Title: Effect of heterogeneous aqueous reactions on the secondary formation of inorganic aerosols during haze events

Abstract

In this study, the effect of heterogeneous aqueous reactions on the secondary formation of inorganic aerosols during haze events was investigated by analysis of comprehensive measurements of aerosol composition and concentrations [e.g., particular matters (PM_2.5), nitrate (NO₃), sulfate (SO₄), ammonium (NH₄)], gas-phase precursors [e.g., nitrogen oxides (NOx), sulfur dioxide (SO₂), and ozone (O₃)], and relevant meteorological parameters [e.g., visibility and relative humidity (RH)]. The measurements were conducted in Beijing, China from Sep. 07, 2012 to Jan. 16, 2013. The results show that the conversion ratios of N from NOx to nitrate (N_ratio) and S from SO₂ to sulfate (S_ratio) both significantly increased in haze events, suggesting enhanced conversions from NOx and SO₂ to their corresponding particle phases in the late haze period. Further analysis shows that N_ratio and S_ratio increased with increasing RH, with N_ratio and S_ratio being only 0.04 and 0.03, respectively, when RH < 40%, and increasing up to 0.16 and 0.12 when RH reached 60–80%, respectively. The enhanced conversion ratios of N and S in the late haze period is likely due to heterogeneous aqueous reactions, because solar radiation and thus the photochemical capacity are reduced by the increases in aerosols and RH. This point was furthermore » affirmed by the relationships of N_ratio and S_ratio to O₃: the conversion ratios increase with decreasing O₃ concentration when O₃ concentration is lower than <15 ppb but increased with increasing O₃ when O₃ concentration is higher than 15 ppb. The results suggest that heterogeneous aqueous reactions likely changed aerosols and their precursors during the haze events: in the beginning of haze events, the precursor gases accumulated quickly due to high emission and low reaction rate; the occurrence of heterogeneous aqueous reactions in the late haze period, together with the accumulated high concentrations of precursor gases such as SO₂ and NOx, accelerated the formation of secondary inorganic aerosols, and led to rapid increase of the PM_2.5 concentration.« less

Authors:

Quan, Jiannong ^[1]; Liu, Yangang ^[2]; Liu, Quan ^[1]; Li, Xia ^[3]; Gao, Yang ^[3]; Jia, Xingcan ^[3]; Sheng, Jiujiang ^[1]

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+ Show Author Affiliations

1. Beijing Key Lab. of Cloud, Beijing (China); Institute of Urban Meteorology, Beijing (China)
2. Brookhaven National Lab. (BNL), Upton, NY (United States)
3. Beijing Key Lab. of Cloud, Beijing (China)

Publication Date:

Wed Sep 30 00:00:00 EDT 2015

Research Org.:

Brookhaven National Laboratory (BNL), Upton, NY (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1228838

Alternate Identifier(s):

OSTI ID: 1250933

Report Number(s):

BNL-108476-2015-JA
Journal ID: ISSN 1352-2310; R&D Project: 2015-BNL-EE631EECA-Budg; KP1703020

Grant/Contract Number:  

SC00112704

Resource Type:

Accepted Manuscript

Journal Name:

Atmospheric Environment (1994)

Additional Journal Information:

Journal Name: Atmospheric Environment (1994); Journal Volume: 122; Journal Issue: C; Journal ID: ISSN 1352-2310

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; Beijing hazes; heterogeneous aqueous reactions; inorganic aerosol; particles size