首都圏の降下物に含まれる金属元素

抄録

Bulk percipitation was collected from 69 sampling sites in Nagatsuta, small town with no outstanding industrial activities, and analyzed for Na, K, Al, Fe, Mn, Zn, Cu, Pb and Ni by atomic absorption spectrophotometry. The metal deposition fluxes were evaluated on the basis of analytical data. The samples collected from forest area were characterized by high values for Na and K. The roadside samples showed high values for most of the elements. At the localities more than 100 meters distant from high- ways, the values for Pb, Cu and Ni remained practically unchanged, thus suggesting that Pb, Cu and Ni originating from roadway traffic precipitate uniformly over the whole town. This study was extended to the southern area of the metropolitan region of Japan. Samples were collected from 43 sites located at a distance of more than 200 meters from heavily traveled highways and apparent sources of metal pollution. The amounts of Pb, Cu and Ni in bulk precipitation can be related to the human activities in the metropolitan region. Those of the analyzed elements were two to five times higher for the thickly inhabited area than for the mountainous area. Even the latter area was found to be polluted by heavy metals of anthropogenic origins. Part of sodium was derived from non-marine sources, so that sodium loses its utility as a reference element for sea spray.