Studies on Chemical Species Dissolved in Groundwaters from the Neogene Strata.

A Comparison between Shallow and Deep Groundwaters.

Abstract

The Kobe Neogelle strata., which have been considered to be Iake scdimellts produced during ca. 1.4×10⁷ years ago, are widely distributed in the Sanda basin situated on the north or north-western sides of the Rokko mountains. In the broundwaters collected from 42 shallow domestic wells used for living and from 19 deep wells bored in golf links, the concentrations of 24 dissolved species were determined by chemical analyses and those of g other species by neutron activation analyses. Seasonal fluctuations of the concentration of major dissolved species in the groundwaters and the differences in the chemical compositions between the shallow and deep ones were studied. Based on the overall analytical results of the species in the groundwaters, it was corleluded that ion exchangereactions by clay minerals in the strata contribute to the chemical Compositlons of groundwaters from the strata. This contributioll is more remarkable in the deep grounclwaters than the shallow ones.