神通川流域の杉の年論とCd, Zn含有量との関係

概要

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Epidemic of the so-called Itai-itai disease is remarkably restricted within the basin of the Jinzu river in Toyama Prefecture. We have found much evidence that the disease is a form of Fanconi syndrome attributed to cadmium.In order to determine the time when the Jinzu river water was contaminated by cadmium, investigation has been done on the annual rings of “Sugi” (cryptomeria japonica, a Japanese ceder) near the Jinzu River. For comparison, several stems of the same variety which grow along other river water systems were also investigated.As to the materials of the Jinzu river, it was found that the width of the annual rings became gradually narrower from the 1910s and narrowest between 1925 and 1943. Their width have become remarkably wider since 1944.Cd and Zn contents of each annual ring were analysed. They were much higher than that of the controls.Hence we have concluded that the growth of the trees was suppressed by these heavy metals, Cd and Zn.Probably under the influence of SO2, these metals dissolved out of the heap of clinkers of the mine factory which is located about 60km up stream from the Itai-itai endemic district on the Jinzu river.
日本衛生学会の論文