Modeling the molecular composition of secondary organic aerosol under highly polluted conditions: A case study in the Yangtze River Delta Region in China.

A near-explicit mechanism, the master chemical mechanism (MCMv3.3.1), coupled with the Community Multiscale Air Quality (CMAQ) model (CMAQ-MCM-SOA), was applied to investigate the characteristics of secondary organic aerosol (SOA) during a pollution event in the Yangtze River Delta (YRD) region in summer 2018.

[Impacts of Anthropogenic Emission Reduction on Urban Atmospheric Oxidizing Capacity During the COVID-19 Lockdown].

In recent years， regional compound air pollution events caused by fine particles （PM） and ozone （O） have occurred frequently in economically developed areas of China， in which atmospheric oxidizing capacity （AOC） has played an important role. In this study， the WRF-CMAQ model was used to study the impacts of anthropogenic emission reduction on AOC during the COVID-19 lockdown period. Three representative cities in eastern China （Shijiazhuang， Nanjing， and Guangzhou） were selected for an in-depth analysis to quantify the contribution of meteorology and emissions to the changes in AOC and oxidants and to discuss the impact of AOC changes on the formation of secondary pollutants.

[Elucidating the Impacts of Meteorology and Emission Changes on Concentrations of Major Air Pollutants in Major Cities in the Yangtze River Delta Region Using a Machine Learning De-weather Method].

This study applied a de-weather method based on a machine learning technique to quantify the contribution of meteorology and emission changes to air quality from 2015 to 2021 in four cities in the Yangtze River Delta Region. The results showed that the significant reductions in PM, NO, and SO emissions(57.2%-68.

Fate of Oxygenated Volatile Organic Compounds in the Yangtze River Delta Region: Source Contributions and Impacts on the Atmospheric Oxidation Capacity.

The Community Multiscale Air Quality model (CMAQv5.2) was implemented to investigate the sources and sinks of oxygenated volatile organic compounds (OVOCs) during a high O and high PM season in the Yangtze River Delta (YRD) region, based on constraints from observations. The model tends to overpredict non-oxygenated VOCs and underpredict OVOCs, which has been improved with adjusted emissions of all VOCs.

Modeling particulate nitrate in China: Current findings and future directions.

Particulate nitrate (pNO) is now becoming the principal component of PM during severe winter haze episodes in many cities of China. To gain a comprehensive understanding of the key factors controlling pNO formation and driving its trends, we reviewed the recent pNO modeling studies which mainly focused on the formation mechanism and recent trends of pNO as well as its responses to emission controls in China. The results indicate that although recent chemical transport models (CTMs) can reasonably capture the spatial-temporal variations of pNO, model-observation biases still exist due to large uncertainties in the parameterization of dinitrogen pentoxide (NO) uptake and ammonia (NH) emissions, insufficient heterogeneous reaction mechanism, and the predicted low sulfate concentrations in current CTMs.

Modeling secondary organic aerosol formation from volatile chemical products.

Volatile chemical products (VCPs) are commonly-used consumer and industrial items that are an important source of anthropogenic emissions. Organic compounds from VCPs evaporate on atmospherically relevant time scales and include many species that are secondary organic aerosol (SOA) precursors. However, the chemistry leading to SOA, particularly that of intermediate volatility organic compounds (IVOCs), has not been fully represented in regional-scale models such as the Community Multiscale Air Quality (CMAQ) model, which tend to underpredict SOA concentrations in urban areas.

PM and O relationships affected by the atmospheric oxidizing capacity in the Yangtze River Delta, China.

The atmospheric oxidizing capacity (AOC), reflecting the self-cleansing capacity of the atmosphere, plays an important role in the chemical evolution of secondary fine particulate matter (PM) and ozone (O). In this work, the AOC and its relationships with PM and O were investigated with a chemical transport model (CTM) in the Yangtze River Delta (YRD) region during the four seasons of 2017. The region-wide average AOC is ~4.

Diagnostic analysis of regional ozone pollution in Yangtze River Delta, China: A case study in summer 2020.

A regional ozone (O) pollution event occurred in the Yangtze River Delta region during August 17-23, 2020 (except on August 21). This study aims to understand the causes of O pollution during the event using an emission-based model (i.e.

Double high pollution events in the Yangtze River Delta from 2015 to 2019: Characteristics, trends, and meteorological situations.

We investigated the spatial distribution and trend of double high pollution (DHP), in which the daily average concentration of fine particulate matter (PM) was above 75 μg/m and the daily maximum 8-hour average ozone (MDA8 O) concentration was above 160 μg/m, in the Yangtze River Delta (YRD) region during 2015-2019, along with the meteorological and chemical characteristics during DHP and differences compared to high O pollution (HOP) and high PM pollution (HPP). In the YRD, Shanghai had the highest frequency of DHP at 7.6%, while Anhui had the least (2.

Effects of using different exposure data to estimate changes in premature mortality attributable to PM and O in China.

The assessment of premature mortality associated with the dramatic changes in fine particulate matter (PM) and ozone (O) has important scientific significance and provides valuable information for future emission control strategies. Exposure data are particularly vital but may cause great uncertainty in health burden assessments. This study, for the first time, used six methods to generate the concentration data of PM and O in China between 2014 and 2018, and then quantified the changes in premature mortality due to PM and O using the Environmental Benefits Mapping and Analysis Program-Community Edition (BenMAP-CE) model.

Criteria pollutant impacts of volatile chemical products informed by near-field modeling.

Consumer, industrial, and commercial product usage is a source of exposure to potentially hazardous chemicals. In addition, cleaning agents, personal care products, coatings, and other volatile chemical products (VCPs), evaporate and react in the atmosphere producing secondary pollutants. Here, we show high air emissions from VCP usage (≥ 14 kg person yr, at least 1.

Driving Forces of Changes in Air Quality during the COVID-19 Lockdown Period in the Yangtze River Delta Region, China.

During the COVID-19 lockdown period (from January 23 to February 29, 2020), ambient PM concentrations in the Yangtze River Delta (YRD) region were observed to be much lower, while the maximum daily 8 h average (MDA8) O concentrations became much higher compared to those before the lockdown (from January 1 to 22, 2020). Here, we show that emission reduction is the major driving force for the PM change, contributing to a PM decrease by 37% to 55% in the four YRD major cities (i.e.

Simulation of organic aerosol formation during the CalNex study: updated mobile emissions and secondary organic aerosol parameterization for intermediate-volatility organic compounds.

We describe simulations using an updated version of the Community Multiscale Air Quality model version 5.3 (CMAQ v5.3) to investigate the contribution of intermediate-volatility organic compounds (IVOCs) to secondary organic aerosol (SOA) formation in southern California during the CalNex study.

Drought Impacts on Secondary Organic Aerosol: A Case Study in the Southeast United States.

Secondary organic aerosol (SOA) is a significant component of fine particulate matter, and it has increased during past drought periods in the U.S. Here, we use the Community Multiscale Air Quality (CMAQ) model to characterize the complex effects of drought on SOA through a case study comparing a drought period (June 2011) and a wet period (June 2013) over the southeast U.

Atmospheric PAHs in North China: Spatial distribution and sources.

Polycyclic aromatic hydrocarbons (PAHs), formed through incomplete combustion process, have adverse health effects. To investigate spatial distribution and sources of PAHs in North China, PAHs with passive sampling in 90 gridded sites during June to September in 2011 were analyzed. The average concentration of the sum of fifteen PAHs in North China is 220±14ng/m(3), with the highest in Shanxi, followed by Shandong and Hebei, and then the Beijing-Tianjin area.