Geochemical Study on Heavy Metals in the Jintsu River Area
Especially on Cadmium
1972 Volume 22 Issue 112 Pages 191-204
Details
1972 Volume 22 Issue 112 Pages 191-204
The writer has studied the geochemical behavior of heavy metals, especially cadmium, in various kinds of rocks, natural and paddy soils, aud river and underground water throughout the Jintsu River area.
The results are summerized as follows :
(1) The amount of cadmium as well as zinc cotained in various rocks in the Jintsu River area is remarkably high, especially in the upper valley area, where many lead and zinc ore deposits had been found.
(2) The cadmium contents in natural soils are generally much higher than that in the original rocks.
Cadmium contents in soils of fine grain size is higher than in those of coarse grain size. Especially the finer particle of soil, suspended in river water, is extremely high in cadmium.
(3) The cadmium contents in soils from the river terrace or the down-stream fan are also remarkably high, reflecting the back ground of up-stream rocks and soils.
The eroded remnants from the outcrop of the ore deposits have also been found in the river terrace, which is supposed to be formed about 40, 000 years ago.
(4) Detailed geochemical soil survey has been carried out in the Toyama plain, a down-stream area of the Jintsu River, where the "Itai-Itai Byoo" disease had been localized.
The cadmium contents in soils are characteristically distributed in three different fan levels;and in the same fan levels the lower and swampy area is a little higher in cadmium content, as the finer particles of sediments were deposited during formation of the fan. Likewise, paddy soil contains more cadmium than other soil within the same fan level, as paddy had been made in lower and swampy area since the ancient time. Also the river water, which suspends finer particle of soil, has fed little additional cadmium into the paddy by irrigation for as long as 200 or 300 years.
Consequently the writer believes that the origin of cadmium in paddy soil in the down-stream area had mostly been derived from the environmental rocks during the sedimentary deposition of the fan and little addition from the irrigated river water for hundreds of years, but not for decades of years, when the mining operation might have influenced the pollution of the river water.
