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Heavy Metal Contamination in the Vicinity of SomeBase-Metal Mines in Korea; a ReviewHyo-Taek Chon a , Joo Sung Ahn a & Myung Chae Jung ba School of Civil, Urban and Geosystem Engineering, College of Engineering, SeoulNational University , Seoul , 151-742 , Koreab Department of Earth Resources and Environmental Geotechnics Engineering ,Semyung University , Jecheon, Choongbuk , 390-711 , KoreaPublished online: 04 Sep 2012.

To cite this article: Hyo-Taek Chon , Joo Sung Ahn & Myung Chae Jung (1998) Heavy Metal Contaminationin the Vicinity of Some Base-Metal Mines in Korea; a Review, Geosystem Engineering, 1:2, 74-83, DOI:10.1080/12269328.1998.10541128

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Geosystem Eng., 1 (2), 74-83, (November 1998)

Heavy Metal Contamination in the Vicinity of Some Base-Metal Mines in Korea; a Review

Hyo-Taek Chon, Joo Sung Ahn1l and Myung Chae Jung2

l

1lSchool of Civil, Urban and Geosystem Engineering, College of Engineering, Seoul National University, Seoul 151-742, Korea

2Tiepartment of Earth Resources and Environmental Geotechnics Engineering, Semyung University, Jecheon, Choongbuk 390-711, Korea (Received July 29, 1998; Accepted September 18, 1998)

ABSTRACT: In order to assess the level of metal pollution and to draw general conclusions about the fate of toxic heavy metals in different environments, investigations of heavy metal contamination in the areas of five typical base-metal mines in Korea were reviewed. Efforts have been made to compare the characteristics of heavy metal contamination, chemical forms and plant uptake of heavy metals in each study area. The main pollution sources in the areas are suggested as tailings and mine waste materials which have to be reclaimed. Non-residual forms of heavy metals in soil and stream sediment were found from the sequential extraction analysis, which indicates the contamination to be progressing by continuing weathering and oxidation. Cadmium and Zn would be of the highest mobility in all study areas. Leafy vegetables tend to accumulate heavy metals higher than other crops, and high metal concentrations in rice crops may affect the local residents' health in the Sambo mine area. This review may help in setting up the reclamation guidelines in mining areas and interdisciplinary studies to assess the adverse health effects to humans.

Key words: base-metal mines, heavy metals, chemical forms, plant uptake

INTRODUCTION

Base-metal mining can be an important source of trace elements in the environment owing to various mining ac­tivities including processing and transportation of ores, disposal of tailings and waste water around mines (Adriano, 1986). The elevated levels of heavy metals discharged from mine waste materials can be found in the nearby streams, agricultural soils and food crops, and eventually, they may pose a potential health risk to residents in the vicinity of mines.

In Korea, base-metal mines producing Cu-Pb-Zn ores were distributed almost all over the country and have been actively operated until the early 1980s. Particularly, the mines of the Taebaeksan metallogenic province in the northeast part of Korea produced up to 143,700 mT

74

per year of ores (converted value to 50% Pb) which was equivalent to 87% of nationwide production in the mid-1970s. Since then, however, base metal production has declined and most of the mines were closed mainly due to the economic reasons. Upon the closing of the mines, improperly disposed mineral waste piles and untreated mine drainage have become the most important sources of heavy metals in the nearby environment.

Environmental surveys of the mining districts have been undertaken since the early 1990s, but further investigation is still needed to make comparison of the degree of metal pollution between sites or to draw general conclusions about the fate of toxic heavy metals in different environments. In this study, five typical base-metal mines, the Samba Pb­Zn-barite, the Shinyemi Pb-Zn-Fe, the Geodo Cu-Fe, the Shiheung Cu-Pb-Zn and the Dalsung Cu-W, were selected, and the results of the environmental surveys in those areas previously conducted by the authors and others (Hwang and Chon, 1995; Jean et al., 1995; Jung, 1995, 1996; Jung and Chon, 1997, 1998; Jung and Thornton, 1996; Kim and Chon, 1993a, 1993b) were discussed.

SITE DESCRIPTION

Locations of five base-metal mines surveyed are shown in Fig. 1, and brief descriptions of the geology and features of each mine are listed in Table 1. The Samba Pb-Zn-barite mine is located about 60 km to the south of Seoul. The mine opened in 1945 and in the peak time of the 1980s, produced about 10% of the total Pb production and 10-20% of the total Zn production of Korea, processing ores up to 400 tons of ore in a day. The mine ceased production in 1991, due to an abrupt declination of ore grade. The study area is underlain by Precambrain muscovite schist with intercalations of quartzite, quartz schist, limestone and lime-silicate, and biotite schist with intercalation of augen gneiss (Jung, 1995). The mineralization is classified as a hydrothermal vein type formed during retrogtade metamorphism from amphibolite facies, and ore minerals consist of , galena,

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Heavy Metal Contamination in the Vicinity of Some Base-Metal Mines in Korea; a Review 75

N

A 127 129

- --------{----------~~-' I I I

I I

• I

: eS!hiny ~Sambo Pb-Zn-barite•Geod

I

38

--- 36

=:::::~~-1iiOOkm

Fig. 1. Locations of five study mines in Korea.

barite and sphalerite (Jung, 1995). Most agricultural areas near the mine have been used for paddy fields. Various crops and vegetables including com, perilla leaves, red. peppers, soybeans, spring onions and tobacco have been growing nearby household gardens.

The Shinyemi Pb-Zn-Fe mine and the Geodo Cu-Fe mine are situated in the northeastern part of Korea. The Shinyemi mine produced Pb and Zn ores from 1967 to 1983, and then, was redeveloped as an Fe-producing mine with 300,000 tons per year. The mineralization is classified as a replacement and skarn type and ore minerals are sphalerite, chalcopyrite, pyrite, pyrrhotite and arsenopyrite (Jean et al., 1995).

The Geodo mine, a skarn type deposit, initiated mining

Table 1. Geology and site description of the study mines

Mine Type of ore Major metallic Main geology deposits minerals

hydrothermal muscovite schist,

Sambo Pb, Zn, barite granite gneiss, vein two mica granite

lens or pipe Zn, Pb limestone Shinyemi skarn Zn, Mo, Cu

Geodo skarn Fe, Cu limestone, diorite porphyry

skarn Pb, Zn, Cu gneiss, schist,

Shiheung lime-silicates

Dalsung breccia pipe Cu, W rhyolite, volcanic ash, tuff

activities in 1964 and produced 1,300 tons of Fe, 130 tons of Cu, 2 kg of Au and 13 kg of Ag per month until closure in 1988 (Jean et al., 1995).

The Shiheung Cu-Pb-Zn mine is located 20 km away from the southwest of Seoul and has been the most famous

·sulphide-producing mine since 1912. Until closure in 1973, 250 tons of ore minerals per day were produced, the amount of which equals 10% of nationwide production. The geology is composed of Precambrian biotite banded gneiss, biotite schist, lime silicate rocks and dyke rocks (Hwang and Chon, 1995). Tailings and waste materials were distributed without proper storage systems, and be­came significant pollution sources of toxic heavy metals for nearby streams and paddy fields. As a result of environ­mental surveys previously made for this area, the heavy metal pollution and higher Cd levels in residents' blood and food crops were identified and reported in public (article of Hankuk-llbo on 1995. 3. 13). Reclamation work of this area, dumping out the waste materials and layering with unpolluted soils, was executed in 1996, and now a incineration facility is being constructed for other land-use.

The Dalsung Cu-W mine was operated in the southern part of Korea from 1934 to 1973. The mine was one of the biggest Cu mines, and recorded the peak years in the 1960s with a production of 5-10% of the total Cu output in Korea. The mine is surrounded by agricultural and residential areas with a small stream flowing from east to west along the valley. The mine is underlain by an alteration zone of andesitic rocks and quartz monzonite, and the mineralization that occurs in a breccia pipe, is classified as a hydrothermal replacement type. The ore minerals are chalcopyrite and wolframite with a minor amount of bismuthinite and pyrite (Jung, 1995).

HEAVY METAL POLLUTION IN THE STUDY AREAS

Data on the heavy metal concentrations of tailings and

Working Topology and Main pollution Reference period land use sources

low hilly, flat Kim and 1945-1991 paddy field, tailings, AMD Chon (1993a);

household garden Jung (1995)

1941- hilly tailings Jeon et al. (1995) present forest, dry field

1921-1988 hilly tailings Jeon et al. (1995) forest, dry field

1912-1973 low hilly, flat tailings Hwang and paddy field, Chon (1995)

1934-1973 hilly

tailings, AMD Jung (1995) forest, dry field

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76 Hyo-Taek Chon et al.

soil, stream sedim((nt and stream water samples of the study areas are summarized in Tables 2, 3 and 4, respectively. Chemical analyses for heavy metals in each survey were based on total concentration measurement with a HN03-HC104 or aqua-regia digestion, thus the results shown in tables are comparable between mines.

The Sambo Pb-Zn-barite Mine Soil samples were collected on a grid pattern to cover

the possibly contaminated area from the mine, and the dispersion pattern and pollution levels of heavy metals were investigated. Forest soils have been contaminated severely by Cd (max 13.7 mg/k:g), Pb (max. 2,880 mg/ kg) and Zn (max. 7,420 mg/k:g) due to wind-blown input of tailings containing significant amounts of Pb and Zn

(Table 2). Agricultural soils are also contaminated by mine drainage and contents of heavy metals in top soil (0-15 em depth) were higher than those in subsoil (15-30 em depth). The contamination levels of heavy metals are different depending on the distance from the mine, and decrease in the order of Cd = Pb > Zn > Cu to 1.2 km downstream. Jung and Thornton (1996) also reported that the large amount of metals in the mine wastes and associated soils provided an important source for con­tinuing dispersion downstream, and have led to a moderate degree of contamination of soils used for crop production.

Stream sediments and waters were contaminated by waterborne transport of heavy metals inherent in the tailings, especially for Cd, Pb and Zn, and the main pollution sources were considered as tailings and drainage from the mine. The

Table 2. Mean concentrations and ranges of Cd, Cu, Pb and Zn in tailings and soils from some base-metal mines in Korea (unit in mglkg)

Mine Sample Cd Cu Pb Zn

tailings 9.6 105 1,140 5,190 (N=5) (3.9-23.1) (35-299) (13-3,540) (2,120-13,500) paddy soil 4.1 33 276 384

•samba (N=47) (1.8-7.9) (13-115) (122-552) (52-2,730) Pb-Zn-barite farmland soil 3.4 22 234 87

(N=30) (2.1-5.0) (14-39) (153-342) (34-245) forest soil 4.5 94 483 533 (N=71) (2.3-13.7) (15-2,230) (132-2,880) (52-7,420)

tailings 28.5 267 1,630 5,940

bShinyemi (N=2) farmland soil 6.2 89 128 802

Pb-Zn-Fe (N=29) (2.1-14.2) (19-324) (23-564) (84-3,480) forest soil 5.1 62 88 753 (N=21) (0.8-21.2) (17-286) (31-301) (65-4,690)

tailings 5.6 952 112 312 (N=3) farmland soil 2.9 142 40 96

bGeodo Cu-Fe (N=20) (1.6-5.1) (64-441) (25-67) (54-168) forest soil 2.7 156 36 96 (N=15) (1.7-5.4) (77-432) (21-59) (52-201) pit soil 4.9 11,000 43 197 (N=3) (4.4-5.6) (10,280-12,220) (35-58) (183-214)

tailings 96.6 5,820 10,410 14,960 (N=5) (34-249) (948-13,980) (2;910-22,320) (5,000-41,200)

cShiheung paddy soil 11 233 742 1620 Cu-Pb-Zn (N=11) (1.4-30) (56-616) (116-2,016) (196-3,960)

forest soil 4.2 101 336 475 (N=2) (3.8-4.6) (78-123) (272-400) (465-484)

mine dump 4.4 1,950 1,030 419 (N=36) (1.0-16.7) (111-7,910) (146-3,020) (55-2,370) alluvial and forest soil 1.8 183 63 136

dDalsung Cu-W (N=6) (1.1-2.3) (68-278) (29-98) (96-175) farmland soil 1.8 269 84 175 (N=30) (0.6-5.1) (78-1,820) (39-292) (100-406) control site 0.9 29 18 97 (N=18) (0.4-2.0) (19-49) (13-26) (75-132)

N=No. of samples 'Kim and Chon (1993a), bJeon et al. (1995), 'Hwang and Chon (1995), 'Jung (1995)

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Heavy Metal Contamination in the Vicinity of Some Base-Metal Mines in Korea; a Review 77

Table 3. Mean concentrations and ranges of Cd, Cu, Pb and Zn in stream sediments from some base-metal 'mines in Korea ' (unit in mg!k:g)

Mine Cd Cu Pb Zn

•sambo Pb-Zn-barite 13.7 53 348 3,500 (N=27) (3.7-49.2) (8-262) (25-3,310) (12-19,110) "Shinyemi Pb-Zn-Fe 7.9 77 132 1,220 (N=21) (1.3-15.4) (19-453) (39-542) (84-3,830) "Geodo Cu-Fe 3.3 398 43 115 (N=25) (1.4-6.4) (71-4,030) (20-77) (52-284) cShiheung Cu-Pb-Zn 25.2 794 1,630 2,950 ~=9) (6.6-41.6) (180-1,930) ( 424-4,020) (781-5,280) Dalsung Cu-W 3.2 1,390 451 262

(N=31) (0.6-11.4) (15-3,800) (14-1,330) (63-1,060)

N=No. of samples 'Kim and Chon (1993b), 'Jeon et al. (1995), 'Hwang and Chon (1995), 'Jung(1996)

Table 4. Physicochemcial properties and concentrations of Cd, Cu, Pb and Zn in nearby ·stream water from some base-metal mines in Korea (unit in jlg/ I)

Mine pH Eh(mV) TDS(ppm) Cd Cu Pb Zn

'Sambo Pb-Zn-barite 6.3 200 15 17 33 15,850 (N=15) (5.3-7.1) (158-281) (1-89) (1-138) (1-183) (20-96,500) "Shinyemi Pb-Zn-Fe 7.4 328 244 4 418 46 1,019 (N=7) "Geodo Cu-Fe

(7.2-7.9) (264-357) (98-354) (1-7) (346-512) (24-69) (93-1,512) 8.1 286 101 3 363 21 416

(N=5) (7.7-8.3) (177-341) (75-121) (2-6) (24-654) (11-32) (124-753) 0Shiheung Cu-Pb-Zn 7.5 325 259 6 41 165 ~N=8) (7.3-7.7) (259-399) (40-485) (n.d.-10) (10-130) (30-310) Dalsung Cu-W 3.8 451

(N=17) (3.2-5.5) (354-527)

N=No. of samples 'Jung (1995), 'Jeon et al. (1995), 'Hwang and Chon (1995), 'Jung (1996)

effluent waste water had maximum contents of 89 J.Lg I l Cd, 138 J.Lg I l Cu, 183 J.Lg I 1 Pb and 96,500 J.Lg I l Zn (Jung, 1995). This sample also had a high S content of 273,000 J.Lg I l, probably derived from sulphide mineralization of the mine.

The Shinyemi Pb-Zn-Fe and the Geodo Cu-Fe Mine Both the mine areas comprise hilly forest and farmland

with relatively few residents, and soil, stream sediment and water samples were collected along the transect lines of streams and their tributaries around the mines. In com­parison with the tolerable levels of heavy metals in soil (Kloke, 1979), relatively high concentrations were found in soils from Shinyemi for Cd, Pb and Zn and from Geodo for Cu (fable 2). Concentrations of Cd, Pb and Zn in stream sediments were higher than soils collected along the same transect lines around the Shinyemi mine, and their contents in water samples were also elevated.

The Shiheung Cu-Pb-Zn Mine In the Shiheung mine, samples were collected along

the tributaries, and the results were compared from the control areas distinguished by topographic conditions. The average contents of Cd, Cu, Pb and Zn in tailings

60 12,700 40 4,890 (10-170) (300-41,600) (10-80) (700-15,400)

were 96.6, 5,820, 10,410 and 14,960 mg!kg, respectively (fable 2). Those high amounts of heavy metals in tailings were dispersed by wind or water erosion along the nearby tributary system, and have deteriorated the paddy soils, sediment and water quality.

The Dalsung Cu-W Mine Jung (1995) reported that soils around the mine dump

site of Dalsung Cu-W mine contained 4.4 mg!kg Cd, 1,950 mg!kg Cu, 1,030 mg!kg Pb and 419 mg!kg Zn, and their dispersion patterns in the surface soil could be expressed by exponential function with distance from the mine (Log Y = Log A+ B Log X; where X = distance from the mine, Y =heavy metal contents in surface soil, and A, B = constants). Jung (1996) has also undertaken the sampling of stream sediments. and waters up to 1.5 km downstream at 50-150 meter intervals from the mine. The pH values of sediment and water samples ranged from 3.0 to 5.5, and concentrations of Cd, Cu, Pb and Zn in sediments were very high (fable 3). Significant levels of heavy metals were also found in water samples (fable 4). These elevated con­centrations of heavy metals may be caused by the weathering of mine waste materials and their high solubilities under acidic and/or oxidizing conditions.

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78 Hyo-Taek Chon et al.

It is well known that most of metal and metalloid contamination in 'the surface environment is associated with a cocktail effect of each contaminant rather than one element. Thus, a pollution index(PI) was introduced to identify multi-element contamination, and suggests the increased overall element toxicity in the area prior to remediation. The PI of soils is computed by the average ratios of element concentrations in soils to the guideline values for metals. When the PI values of soils exceed 1.0, the soils are considered to be contaminated by heavy metals and it may recommend continuous environmental monitoring of the area. The five mine areas above men­tioned were investigated for multi-element contamination with a pollution index concept.

For the Samba, Shinyemi and Geodo mine area, tolerable levels in soil (Kloke, 1979) were used as guide values, and their calculated PI values are illustrated in Fig. 2. Tolerable levels are the threshold values of element con­centrations in soil which can produce crops being unsafe for human or animal consumption, if higher than those. Kloke (1979) calculated that if the content of metals in soil is not higher than the threshold values, it can be expected that the content of metals in human diets will not exceed weekly tolerable intakes established by F AO/ WHO. Therefore, at the areas of high PI values (>1.0) found in Fig. 2, agricultural activity should be forbidden. Kim and Chon (1993a) also found that heavy metal pollu~ tion proceeded southeastward by the effect of prevailing northwest wind.

Jung (1995), however, used the ICRCL trigger concen­trations from the United Kingdom (DoE, 1987) as guideline values, and found the PI values greater than 1.0 at the mine dump sites and the entrance of mine tunnel in the Samba

A

(

1 ~

LJ 0

~ L/

mine. Exceedence of the UK ICRCL levels indicates a requirement for further investigation. In the Dalsung mine, As, Bi and to a less extent Sb and Cu, significantly contnbu­ted to the PI of the soils mainly due to their mineralization in the study area, whereas Cd, Pb and Zn contributed less significantly for the PI (Jung, 1995).

CHEMICAL FORMS OF HEAVY METALS

The chemical forms of metals produced by mmmg activity and discharged into water bodies, and their stabilities in the environment, determine the mobility and toxicity in receiving ecosystems. The fate of deposited metals and metal complexes in soils and waters depends very much on ambient conditions of soil and water pH, organic matter status, redox and temperature. In soils, free metal ions and complex metal species can become strongly adsorbed onto clays, Fe and Mn oxides and soil organic matter, while in waters and in soil solution, metals tend to form organic chelates with humic and fulvic acids (Ross, 1994).

Chemical extraction with sequentially more aggressive reagents is commonly used to characterize various forms of metals in soils and sediments, and a number of di­fferent procedures have been applied (Tessier et al., 1979; Clevenger, 1990; Davidson et al., 1994). Because heavy metals in various geochemical forms are thought to differ in their degree of mobilities and bioavailabilities, this approach is theoretically very useful for site analysis and risk assessment. However, there is some question about the accuracy of this method because the analytical results are affected by selectivity and resorption problems. It is widely recognized that no reagent is perfectly selective, and the

N

A

• Fann land soil • Farmland soil

Samba mine Shinyemi mine Geode mine

PI= [Cd/3+Cu/100+Pb/100+Zn/300]/4 PI= [Cd/3+Cu/100+Pb/100+Zn1300V4 PI= [Cd/3+Cu/100+Pb/100+Zn1300V4

Fig. 2. Pollution index map of soils in the vicinity of the Sambo Pb-Zn-barite, the Shinyerni Pb-Zn-Fe and the Geodo Cu-Fe mines (adopted from Kim and Chon, 1993a; Jeon et al., 1995).

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Heavy Metal Contamination in the Vicinity of Some Base-Metal Mines in Korea; a Review 79

Table 5. Mean concentrations of sequentially extracted Cd, Cu, Pb and Zn in stream sediments from Sambo (A)", Shinyemi (B)b and Geodo (C)", and soils from Shiheung (Dt and Dalsung (E)" - (unit in mg!kg)

Cadmium Copper Fraction

I) E A B c D E A B c Exchangeable 0.6 1.9 0.4 5.1 0.4 0 8.0 138 1.1 85 Carbonates 1.0 1.7 0.7 9.2 0.6 4.2 7.3 133 112 145 Fe-Mn oxides 4.3 0.9 0.5 18.0 0.7 7.9 7.9 60 91 300 Organic 0.8 1.1 0.7 14.3 0.8 30.6 25.2 94 587 882 Residuals 10.5 1.5 1.4 26.8 0.5 25.6 38.6 157 788 1,020 sum 17.2 7.1 3.7 73.4 3.0 68.3 87.0 582 1,579 2,442

Lead Zinc Fraction

A B c D E A B c D E

Exchangeable 25 25 5.2 15 26 90 177 26 43 24 Carbonates 161 30 7.0 339 24 1,100 121 12 936 19 Fe-Mn oxides 179 20 6.2 1,381 76 2,357 179 32 3,442 129 Organic 29 21 8.9 268 20 489 153 21 1,259 78 Residuals 154 28 17.1 691 1,007 1,337 318 45 2,638 216 sum 548 124 44.4 2,694 1,153 5,373 948 136 8,318 466

'Kim and Chon (1993b), n=16 •Jeon et al. (1995), n=lO 'Jeon et al. (1995), n=lO •Hwang and Chon (1995), n=6 'Jung (1994), n=6

Cadmium Copper 100% 100%

80% 80%

60% 60%

40% 40%

20% 20%

0% 0%

A 8 c 0 E A B c 0 E

' '

Lead Zinc 100% 100%

80% 80%

60% 60%

40% 40%

20% 20%

0% 0%

A 8 c 0 E A 8 c 0 e

•Exchangeable IICarbonate-bound 13Fe-Mn oxides •organic •Residual

Fig. 3. Mean chemical partitionings of Cd, Cu,- Pb and Zn in stream sediments from Sambo (A)', Shinyemi (Bt and Geodo (C)c, and soils from Shiheung (Dt and Dalsung (E)". 'Kim and Chon (1993b), N=16; bJeon et al. (1995), N=10; 0Jeon et al. (1995), N=10; dHwang and Chon (1995), N=6; 0Jung (1994), N=6

fractions recovered are best defined operationally (Howard and Shu, 1996). Despite this limitation, sequential extrac-

tions allow for a useful comparison between earth materials, and provide the opportunity to study the speciation of

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heavy metals in large numbers of samples, unlike many microscopic methods.

The results of sequentially extracted metal contents of several studies are summarized in Table 5, and illustrated as fractionation pattern of metals in Fig. 3. Most extraction procedures were based on that designed by Tessier et al. (1979) which characterized the five different fractions of metals, such as exchangeable (1 M MgCh), bound to carbonates (1M NaOAc), bound to Fe-Mn oxides (0.04 M NHzOH · HCl in 25% HOAc), bound to organic matter (0.02 M HN03, 30% HzOz) and residual(HF-HCl04).

At the Samba mine, the chemical forms of Cd, Cu, Pb and Zn were investigated in the stream sediment samples from nearby shallow streams, and appeared to be identified as Fe-Mn oxides or organic-matter bound and carbonate­bound compound with a moderate potential bioavailability. However, the sediments, directly affected by tailings effluent, showed high proportions of non-residual forms, especially for Zn (75%). This was probably a consequence of the chemical oxidation of tailings through the streams, and well in accordance with high contents of Zn in stream water samples.

In the areas of the Shinyemi and the Geodo mines, heavy metals were present predominantly in ion-exchangeable

forms (9-27%) within the heavily polluted sediments, and seemed to be the highest mobility of elements among the five mine areas. Particularly, high proportions in exchange­able fraction of Pb in the Shinyemi (20%) and of Cu in the Geodo mine areas (24%), compared to the data from other study areas, indicated more release of these elements in the above mines.

Results from the Shiheung mine area suggested that ion-exchangeable fraction of Cd (7%) was relatively higher than those of Cu, Pb and Zn in contaminated soils. Most of Cu was bound to organic matter and sulphide (37%), and Pb was mainly associated with Fe-Mn oxides (51%). Zinc was largely bound to Fe-Mn oxides (41 %) and residual fraction (32% ). Carbonate bound fraction of each metal tended to increase as the pH value increased to neutral (Hwang and Chon, 1995).

Jung (1994) has used a modified method from Tessier et al. (1979) to investigate the chemical forms of metals in mine dump soils of the Dalsung mine and found that high proportions of Cd (12%) and Zn (5%) were present in the exchangeable fraction. These metals were more mobile and had a potentially higher bioavailability than Cu and Pb. Copper in soils was present in the organic fraction and major fraction of Pb was in the residual. It

Table 6. Mean concentrations and ranges of Cd, Cu, Pb and Zn in plant samples from the Sambo and the Dalsung mines in Korea (unit in mglkg, DW)

Mine plant species Cd Cu Pb Zn

Com grain 0.26 2.7 0.49 38 (N=8) ' (0.08-1.15) (1.1-8.0) (0.10-1.38) (21-99) Red pepper 0.27 11.6 1.34 51 (N=12) (0.14-0.36) (4.9-15.5) (0.40-1.88) (27-78) Soybean leaves 0.39 10.0 3.95 200 (N=lO) (0.24-0.60) (5.4-15.6) (2.38-5.30) (53-373)

"Sarnbo Spring onions 1.23 10.7 3.33 233 Pb-Zn-barite (N=8) (0.30-3.10) (7.8-14.3) (2.00-4.50) (88-578)

Tobacco leaves 2.56 22.2 7.34 361 (N=16) (1.80-8.45) (9.7-44.5) (2.40-24.0) (103-1620) bRice Grain 0.21 3.0 0.22 25.2 (N=31) (0.10-0.50) (1.2-5.8) (<0.1-0.6) (19.0-37.0) cRice Grain 0.37 2.6 0.5 22.5 (N=lO) (0.09-1.74) (1.0-12.4) (0.3-1.0) (16.6-29.6)

Com grain 0.41 8.9 0.41 41 (N=3) (0.31-0.49) (3.5-13.5) (0.29-0.56) (26-50) Red pepper 0.34 25.5 1.22 32 (N=6) (0.28-0.44) (4.1-38.2) (0.87-1.65) (29-39) Soybean leaves 1.01 18.9 2.42 163

dDalsung Cu-W (N=8) (0.36-1.74) (14.7-25.1) (1.87-3.24) (79-235) Spring onion 1.88 26.4 4.23 256 (N=4) (1.35-2.20) (20.3-32.8) (3.12-6.00) (182-383) Jujube grain 0.47 9.2 0.19 23 (N=6) (0.44-0.49) (8.3-10.2) (0.12-0.25) (19-28) Perilla leaves 0.24 26.0 1.33 81 (N=3) (0.20-0.40) (23.4-29.6) (1.23-1.50) (55-120)

N=No. of samples 'Jung and Thornton (1996), •Jung and Thornton (1997), 'Jung and Chon (1997, 1998), •Jung (1995)

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Heavy Metal Contamination in the Vicinity of Some Base-Metal Mines in Korea; a Review 81

can be concluded that Cd and Zn in soils can be easily leached and discharged into downstream, especially in the Dalsung and the Shinheung mines. Identification of the chemical forms of heavy metals as done in each study may be helpful to estimate the biological availability of metal contaminants and to determine the method of remediation and its operating conditions.

PLANT UPTAKE OF HEAVY METALS

Plants can accumulate heavy metals in or on their tissues due to their great ability to adapt to variable chemical properties of the environment. Thus plants are intermediate reservoirs through which trace elements from soil, and partly from waters and air, move to man and animal. Plants may be passive receptors of trace elements, but they also exert control over uptake or rejection of some elements by appropriate physiological reactions (Kabata-Pendias and Pendias, 1984). One of the basic environmental problems is related to the quantities of accumulated metals in plant parts used as food. In addition to the various soil conditions, the uptake of heavy metals by plants is affected by various factors, such as plant species, cultivars, parts and growing stage. Each case of plant contamination by heavy metals is unique and should be studied for a specific environment.

Jung and Thornton (1996) analyzed metal contents in plants around the Sambo mining area and reported that tobacco leaves had elevated concentrations of metals, es- · pecially Cd and Zn, with ranges of 1.8-8.5 mg!kg (DW) and 103-1,620 mg/kg (DW), respectively (Table 6). Spring onions and soybean leaves also played a role of heavy metal accumulator, thus, the regular consumption of these crop plants could pose a potential health problem from long-term metal exposure. They found that crop plants accumulated Cd and Zn much higher than Cu and Pb based on the calculation of accumulation ratio (defined as the metal con­centration in plant divided by the total metal concentration in soil). Relationships between metal concentrations in surface soils and plants for Cd, Pb and Zn have also been assessed and they noted that metal concentrations in plants increase as concentrations in surface soils increase. Cadmium, Pb and Zn concentrations in tobacco leaves increase sharply in accordance with increasing surface soil metal concentrations. The total metal concentrations in soil and pH were sug­gested as main factors influencing metal content in plants based on the stepwise multiple regression analysis (Jung and Thornton, 1996).

Jung and Chon (1997, 1998) investigated the heavy metal concentrations in rice plants, and examined seasonal variations of metal concentrations in rice stalks and leaves sampled in the paddy fields around the Sambo mine. The average concentrations in rice grain grown on the most polluted area, were 0.37 mg/kg Cd, 2.6 mg/kg Cu, 0.5 mg/kg Pb and 22.5 mg/kg Zn (Table 6), which were

significantly higher than those in rice cultivated from unpolluted areas. In Korea, the intake of rice comprises about a half of total dietary intake, and continuously con­suming the rice grain grown on contaminated soils in the study area can be a significant source of metal intake for the

· residents. Relationships between metal concentrations in rice grains and surface soils are shown in Fig. 4. It can be seen that metal concentrations in rice grain increase with in­creasing levels in surface soils, and positive correlation is found (Jung and Thornton, 1997). Average concentrations of Cd and Zn in rice stalks and leaves taken under the oxidizing soil conditions (in September and October) were higher than those under the reducing soil conditions (in July

~ O. Y=O.I32+0.0613X(r=0.96•u)

~ 0. g

'i 0.

-~ .a 13

1.0 2.0 3.0 4.0 5.0

Cd in swface soil (mg/kg)

~ 5. Y • 1.08 + 0.0461 X (r = 0.83°00)

~

~ 4. .! '[ 3.

·M .a 2.

8 20 30 40 50

Cu in swface soil (mg/kg)

. ~ Y = 0.0961 + 0.00137 X (r = 0.89°00)

"0.7

.s:

.! 0.

-~ 8 0. ·c

8.0 7.0

80 70

50 ~ ~ ~ ~ ~ ~ ~ ~

Pb in surface soil (mglkg)

~ Y = 21.4 + 0.00765 X (r = 0.94°00) •

~ 4

~ .! '! 3

·8 .a tJ

500 1000 1500 2000 Zn in swface soil (mglkg)

••• Significant at p < 0.001

2500 3000

Fig. 4. Relationships between metal concentrations in surface soils (0-15 em depth) and rice grains around the Sambo Pb­Zn-barite mine (Jung and Thornton, 1997).

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82 Hyo-Taek Chon et al.

and August) probably due to the high solubilities of metals in the harvest seaSon.

In the Dalsung mining area, metal concentrations in plants varied with the plant species (fable 6). For example, average Cd contents ranged from 0.24 mglk:g (DW) in perilla leaves to 1.88 mglk:g (DW) in spring onions, and the maximum Cd level of 2.2 mglk:g was found in spring onions. Generally, grain samples (com and jujube) contain relatively lower metal concentrations than leafy samples (soybean and spring onion). Metal concentrations in the plants decrease in the order spring onion > soybean leaves > perilla leaves :::::: red peppers > com grain :::::: jujube grain. Although in the same plant species, metal concentrations decrease in the order Zn > Cu > Pb > Cd, the accumulation ratios of elements varied in a different way as Zn > Cd > Cu > Pb, which was the same trend with the Samba mine. Therefore, it can be concluded that heavy metal uptake by plants would be different for each element due to the differences in total metal concentrations in soils and their bioavailabilities.

CONCLUSIONS

Heavy metal contamination in the areas of five typical base-metal mines in Korea was investigated, and the results of each study were compared between sites. Agricultural soil, stream sediment and stream water around each mine were severely contaminated by heavy metals that comprised the ore mineralogy. Although the degree and extent of contamination varied with each mine, the dispersion pattern of metals was mainly controlled by the feature of geography, prevailing wind and the distance from the mine. The main pollution sources are tailings and mine waste materials abandoned without proper cover system, and metals have been continuously released by wind or drainage from the sources.

Most of chemical forms of metals identified by sequential extraction scheme were non-residual fractions, such as ex­changeable, Fe-Mn oxides or organic matter bound form. Those non-residual forms of metals are susceptible to the change of ambient conditions of a nearby environment and have a high potential of bioavailability. In general, Cd and Zn have a higher fraction in exchangeable form than other elements presenting the highest mobility in the soils or sediments.

Analysis of metals in plants from the study areas in­dicates that leafy vegetables, especially tobacco, tend to accumulate higher metal concentrations than grain or fruit crops. In the Samba mining area, significant levels of metals were found in rice grain which can lead to a large amount of metal intake by residents, and relatively high contents in plants were found under the oxidizing conditions rather than the reducing environment. Particularly, Cd and Zn were more easily uptaken by plants due to the different

geochemical solubilities of the metals. Heavy metal contamination will be continuing in the

areas mentioned above, unless the tailings, contaminated soils and sediments as sources of contamination are left without reclamation. It is strongly recommended that an environmental guideline for reclamation in the vicinity of mining area should be set and the environmental impacts of past and present mining activities must be monitored continuously. Finally, a co-work with other disciplinary approach such as medical geology or environmental toxi­cology is needed to investigate the adverse health effects to the residents or animals in the study areas.

ACKNOWLEDGEMENT

This study was financially supported by the Center for Mineral Resources Research(CMR) sponsored by the Korea Science and Engineering Foundation (KOSEF). ·

REFERENCES

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Davidson, C. M., Thomas, R. P., Mcvey, S. E., Perala, R., Littlejohn, D. and Ure, A. M., 1994, Evaluation of sequential extraction procedure for the speciation of heavy metal in sediments: Analytica Chimica Acta, Vol. 291, p. 277-286.

Department of Environment (DoE), 1987, Guidance on the assessment and redevelopment of contaminated land, ICRCL Guidance Note 59/83. 2nd ed.

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Hwang, H. S. and ChoR, H. T., 1995, Dispersion, speciation and adsorption treatment of heavy metals in the vicinity of the Shi-Heung Cu-Pb-Zn mine: Korea Soc. Econ. Environ. Geol. Vol. 28, p. 455-467.

Jeon, D. J., Chon, H. T. and John, Y. W., 1995, Heavy metal contamination in soils, stream sediments and stream waters in the vicinity of Shinyemi Pb-Zn-Fe and the Geodo Cu-Fe mines: J. Korean Inst. Mineral and Energy Resources Engineers, Vol. 32, p. 409423.

Jung, M. C., 1994, Sequential extraction of heavy metals in soils and a case study: Korea Soc. Econ. Environ. Geol., Vol. 27, p. 469-477.

Jung, M. C., 1995, Heavy metal contamination of soils, plants, waters and sediments in the vicinity of metalliferous mines in Korea: Unpublished PhD thesis, University of London.

Jung, M. C., 1996, Cadmium, Cu, Ph and Zn contamination of stream sediments and waters in a stream around the Dalsung Cu-W mine, Korea: Korea Soc. Econ. Environ. Geol. Vol. 29, p. 305-313.

Jung, M. C. and Chon, H. T., 1997, Environmental contamination

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and seasonal variation on heavy metals in paddy fields around i

the Sambo Pb-Zn mine, Korea: Proceedings of the fourth biennial SGA meeting Turku, Finland, p. 911-914.

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Jung, M. C. and Thornton, 1., 1996, Heavy metal contamination of soils and plants in the vicinity of a lead-zinc mine, Korea: Applied Geochemistry, Vol. 11, p. 53-59.

Jung, M. C. and Thornton, 1., 1997, Environmental contamination and seasonal variation of metals in soils, plants and waters in the paddy fields around a Pb-Zn mine in Korea: Science of the Total Environment, Vol. 198, p. 105-121.

Kabata-Pendias, A. and Pendias, H., 1984, Trace elements in soils and plants, CRC Press, Boca Raton, 315p.

Hyo-Taek Chon, is a professor of the School of Civil, Urban and Geosystem Engineering, College of Engineering, Seoul National University. His recent special interests are on the field of environmental geochemistry, exploration geochemistry and resource geology. He received his bachelor degree from the Seoul National University in 1971, and obtained master and Ph.D. degrees from the same University in 1973 and 1979, respectively. He has also undertaken his post-doctorate research work at the University of Tokyo in Japan and at the Imperial College, University of London in England U.K

Joo Sung Ahn, is an assistant of the School of Civil, Urban and Geosystem Engineering, Collego of Engineering, Seoul National University. He received bachelor and master degrees from the above University in 1994 and 1996 respectively and is currently preparing the Ph.D thesis on environmental investiga­tion and remediation technology for an abandoned Au-Ag mine area.

Hyo-Taek Chon Joo Sung Ahn

Kim, S. H. and Chon, H. T., 1993a, Contamination of heavy metals in soils in the vicinity of the Sambo Pb-Zn-Barite mine: J. Korean Inst. Mineral and Energy Resources Engineers, Vol. 30, p. 228-237.

Kim, S. H. and Chon, H. T., 1993b, Contamination of heavy metals in stream sediments in the vicinity of the Sambo Pb­Zn-Barite mine: Jour. Korean Inst. Mining Geol., Vol. 26, p. 217-226.

Kloke, A, 1979, Content of arsenic, cadmium, chromium, fluorine, lead, mercury, and nickel in plants grown on contaminated soil: paper presented at United Nations-ECE Symp.

Ross, S. M. (Ed.), 1994, Toxic metals in soil-plant systems, John Wiley & Sons Ltd, Chichester, 469p.

Tessier, A., Campell, P. G. C. and Bisson, M., 1979, Sequential extraction procedure for the speciation of particulate trace metals: Anal. Chern., Vol. 51, p. 844-851.

Myung Chae Jung, is a lecturer of the Department of Earth Resources and Environmental Geotechnics Engineering at Semyung University. His research has focused on investiga­tion and evaluation on environmental contamination of soils and groundwaters, and development of the remediation system for those contaminated sites. He receive BSc and MSc degrees in the Department of Mineral and Petroleum Engineering, Seoul National University in 1989 and 1991, respectively, and Ph.D degree in the field of environmental geochemistry from Imperial College, University of London in 1995 (E-mail; imc65@ chollian.net ).

Myung Chae Jung

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