PM
2:5
source attribution for Seoul in May from 2009 to 2013 using
GEOS-Chem and its adjoint model
*
Hyung-Min Lee
a, *
, Rokjin J. Park
b
, Daven K. Henze
c
, Seungun Lee
b
, Changsub Shim
d
,
Hye-Jung Shin
e
, Kwang-Joo Moon
e
, Jung-Hun Woo
f
a
Department of Civil, Environmental, and Architectural Engineering, University of Colorado, Boulder, CO, USA
b
School of Earth and Environmental Sciences, Seoul National University, Seoul, Republic of Korea
c
Department of Mechanical Engineering, University of Colorado, Boulder, CO, USA
d
Korea Environment Institute, 370 Sicheong-daro, Sejong, Republic of Korea
e
National Institute of Environmental Research, Incheon, Republic of Korea
f
Department of New Technology and Fusion, Konkuk University, Seoul, Republic of Korea
article info
Article history:
Received 16 July 2016
Received in revised form
23 November 2016
Accepted 30 November 2016
Available online 5 December 2016
Keywords:
PM2.5
Seoul metropolitan area
Adjoint modeling
Source attribution
Sensitivity analysis
Atmospheric chemical transport model
abstract
Enforcement of an air quality standard for PM
2:5
in the Seoul metropolitan area (SMA) was enacted in
2015. From May to June of 2016, an international airborne and surface measurement campaign took place
to investigate air pollution mechanisms in the SMA. The total and speciated PM
2:5
concentrations since
2008 have been measured at an intensive monitoring site for the SMA operated by the National Institute
of Environmental Research (NIER). To gain insight on the trends and sources of PM
2:5
in the SMA in May,
we analyze PM
2:5
concentrations from 2009 to 2013 using the measurements and simulations from a 3-
dimensional global chemical transport model, GEOS-Chem and its adjoint. The model is updated here
with the latest regional emission inventory and diurnally varying NH
3
emissions. Monthly average PM
2:5
concentration measured by b-ray attenuation ranges from 28 (2010) to 45 (2013) mg/m
3
, decreased from
2009 to 2010, and then continuously increased until 2013. The model shows good agreement with the
measurements for the daily average PM
2:5
concentrations (R 0.5), and reproduces 10 out of 17
measured episodes exceeding the daily air quality standard (50 mg/m
3
). Using the GEOS-Chem adjoint
model, we find that anthropogenic emissions from the Shandong region have the largest modeled in-
fluence on PM
2:5
in Seoul in May. Average contributions to the high PM
2:5
episodes simulated by the
model are 39% from the Shandong region, 16% from the Shanghai region,14% from the Beijing region, and
15% from South Korea. Anthropogenic SO
2
emissions from South Korea are negligible with 90% of the
total contribution originating from China. Findings from this study may guide interpretation of obser-
vations obtained in the KORUS-AQ measurement campaign.
© 2016 Elsevier Ltd. All rights reserved.
1. Introduction
Particulate matter with aerodynamic diameter less than 2.5 mm
(PM
2:5
) is known to have detrimental impacts on human health,
causing increased respiratory disease and stroke related mortalities
(e.g., Burnett et al., 2000; Franklin et al., 2006; Bell et al., 2007). The
Seoul metropolitan area (Seoul, Incheon, and Geonggi) is one of the
most densely populated mega-cities worldwide, having more than
23 million residents (49% of national population) in about
12,000 km
2
(12% of the Korean peninsula) (KOSIS, 2010). Air quality
standards for PM
2:5
, however, have recently been implemented in
Seoul since 2015. The Korean Ministry of Environment devised a
Special Act legislation for improving air quality in the Seoul
metropolitan area in 2003 (enacted in 2005). The first Seoul
Metropolitan Air Quality Improvement Plan (2005e2014) aimed at
reducing PM
10
and NO
2
concentrations. In the second master plan,
formulated for 2015e2024, PM
2:5
and O
3
were added to the regu-
lations. This plan includes PM
2:5
standards of 50 mg/m
3
for 24 h, and
25 mg/m
3
for a year. The goal of the second master plan is reducing
annual PM
2:5
from 27 mg/m
3
in 2010 to 20 mg/m
3
in the Seoul
metropolitan area by 2024 (ME, 2013).
In order to help monitor and enforce these air quality
*
This paper has been recommended for acceptance by Dr. Hageman Kimberly Jill.
* Corresponding author.
E-mail address: hyungmin.lee@colorado.edu (H.-M. Lee).
Contents lists available at ScienceDirect
Environmental Pollution
journal homepage: www.elsevier.com/locate/envpol
http://dx.doi.org/10.1016/j.envpol.2016.11.088
0269-7491/© 2016 Elsevier Ltd. All rights reserved.
Environmental Pollution 221 (2017) 377e384