Concentrations of Atmospheric Sulfur Compounds in an Extremely Snowy Region, the Hokuriku District, Japan

The diurnal and seasonal characteristics in gaseous sulfur dioxide and sulfate in aerosol particles, as well as the concentrations of sulfate in rain and snow, were measured in the Hokuriku District, Japan in order to investigate the spatial spread pattern of sulfur compounds and identify the origin of sulfur. The concentration of sulfur dioxide showed a distinct diurnal pattern, while the concentrations of nss-SO(4) in precipitation and aerosol particles did not. These results implied that the sulfur dioxide might originate in local emissions and did not affect the concentration of nss-SO(4) in precipitation, while nss-SO(4) in aerosol particles seemed to be widespread and might result from long-range transportation. The deposition of nss-SO(4) in precipitation increased in winter, while the concentration of nss-SO(4) in aerosol particles decreased. This could be attributed to the lower cloud base often observed in this district in winter associated with a higher washout ratio.