Geological Society of Malaysia Annual Geological Conference 2001 June 2-3 2001, Pangkor Island, Perak Darul Ridzuan, Malaysia

Minor and trace metals in slurry slime in mined-out ponds in the Kinta Valley, Perak

CHOW WENG SUM

Minerals and Geoscience Department Malaysia 201h Floor, Tabung Haji Building, Jalan Tun Razak,

P.O.Box 11110, 50736 Kuala Lumpur

Abstract: The Kinta Valley was renowned as the largest tin field in the world and up to 1989, there were 70,158 hectares of land under mining leases. Thereafter, the tin mining industry took a down-tum due to falling tin metal prices and what is left of the industry is now mined-out land with abundant abandoned ponds. Stretching from Pengkalan near lpoh to Kampar in the south over a distance of 42km, there is a total of 1,194 mined-out ponds. About 66.7% of these ponds have slurry slime at the pond bottoms, with thickness varying from O.lm to 7.0m. Many of these abandoned ponds are used for the rearing of fish and ducks, or are cultivated with lotus plants. Slime is occasionally admixed with tailing sand for agricultural purposes. As such, should the slime be contaminated with heavy metals the food chain will be affected. Slime from eight ponds in the Kinta Valley was tested for minor and trace metals. Most of the slime contained higher concentrations of uranium and other trace heavy metals such asSn, Hg, Sb, 8i and Cd as compared to the norm in the earth's crust or stream sediments. Amongst the eight test ponds, slime from Pond 881 contained relatively higher concentrations of minor, radioactive and trace metals. Slime from Pond 881 should not be utilised as fill material as the concentration of as is above the trigger concentration and threshold value. It should also not to be used for the planting of crops as the level of zinc is high.

INTRODUCTION

The Kinta Valley was renowned as the largest tin field in the world and up to 1989, there were 70,158 hectares of land under mining leases. Thereafter, the tin mining industry took a down-tum due to falling tin metal prices and what is left of the industry is now mined-out land with abundant abandoned ponds. Stretching from Pengkalan near lpoh to Kampar in the south over a distance of 42km, there is a total of 1,194 mined-out ponds (Figure 1). About 66.7% of these ponds have slurry slime at the pond bottoms, with thickness varying from 0.1m to 7 .Om. Some of these ponds have been utilised for the rearing of fish or ducks. Some of the more shallow ponds are cultivated with lotus plants and the seeds and roots of the plants are considered a culinary delicacy. Slime from some of the ponds has also been recovered and admixed with tailing sand for agricultural purposes.

As slurry slime from these mined-out ponds is derived from the beneficiation of mineralised residual soil or alluvium, it may contain unusually higher concentrations of heavy metals such as Fe, Cu, Zn or As, which are associated with gangue minerals such as arsenopyrite, pyrite, chalcopyrite or sphalerite. Should fishes ingest such slurry slime or crops cultivated on such slime, the plants and fishes may absorb the heavy metals and may contaminate the food chain.

OBJECTIVES OF INVESTIGATION

The objectives of this investigation are to determine if the concentrations of metals in the slurry slime are hazardous

to the environment and to study whether concentrations of precious, radioactive, minor or trace heavy metals present in the slurry slime conform to the norm in earth's crust or are similar to that in the stream sediments.

METHOD OF STUDY

To study the distribution of heavy metals in the slurry slime, eight ponds, five of which (Ponds E814, B72, B20, B 141 and B81) are left overs of the palong method of mining and the remaining three (Ponds B 122, B 127 and BS) which are abandoned dredged ponds were selected (Table 1).

Slurry slime was collected with a slime bailor and air­dried and then crushed in an agate mortar. The crushed samples were sieved to minus 80 mesh. A portion of the sieved samples was analysed by Atomic Absorption Spectrophotometer for bismuth (Bi), cadmium (Cd), chromium (Cr), lead (Pb), copper (Cu), zinc (Zn), cobalt (Co), nickel (Ni), iron (Fe), manganese (Mn), silver (Ag), molybdenum (Mo) and antimony (Sb). For mercury (Hg), a cold-vapour atomic absorption method was employed using a Coleman MAS-50 analyser. For the analysis of uranium (U), a fluorometer was used.

To analyse for tin (Sn), tungsten (W )and arsenic (As), the samples were further crushed to minus 150 to minus 200 mesh and the colorimetry method modified from Stanton (1966) was employed.

The methods of analyses for all 18 elements were adopted after the Geological Survey Special Paper 3 (GSD, 1981).

302 CHow WENG SuM

Table 1. List of ponds tested for heavy metals in study area.

Pond No. Mukim Longitude Latitude Mining Method Bedrock Geology E814 Kampar 101° 7'37.21" 4° 19' 13.46" Palong Limestone B72 Tg. Tualang 101 ° 4' 14.43" 4° 20' 11.39" Pa1ong Limestone with schist lenses B20 Tg. Tualang 101 ° 3' 18.23" 4° 24' 50.12" Pa1ong Limestone B141 Teja 101 ° 5' 26.58" 4° 22' 3.04" Palong Deep limestone B81 Tg. Tua1ang 101 ° 2' 30.38" 4° 20' 48.60" Palong Schist with limestone lenses Bl22 Tg. Tualang 101 ° 4' 51.64" 4° 21' 46.35" Dredging Limestone with schist lenses B127 Teja 101° 5' 0" 4° 20' 51.03" Dredging Limestone B5 Tg. Tualang 101° 3' 25.06" 4° 24' 28.86" Dredging Deep limestone

1\EOAH i /

!" ~ -

. . '

.'

r <

·' -·,

./'·· ...... _ .i

( I K ELANTAN I

' ,) PAHANG .... .. ,

-~ ~ .....

(

Figure 1. Location of the study area.

NATURAL BACKGROUND VALUES The average abundance of the 18 elements within the

earth's crust are shown in Figure 2. Silver and mercury are found in the order of 1 o-2 ppm in the earth's crust. Of slightly higher concentrations are cadmium, antimony and bismuth, which are found in the order of 10·1 ppm. Uranium, arsenic, tungsten , tin and molybdenum are present in concentrations in the order of 10° ppm. Following these are cobalt, nickel, copper, lead and zinc which are present in the order of 101 ppm in the earth's crust. Of even higher concentrations are chromium, manganese and iron, which are present in the order of 102 ppm, 103 ppm and 104 ppm respectively.

However, it must be borne in mind that the granitic rocks which are found in the Kinta Valley are acidic in

composition and the concentration of elements in the rocks may not conform to that as shown in Figure 2.

Geochemical analyses of stream sediments collected from the Kuala Pilah - Gemas area (Abdul et al., 1995 ), Boundary Range area which is around the Kelantan -Trengganu - Pahang border (Chu et al., 1986), South Kelantan (Chu et al., 1982) and within the Kenyir Reservou in Trengganu (Chow, 1986) (Table 2) showed that mercury is present in the order of 10'2 ppm, silver, 10'2 to 10'1 ppm and uranium 10·1 to 10° ppm. Seven other metals, namely, molybdenum, tungsten, antimony, bismuth, nickel , coba~t

and arsenic have concentrations in the order of 10° ppm. Tin and copper vary between concentrations of 10° to 1 " 1

ppm. Lead, zinc and manganese are present in higher concentrations, with lead and zinc in the order of 101 pp and manganese, 102 ppm. Iron has the highest concentratio.:~ in the stream sediments and are present in the order of 100%.

RESULTS The concentrations of precious (silver), radioactive

(uranium), minor (iron and manganese) or trac e (molybdenum, copper, zinc, chromium, tin , tungsten, mercury, antimony, bismuth, cadmium, lead, nickel, cobalt and arsenic) metals in the slurry slime from the eight test ponds were analysed and compared with the average concentration in the earth 's crust (as depicted in Figure 2 which is after Darnley et al., 1995) and the concentrations in stream sediments (Table 2) in the Kuala Pilah-Gema" area (Abdul et al., 1995), Boundary Range area (Chu et al. , 1986), South Kelantan area (Chu et al., 1982) and th Kenyir Reservoir area (Chow, 1986).

Precious Metal

One precious metal silver (Ag) was analysed. Silve1· (A g) is normally present in low concentrations in the earth ' s crust and in the stream sediments (in the order of 10-z ppm).

Silver(Ag) All slurry slime samples, except for two, B 1_41/S 1 and

B 127 /S2, had concentrations of silver (Ag) (Table 3) highe.,.. than the average in the earth 's crust which is in the orde of 10·2 ppm (Figure 2) as well as that of stream sediment~· from the Kuala Pilah - Gemas area, Boundary Range area ,

Geological Society of Malaysia Annual Geological Conference 2001

MINOR AND TRACE METALS IN SLURRY SLIME IN MINED-OUT PONDS IN THE KINTA V ALLEY, PERAK 303

Table 2. Concentrations of precious, radioactive, minor and trace metals in stream sediments. Note: Geochemical results of the Kuala Pilah - Gemas area are after Abdul eta/., 1995; the Boundary Range area after Chu et al., 1986; the South Kelantan area after Chu et al. , I 982; and the Kenyir Reservoir area after Chow, 1996.

Total no. Locality Mo Cu Zn Cr Sn w of samples ppm ppm ppm ppm ppm ppm

512 Kuala Pilah - 1.0 30.0 29.0 - 10.0 3.0 Gemas area

3844 Boundary Range area (Kelantan-Terengganu u 9.4 43.0 5.2 2.5 -Pahang border)

4360 South Kelantan 1.4 12.0 40.0 9.0 1.4

1000 Kenyir Reservoir 1.5 6.4 37.0 6.0 2.6

South Kelantan area and Kenyir Reservoir area which varied from 0.02 to 0.16 ppm (Table 2).

Pond B81 in particular contained high concentrations of si lver, with values recording 0.7 ppm between a depth of 4.5 to 5.5m and 1.00 ppm at a depth of 6.5. to 7.5 mm.

Radioactive Metal

Uranium, which is radioactive was analysed. In the earth's crust, uranium is present in the order of 10° ppm (Figure 2) and in stream sedim~nts, 10·1 to 10° ppm (Table 2).

Uranium (U)

Most of the slurry slime samples have concentrations of uranium which are comparatively higher (Table 3) than that in the earth's crust (Figure 2) or in the stream sediments from the Kuala Pilah - Gemas, Boundary Range, South Kelantan and the Kenyir Reservoir areas where the uranium varied between 0.19 to 1.20 ppm (Table 2). Slurry slime in Pond B81, in particular, contained elevated concentrations of uranium, reaching up to 21 ppm between a depth of 3.5 to 5.5m.

Minor Metals

Two minor metals, iron and manganese were analysed. These two metals are normally present in the order of I 04

ppm and 103 ppm respectively in the earth's crust (Figure 2). In the stream sediments, iron is present in the order of 104 ppm or (10° %) and Mn 102 ppm (Table 2).

Iron (Fe)

Except for Pond B81 which had between 2.0 to 2.6% of Fe at a depth of 3.5 to 8.5m, all other samples in the remaining 7 ponds generally had between 0.4 to 1.3% of iron (Table 4). These concentrations are close to the average in the earth's crust (Figure 2) as well as that of stream sediments in the Kuala Pilah - Gemas, Boundary Range, South Kelantan and Kenyir Reservoir areas which varied between 1.9 to 2.1 % (Table 2).

Manganese (Mn)

The concentration of Mn in the slurry slime in most ponds generally varied between 115 to 430 ppm (Table 4) which is below the average concentration in the earth's

June 2-3 2001, Pangk.or Island, Malaysia

Hg Sb Bi Cd Pb Ni Co As Fe Mn Ag u ppm ppm ppm ppm ppm ppm ppm ppm % ppm ppm ppm

0.07 2.0 1.0 14.0 4.0 4.0 8.0 1.9 155 0.08 1.17

0.06 19.0 3.7 3.7 /6.0 2.0 250 0.02 0.19

0.06 16.0 5.0 5.0 4.0 2.1 240 0.16 0.3

- 19.0 2.8 4.4 6.6 2.0 120 0.05 1.20

crust (Figure 2), but is very close to the stream sediments from the Kuala Pilah - Gemas, Boundary Range, South Kelantan and the Kenyir Reservoir areas which varied between 120 to 250 ppm (Table 2). However, at certain depths in Ponds B 18, E814 and B20, the concentration of manganese was slightly higher. At a depth of 3.5 to 8.5m in Pond B8 1, the concentration of manganese was between 501 to 792 ppm. Pond B20 had between 576 to 605 ppm at a depth of 5.6 to 9.6m. The entire profile of slurry slime in Pond E8 I 4 had high concentrations of manganese varying between 577 to 629 ppm.

Trace Metals

Fourteen trace metals with concentrations less than 100 ppm were analysed. The elements were molybdenum, copper, zi nc, chromium, tin, tungsten, mercury, antimony, bismuth, cadmium, lead, nickel, cobalt and arsenic.

Molybdenum (Mo)

Slurry slime samples from all ponds, except that from Pond B 122, had molybdenum varying between 1.8 to 5.2 ppm (Table 5). These values are close to the average concentration in the earth's crust (Figure 2), as well as that in the stream sediments from the Kuala Pilah - Gemas, Boundary Range, South Kelantan and Kenyir Reservoir areas where concentrations of 1.0 to 1.5 ppm were recorded (Table 2). The concentration of molybdenum in slurry slime in Pond Bl22 was relatively higher, varying between 12 to 19 ppm.

Copper(Cu)

The concentration of copper in slurry slime in five of the ponds (B 122, B 127, E814, B72 and B20) varied between 11 to 30 ppm. Slurry slime in Pond B81 contained relatively higher concentrations of Cu, varying between 36 to 81 ppm (Table 5). These concentrations are generally within the average concentration in the earth's crust, which is in the order of l 0 1 ppm (Figure 2) as well as that in the stream sediments in the Kuala Pilah - Gemas, Boundary Range, South Kelantan and Kenyir Reservoir areas which varied between 6.4 to 30.0 ppm (Table 2). Slurry slime from the remaining two ponds B5 and B141 however, contained lower concentrations of Cu, varying between 4 to 10 ppm.

304 CHow WENG SuM

Table 3. Concentration of precious and raclioactive metals in slurry slime.

Pond Sample Sample Depth (m) Precious Radioactive No. No. Metal Metal

From To ~id-point Ag (ppm) U (ppm) S1 0.9 1.9 1.4 0.05 2.1

8141 S2 1.9 2.9 2.4 0.10 3.4 S3 2.9 3.9 3.4 0.20 4.5 S4 3.9 4.9 4.4 0.30 5.8 Cil 1.!:> ~.!:> ~.u U . ~U f.J S2 2.5 3.5 3.0 0.40 10.6 S3 3.5 4.5 4.0 0.40 21.3

881 S4 4.5 5.5 5.0 0.70 21.0 S5 5.5 6.5 6.0 0.50 15.9 S6 6.5 7.5 7.0 1.00 18.8 S7 7.5 8.5 8.0 0.60 13.8 :::>1 ~.1 ::!.1 ~.b U.1U 1~.!:>

S2 3.1 4.1 3.6 0.20 12.7 8122 S3 4.1 5.1 4.6 0.20 11.5

S4 5.1 6.1 5.6 0.30 13.5 S5 6.1 7.1 6.6 0.40 14.4 S6 7.1 8.1 7.6 0.30 17.0 :::>1 l.tl ~.ts ~.::! u.~u !:l.tl

S2 2.8 3.8 3.3 0.05 9.8 S3 3.8 4.8 4.3 0.30 10.7

8127 S4 4.8 5.8 5.3 0.10 14.9 S5 5.8 6.8 6.3 0.20 11.0 S6 6.8 7.8 7.3 0.30 9.7 S7 7.8 8.8 8.3 0.20 8.0 S8 8.8 9.8 9.3 0.20 11.6 :::> 1 ~.1 ::!.1 ~.!:> U.::!U

~~:~ S2 3.1 4.1 3.5 0.40 B5 S3 4.1 5.1 4.5 0.30 10.9

S4 5.1 6.1 5.5 0.30 11.2 S5 6.1 7.1 6.5 0.10 9.5 S6 7.1 8.1 7.5 0.20 10.9 S7 8.1 9.1 8.5 0.10 9.8

~~ 1.ts ~.ts ~.::! U.!:JU tl .!:l E814 2.8 3.8 3.3 0.30 5.9

S3 3.8 4.8 4.3 0.30 6.3 S4 4.8 5.8 5.3 0.40 5.8 :::>1

~:~ Ui 1.1 U.1U i<:.U S2 2.6 2.1 0.30 12.3 S3 2.6 3.6 3.1 0.40 12.6

872 S4 3.6 4.6 4.1 0.40 13.3 S5 4.6 5.6 5.1 0.20 13.1 S6 5.6 6.6 6.1 0.20 12.3 S7 6.6 7.6 7.1 0.30 12.4

~~ U.ti 1.0 1.1 U.1U 11.1 1.6 2.6 2.1 0.10 11 .9

S3 2.6 3.6 3.1 0.20 12.5 S4 3.6 4.6 4.1 0.20 13.2

820 S5 4.6 5.6 5.1 0.20 11 .1 S6 5.6 6.6 6.1 0.30 14.3 S7 6.6 7.6 7.1 0.20 13.1 S8 7.6 8.6 8.1 0.30 14.5 S9 8.6 9.6 9.1 0.30 14.6

Zinc (Zn)

The concentration ofzinc in slurry slime in most of the test ponds varied between 39 to 81 ppm (Table 5). These concentrations are close to the average val ue of zinc in the earth's crust, which is in the order of 10 1 ppm (Figure 2) as well as that in the stream sediments in the Kuala Pilah - Gemas, Boundary Range, South Kelantan and Kenyir Reservoir areas which varied between 29 - 43 ppm (Table 2). However, the uppermost layer of slurry in Pond E814, and the layer of slime between 2.5 to 8.5m in Pond B81

Table 4. Concentration of minor metals in slurry slime.

Pond Sample Sam_j)le Der th (m) Minor Metals No. No. From To Mid-point Fe(%) Mn (ppr1)

S1 0.9 1.9 1.4 0.4 116 8141 S2 1.9 2.9 2.4 0.4 130

S3 2.9 3.9 3.4 0.9 220 S4 3.9 4.9 4.4 1.2 316

~~ l.!:l ~ - ~ ~ : ~

i.U 11 !:l 2.5 3.5 1.3 204

S3 3.5 4.5 4.0 2.4 659 881 S4 4.5 5.5 5.0 2.6 792

S5 5.5 6.5 6.0 2.0 501 S6 6.5 7.5 7.0 2.6 771 S7 7.5 8.5 8.0 2.3 524

~~ <: .1 J.1

~:~ 1.J 4U 3.1 4.1 1.2 350

8122 S3 4.1 5.1 4.6 1.1 358 S4 5.1 6.1 5.6 1.2 362 S5 6.1 7.1 6.6 1.2 358 S6 7.1 8.1 7.6 1.1 334

~~ ~ :~ ~ : ~ ~ : ~ u.r ::!1U 0.8 350

S3 3.8 4.8 4.3 0.7 300 8127 S4 4.8 5.8 5.3 0.7 313

S5 5.8 6.8 6.3 0.8 322 S6 6.8 7.8 7.3 0.6 290 S7 7.8 8.8 8.3 0.7 319 S8 8.8 9.8 9.3 0.7 317 ::>1 ~.1 J.1 ~-~ 1 . ~ ~4tl

S2 3.1 4.1 3.5 1.1 212 85 S3 4.1 5.1 4.5 1.0 178

S4 5.1 6.1 5.5 0.9 165 S5 6.1 7.1 6.5 0.8 151 S6 7.1 8.1 7.5 0.9 157 S7 8.1 9.1 8.5 0.9 160

~~ ~ : ~ ~:~ g 1 .~ !)((

E81 4 0.8 629 S3 3.8 4.8 4.3 0.8 588 S4 4.8 5.8 5.3 0.8 592

~~ ~:~ ~:~ ~: ~ 1.U Jots 1.0 302

S3 2.6 3.6 3.1 0.9 260 872 S4 3.6 4.6 4.1 0.9 332

S5 4.6 5.6 5.1 0.9 249 S6 5.6 6.6 6.1 0.7 255 S7 6.6 7.6 7.1 0.8 269

~~ ~:~ ~:~ ~:~ U.tl JUU 0.8 320

S3 2.6 3.6 3.1 0.8 310 S4 3.6 4.6 4.1 0.8 381

820 S5 4.6 5.6 5.1 0.9 478 S6 5.6 6.6 6.1 1.0 '576 S7 6.6 7.6 7.1 1.0 605 S8 7.6 8.6 8.1 1.0 580 S9 8.6 9.6 9.1 0.9 590

contained elevated concentrations of zinc with values of 122 ppm and 127 to 340 ppm respectively.

Chromium (Cr)

The concentration of chromium in slime in all the eight ponds varied between 19 to 36 ppm (Table 5). These va lues are below the average concentration of chromium ir the earth's crust, which is in the order of 102 ppm (Figur 2). The stream sediments in the the Kuala Pilah - Gemas Boundary Range, South Kelantan and Kenyir Reservoir were not analysed for chromium (Table 2).

Geolog ical Society of Malaysia Annual Geological Conference 200

MINOR AND TRACE METALS IN SLURRY SLIME IN MINED-OUT PONDS IN THE KINTA VALLEY, PERAK 305

10_, 10-z 10- 1 10°10 1 10 2 103 10 4 10 5 mo/kQ

H • He ~o ~-- -- -- -- --~----- -- 2 Li 0 Be e B e c • N e 0 • F • Ne -o '--- ------- --,.--- __ ,__-' 10

Na • Mo • AI • Si e p • s • Cl e Ar 0 ------ --,.---~-- -- -- - 18 K e Ca e Sc 0 ~ 0 v • Cr • • ~ . Co e Ni e Cu • Zn e Ga 0 Ge 0 As e Se e Br 0 Kr 0 -- -- -- -- -- __ ,__ ---36 Rb 0 Sr 0 y 0 Zr 0 Nb 0 Ma • Tc 0 Ru 0 Rn 0 Pd e Ag e Cd e I n 0 Sn e Sb e Te e I • Xe 0 1---- --1-- -- -- -- -- -- 54 Cs 0 Ba 0 La 0 Ce ~ 0 REE ~ 0 Hf 0 Ta 0 w 0 Re 0 Os e ATOMIC lr 0 NUMBER Pt e Au 0 Ho • T l e Pb e Bi 0 :o • e Known btologicol effects R~ • ____ 0 Biological effects uncertain SG Fr e based on Krouskapf,1979 Ra e and Mo rkert, 1992 . Ac e Th • Pa e u •

1C)3 1<r2 \C)1 1Cf 10 1 10 2 10 3 10 4 10 5

Figure 2. Abundance of metals in the earth's crust, by order of magnitude (after DarnJey et al., 1995).

June 2-3 2001, Pangkor Island, Malaysia

Tin (Sn) Slurry slime samples in seven of the ponds (B 141,

Bl22, Bl27 , B5 , E814, B72 and B20) contained between 20 to 70 ppm of Sn (Table 5). These tin values are higher than the average concentration in the earth's crust (Figure 2) as well as that in the stream sediments in the Kuala Pilah - Gemas, Boundary Range, South Kelantan and Kenyir Reservoir areas (Table 2) which is in the order of 10° ppm. The concentration of tin values in Pond B81 were very high, varying between 140 to 240 ppm.

Tungsten (W)

The content of Win six of the ponds [B141, B122, B 127, (except for a section between 1.8 to 2.8m depth), B5, B72 and B20] varied between 8 to 16 ppm (Table 5). These values are close to the average concentration of tungsten in the earth's crust (Figure 2) as well as that in the stream sediments in the Kuala Pilah - Gemas, Boundary Range, South Kelantan and Kenyir Reservoir areas (Table 2), which is in the order of 10° ppm. At depths between 2.5 to 8.5m in Pond B81 and between 2.8 to 6.8m in Pond E814, the concentrations of tungsten were slightly higher, with values varying between 28 to 60 ppm and 20 to 40 ppm respectively.

Mercury (Hg)

Slime in five ponds (B81, B 122. B5, B72 and B20) had 0.10 to 0.24 ppm of mercury (Table 5). The remaining three ponds (B 141, B 127 and E814) had higher concentrations of mercury, varying between 0.26 to 0.54 ppm. These concentrations of mercury (in all 8 ponds) are above the average concentration in the earth's crust (Figure 2) as well as that in the stream sediments in the Kuala Pilah - Gemas, Boundary Range, South Kelantan and Kenyir Reservoir areas (Table 2), which is in the order of 10-2

ppm.

Antimony (Sb)

The concentration of antimony in the eight test ponds generally varied between 1 to 8 ppm (Table 5). However, Pond B81 had slightly higher concentrations of antimony, with values between 9 to 14 ppm. The concentration of antimony in the slurry slime in all eight test ponds are higher than the average concentration in the earth's crust, which is in the order of I0- 1 ppm (Figure 2). However, the concentration is close to that in the stream sediments in the Kuala Pilah - Gemas area which have a concentration of 2 ppm (Table 2).

Bismuth (Bi)

The concentration of bismuth in the slurry slime in most ponds varied between 1 to 7 ppm except for Pond B81 where the concentration varied between 12 to 21 ppm and in the upper layer of the slurry slime (between a depth of 1.8 to 5.8m) in Pond B127 where the concentration of bismuth varied between 8 to 14 ppm (Table 5). These

306 CHow WENG SuM

Table 5. Concentration oftrace metals in slurry slime.

Pond Sample Sample epth (m) No. No. From To Mid-point Mo Cu Zn Cr

S1 0.9 1.9 1.4 2.9 4 39 17 8141 S2 1.9 2.9 2.4 3.7 5 42 19

S3 2.9 3.9 3.4 3.4 7 55 23 S4 3.9 4.9 4.4 4.4 8 66 24

~~ 1.5 2.5 ~.u 4.~ ;jt) (~

~~ 2.5 3.5 3.0 . 4.2 42 127 S3 3.5 4.5 4.0 4.3 71 310 34

881 S4 4.5 5.5 5.0 5.1 75 340 35 S5 5.5 6.5 6.0 4.2 67 280 32 S6 6.5 7.5 7.0 5.2 81 270 36 S7 7.5 8.5 8.0 5.2 76 250 34

~~ ~.1 J.1 ~.ti 1!:1 ~~ ~~ ~~ 3.1 4.1 3.6 16

8122 S3 4.1 5.1 4.6 15 15 70 27 S4 5.1 6.1 5.6 15 15 71 25 S5 6.1 7.1 6.6 15 15 69 23 S6 7.1 8.1 7.6 12 12 68 23

s~ l.tl ~.tl ~.;j l.tl 14 (';) ~1

2.8 3.8 3.3 2.4 14 73 21 S3 3.8 4.8 4.3 2.5 13 73 22

8127 S4 4.8 5.8 5.3 3.1 12 70 20 S5 5.8 6.8 6.3 3.2 12 76 21 S6 6.8 7.8 7.3 2.6 12 72 19 S7 7.8 8.8 8.3 2.6 13 66 19 S8 8.8 9.8 9.3 2.7 12 70 19

~~ 2.1

~:~ 2.0 121.!! ~u ~~ ~~ 3.1 3.5 3.5 85 S3 4.1 5.1 4.5 3.6 9 65 23

S4 5.1 6.1 5.5 3.5 8 56 21 S5 6.1 7.1 6.5 3.3 8 57 20 S6 7.1 8.1 7.5 3.5 8 60 20 S7 8.1 9.1 8.5 3.3 8 58 20

E814 ~~ 1.!! 2.!! 2.3 4.4 JU 1~~ ~1

2.8 3.8 3.3 4.1 20 81 19 S3 3.8 4.8 4.3 4.1 20 79 19 S4 4.8 5.8 5.3 3.4 21 81 19

s~ u.o 1.0 1.1 J.ti 14 titi ~1

1.6 2.6 2.1 3.6 13 62 20 S3 2.6 3.6 3.1 3.4 12 59 19

872 S4 3.6 4.6 4.1 2.9 13 69 20 S5 4.6 5.6 5.1 3.2 12 62 22 S6 5.6 6.6 6.1 3.5 11 60 18 S7 6.6 7.6 7.1 3.3 11 57 18 ::i1 U.ti 1.0 1.1 2.0 11 tiU lf S2 1.6 2.6 2.1 2.8 13 62 17 S3 2.6 3.6 3.1 3.0 13 62 17 S4 3.6 4.6 4.1 3.4 14 62 18

820 S5 4.6 5.6 5.1 3.0 16 63 17 S6 5.6 6.6 6.1 3.4 17 68 20 S7 6.6 7.6 7.1 3.1 18 76 22 S8 7.6 8.6 8.1 3.3 18 76 23 S9 8.6 9.6 9.1 3.3 19 78 23

concentrations are above the average in the earth's crust, which is in the order of 10·1 ppm (Figure 2) as well as that in the stream sediments in the Kuala Pilah - Gemas area which have a concentration of 1 ppm (Table 2).

Cadmium (Cd) The concentration of cadmium in slurry slime in almost

all the test ponds was fairly constant with a concentration of 1 ppm except for Pond B81 where between a depth of 3.5 to 8.5m, the concentration of the cadmium was 2 ppm (Table 5). These concentrations (i.e. 1 to 2 ppm), are relatively higher than the average concentration on the

Trace Melflls (pprn) Sn w Hg Sb 8i Cd Pb Ni Co As 40 8 0.40 1 1 1 36 5 1 10 20 16 0.42 1 2 1 34 6 1 15 20 8 0.44 1 2 1 56 9 3 10 30 12 0.42 1 3 1 72 10 4 10

~ri~ 2!!8 U.1ti lU 10 1

1~~ r4 ~ ~~ 0.18 9 12 1 200 40 0.12 10 12 2 165 30 8 100 200 40 0.10 9 14 2 181 32 8 100 240 60 0.12 9 18 2 167 25 7 150 200 32 0.10 12 19 2 210 33 9 100 240 60 0.14 14 21 2 230 29 6 200

~~ 1!!2 0.22 1 4 1 tif

~~ ~ ~~ 0.24 1 5 1 67 20 16 0.24 3 3 1 67 11 5 15 40 12 0.22 1 2 1 66 11 5 20 30 12 0.18 1 4 1 62 11 5 20 40 16 0.18 1 1 1 63 11 5 20 4U

~~ K~~ l ~4 ~ {';) 1~ ti 1';)

40 75 12 7 10 20 16 0.28 6 10 1 76 11 6 10 30 16 0.26 4 8 1 74 11 7 10 40 16 0.28 5 3 1 71 12 7 10 35 12 0.34 5 3 1 69 10 6 10 30 12 0.32 4 1 1 69 11 6 10 20 8 0.34 4 5 1 70 11 6 15 ~u lZ U.1tl ';) 4 1

~~ ~ 4

~~ 20 8 0.22 1 4 1 4 20 8 0.20 2 4 1 61 9 4 10 20 8 0.20 1 4 1 65 8 4 10 30 8 0.20 3 4 1 56 8 4 10 30 8 0.22 4 2 1 61 8 3 10 30 6 0.22 3 2 1 60 8 3 10 ru ~u U.;jti tl 1 1 ts!:l 21

~ ~~ 40 40 0.54 4 1 1 65 21 40 24 0.54 2 3 1 65 21 8 10 40 24 0.54 5 2 1 66 20 8 10 tiU lU u.~2 1 ti 1

~~ n : 1U 60 10 0.22 1 6 1 10 50 8 0.22 1 6 1 70 10 4 15 40 8 0.24 1 6 1 76 10 5 20 40 2 0.20 1 3 1 79 10 4 15 30 8 0.18 3 2 1 76 8 4 15 40 8 0.18 2 4 1 73 9 4 25 ;jU ts U.12 1 4 1

~~ ~ : ~ 30 8 0.12 1 4 1 35 8 0.14 1 4 1 58 9 4 10 35 12 0.14 1 4 1 62 10 5 10 40 8 0.12 3 6 1 60 10 4 15 50 12 0.18 3 6 1 64 10 6 20 50 8 0.16 3 5 1 69 13 6 20 60 16 0.18 3 6 1 70 14 6 20 60 16 0.18 3 6 1 70 14 6 15

earth's crust which is in the order of 10·1 ppm (Figure 2).

Lead(Pb) The concentration of the lead in slurry slime in almost

all the ponds varied between 34 to 89 ppm except for Pond 81 where the concentration of lead was relatively higher, with values· between 89 to 230 ppm (Table 5). These concentrations are within the average in the earth's crust, which is in the order of 101 ppm (Figure 2) and close to that in the stream sediments in the Kuala Pilah - Gemas, Boundary Range, South Kelantan and Kenyir Reservoir areas which varied between 14 to 19 ppm (Table 2).

Geological Society of Malaysia Annual Geological Conference 2001

MINOR AND TRACE METALS IN SLURRY SLIME IN MINED-OUT PONDS IN THE KINTA VALLEY, PERAK 307

Nickel (Ni) The concentration of nickel in the slurry slime in six

of the ponds (Bl27, B5, B72, B20, Bl41, Bl22) varied between 5 to 14 ppm (Table 5). The remaining two ponds (B81 and E814) had higher concentrations of nickel. At a depth between 3.5 to 8.5m in Pond B81, the slurry slime contained 25 to 33 ppm of nickel. Pond E814, likewise, had relatively higher concentrations of nickel, with values between 20 to 21 ppm. These concentrations are of similar quantum as the average in the earth's crust which is in the order of I0-1 ppm (Figure 2), but are slightly higher than those in the stream sediments in the Kuala Pilah - Gemas Boundary Range, South Kelantan and Kenyir Reservoi; areas where 2.8 to 5.0 ppm of Ni were recorded (Table 2).

Cobalt(Co) The concentration of cobalt in slurry slime in all the

eight ponds varied between 1 to 9 ppm (Table 5). These concentrations are lower than the average in the earth's crust, which is in the order of 101 ppm (Figure 2). However, these concentrations are almost similar to that in the stream sediments in the Kuala Pilah - Gemas, Boundary Range, South Kelantan and the Kenyir Reservoir areas where there are 3.7 - 5.0 ppm of cobalt (Table 2).

Arsenic (As)

The concentration of arsenic in slurry slime in almost all the ponds (except for Pond B81) varied between 10 to 25 ppm (Table 5). In Pond B81, the concentrations of arsenic at a depth between 2.5 to 8.5m were relatively higher, varying between 40 to 200 ppm. These concentrations are slightly higher than the average in the earth's crust, which is ih the order of 10° ppm (Figure 2) as well as that in the stream sediments in the Kuala Pilah - Gemas, Boundary Range, South Kelantan and the Kenyir Reservoir areas where ~.0 to 8.0 ppm of arsenic were present.

HEAVY METAL TOXICITY

Rowell (1994) had suggested that high concentrations of zinc, copper, nickel and boron had direct effects on the growth of crops. Other elements/metals like cadmium, lead, mercury, molybdenum, selenium, chromium and fluorine ~re non-toxic to crops but they may affect animals feeding m the crops grown over soils which contain high concentration of the elements/metals.

In England, the concept of "trigger concentrations" (ICRCL, 1987) which is directly related to the intended use of a site, has been introduced to determine the maximum concentration of contamination allowable in a site. In Europe, the concept of "threshold concentration" (Wild, 1993) which addresses the same problem, albeit on a less stringent level, is adopted. The limits of trigger concentration and threshold concentration are given in Table 6. Soil samples having concentrations of elements/metals below

June 2-3 2001, Pangkor lsland, Malaysia

the trigger or threshold concentrations are regarded as uncontaminated. On the other hand, soil samples with concentrations of elements/metals exceeding the trigger and threshold concentrations should be considered as toxic, particularly to agricultural practices and some remedial action has to be implemented.

It was observed that the concentrations of cadmium, chromium, lead, mercury, copper and nickel in the slurry slime were well below the trigger concentrations (of English Standards) and the threshold values (of European Standards).

However, arsenic from slurry slime in Pond B81 were high, varying between 25 to 200 pm and are above the trigger concentrations and threshold values. The concentration of arsenic in slurry slime in certain sections of the profile in the remaining seven ponds were marginally above the trigger concentrations (Table 6).

The concentration of zinc in the slurry slime in seven ponds (B141, B122, Bl27, B5, E814, B72 and B20) were well below the trigger concentrations. However, in Pond B8l, slurry slime from a depth of 3.5 - 5.5m had high concentrations of zinc which were above the trigger concentration of 300 ppm. Further down from 5.5- 8.5m depth, the concentration of Zn (250 - 280 ppm) was very close to .the trigger concentration.

DISCUSSION

i) Slurry slime in Pond B81 contained relatively higher concentrations of minor, precious, radioactive and trace metals (except for mercury, cobalt and cadmium) as compared to that in the other seven ponds. Elevated concentrations of manganese (501-792 ppm), iron (2.0 to 2.6 %), uranium (21 ppm), nickel (25-33 ppm), zinc (127-340 ppm), tungsten (28-60 ppm), lead (80-230 ppm), arsenic (40-200 ppm), silver (0.5 to 1.0 ppm), copper (36-81 ppm), tin (140-240 ppm), antimony (9-14 ppm) and bismuth (12-21 ppm) were present within certain sections of the slurry slime profile in Pond B81. This trend is also reflected in the pond water tested earlier (Chow, 1988) where the concentration of arsenic, iron, manganese were also relatively high and the water was slightly more acidic with a pH of 6.1. The pattern is a reflection of the source material. Pond B81 has limestone-schist bedrock very near to the granite contact. It is likely that the contact zone is mineralised and the slime is in part, derived from these mineralised soils.

(ii) Some of the other seven ponds had elevated concentrations of certain metals at certain depths. Pond E814 had elevated concentrations of manganese (577-629 ppm), mercury (0.36-0.54 ppm) and nickel (20-21 ppm) for the entire slurry slime profile and zinc ( 122 ppm) between 1.8 to 2.8m depth. Pond Bl27 had elevated concentrations of mercury (0.26-0.34 ppm) between depths of 1.8 to 9.8 m and

308 CHow WENG SuM

Table 6. Trigger concentrations and threshold values for selected inorganic contaminants (after ICRCL, 1987).

Contaminants Planned Uses Trigger Concentration, !Jg/g fair( !dried soil), Threshold

Group A: Contaminants which may pose hazards to health Arsenic (As) Domestic gardens, allotments, parks, playing field, open space [10], (40) Cadmium (Cd) Domestic·gardens, allotments, parks, playing field, open space [3], (15) Chromium (Cr) Domestic gardens, allotments, parks, playing field, open space [600], (1,000) Lead (Pb) Domestic gardens, allotments, parks, playing field, open space [500], (2,000) Mercury (Hg) Domestic gardens, allotments, parks, playing field, open space [1], (20)

Group B: Contaminants which are phytotoxic but not normally hazards to health Boron (B) Any uses where plants are to be grown 3 Copper (Cu) Any uses where plants are to be grown 130 Nickel (Ni) Any uses where plants are to be grown 70 Zinc (Zn) Any uses where plants are to be grown 300 Selenium (Se) Domestic gardens, allotments, parks, playing field, open space [3], (6)

Table 7. Distribution trend of metals in slime-slurry profile.

Pond No. Mining Concentration of metals increasing with the Concentration of metals decreasing with the Concentration of metals which remain Method depth of the slurry slime profile depth of the slurry slime profile almost constant in the slurry slime profile

881 Palong Ni, Pb, Mo, Cu, Zn, Cr, Sn, W, Co, 8i, As, Hg Cd Sb, Fe, Mn, Ag, U

820 Palong Ni, Pb, Mo, Cu, Zn, Cr, Sn, W, Co, 8i, As, . Cd Sb,Fe,Mn,Ag,Hg,U

8141 Palong Ni, Pb, Mo, Cu, Zn, Cr, W, Co, 8i, Fe, Mn, Sn Sb,As,Cd Ag,Hg, U

8127 Dredging Mo,Sb,Hg, U Ni, Pb, Sn, W, 8i, Cr, Zn, Cu As,Co,Cd,Ag,Mn,Fe

872 Palong Pb,As,Ag,Sb,U Ni, Sn, W, 8i, Mn, Fe, Hg, Cr, Cu, Zn, Mo Co,Cd

E814 Palong 8i, W,Mn,Hg Ni, Sn, Fe, Cr, Cu, Zn, Mo, Pb, Ag, U, Sb, As Co,Cd

8122 Dredging W,Ag,U Ni, Sn, Fe, Cr, Cu, Zn, Mo, Pb, Mn, 8i, Hg, Co, As, Sb, Cd

85 Dredging Sn,Hg Pb, Mo, Cu, Zn, Cr, W, Sb, Fe, Mn, Ag, U Ni, Co, 8i, As, Cd

bismuth (8-14 ppm) between 1.8 to 5.8 m. Pond B20 had relatively high manganese concentrations of 576-605 ppm between 5.6 to 9.6 m depth. Pond B 141 had relatively high mercury values of 0.40 to 0.44 ppm between depths of 0.9 to 4.9 m. It is likely that the relatively high concentrations of these metals (i.e. manganese, mercury, bismuth and nickel) in the slurry slime in these ponds are attributed to the inherent composition of the original soil.

(iii) Almost all the metals in the slurry slime in Ponds B20 (except for cadmium), B81 (except for mercury, cadmium) and B 141 (except for tin, antimony, arsenic and cadmium), showed an increase in concentration as the depth of the slurry slime profile increased (Table 7). Ponds B72 and E814 showed a different pattern where the concentration of most of the metals (except for lead, arsenic, silver, antimony, uranium, cobalt and cadmium in Pond B72 and bismuth, tungsten, manganese, mercury, cobalt and cadmium in Pond E814) were relatively higher in the uppermost part of the slurry-slime profile, but the concentrations decreased as the depth of the profile increased. All these five ponds are left overs of the palong mining method.

iv) Ponds Bl27, B122 and B5, which are left-overs of the dredging method of mining have a pattern similar to that of Ponds B72 and E814, that. is, the concentrations of most metals (except for tungsten, silver, uranium, cobalt, arsenic, antimony and cadmium in B122, and tin, mercury, nickel, cobalt, bismuth, arsenic and cadmium in B5 and molybdenum, antimony, mercury, uranium, arsenic, cobalt, cadmium, silver, manganese and iron in B 127) decreased as the depth of the slurry­slim~ profile increased (Table 7).

v) Most of the slurry slime samples contain higher concentrations of uranium and other trace heavy metals such as tin, mercury, antimony, bismuth and cadmium as compared to that in the earth's crust or stream sediments. A survey should be carried out to check the level of radioactivity emissions from the slurry slime.

CONCLUSION

i) Slurry slime from Pond B81 should not be utilised for the construction of residential houses or used as fill material for the creation of domestic gardens, parks, playing fields as the concentration of arsenic in the slurry slime is above the trigger concentration and

Geological Society of Malaysia Annual Geological Conference 2001

MINOR AND TRACE METALS IN SLURRY SLIME IN MINED-OUT PONDS IN THE KiNTA VALLEY, PERAK 309

threshold value. The concentration of arsenic in slurry slime from certain sections of the remaining seven ponds are marginally above the trigger concentration and it would be best to blend it with some other low arsenic-bearing slurry slime before being utilised as fill material. As slurry slime from Pond B81 also contained high concentrations of zinc, it should not be used for the planting of crops. The concentrations of toxic metals in the slurry pond in the remaining seven ponds are well below the trigger concentrations and threshold values and can be used as fill material for the development of domestic gardens, parks, playing fields as well as for the planting of crops.

ii) Slurry slime in Pond B81 contained elevated concentrations of precious, radioactive, minor and trace metals (except for mercury, cobalt and cadmium) as compared to the norm in the crustal rocks and stream sediments. The limestone-schist bedrock of the mine-pit is very close to the granite contact and it is likely that the contact zone near the mine is highly mineralised.

iii) Data on the concentration of precious, radioactive, minor and trace metals in the slurry slime is a useful baseline reference for environmental auditing especially for the development of industrial parks in the vicinity of the eight ponds studied.

June 2-3 2001, Pangkor Island, Malaysia

REFERENCE ABDUL, H. ET AL., 1995. Geochemical Exploration Of The Kuala

Pilah - Gemas Area, Negeri Sembilan. Geological Survey Unplublished Report EMR l/95.

CHow, W.S., 1986. Geology And Mineral Resources OfThe Gunung Gajah Terom Area, Sheet48. Geological Survey Unpublished Report (in manuscript).

CHow, W.S., 1998. Studies Of Slurry Slime In Mined-out Ponds, Kinta Valley, Peninsular Malaysia, For Purposes Of Reclamation. Ph. D Thesis, University of Malaya.

CHu, L.H. ET AL., 1982. Regional Geochemistry Of South Kelantan. Geological Survey Geochemical Report l.

CHu, L.H. ET AL., 1986. Regional Geochemistry Of The Boundary Range Area. Geological Survey Geochemical Report 1.

DARNLEY, A.G. ET AL., 1995. A Global Geochemistry Database Of Environment And Resource Management. Final Report of IGCP Project 259.

ICRCL (INTERNATIONAL CoMMITTEE FoR REDEVELOPMENT OF CoNTAMINATED LAND), 1987. Guidance In The Assessment And Redevelopment Of Contaminated Land. ICRCL 59/83, 2nd Edition. CDEPIEPTS Department Of Environment, London.

GSD (GEOLOGICAL SuRVEY DEPARTMENT), 1981. A Manual Of Geochemistry Exploration Methods. Geological Survey Special Page 3.

RoWEL, D.L., 1994. Soil Science Methods and Applications. Longman Scientific and Technical, United Kingdom.