Sulfur Isotope Variations in Atmospheric Sulfur Oxides, Particulate Matter and Deposits Collected at Kyushu Island, Japan

Atmospheric sulfur oxides, particulate matter and deposits (wet and dry deposits) were collected from July 1998 to June 1999 at Kyushu Island, Japan. The isotopic composition of sulfur (δ34S) was measured to identify the source of sulfur in the samples. The monthly δ34S values were always low in the order of the sulfur oxides, sulfate in particulate matter and deposits. The δ34S values of the sulfur oxides ranged from −2.7 ‰ to −0.4 ‰ and were close to those of fossil fuels used in Japan. The δ34S values of sulfate in the particulate matter and deposits correlated with seasalt contribution, so that the δ34Snss value was calculated for non-seasalt sulfate. The δ34Snss values of sulfate in the particulate matter and deposits trended higher in winter than summer, suggesting the possibility of isotopic fractionation during chemical transformation (SO2 to SO42−) and of contribution of sulfate derived from sulfur sources with higher δ34S values.