Distribution of Minor Metallic Elements in River Water of Green Tuff Region, Yamagata Pref.

Abstract

The concentrations of 7 minor heavy metallic elements (Cd, Cr, Cu, Mn, Ni, Pb and Zn) were determined by the A.A.S. method in 116 river water samples, of which 13 samples were collected from the granitic region and others from the green tuff region in Yamagata Prefecture. High concentration areas of the metallic elements were found in the east, southeast and central part of the survey area. In consideration of their flow rate, the mean concentrations of the metallic elements in river water were obtained. The mean values of 0.35 ppb of Cd, 3.74 ppb of Cr, 6.92 ppb of Cu, 15.39 ppb of Mn, 3.32 ppb of Ni, 5.45 ppb of Pb and 17.26 ppb of Zn were found in the green tuff region. The mean values of these elements in the granitic region was lower than that of the green tuff region except for Cr.
Since it can be considered that these river water sampling sites are not affected by human activities, these values, except for lead, represent the minor metal concentration in close to its natural state.