Pioneering observation of atmospheric volatile organic compounds in Hangzhou in eastern China and implications for upcoming 2022 Asian Games

Understanding the emission sources of volatile organic compounds(VOCs)is critical for air pollution mitigation.Continuous measurements of atmospheric VOCs were conducted from January to February in Hangzhou in 2021.The average measured concentration of total VOCs(TVOCs)was 38.2±20.9 ppb,>42% lower than that reported by previous studies at the urban center in Hangzhou.The VOC concentrations and proportions were similar between weekdays and weekends.During the long holidays of the Spring Festival in China,the concentrations of TVOCs were∼50% lower than those during the regular days,but their profiles showed no significant difference(p>0.05).Further,we deduced that aromatics and alkenes were the most crucial chemicals promoting the formation of O3 and secondary organic aerosol(SOA)in Hangzhou.According to interspecies correlations,combustion processes and solvent use were inferred as major VOC emission sources.This study provides implications for air quality improvements before and during the upcoming Asian Games that will be hosted in Hangzhou in 2022.

Global methyl halide emissions from biomass burning during 2003-2021

Methyl halides(CH3Cl,CH3Br,and CH3I)are ozone-depleting substances.Biomass burning(BB)is an important source of methyl halides.The temporal variations and global spatial distribution of BB methyl halide emissions are unclear.Thus,global methyl halide emissions from BB during 2003e2021 were estimated based on satellite data.A significant decreasing trend(p<0.01)in global methyl halide emissions from BB was found between 2003 and 2021,with CH3Cl emissions decreasing from 302 to 220 Gg yr^(-1),CH3Br emissions decreasing from 16.5 to 11.7 Gg yr^(-1),and CH3I emissions decreasing from 8.9 to 6.1 Gg yr^(-1).From a latitudinal perspective,the northern high-latitude region(60e90N)was the only latitude zone with significant increases in BB methyl halide emissions(p<0.01).Based on an analysis of the drivers of BB methyl halide emissions,emissions from cropland,grassland,and shrubland fires were more correlated with the burned area,while BB emissions from forest fires were more correlated with the emissions per unit burned area.The non-BB emissions of CH3Cl increased from 4749 Gg yr^(-1)in 2003 to 4882 Gg yr^(-1)in 2020,while those of CH3Br decreased from 136 Gg yr^(-1)in 2003 to 118 Gg yr^(-1)in 2020(global total CH3I emissions are not available).The finding indicates that global CH3Cl and CH3Br emissions from sources besides BB increased and decreased during 2003e2020.Based on our findings,not only searching for unknown sources is important,but also re-evaluating known sources is necessary for addressing methyl halide emissions.