Geographical distribution and background levels of total mercury in air in Japan and neighbouring countries.

Concentrations of total atmospheric mercury were determined in air collected from several locations in Japan and neighbouring countries to elucidate the geographical distribution and the background levels of total mercury in environmental air. The concentrations of mercury in urban air in Japan were 2.3-67 ng/m3, mean value 11.2 ng/m3. Those values were higher relative to those in urban air of other countries around Japan. In the past, a large quantity of mercury was used as an agricultural fungicide and a chloralkali catalyst in Japan. Therefore, the concentrations of mercury in rural air were higher rather than those in urban air. This phenomenon supports the hypothesis that the residual mercury used in the paddy field in the 1970s still remains in soils of Japan.