SULFUR ISOTOPIC VIEW ON THE SOURCES OF SULFUR IN ATMOSPHERIC FALLOUT ALONG THE COAST OF THE SEA OF JAPAN

Sulfur isotopic ratios of atmospheric fallout collected from Niigata P refecture, Japan, were measured to understand the cause(s) of the seas onal variation of sulfate fallout along the coast of the Sea of Japan. The amount of sulfate fallout increased in winter. The delta(34)S val ues ranged from +0.9 to +12.3 parts per thousand, clearly showing a wi nter maximum and a summer minimum. This seasonal variation can be expl ained by taking into account sulfur from coal combustion in northeaste rn Asia, in addition to the variation in contribution of sea salt, loc al anthropogenic, biogenic and volcanic sulfur to the atmospheric fall out of the study area. Material balance calculations suggest that the winter fallout contains about 20% contribution of sulfur released by c ombustion of coals in northeastern Asia. (C) 1997 Elsevier Science Ltd .