Aerial measurement of air pollutants and aerosols during 20–22 March 2001 over the East China Sea

Abstract

[1] Aerial measurement of atmospheric pollutants was carried out over the East China Sea on 20, 21, and 22 March 2001. High concentrations of not only gaseous species (maximum concentrations of SO 2 > 10 ppb and O 3 > 100 ppb in the marine boundary layer) but also particulate matter (PM) (average concentration of PM 2.5 $ 30 mg m À3 and PM 10 $ 1000 mg m À3 in the marine boundary layer) were observed on 21March. Such high concentrations were observed only at low altitude. A cold front passing over the Korean Peninsula and extension of a high-pressure system from central China to the East China Sea were responsible for the transport of pollutants. High concentrations of pollutants were confined to lower altitude by the high-pressure system. This result is in marked contrast to our previous observation: A highly polluted air mass was transported from central China when a low-pressure system originating near Taiwan moved northeast to Japan along the south coast of the main islands. Anthropogenic sulfate aerosols were transported ahead of Kosa particles (fine yellow sand dust particles). A humid air mass containing a high concentration of sulfate (>20 mg m ) was followed by a dry air mass containing a high concentration of calcium (>1000 mg m À3). Interactions between aerosol components and anthropogenic gaseous species gave insight into the formation process of aerosols over the East China Sea. Nitrate showed a good correlation with calcium except in the highly polluted air mass, indicating that gaseous nitric acid was adsorbed on the surface of coarse particles. No correlation between nitrate and ammonium supported this contention. In contrast, sulfate showed an excellent linear correlation with ammonium, indicating quick neutralization of sulfuric acid by ammonia in the polluted air mass. Exceptions were observed when the calcium concentration was >4 mg m À3 , suggesting that SO 2 gas was adsorbed on the surface of yellow sand dust particles and that oxidation took place on the surface.

Aerial Observation of Aerosols Transported from East Asia — Chemical Composition of Aerosols and Layered Structure of an Air Mass over the East China Sea

“…Both the global and regional aspects of the long-range transport of pollutants are very important, and several cooperative international experiments have thus been conducted in the western Pacific region (Huebert et al, 2003;Parrish et al, 2004;Nakajima et al, 2007). The current authors have also reported the results of aerial observations of atmospheric pollutants in a source region in China (Hatakeyama et al, 2005;Wang et al, 2006;Wang et al, 2007;Wang et al, 2008), and a receptor region (Hatakeyama et al, 1995a, b;Hatakeyama et al, 1997;Hatakeyama et al, 2004). Transformation of pollutants during their long-range transport is an important problem from the perspective of regional air quality and acid rain.…”

“…NaCl + HNO 3  NaNO 3 + HCl 2NaCl + H 2 SO 4  Na 2 SO 4 + 2HCl Nitric acid is usually well neutralized with calcium compounds within the air mass transported long range over the East China Sea (Hatakeyama, 2004). Therefore, the contribution of sulfuric acid, which is formed by the oxidation of SO 2 during the transport, should become larger.…”

Morphological and chemical modification of mineral dust: Observational insight into the heterogeneous uptake of acidic gases

“…[4] The sporadic Asian dust events might not be the only occasions when the dust modification can be studied, because dust-laden air is often dry and separated from polluted air as it sweeps across the region [Zhang et al, 2005;Hatakeyama et al, 2004;Bates et al, 2004;MaxwellMeier et al, 2004]. Laboratory studies suggest increased uptake coefficients of HNO 3 , NO 2 , and SO 2 gases on mineral dust under higher relative humidity (which determines the amount of water associated with the particles) [Dlugi et al, 1981;Goodman et al, 2000;Hanisch and Crowley, 2001;Underwood et al, 2001;Usher et al, 2002].…”

Episodic Particulate Sulfate and Sulfur Dioxide on the Southwestern Japan Coast in March and April 2010

“…Since we did not measure chemical compositions of aerosol particles, it is uncertain how much sea salt contributed to the sulfate concentration. According to the previous studies, sea-salt related sulfate in particulate matters usually occupied only a small fraction in total sulfate in this area when the air parcels were from the Asian continent (Hatakeyama et al, 2004;Koike et al, 2003).…”

“…Sahu et al, 2009;Hatakeyama et al, 2004;Koike et al, 2003) and model simulations (e.g. Heald et al, 2006;Takemura et al, 2003;Uno et al, 2003).…”