Econ. Environ. Geol. 2002; 35(6): 553-565

Published online December 31, 2002

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Geochemical Behavior of Metals in the Contaminated Paddy Soils around Siheung and Deokeum Mines through Laboratory Microcosm Experiments

Jung-Hyun Kim1, Hi-Soo Moon1*, Joo Sung Ahn1, Jae-Gon Kim2 and Yungoo Song1

1Department of Earth System Sciences, Yonsei University, Seoul 120-749, Korea
2Korea Agricultural & Rural Infrastructure Corporation, Anyang 430-600, Korea

Correspondence to :

Hi-Soo Moon

hsmoon@yonsei.ac.kr

Received: September 3, 2002; Accepted: December 6, 2002

Abstract

Seasonal variations in vertical distributions of metals were investigated in the contaminated paddy soils around Siheung Cu-Pb-Zn and Deokeum Au-Ag mines. Geochemical behavior of metals was also evaluated with respect to redox changes during the cultivation of rice. Two microcosms simulating the rice-growing paddy field were set up in the laboratory. The raw paddy soils from two sites showed differences in mineralogy, metal concentrations and gecochemical parameters, and it is suggested that high proportions of exchangeable fractions in metals may give high dissolution rates at Deokeum. In both microcosms of Siheung and Deokeum, redox differences between surface and subsurface of paddy soils were maintained during the flooded period of 18 weeks. Siheung soil had neutral
to alkaline pH conditions, while strongly acidic conditions and high Eh values were found at the surface soil of Deokeum. The concentrations of dissolved Fe and Mn were higher in the subsurface pore waters than in interface and upper waters from both microcosms, indicating reductive dissolution under reducing conditions. On the contrary, dissolved Pb and Zn had high concentrations at the surface under oxidizing conditions. From the Siheung microcosm, release of dissolved metals into upper waters was decreased, presumably by the trap effect of Fe- and Mn-rich layers at the interface. However, in the Deokeum microcosm, significant amounts of Pb and Zn were released into upper water despite the relatively lower contents in raw paddy soil, and seasonal variations in the chemical fractionation of metals were observed between flooded and drained conditions. Under acidic conditions, rice may uptake high amounts of metals from the surface of paddy soils during the flooded periods, and increases of exchangeable phases may also increase the bioavailability of heavy metals in the drained conditions.

Keywords paddy soils, heavy metals, abandoned mines, microcosm, redox environment

Article

Econ. Environ. Geol. 2002; 35(6): 553-565

Published online December 31, 2002

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Geochemical Behavior of Metals in the Contaminated Paddy Soils around Siheung and Deokeum Mines through Laboratory Microcosm Experiments

Jung-Hyun Kim1, Hi-Soo Moon1*, Joo Sung Ahn1, Jae-Gon Kim2 and Yungoo Song1

1Department of Earth System Sciences, Yonsei University, Seoul 120-749, Korea
2Korea Agricultural & Rural Infrastructure Corporation, Anyang 430-600, Korea

Correspondence to:

Hi-Soo Moon

hsmoon@yonsei.ac.kr

Received: September 3, 2002; Accepted: December 6, 2002

Abstract

Seasonal variations in vertical distributions of metals were investigated in the contaminated paddy soils around Siheung Cu-Pb-Zn and Deokeum Au-Ag mines. Geochemical behavior of metals was also evaluated with respect to redox changes during the cultivation of rice. Two microcosms simulating the rice-growing paddy field were set up in the laboratory. The raw paddy soils from two sites showed differences in mineralogy, metal concentrations and gecochemical parameters, and it is suggested that high proportions of exchangeable fractions in metals may give high dissolution rates at Deokeum. In both microcosms of Siheung and Deokeum, redox differences between surface and subsurface of paddy soils were maintained during the flooded period of 18 weeks. Siheung soil had neutral
to alkaline pH conditions, while strongly acidic conditions and high Eh values were found at the surface soil of Deokeum. The concentrations of dissolved Fe and Mn were higher in the subsurface pore waters than in interface and upper waters from both microcosms, indicating reductive dissolution under reducing conditions. On the contrary, dissolved Pb and Zn had high concentrations at the surface under oxidizing conditions. From the Siheung microcosm, release of dissolved metals into upper waters was decreased, presumably by the trap effect of Fe- and Mn-rich layers at the interface. However, in the Deokeum microcosm, significant amounts of Pb and Zn were released into upper water despite the relatively lower contents in raw paddy soil, and seasonal variations in the chemical fractionation of metals were observed between flooded and drained conditions. Under acidic conditions, rice may uptake high amounts of metals from the surface of paddy soils during the flooded periods, and increases of exchangeable phases may also increase the bioavailability of heavy metals in the drained conditions.

Keywords paddy soils, heavy metals, abandoned mines, microcosm, redox environment

    KSEEG
    Apr 30, 2024 Vol.57 No.2, pp. 107~280

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