ABSTRACT

Sulfate samples from rain and snow water, collected in Japan and in U.S.A. have been studied isotopically in an attempt to determine the sources of atmospheric sulfur. δ³⁴S values of the samples are 5 to 18 ‰ lighter than that of sea water sulfate. Based on these isotopic data, it is suggested that the most important sources of atmospheric sulfate are hydrogen sulfide derived from bacterial reduction of sulfate and SO₂ from industrial activities. Sea spray sulfate is a minor contributor. In industrial sites, the sulfur in precipitation indicates depletion in ³⁴S, viz. +3.2 to +7.3 ‰, in contrast to δ³⁴S values in non-industrial sites, that vary from +12.3 to +19.0 ‰. It is suggested that the lighter isotopic composition of atmospheric sulfur may be explained by the contribution of light sulfur from sulfur bearing fuels through industrial burning.