Nitrate-Photolysis Shortens the Lifetimes of Brown Carbon Tracers from Biomass Burning.

Biomass burning is an important source of brown carbon (BrC) aerosols, which influence climate by affecting the Earth's radiative balance. However, the transformation pathways of BrC chromophores, especially in the presence of photochemically active species, such as nitrate, are not well understood. In this study, the nitrate-mediated aqueous-phase photooxidation of three typical BrC chromophores from biomass burning was investigated, including 4-nitrocatechol, 3-nitrosalicylic acid, and 3,4-dinitrophenol.

Understanding the variability of ground-level ozone and fine particulate matter over the Tibetan plateau with data-driven approach.

The Tibetan Plateau, known as the "Third Pole", is susceptible to ground-level ozone (O) and fine particulate matter (PM) pollution due to its unique high-altitude environment. This study constructed random forest regression models using multi-source data from ground measurements and meteorological satellites to predict variations in ground-level O and PM concentrations and their influencing factors across seven major cities in the Tibetan Plateau over two-year periods. The models successfully reproduced O and PM levels with satisfactory R-squared values of 0.

Trimethylamine from Subtropical Forests Rival Total Farmland Emissions in China.

Many types of living plants release gaseous trimethylamine (TMA), making it a potentially important contributor to new particle formation (NPF) in remote areas. However, a panoramic view of the importance of forest biogenic TMA at the regional scale is lacking. Here, we pioneered nationwide mobile measurements of TMA across a transect of contiguous farmland in eastern China and a transect of subtropical forests in southern China.

Understanding the spatial and seasonal variation of the ground-level ozone in Southeast China with an interpretable machine learning and multi-source remote sensing.

Ground-level ozone (O) pollution poses significant threats to both human health and air quality. This study uses ground observations and satellite retrievals to explore the spatiotemporal characteristics of ground-level O in Zhejiang Province, China. We created data-driven machine learning models that include meteorological, geographical and atmospheric parameters from multi-source remote sensing products, achieving good performance (Pearson's r of 0.

Staggered-peak production is a mixed blessing in the control of particulate matter pollution.

Staggered-peak production (SP)-a measure to halt industrial production in the heating season-has been implemented in North China Plain to alleviate air pollution. We compared the variations of PM composition in Beijing during the SP period in the 2016 heating season (SP) with those in the normal production (NP) periods during the 2015 heating season (NP) and 2016 non-heating season (NP) to investigate the effectiveness of SP. The PM mass concentration decreased from 70.

Direct emissions of particulate glyoxal and methylglyoxal from biomass burning and coal combustion.

Glyoxal (Gly) and methylglyoxal (Mgly) are key precursors globally for secondary organic aerosol (SOA) formation. These two species were often thought to be formed in the atmosphere via photochemical oxidation of organics from biogenic and anthropogenic origins, although few studies have shown their direct emissions. In this study, we report direct emissions of particulate Gly and Mgly from different residential fuels typically used in north China.

Large contribution from worship activities to the atmospheric soot particles in northwest China.

Worship activities like burning joss paper during the Chinese Hanyi festival is a common, traditional custom in northwest China. However, the pollutants of e.g.

Polycyclic aromatic hydrocarbons from cooking emissions.

Air pollution studies have often overlooked the contribution from cooking to the particle-bound polycyclic aromatic hydrocarbons (PAHs) in the ambient environment, despite cooking emissions have been identified as an important source of organic aerosol in most urban areas, known as the cooking-like organic aerosol factor (i.e., COA).

Organic aerosol formation and aging processes in Beijing constrained by size-resolved measurements of radiocarbon and stable isotopic C.

This study investigates the sources and atmospheric processes of size-resolved carbonaceous aerosols in winter 2018 in urban Beijing, based on analysis of dual-carbon isotopes (i.e., radiocarbon and the stable isotope C).

Measurement report of the change of PM composition during the COVID-19 lockdown in urban Xi'an: Enhanced secondary formation and oxidation.

Enhanced secondary aerosol formation was observed during the COVID-19 lockdown in Xi'an, especially for polluted episodes. More oxidized‑oxygenated organic aerosol (MO-OOA) and sulfate showed the dominant enhancements, especially in large particle-mode. Meanwhile, relative humidity (RH) showed a positive promotion on the formation of sulfate and MO-OOA during the lockdown, but had no obvious correlation with less oxidized‑oxygenated organic aerosol (LO-OOA) or nitrate.

Characteristics and sources of hourly elements in PM and PM during wintertime in Beijing.

Characteristics and sources of ambient particle elements in urban Beijing were studied by hourly observations in two size fractions (PM and PM) during November and December 2017 using an online multi-element analyzer. The reconstructed oxide concentrations of 24 elements (from Al to Pb) comprise an appreciable fraction of PM and PM accounting for 37% and 17%, respectively on average. We demonstrate the benefit of using high-time-resolution chemical speciation data in achieving robust source apportionment of the total elemental PM (PM) and elemental PM (PM) mass using positive matrix factorization (PMF).

The formation and evolution of secondary organic aerosol during summer in Xi'an: Aqueous phase processing in fog-rain days.

Secondary organic aerosol (SOA) is an important contributor to organic aerosol (OA), however, the model simulations of SOA concentrations and oxidation states remain significant uncertainties because of inadequate cognition of its formation and aging chemistry. In this study, SOA formation and evolution processes during summer in Xi'an were investigated, based on high-resolution online measurements of non-refractory PM (NR-PM) species and OA source apportionment using positive matrix factorization. The results showed that the total SOA, including less oxidized-oxygenated OA (LO-OOA), more oxidized-oxygenated OA (MO-OOA), and aqueous-phase-processed oxygenated OA (aq-OOA), on average constituted 69% of OA, and 43% of NR-PM, suggesting the high atmospheric oxidation capacity and the dominance of SOA during summer in Xi'an.

Seasonal variations in the sources of organic aerosol in Xi'an, Northwest China: The importance of biomass burning and secondary formation.

The Guanzhong basin is a part of the three top priority regions in China's blue sky action as of 2019. Understanding the chemical composition, sources, and atmospheric process of aerosol in this region is therefore imperative for improving air quality. In this study, we present, for the first time, the seasonal variations of organic aerosol (OA) in Xi'an, the largest city in the Guanzhong basin.

Cobalt decorated nitrogen-doped carbon bowls as efficient electrocatalysts for the oxygen reduction reaction.

Cobalt decorated nitrogen-doped carbon bowls (Co@NCB) have been successfully constructed by impregnating bowl-like resin particles with cobalt salt followed by annealing. The cobalt exists in the following two forms in the obtained Co@NCB: Co nanoparticles and CoN. The Co@NCB outperforms the commercial Pt/C in the oxygen reduction reaction in terms of half-wave potential and stability.