27.47%), vehicle emissions (23.70%), ship emissions (9.69%), and dust sources (6.83%) during period Ⅱ. The contribution ratio of dust sources and ship emissions decreased by 20.73% and 8.83%, respectively, whereas for coal combustion and industrial emissions it increased by 2.50% and 13.52%, respectively, when compared with that during period Ⅰ. The total carcinogenic risk induced by PM2.5-bound heavy metals of period Ⅱ increased, with the highest contributions by Cr and Cd. The total non-carcinogenic risk decreased, with Mn contributing the most. Therefore, in the process of air pollution control, the control of pollution sources of heavy metals such as Cr and Mn should be reinforced.

Deciphering roles of microbiota in arsenic biotransformation from the earthworm gut and skin.

Biotransformation mediated by microbes can affect the biogeochemical cycle of arsenic. However, arsenic biotransformation mediated by earthworm-related microorganisms has not been well explored, especially the role played by earthworm skin microbiota. Herein, we reveal the profiles of arsenic biotransformation genes (ABGs) and elucidate the microbial communities of the earthworm gut, skin, and surrounding soil from five different soil environments in China. The relative abundance of ABGs in the earthworm skin microbiota, which were dominated by genes associated with arsenate reduction and transport, was approximately three times higher than that in the surrounding soil and earthworm gut microbiota. The composition and diversity of earthworm skin microbiota differed significantly from those of the soil and earthworm gut, comprising a core bacterial community with a relative abundance of 96% Firmicutes and a fungal community with relative abundances of 50% Ascomycota and 13% Mucoromycota. In addition, stochastic processes mainly contributed to the microbial community assembly across all samples. Moreover, fungal genera such as Vishniacozyma and Oomyces were important mediators of ABGs involved in the biogeochemical cycle of arsenic. This is the first study to investigate earthworm skin as a reservoir of microbial diversity in arsenic biotransformation. Our findings broaden the current scientific knowledge of the involvement of earthworms in the arsenic biogeochemical cycle.

Quantitative evaluation for the sources and aging processes of organic aerosols in urban Guangzhou: Insights from a comprehensive method of dual­carbon isotopes and macro tracers.

Organic carbon aerosol (OC) is a pivotal component of PM2.5 in the atmospheric environment, yet its emission sources and atmospheric behaviors remain poorly constrained in many regions. In this study, a comprehensive method based on the combination of dual­carbon isotopes (13C and 14C) and macro tracers was employed in the PRDAIO campaign performed in the megacity of Guangzhou, China. The 14C analysis showed that 60 ± 9 % of OC during the sampling campaign was associated with non-fossil sources such as biomass burning activities and biogenic emissions. It should be noted that this non-fossil contribution in OC would significantly decrease when the air masses came from the eastern cities. Overall, we found that non-fossil secondary OC (SOCNF) was the largest contributor (39 ± 10 %) to OC, followed by fossil secondary OC (SOCFF: 26 ± 5 %), fossil primary OC (POCFF: 14 ± 6 %), biomass burning OC (OCbb: 13 ± 6 %) and cooking OC (OCck: 8 ± 5 %). Also, we established the dynamic variation of 13C as a function of aged OC and the volatile organic compounds (VOCs) oxidized OC to explore the impact of aging processes on OC. Our pilot results showed that atmospheric aging was highly sensitive to the emission sources of seed OC particles, with a higher aging degree (86 ± 4 %) when more non-fossil OC particles were transferred from the northern PRD.