Sensitivity Analyses for the Atmospheric Dry Deposition of Total PCDD/Fs-TEQ for Handan and Kaifeng Cities, China

Rong Zhao,Ya-Fen Wang,Weiwei Wang,Kangping Cui,Lin-Chi Wang

doi:10.4209/aaqr.2018.03.0109

Abstract

During the period 2016–2017, the atmospheric wet, dry, and total deposition fluxes and scavenging ratios of the total PCDD/Fs-WHO2005-TEQ in Handan and Kaifeng were investigated. In addition, a sensitivity analysis for the dry deposition fluxes of the total PCDD/Fs-WHO2005-TEQ was conducted. The annual wet deposition fluxes of total PCDD/Fs-WHO2005-TEQ in Handan ranged between 51.1 and 83.5 and averaged 72.3 pg WHO2005-TEQ m–2 year–1, which was approximately 1.04 times of magnitude higher than that in Kaifeng (69.3 pg WHO2005-TEQ m–2 year–1). From 2016–2017, the contribution fraction of dry deposition to the total PCDD/Fs-WHO2005-TEQ deposition flux ranged between 60.8% and 100% and averaged 80.4%. Dry deposition fluxes were more dominant than wet deposition fluxes. In terms of the seasonal variations in total PCDD/Fs-WHO2005-TEQ dry deposition fluxes (the mean values for 2016 and 2017) in Handan, those in spring, summer, fall, and winter were 1084, 563, 964, and 1325 pg WHO2005-TEQ m–2 month–1, respectively, while in Kaifeng, they were 963, 428, 715, and 1016 pg WHO2005-TEQ m–2 month–1, respectively. The total PCDD/Fs-WHO2005-TEQ deposition fluxes in winter was approximately 2.0 times of magnitude higher than that in summer. The sensitivity analysis of total PCDD/FsWHO2005-TEQ dry deposition fluxes in Handan and Kaifeng showed that the PM10 concentration was the most positively correlated sensitive factor. When ΔP/P was changed from 0% to +50%, ΔS/S responded from 0% to +46.1% and +46.3%, respectively. The second positively correlated sensitive factor was the PM2.5 concentration, where when ΔP/P was changed from 0% to +50%, ΔS/S responded from 0% to +47.8% and +40.8%, respectively. For PCDD/Fs mass concentration, when ΔP/P was changed from 0% to +50%, ΔS/S responded from 0% to +32.2% and +28.1%, respectively. This was followed by the atmospheric temperature, and its effect was negatively correlated. When ΔP/P was changed from –50% to +50%, ΔS/S responded from +46.4% to –26.9% and +57.0% to –30.5%, respectively. The results of this study provide useful information that can be used to achieve more insights into both atmospheric deposition of total PCDD/Fs-WHO2005-TEQ and the sensitive factors for dry deposition fluxes.

Highlights

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are persistent organic pollutants (POPs) because they are toxic, persistent, and bio-accumulative (MichelettiZhao et al, Aerosol and Air Quality Research, 18: 1255–1269, 2018Chen et al, 2010)
The results of this study provide useful information that can be used to achieve more insights into both atmospheric deposition of total PCDD/Fs-WHO2005-TEQ and the sensitive factors for dry deposition fluxes
Fd,T: the total PCDD/F deposition flux contributed by adding both gas- and particle-phase deposition fluxes, where Fd,g: the PCDD/F deposition flux contributed by the gas phase; Fd,p: the PCDD/F deposition flux contributed by the particle phase; CT: the measured concentration of total PCDD/Fs in the ambient air; Vd.T: the dry deposition velocity of total PCDD/Fs; Cg: the calculated concentration of PCDD/Fs in the gas phase; Vd,g: the dry deposition velocity of gas-phase PCDD/Fs; Cp: the calculated concentration of PCDD/Fs in the particle phase; Vd,p: the dry deposition velocity of particle-phase PCDD/Fs

Summary

Introduction

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are persistent organic pollutants (POPs) because they are toxic, persistent, and bio-accumulative (MichelettiZhao et al, Aerosol and Air Quality Research, 18: 1255–1269, 2018Chen et al, 2010). Removal of PCDD/Fs from the atmosphere occurs via both dry and wet deposition (Giorgi, 1988; Chi et al, 2009; Wu et al, 2009; Huang et al, 2011; Mi et al, 2012) Since they were first found in the fly ash of municipal solid waste incinerators (MSWIs), researchers have paid more attention to various emissions sources (Wang et al, 2003; Wang et al, 2010; Chi et al, 2015; Cheruiyot et al, 2015, 2016; Wei et al, 2016; Li et al, 2017)

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