中国四川省峨眉山において高度別に採取した大気降下物のイオン組成

抄録

We collected atmospheric depositions along the altitudinal gradient on Mt. Emei, China. This study was intended to estimate the deposition rate of the major ionic components by below-cloud scavenging using their altitude distribution of Mt. Emei, which is located in a region of severe air pollution. The precipitation rate tends to increase because of cloud deposition (1500-2500 m) . The atmospheric depositions collected at St. 12, 13 and 17 seemed to evaporate from the altitude distribution pattern of δD and precipitation rate. The deposition flux of ionic components increased at lower altitudes, without dependence on precipitation rate. The main ionic components that influenced atmospheric deposition in this region were SO₄^2-, NO₃^-, NH₄⁺ and Ca²⁺. We estimated the increase rate in ionic components by below-cloud scavenging based on the altitude distribution of ion concentrations, except NH₄⁺, which did not show good correlation with the first approximation. Respective rates of increase in SO₄^2-, NO₃^- and Ca²⁺ were 5.33, 1.36 and 9.51 μeq·L^-1, when raindrops fell 100m.