Rapid industrial development have turned China into the engine of the economic growth in the
world. Accompanied with the increasing manufacturing production, substantial amount of SO
2,
NO
x, particulate matter and VOC are emitted into the atmosphere and causes the air pollution
issue in this country. Facing this top environmental concern, it is important for the policy makers
to know about: 1) where are the ambient pollutants coming from? 2) to what degree do the
ambient pollutants influence human’s health? 3) what are the reaction mechanisms behind the
pollutants in the atmosphere. Answering these three questions can help to further improve the
emission control policy for related regions.
3D Air quality model together with its source apportionment module is a promising tool to solve
the first question. I used the Integrated Source Apportionment Technique (ISAM) hosted in
Community Multiscale Air Quality Model (CMAQ), Particulate Source Apportionment
Technique (PSAT) and Ozone Source Apportionment Technique (OSAT) hosted in
Comprehensive Air Quality Model with extensions (CAMx) to study the source apportionment
of sulfate/nitrate in the rainwater, particulate sulfate/nitrate in the air and ambient NO
x,
respectively. The target place I studied was the Pearl River Delta (PRD) region. Results show
that no matter in the rainwater or in the air, the sulfate and nitrate were mainly contributed by the
long-rang transport, which means that substantial amount of these two pollutant species were
generated locally. It is totally different for the ambient NO
x, which was mainly contributed by
the local vehicle emission, especially by the heavy duty diesel vehicle (HDDV). Hence, besides
controlling the emission locally, it is also of great significance to enhance the cross-boundary
cooperation to improve the air quality together.
For the second question, I studied the mortality caused by both short-term and long-term
exposure to the ambient pollutants in the PRD region. I first studied the mortality and economic
loss caused by the short-term exposure to SO
2, NO
2, O
3 and PM
10 in PRD region by using the
CMAQ model. Results show that the estimated total mortality caused by NO
2, PM
10 and O
3
ranged from 13,000 to 22,800 in this region. The total economic cost ranged from 14,000 to
25,000 million USD, which was equivalent to 1.4% to 2.3% of the local GDP. I then estimated
the mortality (2004-2013) caused by the long-term exposure to the PM
2.5 by using the satellite
retrieved surface PM
2.5 data. The mortality reached the highest in 2012 with a value of 45,000 in
this region. These results show the public that the ambient pollutants indeed can cause large
adverse health effect to the residents. It is an urgent task for the local government to control the
emission and improve the air quality condition for the local residents in this region.
Comprehensive reactions take place in the atmosphere at every moment. Up to now, many
reaction mechanisms still remain unclear and because of this, the air quality model cannot
simulate some trace gas correctly (e.g. HONO, VOC and HO
x). This further influence the O
3
simulation accuracy by the 3D air quality model. I used a 0-D box model to study the HO
x
budget, HONO and O
3 production rate at an urban site in Wuhan City. Results implicate that the
unknown HONO contributed around 36%, 26%, 27 and 31% of the OH, HO
2, RO
2 and O
3
production at this site. Hence, without understanding the HONO chemistry in the atmosphere, it
is difficult to get a good O
3 simulation in the 3D air quality model. Then I collected the HONO
observation data around the world and combined the 3D CTM to study the daytime unknown
HONO source. I found that the R
2 between unknown HONO source and wet aerosol surface area
reached 0.89, which implicates that the unknown HONO might possibly come from the NO
2
heterogeneous reaction on the aerosol surface. The NO
2 uptake coefficient has been calculated
and implemented into CMAQ to study the HONO impact on the O
3 concentration over the China.
Post a Comment