Accurate quantification of the absorption properties of brown carbon (BrC) aerosols is crucial to assess the Earth‐atmosphere radiative impacts of BrC. However, the BrC absorption properties were ...often misestimated in field observations, due to neglecting the contribution of dust absorption. This study solved this problem by coupling a method for calculating the dust concentration into the traditional model for quantifying BrC absorption. The results show that dust absorption was up to 16.8% of the sum of BrC and dust absorption in northwestern China. The potential contribution of dust to the sum of BrC and dust absorption was significantly higher in the Asia‐located studies (0.4%–16.8%) than in the Americas‐located (<1.2%) and Europe‐located (<2.3%) studies. This work underscores the necessity of eliminating the negative effect of dust in BrC quantitative model. It prompts us to revisit the BrC absorption properties resolved by previous studies, especially in dust‐influenced areas such as Asia.
Plain Language Summary
Organic components in aerosols that can absorb light are collectively referred to as brown carbon (BrC), and dust aerosols can also absorb light. Their ability to change weather and climate by absorbing solar radiation has received a lot of attention from the academic community. Previous studies have often misestimated the BrC absorption properties because of the difficulty in separating BrC and dust absorption. To solve this difficulty, we proposed a new method to separate the BrC and dust absorption properties, which was successfully applied at a northwestern Chinese site. Subsequently, we found that the contribution of dust to absorption was generally high in the Asia‐located studies, not only in this study, emphasizing the necessity of applying the new method proposed in this study in dust‐affected regions such as Asia.
Key Points
A method was developed to remove dust effect when quantifying light absorption properties of brown carbon (BrC)
Dust absorption was up to 16.8% of the sum of BrC and dust absorption at a typical site in northwest China
Absorption properties of BrC in dust‐affected areas such as Asia need to be reassessed due to high dust absorption contribution
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The region surrounding the Tibetan Plateau (TP) is widely considered a primary global dust source, with mineral dust comprising a significant proportion of aerosols over the TP. Current research on ...TP dust has mainly focused on transport from the surrounding deserts, with little focus on dust emissions from the TP's interior. The erodibility factor used by the WRF‐Chem (ERODDEF) is 0 for the TP, so the model cannot simulate the dust emissions inside the plateau. Thus, we constructed a high‐resolution erodibility data set (ERODSDS) based on a reliable dust source distribution and intensity map. Based on the modified EROD map, the WRF‐Chem model was used to simulate dust emissions and direct radiative forcing on the TP in 2018. With the modified EROD map, WRF‐Chem can well simulate the temporal variation and spatial pattern of mineral dust on the plateau, which greatly improves the model's dust emissions simulation accuracy on the TP.
Plain Language Summary
Due to certain limitations of the ERODDEF, the previous WRF‐Chem model was unable to accurately simulate dust emissions from the TP's interior. Thus, we constructed a more realistic ERODSDS and improved simulations of dust emissions and dust direct radiative forcing within the plateau. The west‐central part of the plateau is also an important source of dust emissions, and the amount of dust emitted within the plateau should not be neglected.
Key Points
The WRF‐Chem model seriously underestimates local dust emissions on the Tibetan Plateau
High‐precision erodibility data on the Tibetan Plateau is constructed to accurately describe the surface dust emission potential
The temporal and spatial distribution of the local dust emission on the Tibetan Plateau was estimated
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
This work was undertaken to observe therapeutic effect of Xiebai and Zengye (XBZY) decoction on post-infectious cough (PIC) in rats, as well as its effect on gut microbiota and the exploration of the ...intestinal microecological mechanisms of XBZY decoction in the treatment of PIC. Using a random number table, the rats that were successfully modelled were assigned to the PIC, XBZY group (14.8 g/kg/d), and montelukast sodium treatment (MAS) group (1 mg/kg/d). The cough sensitivity of rats and changes in fecal water content were assessed, and serum interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-α) levels were determined by ELISA. The histopathological changes in the bronchus and colon tissues were observed under the microscope after hematoxylin-eosin staining. Short-chain fatty acids (SCFAs) in fecal samples were measured by gas chromatography, and changes in gut microbiota were observed using 16S rRNA sequencing. The PIC rats showed decreased fecal water content, increased cough sensitivity, elevated serum TNF-α and IL-8 levels, and higher bronchitis scores comparing to normal control group. The PIC rats showed reductions in SCFAs and significant changes in the structure of gut microbiota. XBZY decoction intervention led to increased fecal water content in rats, reduced cough sensitivity, decreased serum IL-8 and TNF-α levels, decreased bronchitis scores, and alleviated inflammatory cell infiltration was observed in the colonic mucosa. Additionally, elevated SCFAs levels were observed in the PIC rats. XBZY decoction intervention improved alpha-/beta-diversity, and corrected microbiota imbalance in PIC rats. SCFAs, TNF-α and IL-8, acetic acid was revealed to be positively associated with Allobaculum but inversely correlated with unclassified_f_Oscillospiraceae; propanoic acid was positively associated with Lactobacilli but negatively associated with Romboutsia; butanoic acid exhibited positive correlations with Akkermansia and Lactobacilli, but negative correlations with unclassified_f_Oscillospiraceae, Eubacterium_xylanophilum_group, and Lachnospiraceae_NK4A136_group; Additionally, TNF-α was inversely linked to Allobaculum, while IL-8 was positively related to Romboutsia and Turicibacter. In conclusion, XBZY decoction significantly reduced cough sensitivity and airway inflammation in PIC rats while ameliorating stool dryness and colonic inflammation. The protective effects of XBZY decoction could be linked to modulat gut microbiota in PIC rats, and regulat SCFAs contents in PIC rats, while the regulator mechanisms of XBZY decoction in gut microbiota still requires further in-depth investigation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
As a precursor process to cloud formation, aerosol activation over the Tibetan Plateau (TP) plays a pivotal role in regional cloud-precipitation and global climate. However, its ...characteristics remain unclear due to the absence of targeted observations in the TP. We conducted a ground in-situ aerosol-cloud-precipitation experiment in the southern TP (GACPE-STP), thereby unveiling the aerosol activation characteristics in this crucial region. Our findings reveal a weak aerosol activation capacity with low hygroscopicity (
κ
) values of less than 0.1 through multi-method
κ
measurements, contrasting starkly with the widely recommended
κ
value of 0.3 for continental regions. A
κ
parameterization is developed for predicting aerosol activation in this region, which can significantly reduce the overestimations of cloud droplet number concentration and hence aerosol indirect effects caused by using the recommended
κ
of 0.3. These findings address the unclear characteristics of aerosol activation in the TP region, contributing to the enhancement of regional cloud precipitation and global climate simulations.
The transport of air pollutants from areas surrounding the Tibetan Plateau (TP) has recently been studied. However, the major sources of atmospheric total suspended particulate matter (TSP) on the ...central TP remain unclear due to a lack of
in-situ
observations on aerosol physico-chemical properties. Therefore, to quantitatively investigate the physico-chemical properties and reveal the major sources of atmospheric aerosols, a comprehensive field campaign was conducted at the site of Nam Co from August 6 to September 11, 2020. Aerosol loading was low during the campaign with average TSP mass concentration, scattering coefficient at 550 nm, and absorption coefficient at 670 nm being 10.11 ± 5.36 μg m
−3
, 1.71 ± 1.36 Mm
−1
, and 0.26 ± 0.20 Mm
−1
, respectively. Organic matter (63.9%) and mineral dust (27.8%) accounted for most of the TSP mass concentrations. The average scattering Ångström exponent of 0.59 ± 0.14 reflected the influence of mineral dust, and the elemental fractions and the results of enrichment factor illustrated that crustal materials were the main contributors of mineral dust. The organic to elemental carbon ratio of 15.33 is probably caused by the aging that occurs during the transport of aerosols. The strong correlation between organic carbon and Ca
2+
and the results of the electron microscopy analysis of single particles indicated that organic carbon and mineral dust had the same sources; however, the weak relation between mineral dust and wind speed indicated that local wind erosion was not the main contributor to the mineral dust. The potential source contribution function further illustrated that the summertime TSP in the central TP was mainly characterized by background biomass and mineral dust aerosols originating regionally from the ground within the TP.
Angstrom exponent (AE) and aerosol optical depth (AOD) obtained from the aerosol robotic network (AERONET) and volume depolarization ratio (VDR) obtained from the cloud-aerosol Lidar with orthogonal ...polarization (CALIOP) from March 2018 to February 2019 were used in our study. Data used in this study are direct observation, avoiding the limitations and uncertainties from the inversion process, and providing accurate information about the aerosol properties. Both instruments were within colocation criteria of a 40-km radius and ±2 h were defined as coincident cases. Six aerosol types were differentiated using the threshold method based on the AE, AOD, and VDR data. Discussion of the aerosol classification yielded the following results: 1) clean marine aerosols were the most abundant and widely distributed aerosols, followed by other types of aerosol (33.2%), polluted dust aerosols (26.8%), natural dust aerosols (2.3%), biomass burning aerosols (1.8%), and clean continental aerosols (1.1%); 2) clean marine aerosols were mainly distributed in North America and Europe, and polluted dust aerosols frequently appeared on the edges or downwind of deserts; and 3) the aerosols controlled by natural conditions (e.g., natural dust aerosols) were sensitive to seasonal variations, whereas those controlled by anthropogenic activities (e.g., polluted dust aerosols) were not. This study provides a new method for the collaborative observation of aerosol types with ground-based and satellite data. It is rare to provide annual global distribution of aerosol types and their seasonal variations; these results provide a reference for understanding the global aerosol distribution status.
Abstract
This study aimed to determine the effects of Xiebai Zengye decoction (XBZY) on airway inflammation and respiratory function in rats with postinfectious cough (PIC), and its regulatory ...effects on the extracellular signal‐regulated kinase (ERK) signaling pathway. Compared with the normal group, the rats from the PIC group had significantly shortened expiratory time (TE) and enhanced pause (EEP), increased resistance (RT), and enhanced pause (Penh), along with increased levels of serum interleukin‐4 (IL‐4) and IL‐6, and decreased levels of IL‐10. The lung and colon tissues of rats from the PIC group showed histopathological changes, including inflammatory cell infiltration, damaged mucosal epithelium, and crypt structure, with significantly increased ERK mRNA and protein expression levels. Treatment with XBZY and montelukast sodium (MAS) improved the respiratory function and serum cytokine levels, reduced tissue inflammation, and decreased ERK mRNA and protein expression levels in the lung and colon tissues. In the lung tissues, XBZY treatment significantly decreased the expression of phosphorylated‐ERK (p‐ERK) protein, as well as p‐MEK1/2, p‐ERK1/2, and p‐c‐Fos proteins, while in the colon tissues, XBZY significantly decreased the expression of p‐ERK1/2 and p‐c‐Fos proteins. However, MAS treatment only showed significant improvement in the lung tissue inflammation score, and the expression level of p‐ERK protein in the lung tissue was decreased. In conclusion, the present study suggests that XBZY has a potential therapeutic effect on PIC by improving respiratory function and attenuating inflammation, and this effect may be associated with the inhibition of the ERK signaling pathway. These findings could provide a new direction for the development of treatments for PIC. However, further research is needed to elucidate the underlying molecular mechanisms of XBZY and to confirm its safety and efficacy in clinical trials.
Significance statement
Postinfectious cough (PIC) accounts for 21.73% of the causes of chronic cough in Chinese children and has a higher incidence rate in preschool children. This study aims to observe the effects of Xiebai Zengye decoction (XBZY) on airway inflammation and reactivity in young rat model of PIC cough, and to explore its regulatory effects on the ERK signaling pathway, to preliminarily elucidate the mechanism of XBZY in treating PIC.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Flexible, heteroatoms-rich activated carbon nanofibers with fascinating cross-linked architectures are successfully gained in a facile and controllable way via electrospinning polyacrylonitrile (PAN) .../dicyandiamide (DICY) composite nanofibers followed by carbonation and a CO2 activation process. The unique inter-bonded structures and heteroatoms contents could be easily controlled by adjusting the preoxidation temperature applied in the calcining procedure and the addition of DICY. Significantly, the resultant samples display hierarchical pores with micro/meso/macropores, abundant N, O species doped and unique fiber-fiber interconnections, which considerably boost the electrochemical properties. As an electrode material, the activated N-doped cross-linked carbon nanofibers (ANCLCNFs) show a high capacitance of 323 F g−1 with a current density of 0.5 A g−1, excellent rate capacity (230.1 F g−1 at 20 A g−1) and long-term duration (over 95% after 10000 cycles). Furthermore, the symmetrical supercapacitor delivers a maximum energy density of 14.3 Wh kg−1 at a power density of 162.5 W kg−1.
Aerosols over the Tibetan Plateau (TP) play an important role in the regional and global climate change and ecological environment. The Second Tibetan Plateau Scientific Expedition and Research ...Program (STEP) carried out observation experiment at the Nam Co Station for Multisphere Observation and Research, Chinese Academy of Sciences (Nam Co Station, 30°46′N, 90°59′E, 4730 m) in the central TP from August 5 to September 11, 2020. This paper investigated the aerosol optical properties and its potential sources over Nam Co region. The main results are as follow: the average aerosol optical depth was 0.025 during the observation period; the average black carbon (BC) concentration and aerosol number concentration was 37 ng/m3 and 129 N/cm3, respectively; the diurnal variation and vertical distribution of aerosol were affected by the local meteorological elements. Frequent southerly winds during the summer monsoon led to a certain contribution of South Asia to the BC concentration in Nam Co region. And particles from the Taklimakan Desert led to dramatic increasing of aerosol number concentration over Nam Co region. The aerosol optical characteristics and influencing factors over the central TP were analyzed, which is beneficial to further study the influence of aerosols over the TP on regional and global weather and climate.
•Optical properties of aerosol over Nam Co station were observed by the STEP of China.•Nam Co region was generally influenced by BC from South Asia, local pollution emissions and north particles.•The average of AOD, depolarization ratio and BC over Nam Co station was 0.026, 0.033 and 37 ng/m3, respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The quantitative estimation of urban particulate matter (PM) sources is essential but limited because of various reasons. The hourly online data of PM2.5, organic carbon (OC), elemental carbon (EC), ...water-soluble ions, and elements from December 2019 to November 2020 was used to conduct PM source appointment, with an emphasis on the contribution of vehicle emissions to fine PM pollution in downtown Lanzhou, Northwest China. Vehicle emissions, secondary formation, mineral dust, and coal combustion were found to be the major PM sources using the positive matrix factorization model. The seasonal mean PM2.5 were estimated to be 72.8, 39.2, 24.3, and 43.6 μg·m−3 and vehicle emissions accounted for 35.7%, 25.8%, 30.0%, and 56.6% in winter, spring, summer, and autumn, respectively. Vehicle emissions were the largest source of PM considering the high PM pollution in winter and its significantly large contribution in autumn. Furthermore, the contribution of vehicle emissions increased with increasing PM in winter and autumn. Vehicle emissions were also the most important source of EC, accounting for 70.3%, 91.0%, 83.5%, and 93.7% of the total EC in winter, spring, summer, and autumn, respectively. With the reduction in industrial emissions and increase in vehicle numbers in China in recent years, vehicle emissions are going to be the largest source of urban PM pollution. To sustainably improve air quality in Lanzhou and other Chinese cities, efforts should be made to control vehicle emissions such as promoting clean-energy vehicles and encouraging public transportation.
Display omitted
•Vehicle emissions were the largest source of particulate matter (PM) pollution.•Contribution of vehicle emissions increased with increasing PM in winter and autumn.•Vehicle emissions contributed most to the elemental carbon.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
