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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Strong anthropogenic control of secondary organic aerosol formation from isoprene in Beijing
AU - Bryant, D.J.
AU - Dixon, W.J.
AU - Hopkins, J.R.
AU - Dunmore, R.E.
AU - Pereira, K.L.
AU - Shaw, M.
AU - Squires, F.A.
AU - Bannan, T.J.
AU - Mehra, A.
AU - Worrall, S.D.
AU - Bacak, A.
AU - Coe, H.
AU - Percival, C.J.
AU - Whalley, L.K.
AU - Heard, D.E.
AU - Slater, E.
AU - Ouyang, B.
AU - Cui, T.
AU - Surratt, J.D.
AU - Liu, D.
AU - Shi, Z.
AU - Harrison, R.
AU - Sun, Y.
AU - Xu, W.
AU - Lewis, A.C.
AU - Lee, J.D.
AU - Rickard, A.R.
AU - Hamilton, J.F.
PY - 2020/6/30
Y1 - 2020/6/30
N2 - Isoprene-derived secondary organic aerosol (iSOA) is a significant contributor to organic carbon (OC) in some forested regions, such as tropical rainforests and the Southeastern US. However, its contribution to organic aerosol in urban areas that have high levels of anthropogenic pollutants is poorly understood. In this study, we examined the formation of anthropogenically influenced iSOA during summer in Beijing, China. Local isoprene emissions and high levels of anthropogenic pollutants, in particular NOx and particulate SO2-4 , led to the formation of iSOA under both high- A nd low-NO oxidation conditions, with significant heterogeneous transformations of isoprene-derived oxidation products to particulate organosulfates (OSs) and nitrooxyorganosulfates (NOSs). Ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry was combined with a rapid automated data processing technique to quantify 31 proposed iSOA tracers in offline PM2.5 filter extracts. The co-elution of the inorganic ions in the extracts caused matrix effects that impacted two authentic standards differently. The average concentration of iSOA OSs and NOSs was 82.5 ngm-3, which was around 3 times higher than the observed concentrations of their oxygenated precursors (2-methyltetrols and 2-methylglyceric acid). OS formation was dependant on both photochemistry and the sulfate available for reactive uptake, as shown by a strong correlation with the product of ozone (O3) and particulate sulfate (SO2-4). A greater proportion of high-NO OS products were observed in Beijing compared with previous studies in less polluted environments. The iSOA-derived OSs and NOSs represented 0.62% of the oxidized organic aerosol measured by aerosol mass spectrometry on average, but this increased to ∼ 3% on certain days. These results indicate for the first time that iSOA formation in urban Beijing is strongly controlled by anthropogenic emissions and results in extensive conversion to OS products from heterogenous reactions.
AB - Isoprene-derived secondary organic aerosol (iSOA) is a significant contributor to organic carbon (OC) in some forested regions, such as tropical rainforests and the Southeastern US. However, its contribution to organic aerosol in urban areas that have high levels of anthropogenic pollutants is poorly understood. In this study, we examined the formation of anthropogenically influenced iSOA during summer in Beijing, China. Local isoprene emissions and high levels of anthropogenic pollutants, in particular NOx and particulate SO2-4 , led to the formation of iSOA under both high- A nd low-NO oxidation conditions, with significant heterogeneous transformations of isoprene-derived oxidation products to particulate organosulfates (OSs) and nitrooxyorganosulfates (NOSs). Ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry was combined with a rapid automated data processing technique to quantify 31 proposed iSOA tracers in offline PM2.5 filter extracts. The co-elution of the inorganic ions in the extracts caused matrix effects that impacted two authentic standards differently. The average concentration of iSOA OSs and NOSs was 82.5 ngm-3, which was around 3 times higher than the observed concentrations of their oxygenated precursors (2-methyltetrols and 2-methylglyceric acid). OS formation was dependant on both photochemistry and the sulfate available for reactive uptake, as shown by a strong correlation with the product of ozone (O3) and particulate sulfate (SO2-4). A greater proportion of high-NO OS products were observed in Beijing compared with previous studies in less polluted environments. The iSOA-derived OSs and NOSs represented 0.62% of the oxidized organic aerosol measured by aerosol mass spectrometry on average, but this increased to ∼ 3% on certain days. These results indicate for the first time that iSOA formation in urban Beijing is strongly controlled by anthropogenic emissions and results in extensive conversion to OS products from heterogenous reactions.
KW - aerosol
KW - concentration (composition)
KW - ion
KW - isoprene
KW - ozone
KW - photochemistry
KW - Beijing [China]
KW - China
U2 - 10.5194/acp-20-7531-2020
DO - 10.5194/acp-20-7531-2020
M3 - Journal article
VL - 20
SP - 7531
EP - 7552
JO - Atmospheric Chemistry and Physics
JF - Atmospheric Chemistry and Physics
SN - 1680-7316
IS - 12
ER -