愛媛県砥部町の砒素に富む万年変質安山岩体周辺の河川水中の微量元素濃度

概要

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Seventeen trace element abundance (Li, Al, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, As, Rb, Sr, Cd, Cs, Ba and Pb) for 4 fountains and 8 river waters derived from the high As-bearing Mannen andesite body, Tobe-town, Ehime prefecture, were determined for environmental assessment by inductively coupled plasma-mass spectrometry (ICP-MS). We had predicted high arsenic contents in the surface waters, because the local geologic background contains extremely high arsenic content (max. 1200 ppm As). The arsenic contents in the waters are low (<3.5 ng/g) contrary to our expectations, which the concentrations of the arsenic are below the environmental standard (<10 ng/g As). However, there is still in danger of increasing the arsenic contents by abrupt environmental change such as expansion project of road and tunnel in the area. The construction may produce large amount of rock debris including abnormally high arsenic. Consequently, further weathering of the debris at the surface condition must cause new liquation into surface water of arsenic from the rock. On the other hand, river water around the former Choshi-daki sulfide-ore Mine in the andesite body contains abnormally high zinc content (ca. 200 ng/g). This must be influenced by solve out of zinc ions to the water from the country rock. We need further environmental monitoring for the water condition.
愛媛大学の論文
2005-03-25