| Budget Amount *help |
¥6,900,000 (Direct Cost: ¥6,900,000)
Fiscal Year 1992: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1991: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1990: ¥5,000,000 (Direct Cost: ¥5,000,000)
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| Research Abstract |
In this year, the studies on the effects of the acidification of soils on the changes of the forms of heavy metals were carried out. Soil samples were collected in the mulberry field of Tokyo University of Agriculture and Technology, the plluted area with heavy metals in Asio Town of Gumma Prefecture and in Aso region of Kumamoto Prefecture. Soil pH was adjusted to 7.0, 6.0, 5.0, and 4.0 respectively and incubated for ten days. Each soil was patitioned into five fractions, exchangeable, bound to carbonate, bound to Fe-Mn oxides, bound to organic matter, and residual. As a result, the amounts of Cd, Pb and Zn in the exchangeable fraction increased accompanying with the lowering of soil pH.
In general, Cd existed more in the exchangeable fraction, Pb in the bound fraction to organic matter, and Zn in the residual. Exchangeable heavy metals are tended to be easily absorbed by plants on account of the weak binding to the soil granules.
And further, after simulated acid rains at pH4.0 and 3.0 were sprayed, the leached amounts of inorganic elements from mulberry leaves and their contents in mulberry organs were measured.
The amounts of leached elements from leaves increased accompanying with the lowering of simulated rains pH. Following the above phenomena, the amounts of elements in mulberry leaves decreased and the amounts of Mg and Fe in roots and Mn and Zn in soft woods decreased, too.
It was considered that the supply of elements from roots and soft woods were induced in correspondence with the leaching of elements from leaves.
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