Evaluation of SO<SUB align=right>2 dry deposition over a cassava plantation in Rayong, Thailand

Abstract

SO2 emissions have become a significant problem in the East Asian region. Long term exposure to high SO2 concentration can affect human health and the environment. Approximately half of the SO2 is delivered to the earth by the dry deposition process; the other half is deposited by wet deposition. Thus, an assessment of SO2 dry deposition is necessary for understanding its qualitative and quantitative effects. In the research program described here, SO2 dry deposition was studied in terms of SO2 dry deposition flux and deposition velocity using the Bowen ratio technique. All necessary parameters were measured above a cassava plantation at a site in Rayong, Thailand during the period from June to September 2004. The Bowen ratio technique was most applicable during the 8:00 to 17:00 time period of each day. The results yield an average transfer coefficient of 10.6 cm/s, relevant to the height interval across which differences were measured. The average dry deposition flux was 0.17 mg/m²/hr and the average dry deposition velocity was 0.14 cm/s.