1. Emission and dispersion of PAHs from heavy traffic road
N. Ozaki, K. Nitta, T. Sugihara,
T. Fukushima & T. Komatsu

2. Background (1)
Air pollution in urban area has been a special concern for many years.
Group of polycyclic aromatic hydrocarbons (PAHs) are becoming the major concern because of their higher emission and toxicity.
PAHs are generated mainly from combustion processes such as vehicle emmisions, industrial processes, heating processes, etc.

3. Background (2)
Many researchers have been investigating the behavior of PAHs.
Emission and dispersion from heavy traffic road is one of the important processes especially in atmospheric environment.

4. Objectives
The atmospheric concentration and deposition of particulate matter and PAHs were measured in the vicinity of a heavy traffic road.
The spacial and temporal variations in the atmospheric dispersion and ground surface loading due to the traffic sources were discussed.
The analysis of origin was conducted.

5. What’s PAHs? PAHs: Polycyclic aromatic hydrocarbons
Benzo(a)pyrene
Fluoranthene
Indeno(1,2,3-cd)pyrene
PAHs are generated mainly through incomplete combustion processes of petroleum.
Several of them has carcinogenicity.
Anthracene

6. Roadside sampling Station
In a suburban area
Traffic density: 20,000~30,000 vehicles d-1

8. Sampling schedule Sampling was conducted every 24 hours.
Sampling periods：2001/Nov./19~26 (Winter)
　　　　　　 /Aug./14~21 (Summer)
In the sampling terms, the climate was mild and moderate, and no major precipitation occurred during the sampling and precedent several days of sampling.

9. Sampling items Dry deposited particulate matter Particulate matters
　Fine Particulate matter (7~0.6μm)
　Coarse Particulate matter (over 7μm)
Dry deposited particulate matter
16 PAHs contents adsorbed on particulate matters
Air temperature, Precipitation, Wind velocity and direction, and Traffic density
なお、PAHsはすべて粒子付着態のみを対象としており、気相は対象としていない

10. 解析に際しての3つの特性量 粉塵濃度 PAHs濃度 PAHs含量 粉塵の、大気単位体積当たりの重量 (降下粉塵の場合はフラックス)

12. (Winter sampling, 1m from the roadside)

14. Road
Winter
Fine
Coarse
Deposited 1m
16m
LDV
HDV

15. Winter
Summer
Fine
Coarse
Deposited
LDV
HDV
LDV
Traffic
HDV

16. Patterns of PAHs contents (mg/gdw)
Winter
Summer

19. Source apportionment analysis
•CMB(Chemical Mass balance) method
•The less than four rings PAHs were excluded.

20. 冬 夏 Source apportionment (for PAHs) Traffic HDV LDV Weekday Holiday小径 大径 夏
Weekday
Holiday
Source apportionment
(for PAHs)
LDV
HDV
Traffic 降下

21. Winter
Summer
Fine
Source apportionment
(for PM)
Coarse
Dry deposited

22. Source apportionment for each PAH (fine PM)
(μg•g-1)
Workday
Holiday
(μg•g-1)
Observed value

23. Conclusions
The dispersion and deposition profile of PAHs were clarified from measurements and analysis of atmospheric concentration from a heavy traffic road.
The contribution of each source of particulate matter was quantified using the CMB receptor model.
Diesel and gasoline emissions were the main source of atmospheric particulate matter, and debris from tires was the main source of deposited particulate matter.

24. Future Perspectives
Secondary generation process should be considered for applying the CMB method.
Coagulation of particulate matters
Photolysis