Photochemical Ozone Pollution in Southern and Eastern PRC

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Photochemical Ozone Pollution in Southern and
Eastern PRC

• T. Wang, Joey Kwok, Steven Poon, A. J. Ding, C.
  H. Chueng, Tracia Wong, and Y. S. Li
• The Hong Kong Polytechnic University

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• Introduction
• Major air-pollution problems in China
• - North high PM (dust storm) and SO2
• - South acid rain
• - Emerging vehicle pollution in cities
• photochemical pollution much less understood

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• Background
• VOC NOx sunlight -gt O3
• NOx (NO NO2) is produced primarily in
  high-temperature combustion, e.g., power plant
  and vehicle exhaust.
• VOC is released from vehicle exhaust, fuel
  evaporation, industrial processes, and naturally
  from and trees.
• O3 episodes often occur in calm weather with
  high solar radiation and warm temperature

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• Unique Features of Ozone Pollution
• Several hours to form - peak in downwind
  areas
• Long life time - long-range transport
• Nonlinear chemistry

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Map showing the locations of study areas
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Daily 1-h max O3 con. 1999-2000 at Linan
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O3 vs. CO (1300-1700) at Linan
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Scatter Plots of CO vs. NOy and SO2 vs. NOy
at Linan
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Correlation of CO and CH4, CH3Cl, and C2Cl4
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Map of the PRD and Hong Kong
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Time series plots for O3, CO, SO2 and NOy at Tai
O from October-November 2002
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Time series plots for ethane, ethyne, CHCl3,
C2Cl4, and isoprene at Tai O from
October-November 2002
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Multi-day Pollution Episode at Rural Tai O
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Regional pattern of ozone pollution on Sept 15,
2001(Unit ppbv, HKAQO122)
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Back trajectories for Sept 15 and 16
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• Future research needed to support control policy
• - regional network on ozone and its precursors
  (adding non-urban sites)
• - extent of transboundary transport
• - NOx vs.VOC control
• - emission inventories
• - linkage O3, PM, and acid rain