Geo-Pollution Science, Medical Geology and Urban Geology
Vol.3 No.1/2 2007

ContentsArticles
1

Characteristic of the arsenic concentrations in travertine at Hirano springs in Kawanishi City, eastern part of Hyogo
PrefectureYoshihiro TAKASHINA and Yoshiaki TAINOSHO

11

Arsenic and antimony concentrations in river water and effect of iron hydroxides on their environmental mobility: Casestudy of Ichinokawa mine area
Sakae SANO, Masayuki SAKAKIBARA and Etsuko CHIBA

News20Characteristic of the arsenic concentrations in travertine at Hiranosprings in Kawanishi City, eastern part of Hyogo Prefecture
Yoshihiro TAKASHINA 1 and Yoshiaki TAINOSHO2
1: Graduate School and Science and Technology, Kobe Univ.
Present Adress: Rakuryo Technica Co., LTD.

8-1, rokkoudaicho, nadaku, Kobe City, 657-0013 Japan1, baba-zusho, Nagaokakyo City, Kyoto, 617-8550 Japan

2: Faculty of Human Development, Kobe Univ.

3-11, turukabuto, nadaku, Kobe City, 657-8501 Japan

Abstract
The Reddish-brown and white travertine are formed at Hirano springs in Kawanishi City, eastern part of
Hyogo Prefecture, Japan. The spring water contains very high concentration of arsenic. ED-XRF and XRDanalyses show that the reddish-brown travertine is mainly amorphous iron compound. On the other hand, white
travertine is mainly calcite. EDX analysis showed high arsenic concentration in the reddish-brown travertine.
EPMA analysis shows that the arsenic is concentrated especially in the dark brown part along with phosphorousin the reddish-brown travertine. Direct FESEM observation shows the presence of tubular amorphous ironcompound in the arsenic concentrated part of the reddish-brown travertine. XANES analysis revealed apresence of As (Ⅴ) and Fe (Ⅲ), suggesting an importance of oxidation process in arsenic accumulation in thereddish-brown travertine.

Keywords: Arsenic, Travertine, Accumulation, Spring 8, XANES

Arsenic and antimony concentrations in river water and effect of ironhydroxides on their environmental mobility: Case study of Ichinokawa
mine area
Sakae SANO1 , Masayuki SAKAKIBARA2 and Etsuko CHIBA2
1: Earth Science Laboratory, Faculty of Education, Ehime University, 3 Bunkyo-cho, Matsuyama, 790-8577 Japan
2: Graduate school of Sciences and Engineering, Ehime University, 2 -5 Bunkyo-cho, Matsuyama, 790-8577 JapanAbstractIchinokawa abandoned mine is one of the famous stibnite mines in Japan. A considerable amount of antimony
from the country rock is dissolved to adjacent river water (~ 280μg/L Sb) by the chemical weathering.
Precipitation of iron hydroxides is observed in the streambed at the downward of the Median Tectonic Line
(MTL). Arsenic and antimony contents in the river water at the upstream of the appearance of the MTL are >13 and > 280μg/L, respectively. On the other hand, the contents of the arsenic and antimony in the downstream
water from the MTL change to 39 and 4.5μg/L, respectively. Arsenic content in the water increases once withappearance of iron hydroxides on the streambed, and decreases gradually to the downstream (39 to 11μg/L As).
Antimony content in the water decreases drastically near MTL (280 to 4.5μg/L), and increases gradually to thedownstream (4.5 to 52μg/L). The pH value and water temperature decrease once at the MTL (pH = 6.9, T =16.6°C), and increase again (pH = 7.7, T = 19.5°C) to the downstream. Concentration ratios between ironhydroxides and water (concentration in iron hydroxides / concentration in water) for arsenic and antimonychange with the position of the sampling site. Namely, the concentration ratios from up- to downstream samples
change from 200,000 to 530,000 for arsenic and from 140,000 to 14,000 for antimony. This suggests that
migration behavior of antimony is different from that of arsenic depending on environmental conditions.
Natural purification of antimony contaminated river water around the Ichinokawa abandoned mine may
perform effectively but locally by formation of iron hydroxides. In accordance with change of the watercondition such as pH and crystal structure of iron hydroxides, antimony absorbed once in the precipitates may
liquate out gradually again in the river water.

Keywords: Arsenic, Antimony, Iron hydroxide, Ichinokawa