Record for Long-range Transport of Fly-ash Particles during Past 100 Years in the Pond Sediments in Oki Islands, Japan Sea

Fly-ash particles such as spheroidal carbonaceous particles (SCPs) and inorganic ash spheres (IASs) in sediments indicate modern fossil fuel combustion. A lake or pond away on the leeward of industrialized areas accumulates these particles in sediments to record the temporal change of fossil fuel combustion in the industrialized areas. The authors analyzed the fly-ash particles in a sediment core from Oike Pond in Oki Islands in the Japan Sea. The age of the core covers the last 100 years. The amount of both SCPs and IASs gradually increases from 1950s to the present. SCPs appear for the first time around the 1950s, while IASs have appeared around the 1920s. The profiles of lead and mercury concentration are similar to the profiles of the fly-ash particles. This evidences the increase of air-pollutants by coal combustion. The primary source of the IASs and SCPs is supposed to be coal combustion. The SCPs profile from Oike Pond resembles to that of Taihu Lake in eastern China after 1950s. Therefore the IASs deposited in Oike Pond after 1950s are inferred to have derived from China following increased coal consumption.