Temporal Pattern of Ground Level Ozone in Different Land Habitats of Mie Prefecture, Japan
Mizanur Rahman, Yuichi Nagaya, Fukuji Yamada, Atsushi Hashimoto and Takaharu Kameoka, Mie University, Japan
Temporal pattern of ground level ozone has been analyzed statistically for five selected monitoring sites in five cities of Mie Prefecture of Japan for the period of 1991-2001. The monitoring sites represent different types of land uses namely coast-industrial, coastal, mountain, coast-commercial, and inland urban. Ozone level was found relatively high in the coastal-industrial city of Yokkaichi and low in the inland city of Matsusaka. Ozone exceedance events, over the threshold of 1-hr average of 60 ppb, were observed in all the monitoring stations. Median percentage increase in total hourly ozone exceedance events was highest of 9.81% for Yokkaichi (coastal-industrial city), and lowest of 4.88% for inland city of Matsusaka but for peak hours (12.00-18.00) observations, such exceedance increased to 23.68% and 12.96% respectively. The annual averages of both daily mean and daily 99-percentile level of ozone showed increasing trend and patterns of areas with high influence of background ozone. During the past decade, annual mean ozone level increased by highest of 27.62% in the inland site and lowest by 21% in the coastal city of Tsu contributed by the overall increase in background level ozone. Seasonal patterns showed spring maxima mainly associated with background conditions of all the sites with relatively higher level in the coast and lower level in the inland site. Diurnal patterns showed afternoon maxima (12.00-18.00 hrs) that indicates local photochemical conditions. Besides, there are slight variations (minima and maxima) in ozone level among the monitoring sites due to different land habitat types, meteorology (wind speed and directions), and anthropogenic sources. Increasing trend of the ozone level and frequent exceedance of the standard limit would pose adverse effect on both agriculture production and human health of the region unless a sustainable air pollution control program is undertaken.

Keywords: Temporal pattern, Ozone exceedance, Photochemical, Land habitats

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