Chemical composition of ambient PM<sub>2. 5</sub> over China and relationship to precursor emissions during 2005–2012

Abstract

Abstract. In this work, we presented the characteristics of PM 2.5 chemical composition over China for the period of 2005-2012 by synthesis of in situ measurement data collected from literatures and satellite-based estimates using aerosol optical depth (AOD) data and the GEOS-Chem chemical transport model. We revealed the spatiotemporal variations in PM 2.5 composition during 2005-2012 and investigated the driving forces behind the variations by examining the changes in precursor emissions using a bottom-up emission inventory. Both in situ observations and satellitebased estimates identified that secondary inorganic aerosols (i.e., sulfate, nitrate, and ammonium; SNA) ranked as the highest fraction of dust-free PM 2.5 concentrations, followed by organic matter (OM) and black carbon (BC). For instance, satellite-based estimates found that SNA, OM, and BC contributed to 59, 33, and 8 %, respectively, of national population-weighted mean dust-free PM 2. In contrast, growth of energy consumption and lack of control measures for NO x resulted in a persistent increase in NO x emissions until the installation of denitrification devices on power plants late in 2011, which began to take effect in 2012. The results of this work indicate that the synchronized abatement of emissions for multipollutants is necessary for reducing ambient PM 2.5 concentrations over China.

Random forest models for PM2.5 speciation concentrations using MISR fractional AODs

“…However, information regarding the health effects of PM 2.5 components is limited, mainly hindered by the sparse or non-existent coverage of ground PM 2.5 speciation monitors. Meanwhile, the changes in PM 2.5 mass concentrations are driven by the variations of its chemical composition that are related directly to precursor emissions [7,8], thus, understanding the spatiotemporal changes of PM 2.5 speciation also helps designing more effective air pollution mitigation measures.…”

“…However, attempts to estimate highresolution PM 2.5 speciation concentrations have been few. Some works [7,12,13] used satellite-based total aerosol optical depth (AOD) and composition information from the CTMs to estimate PM 2.5 speciation concentrations. For example, global PM 2.5 chemical composition were inferred by combining AOD with conversion factors between AOD and PM 2.5 species provided by the GEOS-Chem model [12].…”

“…For example, global PM 2.5 chemical composition were inferred by combining AOD with conversion factors between AOD and PM 2.5 species provided by the GEOS-Chem model [12]. Such a method does not rely on ground observation data; however, without calibration against observation data, the estimated results had relatively low accuracy (e.g., r between 0.65 and 0.75 for different species in Geng et al [7]). Some studies [14,15] utilized ground observations, meteorological fields and land use variables to calibrate and downscale the CTM-simulated results and obtained high-resolution PM 2.5 speciation data.…”

SO2 Emission Estimates Using OMI SO2 Retrievals for 2005–2017

“…Bottom‐up anthropogenic SO 2 emission inventories from MACC/CityZEN (MACCity, http://ether.ipsl.jussieu.fr/eccad), Emissions Database for Global Atmospheric Research (EDGAR; http://edgar.jrc.ec.europa.eu/), the Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS, https://gains.iiasa.ac.at/gains/),REanalysis of the TROpospheric chemical composition over the past 40 years (RETRO, http://accent.aero.jussieu.fr/RETRO_metadata.php), and Hemispheric Transport of Air Pollution (HTAP, Janssens‐Maenhout et al, ) have tracked the magnitude and trend of global SO 2 emissions from human activities over the past decades. Bottom‐up inventories show a decrease of SO 2 due to emission regulation in the United States (de Gouw et al, ), China (Liu et al, ), and Europe (Crippa et al, ), which also contributes to the decline of sulfate and organic aerosol concentrations (Geng et al, ; Marais et al, ; Paulot et al, ). However, SO 2 emissions in India are still on the rise, and will likely continue to increase during the 2020–2050 period if emissions remain unregulated, driven by the growth of electricity demand and industrial production (Venkataraman et al, ).…”

“…over the past 40 years (RETRO, http://accent.aero.jussieu.fr/RETRO_metadata.php), and Hemispheric Transport of Air Pollution (HTAP, Janssens-Maenhout et al, 2015) have tracked the magnitude and trend of global SO 2 emissions from human activities over the past decades. Bottom-up inventories show a decrease of SO 2 due to emission regulation in the United States (de Gouw et al, 2014), China , and Europe (Crippa et al, 2016), which also contributes to the decline of sulfate and organic aerosol concentrations (Geng et al, 2017;Marais et al, 2017;Paulot et al, 2016). However, SO 2 emissions in India are still on the rise, and will likely continue to increase during the 2020-2050 period if emissions remain unregulated, driven by the growth of electricity demand and industrial production (Venkataraman et al, 2018).…”