• Economic and Environmental Geology
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• v.36 no.4
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• pp.295-304
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• 2003

The Dukpyung and the Chubu areas were selected to investigate the migration and enrichment of arsenic and other toxic elements in soils and crop plants in areas covered with black shales. Rock and soil samples digested in 4-acid solution (HCI+HNO$_3$+HF+HC1O$_4$) were analyzed fer arsenic and other heavy metals by ICP-AES and ICP-MS, and plant samples by INAA. Mean concentration of As in Okchon black shale is higher than those of both world average values of shale and black shale. Especially high concentration of 23.2 mg/kg As is found in black shale from the Dukpyung area. Mean concentration of As is highly elevated in agricultural soils from the Duk-pyung (28.2 mg/kg) and the Chubu areas (32.6 mg/kg). Arsenic is highly elevated in rice stalks and leaves from the Dukpyung (1.14 mg/kg) and the Chubu areas (1.35 mg/kg). The biological absorption coefficient (BAC) of As in plant species decreases in the order of rice leaves>com leaves>red pepper>soybean leaves=sesame leaves>corn stalks>corn grains.

• Economic and Environmental Geology
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• v.30 no.2
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• pp.89-103
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• 1997

The purpose of this research is to investigate the enrichment and distribution patterns of naturally occurring potentially toxic elements in soils derived from black shales and slates. Soil samples were collected from the Chubu area covered with uranium-enriched black shales and slates of the Changri Formation of the Okchon Super Group, and analysed for multiple-elements using INAA, ICP-AES and AAS. Soil pH and loss-an-ignition were also measured. Trace element contents in black shale and slate of the Chubu area are relatively lower than those in black shales, and higher than those in black slates reported elsewhere (Chon, Jung, 1991; Chon et al., 1996). Soil pH values range from 3.5 to 6.5, and loss-an-ignition values are in the range from 3 to 10%. Potentially toxic elements including As, Ba, Cr, Cu, Mo and U are highly enriched in residual soils with maximum content of $540{\mu}g/g$, $35,000{\mu}g/g$, $280{\mu}g/g$, $300{\mu}g/g$, $240{\mu}g/g$ and $860{\mu}g/g$, respectively. Significant concentrations of those elements were found in soils taken from the Tojangkol, the Chubu tunnel and the Meokti areas. Soils derived from black shales and slates, calcareous and phyllitic rocks, and intrusions were discriminated in terms of As, Ba, Co, Cr, Cu, Mo, Sc and U contents. Enrichment index was calculated using the concentrations of As, Ba, Cr and Mo, and enrichment index map shows very similar trend with U distribution in soils.

• Economic and Environmental Geology
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• v.30 no.6
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• pp.587-601
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• 1997

This study had three purposes: (1) to investigate the enrichment levels and dispersion patterns of potentially toxic elements in the rock-soil-plant system; (2) to evaluate the uptake ratios of heavy metals from soils into plants and (3) to assess the chemical speciation of heavy metals in soils. Rock, surface soil and plant samples were collected in the Boeun area underlain by black shales of the Okchon Zone. These samples were analyzed for multi-elements using INAA, ICP-AES and AAS. The maximum abundance of U in black shales is 16 mg/kg and radioactivity counts up to 300 cpm. In particular, Mo, V, Ba, Cd, Pb and U are enriched in black shales. Most of soils derived from black shales show high concentrations of U, As, Mo, Ba, Cu, Cd, Pb, Zn and mean concentrations of As and Mo in soils (20 mg/kg of As and 6.6 mg/kg of Mo) are higher than the permissible level suggested by Kloke (1979). Enrichment index values of soils are calculated and higher than 1.0 in the black shale area with the highest value of 6.4. Mean concentration of Cd in plants is higher than those of Cu, Pb and Zn. The concentration of Cd in plant species decreases in the order of Chinese cabbage > red pepper > soybean=sesame > rice stalk > com > rice grain. The biological absorption coefficients (BAC) in plants are in the order of Cd > Zn=Cu > Pb, which suggests that Cd is more bioavailable to plants than Cu, Pb and Zn. From the results of sequential extraction analysis of soils, relatively high proportion of Cu, Pb and Zn are present as residual fractions whereas that of Cd as non-residual fractions. Cadmuim occurs predominantly as exchangeable/water-acid soluble phase in soils, and Cd is more mobile and bioavailable than Cu, Pb and Zn.