Studies on the dry deposition estimation and concentration monitoring in the Acid Deposition Monitoring Network in East Asia (EANET) countries

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3 Studies on the dry deposition estimation and concentration monitoring in the Acid Deposition Monitoring Network in East Asia () countries Tomomi Endo This study aimed to understand the dry deposition amount accurately in the Acid Deposition Monitoring Network in East Asia () region. Dry deposition amounts of gaseous and particulate matter in ambient air are generally estimated as the product of an atmospheric concentration and a deposition velocity (V d ). It is important to estimate the dry deposition amount in order to quantify the accurate amount of atmospheric deposition which consists of wet and dry depositions in region. At first, for the preliminary estimation, the annual dry deposition of SO 2 and no sea salt particulate sulfate (nss-pso 4 ) were estimated at 19 points of monitoring sites. The estimated dry deposition was same level or higher than wet deposition at these sites, thus it suggested the importance of estimating dry deposition amounts. Secondly, the regional characteristics of the estimated amounts of dry deposition and total atmospheric deposition at 1 sites in Japan were discussed. The components examined were sulfur compounds and nitrogen compounds (HNO 3, NH 3, pno 3, and pnh + 4 ). V d was evaluated from the modified resistance model for forest and grass surfaces. Atmospheric deposition amounts in Japan were larger than those in foreign monitoring networks because of high wet deposition, which implied that the increasing emissions of air pollutants in East Asia caused high atmospheric depositions. Finally, the field comparison test between passive method and automatic monitor was conducted in Japan and Thailand in order to confirm the accuracy of atmospheric concentration monitoring. As a result, the concentrations of O 3 and NO 2 by passive method were good agreement with those by the automatic monitor, thus it indicated that these concentrations by passive method could be usable to estimate dry deposition amount. Keywords: Dry deposition, deposition velocity, sulfur, nitrogen, Passive method, East Asia SO 2

4 O 3 m s 1 nss-pso 4 2 Dry deposition (nss-pso42-) 4 ) Wet deposition (nss-so42-) 4 ) Dry deposition (SO2) 2) ) 9 3) SO 2 2 pso 4 HNO 3 pno 3 NH 3 + pnh 4 Tappi Sadoseki Oki Banryu Yusuhara Hedo EMEP CASTNET (a) 4 3 SO 2 nss-pso 4 2- ss-pso , 4,5) (b) HNO 3 NH 3 pno 3 - pnh O 3 NO 2 2 Bangkok NO 2, 2 1 (a), b 5, O 3 NO 2

5 1 CASTNET EMEP Network Number of sites or grids Observation period Japan network CASTNET a, * b, ** EMEP 1sites 78sites 2447grids (.5º.5ºeach) April 23 March 28 January 23 December 27 January 23 December 27 Type of deposition Dry Wet Total Dry Wet Total Dry Wet Total Sulfur (kgs ha 1 ) Nitrogen (kgn ha 1 ) Average Median Max Min Average Median Max Min a: The CASTNET data is available online ( b: The EMEP data is available online ( *: The dry deposition amount of NH 3 was excluded from the total deposition amount of nitrogen compounds in CASTNET. **: The total deposition amount in EMEP has been estimated in 27 EMEP countries. 1) Kominami T., Matsuda K., Ohizumi T. and Hara H. : Journal of Japan Society for Atmospheric Environment 4(3), 14 (25). [In Japanese with an English abstract] 2) Endo T., Yagoh H., Sato K., Matsuda K., Hayashi K., Noguchi I., Sawada K. : Atmospheric Environment 45, 1259 (211). 3) Matsuda K. : Journal of Japan Society for Atmospheric Environment 43(6), 332 (28). [In Japanese with an English abstract] 4) Ogawa & Co., USA, Inc. : Protocol for ozone measure ment using the ozone passive sampler badge (21). ww.ogawausa.com/index.html. 5) Ogawa & Co., USA, Inc. : NO, NO 2, NOx and SO 2 sampli ng protocol using the Ogawa sampler. Version tp:// 6. (26). ht