抄録
It has been suggested that Cd causing “Itai-itai” disease came from the mine factory situated on the Jinzu River and was carried from there by the river water.
To confirm the evidence of that suggestion, soil samples from the rice fields whose water is supplied by the Jinzu River were collected and analysed for Cd, Pb and Zn.
The results are as follows:
1. The rice field soil whose water is supplied by the Jinzu River contains higher Cd, Pb and Zn than that of other neighbouring rivers.
2. In a patch of rice field watered from the Jinzu River, the concentration of heavy metals in the soil is at the highest degree near the water-inlet point of the field and in the upper layer of the rice field ground, a higher concentration is found than in other deeper layers of the soil. Statistical analysis of heavy metals in the soil suggest there are at least two accumulation mechanisms.
3. The “Itai-itai” disease epidemic district corresponds to the area in which the rice field soil contains heavy metals to a high degree.
It may be concluded that the high degree of concentration of heavy metals (including Cd) in the district has been carried in the water from the Jinzu River.
