Estimation of the direct and indirect impacts of fireworks on the physicochemical characteristics of atmospheric PM10 and PM2.5

摘要

To quantify the total, direct and indirect impacts of fireworksindividually, size-resolved PM samples were collected before, during andafter a Chinese folk festival (Chinese New Year) in a megacity inChina. Through chemical analysis and morphological characterisation, astrong influence of fireworks on the physicochemical characteristics ofPM and PM was observed. The concentrations of many speciesexhibited an increasing trend during the heavy-firework period, especiallyfor K, Mg and Cr; the results of the non-sea-salt ionsdemonstrated an anthropogenic influence on K and Mg. Then,source apportionment was conducted by receptor models and peak analysis (PA). Thetotal influence of the fireworks was quantified by positive matrix factorisation (PMF), showing that thefireworks contributed higher fractions (23.40% for PM and29.66% for PM) during the heavy-firework period than during thelight-firework period (4.28% for PM and 7.18% for PM).The profiles of the total fireworks obtained by two independent methods (PMFand peak analysis) were consistent, with higher abundances of K, Al,Si, Ca and organic carbon (OC). Finally, the individual contributions of the direct andindirect impacts of fireworks were quantified by chemical mass balance (CMB). The percentagecontributions of resuspended dust, biomass combustion and direct fireworkswere 36.8 ± 8.37%, 14.1 ± 2.82% and 44.4 ± 8.26%,respectively, for PM and 34.9 ± 4.19%, 16.6 ± 3.05%and 52.5 ± 9.69%, respectively, for PM, in terms of thetotal fireworks. The quantification of the total, direct and indirectimpacts of fireworks in the ambient PM gives a original contribution for understanding the physicochemical characteristics and mechanisms of suchhigh-intensity anthropogenic activities.