HALIDE-IONS IN RIVER WATERS IN THE KUSATS U-SHIRANE VOLCANO AREA, GUNMA

Concentrations of halide ions of river waters in the Kusatsu-Shirane v olcano area, Gunma, were measured by ion chromatography. The decreasin g order of concentration among halide ions at various sampling locatio ns is in general; chloride ion>fluoride ion>bromide ion>iodide ion. A strong correlation was observed between the concentrations of the chlo ride and bromide ions. High halide ion concentrations were observed in river waters indicating that the volcanic activity of Mt. Kusatsu-Shi rane is the major source of halide ions in river waters of the area. M easurements of halide ion concentrations along the downward streams of selected rivers revealed that concentration ratios among halide ions were not varied substantially in the absence of any circumstantial cha nge. The amounts of halide ions transported from the Kusatsu-Shirane v olcano area by rivers per year were estimated to be 1.4 x 10(7) mol fo r the fluoride ion, 3.8 x 10(8) mol for the chloride ion, 4.1 x 10(5) mol for the bromide ion and 1.0 x 10(5) mol for the iodide ion.