Black acidic rime ice in the remote island of Yakushima, a world natural heritage area

In order to clarify the long-range transport of atmospheric pollutants in t he East Asian regions, we have studied the components in rime ice on Yakush ima Island, located in southwestern Japan near the China continent. The pre sence of a large number of particles has been found in the rime ice. Very s mall particles whose diameters are around 1 mum were identified as coal fly ash. The air mass at an altitude between 1500 m to 2000 m was probably lon g-range transported in association with a stable atmospheric layer in which the particles were efficiently scavenged by supercooled droplets. A back t rajectory analysis also indicated the predominance of a north wind in the w inter and in the other seasons as well. Such transport and deposition mecha nisms may produce the greater pollutant deposition sometimes observed in mo untain areas. Similar events may not be rare and could make an important co ntribution to the annual pollutants.