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Formaldehyde (HCHO) is a serious hazardous air pollutant and crucial precursor of PM2.5 and ozone compound pollution. There has been a dearth of HCHO research in Tibet where pressing need to protect the unique ecosystem. Therefore, this study aims to investigate the spatial-temporal distribution of HCHO from 2013 to 2021 and identify its influencing factors using satellite observations. Our findings reveal a noteworthy annual growth rate of 2.25% yr−1 in HCHO vertical column density (VCD) in Tibet. This rate is comparable to that in India and even surpasses levels observed in many other regions worldwide, including eastern China. Furthermore, unlike other areas, the eastern region of Tibet exhibits no discernible seasonal pattern in HCHO VCD. The anomalous variation in HCHO concentrations in Tibet can primarily be attributed to long-distance transnational transport originating from incomplete combustion in India Assam. Our research underscores the urgent need for enhanced atmospheric environmental management in Tibet. [ABSTRACT FROM AUTHOR]

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Ammonia (NH) plays vital roles in new particle formation and atmospheric chemistry. Although previous studies have revealed that it also influences the formation of secondary organic aerosols (SOA) from ozonolysis of biogenic and anthropogenic volatile organic compounds (VOCs), the influence of NH on particle formation from complex mixtures such as vehicle exhausts is still poorly understood. Here we directly introduced gasoline vehicles exhausts (GVE) into a smog chamber with NH absorbed by denuders to examine the role of NH in particle formation from GVE. We found that removing NH from GVE would greatly suppress the formation and growth of particles. Adding NH into the reactor after 3 h photo-oxidation of GVE, the particle number concentration and mass concentrations jumped explosively to much higher levels, indicating that the numbers and mass of particles might be enhanced when aged vehicle exhausts are transported to rural areas and mixed with NH-rich plumes. We also found that the presence of NH had no significant influence on SOA formation from GVE. Very similar oxygen to carbon (O:C) and hydrogen to carbon (H:C) ratios resolved by aerosol mass spectrometer with and without NH indicated that the presence of NH also had no impact on the average carbon oxidation state of SOA from GVE. [ABSTRACT FROM AUTHOR]

Residential cooking in China's urban areas could be a more significant contributor to organic aerosols when compared to restaurant cooking, yet no source profiles are available for Chinese residential cooking. In this study, a typical nine-floor residential apartment building in urban Guangzhou was selected to investigate the particulate mass emissions and chemical compositions of organic aerosols from Chinese residential cooking. During dinner cooking period, the average of total suspended particle (TSP) mass concentrations increased by a factor of 4.40 compared with that during non-cooking period. Organic matter (OM) was the major component of aerosols from cooking, and accounted for 66.9 % of the TSP mass. Over 90 organic species were identified and quantified, and could explain 14.5 % of OC in cooking emissions. Fatty acids alone shared 75.7 % of the total mass of quantified organic compounds, with palmitic acid as the predominant one. Sterols, monosaccharide anhydrides and polyols were also significant compositions and they together contributed 14.3 % in the total mass of the quantified organic compounds. While cholesterol was detected from western-style cooking, phytosterols were additionally observed from Chinese-style cooking, and campesterol and polyols were only reported in the present study. Chinese residential cooking emission showed small differences in composition patterns of organic compounds when compared to previously report Chinese restaurant cooking emissions, however, large differences existed when compared to western style cooking. Using cholesterol as a tracer for cooking emissions, in Guangzhou we found cooking emissions contributed 3.9-8.2 % of OC in PM. Spatial distributions of cooking emission contribution were consistent with the distributions of population. [ABSTRACT FROM AUTHOR]

Considerable efforts have been made to extend temperature records beyond the instrumental period through proxy reconstructions, in order to further understand the mechanisms of past climate variability. Yet, the global coverage of existing temperature records is still limited, especially for some key regions like the Tibetan Plateau and for earlier times including the Medieval Warm Period (MWP). Here we present decadally-resolved, alkenone-based, temperature records from two lakes on the northern Tibetan Plateau. Characterized by marked temperature variability, our records provide evidence that temperatures during the MWP were slightly higher than the modern period in this region. Further, our temperature reconstructions, within age uncertainty, can be well correlated with solar irradiance changes, suggesting a possible link between solar forcing and natural climate variability, at least on the northern Tibetan Plateau. [ABSTRACT FROM AUTHOR]