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 (delta S-34) was measured to identify the source of sulfur in the samples. The monthly delta S-34 values were always low in the order of the sulfur oxides, sulfate in particulate matter and deposits. The delta S-34 values of the sulfur oxides ranged from -2.7 parts per thousand to -0.4 parts per thousand and were close to those of fossil fuels used in Japan. The delta S-34 values of sulfate in the particulate matter and deposits correlated with seasalt contribution, so that the delta (34)Snss value was calculated for non-seasalt sulfate. The delta (34)Snss 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 delta S-34 values.