Ozone Concentrations in Rural Regions of the Yangtze Delta in China |
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Authors: | Wang Huixiang Zhou Lijun Tang Xiaoyan |
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Institution: | (1) College of Environmental Sciences, Peking University, Beijing, 100871, China |
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Abstract: | Elevated concentrations of ozone have been observed at six non-urban, surface monitoring sites in the Yangtze Delta of China
during a 16-month field experiment carried out in 1999 and 2000 as part of the joint Chinese-American China-MAP Project (the
Yangtze Delta of china as an Evolving Metro-Agro-Plex). The average daytime (0900–1600 h) ozone levels for the monitoring
period at sites ranged from 35 to 47 ppbv (parts per billion by volume) and the mean ozone levels from 26 to 35 ppbv. Observed
data show seasonal variation obviously, with highest mixing ratios of ozone in May. Average daytime ozone levels in May at
sites were between 60 and 79 ppbv. High ozone concentrations were most prevalent during the late spring. Frequency counts
of hourly mean ozone concentration over 60 ppbv and 40 ppbv appeared peak values of 22–39% and 42–74% in May at sites. Even
higher daytime ozone levels were observed during two regional episodes, in which average daytime (0900–1600 h) ozone concentrations
during 10 May and 23 May 2000 were 68 to 81 ppbv, during Oct. 18 and Oct. 28, 1999 were 59 to 67 ppbv at sites.
Peak value of ozone mixing ratio appearing in late spring, instead of in summer, was attributed to summer monsoon. Backward
trajectories showed that ozone episodes associated with meteorological conditions. Also many high ozone levels associated
with high CO levels and high CO to NO
x
ratios, which suggests a contribution from sources of emission involving incomplete combustion. |
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Keywords: | Surface ozone Observation Yangtze Delta of China China-MAP Project |
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