Trends of Full-Volatility Organic Emissions in China from 2005 to 2019 and Their Organic Aerosol Formation Potentials

Emissions of organic compounds have strong influences on the environment. Most previous emission inventories only cover the emissions of particulate organic carbon and nonmethane volatile organic compounds (NMVOC) but neglect the semivolatile and intermediate volatile organic compounds (S/IVOC), which considerably contribute to the organic aerosol (OA) burden. Herein, we developed a full-volatility emission inventory of organic compounds in China from 2005 to 2019 and analyzed the OA formation potential (OAFP) of each volatility bin and source using a two-dimensional volatility basis set (2D-VBS) box model. The emissions of low/extremely low/ultralow VOC (xLVOC) decreased substantially during 2005–2019, while the emissions of SVOC showed significant decline after 2014, mainly because of reduced residential biomass consumption. IVOC and VOC emission amounts in 2019 were similar to those in 2005; however, the major sources of emissions changed substantially. Emissions from volatile chemical products (VCP) increased significantly and became the dominant source of IVOC and VOC emissions. The S/IVOC from VCP contributed 1322 kt of OAFP in 2019, higher than the total anthropogenic xLVOC emissions. Considering the high of S/IVOC, future air pollution control policies should prioritize VCP, residential biomass burning, and diesel vehicles

Trends of Full-Volatility Organic Emissions in China from 2005 to 2019 and Their Organic Aerosol Formation Potentials

Emissions of organic compounds have strong influences on the environment. Most previous emission inventories only cover the emissions of particulate organic carbon and nonmethane volatile organic compounds (NMVOC) but neglect the semivolatile and intermediate volatile organic compounds (S/IVOC), which considerably contribute to the organic aerosol (OA) burden. Herein, we developed a full-volatility emission inventory of organic compounds in China from 2005 to 2019 and analyzed the OA formation potential (OAFP) of each volatility bin and source using a two-dimensional volatility basis set (2D-VBS) box model. The emissions of low/extremely low/ultralow VOC (xLVOC) decreased substantially during 2005–2019, while the emissions of SVOC showed significant decline after 2014, mainly because of reduced residential biomass consumption. IVOC and VOC emission amounts in 2019 were similar to those in 2005; however, the major sources of emissions changed substantially. Emissions from volatile chemical products (VCP) increased significantly and became the dominant source of IVOC and VOC emissions. The S/IVOC from VCP contributed 1322 kt of OAFP in 2019, higher than the total anthropogenic xLVOC emissions. Considering the high of S/IVOC, future air pollution control policies should prioritize VCP, residential biomass burning, and diesel vehicles

Fostering a Holistic Understanding of the Full Volatility Spectrum of Organic Compounds from Benzene Series Precursors through Mechanistic Modeling

A comprehensive understanding of the full volatility spectrum of organic oxidation products from the benzene series precursors is important to quantify the air quality and climate effects of secondary organic aerosol (SOA) and new particle formation (NPF). However, current models fail to capture the full volatility spectrum due to the absence of important reaction pathways. Here, we develop a novel unified model framework, the integrated two-dimensional volatility basis set (I2D-VBS), to simulate the full volatility spectrum of products from benzene series precursors by simultaneously representing first-generational oxidation, multigenerational aging, autoxidation, dimerization, nitrate formation, etc. The model successfully reproduces the volatility and O/C distributions of oxygenated organic molecules (OOMs) as well as the concentrations and the O/C of SOA over wide-ranging experimental conditions. In typical urban environments, autoxidation and multigenerational oxidation are the two main pathways for the formation of OOMs and SOA with similar contributions, but autoxidation contributes more to low-volatility products. NOx can reduce about two-thirds of OOMs and SOA, and most of the extremely low-volatility products compared to clean conditions, by suppressing dimerization and autoxidation. The I2D-VBS facilitates a holistic understanding of full volatility product formation, which helps fill the large gap in the predictions of organic NPF, particle growth, and SOA formation

Modeling the Formation of Organic Compounds across Full Volatility Ranges and Their Contribution to Nanoparticle Growth in a Polluted Atmosphere

Nanoparticle growth influences atmospheric particles’ climatic effects, and it is largely driven by low-volatility organic vapors. However, the magnitude and mechanism of organics’ contribution to nanoparticle growth in polluted environments remain unclear because current observations and models cannot capture organics across full volatility ranges or track their formation chemistry. Here, we develop a mechanistic model that characterizes the full volatility spectrum of organic vapors and their contributions to nanoparticle growth by coupling advanced organic oxidation modeling and kinetic gas-particle partitioning. The model is applied to Nanjing, a typical polluted city, and it effectively captures the volatility distribution of low-volatility organics (with saturation vapor concentrations 3), thus accurately reproducing growth rates (GRs), with a 4.91% normalized mean bias. Simulations indicate that as particles grow from 4 to 40 nm, the relative fractions of GRs attributable to organics increase from 59 to 86%, with the remaining contribution from H2SO4 and its clusters. Aromatics contribute much to condensable organic vapors (∼37%), especially low-volatility vapors (∼61%), thus contributing the most to GRs (32–46%) as 4–40 nm particles grow. Alkanes also contribute 19–35% of GRs, while biogenic volatile organic compounds contribute minimally (<13%). Our model helps assess the climatic impacts of particles and predict future changes