[The distribution and the origin of trace elements in fresh waters in the Mikurajima Island (author's transl)].

The distribution and the origin of 21 elements in fresh waters in the Mikurajima Island were studied. The determination of these elements in stream water and rain water samples collected in the Island were carried out by using the thermal neutron activation method. The results are as follows: In the first place, it was concluded that a great portion of alkali and alkaline-earth elements in stream waters might be driven from sea salt. Meanwhile, the existence of trace elements such as Al, Fe, Mn, Sc, Sm, etc. might be explained by transfer from soil particle in the drainage basin. Furthermore, it seems that trace elements such as As, Co, Cr, Sb, V, W, etc. were supplied from airborne dust by precipitation. In the second place, in general, the content of Cl, Na, Al and Sc in stream waters in the Island were higher by several times than those in the headwater areas of the Tamagawa river and the Arakawa river in the mainland. On the other hand, the contents of trace elements such as As, Sb, W, etc. in the Island were much lower than these in the mainland.