文摘
Sulfur and lead isotope ratios in the atmosphere weremeasured at several selected sites (Harbin, Changchun,Dalian, Waliguan, Shanghai, Nanjing, Guiyang) in China andTsukuba (Japan), to reveal regional sources characteristicsover Eastern Asia. Average S isotope ratios for SO2and sulfate in the atmosphere in China were close tothose of the coals used in each region, indicating aconsiderable contribution of coal combustion to the sulfurcompounds in the atmosphere. Most northern cities hadaround 5 sulfur isotope ratio, while Guiyang, a southwesterncity in China, showed a considerably lower sulfur isotoperatio (about -3) because of the unusually light sulfurisotope ratio of coals in this region. These were considerablydifferent from the value (-1.4) for Tsukuba (Japan).Lead isotope ratios also suggested that coal combustionconsiderably contributed to atmospheric lead in some casesin China. At the same time, influences by the emissionof Chinese lead ores were also observed in northern cities.Seasonal variations of both sulfur and lead isotoperatios indicated the existence of a certain amount ofindustrial sources other than coal combustion. In addition,fractionation effect between SO2 and sulfate showed aseasonal tendency (high in winter (0-6) and low in summer(-1-3)), suggesting the oxidation pathway of SO2changed seasonally.