Phytoremediation of soil contaminated with heavy metals using Brassica napus

Jiyeon Park, Ju-Yong Kim and Kyoung-Woong Kim*

School of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), 261 Cheomdam-gwagiro,Buk-gu, Gwangju 500-712, Korea

(Received 9 February 2012; final version received 9 March 2012)

In order to examine the feasibility of utilizing oil extracted from plant seed in the contaminated areas, the phytoremediationapplicability of soils contaminated with heavy metals and its follow-up result in the production of biodiesel wasinvestigated. Brassica napus was chosen as the main target plant because it is widely used for phytoremediation and is anadvantage of biodiesel production. From the perspective of heavy metal concentrations in Brassica napus, plants grown incontaminated soil show significantly higher concentration than those in non-contaminated soil. From the results ofsequential extraction analysis, it was also found that heavy metal concentrations in plant may be increased with theenhancement of phyto-available fraction of heavy metal in the soil. These results show the feasibility of oil productionextracted from Brassica napus, which was grown in heavy metal-contaminated soil. The seed contains a low concentrationof most kinds of heavy metals except Zn in soil, which is essential for seed growth. The results of oil analysis show that morethan 50% of heavy metal remained in the residues. Therefore, the application of phytoremediation by Brassica napus is afeasible technique for the removal of heavy metals and its following biodiesel production as an energy source is acceptable.

Keywords: phytoremediation; heavy metal; Brassica napus; biodiesel production

Introduction

Soils can be contaminated with heavy metal by various

sources, such as mining, urban and industrial activities

(Hanh, Kim, Bang & Kim, 2010; Teparut & Sthiannopkao,

2011). There have been many remediation technologies

for heavy metal-contaminated soils including physical,

chemical and biological processes (Kim, Moon & Kim,

2001; Lee et al., 2012). Physical and chemical

technologies include soil washing, excavation, extraction,

solidification and stabilization and biological processes

include technologies that use microorganisms or plants

(Chang, Kim & Kim, 2008). There have been a certain

number of case studies and improvements for those

technologies. However, phytoremediation using plants for

the remediation has just been focused on finding a new

hyper-accumulator or enhancing the remediation effi-

ciency (Alkorta et al., 2004; Chang, Kim, Yoshida & Kim,

2005; Szczygłowska, Piekarska, Konieczka & Namiesnik,

2011; Turan & Esringu, 2007).

An interesting question can be raised at the following

step. The first question may be how heavy metal that is

accumulating in plants can be managed. The only possible

method introduced in this stage is to burn the plant, which,

in turn, reduces the mass volume of the heavy metal

accumulated in the plant but accumulates heavy metals in

the ash. In this case, the remaining ash of the burnt plant

should be discarded although green energy such as

biomass or biodiesel can be obtained from the plant. This

paper introduces a method for managing heavy metals

accumulated in plants by utilizing energy crop. Brassica

napus was chosen as the main target plant because it is

widely used for phytoremediation and contains a

significant amount of energy sources (e.g. oil) in its seeds.

Brassica napus belongs to the Brassicacea family and

some members of the Brassicacea family have shown their

abilities of heavy metal accumulation in many previous

studies. Brassica Juncea (Indian mustard), for instance, is

well known as a Cd, Cu, Ni, Zn, Pb-hyperaccumulator

(Banuelos & Meek, 1990; Gisbert et al., 2006; Nanda-

Kumar, Dushenkov, Motto & Raskin, 1995). Thlaspi

caerulescens is also reported as a Zn-hyperaccumulator

(Chaney, 1983) and Brassica napus (also called rape) has

shown the potential of heavy metal accumulation from

many case studies (Angelova, Ivanova, Todorov &

Ivanovi, 2008; Marchiol, Assolari, Sacco & Zerbi, 2004).

Currently, many researchers focus on Brassica napus

from the aspect of phytoremediation as well as biodiesel

production and Brassica napus is one of the most common

biodiesel sources due to its large quantities worldwide.

Brassica napus contains 40–44% of oil in its seed

(Laaniste, Joudu & Eremeev, 2004) and therefore

phytoremediation using Brassica napus is important for

both decontamination of heavy metal from the soil and its

resulting biodiesel production.

The objectives of this research are: (1) to evaluate the

feasibility of using Brassica napus for phytoremediation to

ISSN 1226-9328 print/ISSN 2166-3394 online

q 2012 Taylor & Francis

http://dx.doi.org/10.1080/12269328.2012.674428

http://www.tandfonline.com

*Corresponding author. Email: kwkim@gist.ac.kr

Geosystem Engineering

Vol. 15, No. 1, March 2012, 10–18

remove heavy metals from contaminated soils; (2) to

investigate the characteristics of heavy metal accumu-

lation in plants; (3) to examine the feasibility of oil

extraction from the produced rape (Brassica napus) seed.

Materials and methods

Site description

Soil and plants were collected from the agricultural area

near the Jang-Hang smelter (Figure 1). The Jang-Hang

smelter was one of the biggest dry refining smelters located

in Chungnam province, South Korea and was used as a

copper refinery from 1936. However, the blast furnace has

been closed since 1986 due to sulfur dioxide gas, which

caused a serious problem to the cultivated crop. Recently,

the issue that residents near the Jang-Hang smelter are

suffering from cancer is controversial. In addition to this

problem, most of the nearby areas were contaminated with

Cu, Zn, Cd, Pb and As. Within 0.5 km radius of the chimney

in the Jang-Hang smelter, heavy metal concentration

exceeds the level of Korean acting criteria (Cd 4, Cu 125,

Pb 300, Zn 700 and As 15mgr1 kg21). In addition, within

1.5,4 km radius of the pollutant source, only As

concentration exceeds the level of Korean warning criteria

(As 6mgr1 kg21). The fact that cultivation is being damaged

in the agricultural area by much heavy metal contamination

from the Jang-Hang smelter is still an ongoing problem e.

The detailed geochemical soil survey conducted

under the supervision of the Environment Management

Corporation and Mine Reclamation Corporation fromMay

2008 to February 2009 prohibited cultivation and only the

rape species is cultivated around the agricultural area for

scenic purposes.

Sample collection

The preliminary sampling was to examine the accumu-

lation ability of heavy metals by Brassica napus. There-

fore, samples of soil and Brassica napus were collected

from the study site of the Jang-Hang area and the control

site, which was far away from Jang-Hang and without

contamination. Brassica napus was collected from this site

at almost same stage of growth as that from the Jang-Hang

sample and was used as the control. The Brassica napus

used in this experiment is a relatively young plant with a

flower that is not yet producing the seed.

The main sampling was to investigate the character-

istics of heavy metal accumulation as well as the feasibility

of oil extracted from the seed. The soil was collected from a

depth of 0–10 cm from 12 points that have various

concentrations of heavy metals in nearby agricultural

fields. The soil samples were collected in the rhizosphere

and then put into a polyethylene bag to transfer to the

laboratory. The transferred soil sample was dried at 408C in

an oven for 2 days. Brassica napuswas also collected at the

equivalent points as the soil. After transfer to the

laboratory, the plant was washed with tap water and rinsed

several times with deionized water. The plant sample was

Figure 1. Sampling points on the location map of the study area.

Geosystem Engineering 11

separated into five parts, such as seed, flower, leaf, shoots

and roots. Plant tissues were freeze-dried and then

homogenized using a mill by sieving through 1mm mesh

to remove large plant tissues. The oil sample was carefully

extracted from the rape seeds. A home oil squeezer was

used for oil extraction.

Sequential extraction analysis

Sequential extraction can provide useful information

regarding the chemical speciation of As and heavy metal

in the soil. For appropriate extraction of As and heavy

metal, a different method was used for each element. The

sequential extraction method for As was modified from

Wenzel et al. (2001). Arsenic speciation in soil was

classified as the non-specially sorbed phase (step 1), the

specifically sorbed phased (step 2), amorphous and poor

crystalline hydrous oxides of Fe andAl phase (step 3), good

crystalline hydrous oxides of Fe and Al phase (step 4) and

the residual phase (step 5). The sequential extraction

method by Tessier, Campell and Bisson (1979) was used

for other heavy metals. Heavy metal exists in various

forms, such as the exchangeable form (step 1), carbonate

form (step 2), Fe-Mn oxide form (step 3), organic matter

form (step 4) and residual form (step 5). Details of the

procedures are described in Tables 1 and 2.

Analysis of samples

Total concentrations of heavy metal and As in the soil

samples were determined after aqua regia digestion. Total

digestion of 0.4 g soil sample using 4mL of acid mixture

(3:1; HCl: HNO3 by volume) was followed by heating at

708C in a water bath for 1 hr. After the digests were cooled

down, they were filtered using a 0.45mm nylon syringe

filter (Whatman) and the final solution was analyzed by

inductively coupled plasma-optical emission spectrometer

(PerkinElemer 5300 DV).

Concentrations of As and heavy metals in plant tissues

were determined by the wet digestion procedure described

by Hansel, La Force, Fendorf and Sutton (2002). Aliquots

of plant tissues (0.1 g) were digested in 15mL poly-

propylene centrifuge tubes with 2mL of 5% HNO3 for

24 hr. Successive additions of 30% H2O2 (2mL) was then

followed by heating at 100 ^ 28C for 1 hr. The heating

with H2O2 was conducted until plant residues disappeared.

The concentrations of As and heavy metal in the final

solution were analyzed by inductively coupled plasma-

mass spectrometry (ICP-MS, Agilent 7500 CE).

Analysis of heavy metal in the oil sample was

conducted by following the Korea Food and Drug

Administration method. For the pretreatment, 5mL of

electronic grade HNO3 was added to the oil sample

followed by adding 2mL of deionized water. After that, the

oil sample was heated by the microwave digestion method.

Oil solution from the microwave digestion was mixed with

100mL deionized water. Heavy metal concentrations in

the final oil sample were determined by ICP-MS.

Results and discussion

Heavy metal accumulation in Brassica napus

In order to evaluate the accumulation ability of heavy

metal by Brassica napus, the concentration of heavy

metals in plants from the Jang-Hang and the control areas

were compared. Heavy metal concentrations in soils from

Jang-Hang and the control areas are shown in Table 3 and

it was found that heavy metal concentrations from the

control soil were significantly lower than those from the

Jang-Hang soil.

Table 1. Sequential extraction procedure for As (modified from Wenzel et al., 2001).

Step Form Extractant Condition

1Non-specifically sorbedphase 10mL of (NH4)2SO4 (0.05M) 4 hr at 208C

Continuous agitation2 Specifically sorbed phase 10mL of (NH4)H2PO4 (0.05M) 16 hr at 208C

Continuous agitation4 hr at 208C

3

Amorphous and poorcrystalline hydrous oxidesof Fe and Al phase

10mL of NH4-oxalate buffer(0.2 M), pH 3.25Washing: 5mL of NH4-oxalate buffer Continuous agitation

Washing: 10min at 208CContinuous agitation in the dark30min at 96 ^ 38C

4Good crystalline hydrousoxides of Fe and Al phase

10mL of NH4-oxalate buffer(0.2 M) þ ascorbic acid (0.1 M), pH 3.25Washing: 5mL of NH4-oxalate buffer Washing: 10min at 208C

Continuous agitation in the dark5 Residual phase 4mL of HCl þ HNO3 (3:1) 1 hr at 708C

Jiyeon Park et al.12

Figure 2 shows the comparison of heavy metal

concentration in various parts of the plant. Cadmium

concentrations in every specific part of the plant from the

Jang-Hang area were 6 to 16 times higher than those from

the control area with particular reference to the flower part,

16 times higher. For the case of Cu, there was no significant

difference in soils between those from the Jang-Hang and

control areas. This may be explained by the fact that Cu is

an essential element for a plant. However, Pb concen-

trations in each part of the plant from the Jang-Hang area

were significantly higher than those from the control area.

The flower in the Jang-Hang area had accumulated about

15 times higher Pb than that in the control area. Most of the

heavy metals in other parts, such as shoots, leaves, and

roots, showed a great difference in the concentration from

the two different areas. Heavy metal concentrations in

shoots, leaves and roots from the control area were below

the detection limitation. However, plants from the Jang-

Hang area accumulated significantly greater quantities of

Pb. Zinc concentrations in the plants did not show a

difference because Zn is an essential nutrient for plant

growth. Arsenic was accumulated in plant parts up to levels

between 4.7 and 11 times from the Jang-Hang area

compared with the plants from the control area. Arsenic

showed different variations with 10 times higher in shoots,

5.8 times in leaves and 10 times in roots from the Jang-

Hang area compared with those from the control area.

Consequently, a large part of the heavy metals was

extracted from the soil and accumulated in plant tissue.

The results may show the ability of heavy metal

accumulation in Brassica napus. Rossi, Figliolia, Socciar-

elli and Pennelli (2002) also revealed the superiority of

Brassica napus in heavy metal accumulation. According

to their evaluation, the upper threshold of Cd and Zn

accumulation of Brassica napuswas not shown and further

study is required in order to investigate the limitation of

heavy metal accumulation in Brassica napus,

Characteristics of heavy metal accumulation

Phytoavailable heavy metal fraction to Brassica napus

In this experiment, sequential extraction analysis was

used to estimate the phyto-available fraction of heavy

metal to plants. From the results, the assumption that

total metal concentrations in the soil are significantly

related to levels of heavy metal in the plant tissues was

not proved. According to several previous studies, the

phyto-availability of metal fractions is far more

dependent on the exchangeable fraction of heavy metal

than the total metal contents of soils (Kabata, 1993;

Krishnamurti, Smith & Naidu, 2000; Menzies, Donn &

Kopittke, 2007). Extractable heavy metal by MgCl2 (step

1) is significantly related to heavy metal concentration in

Table 2. Sequential extraction procedure for heavy metals (modified from Tessier et al., 1979).

Step Form Extractant Condition

1 Exchangeable 1M MgCl2, pH 7.0 1 hr at 258CContinuous agitation

2 Carbonates 1M NaOAc, pH 5.0 5 hr at 258CContinuous agitation

3 Fe-Mn oxides 0.04M NH2OH*HCl in 25% (v/v) HOAc 6 hr at 96 ^ 38COccasional agitation

4.1 0.02M HNO3 2 hr at 85 ^ 28C30% H2O2

pH 2.0Occasional agitation

4.2 Organic matter 30% H2O2, pH 2.0 3 hr at 85 ^ 28COccasional agitation

4.2 3.2 M NH4OAc in 20% (v/v) HNO3 30min at 258CContinuous agitation

5 Residual Aqua regia (1: 3 HNO3: HCl) 30min at 96 ^ 38COccasional agitation

Table 3. Heavy metal concentrations (mg kg21) in soil from the Jang-Hang area (n ¼ 3).

Cd Cu Pb Zn As

JangHang 0.56 ^ 0.15 95.93 ^ 16.27 182.98 ^ 72.81 76.05 ^ 8.99 66.53 ^ 7.66Control BDL 13.84 ^ 1.87 28.41 ^ 1.91 41.23 ^ 8.97 5.36 ^ 0.82Natural contentsa 0.35 (0.01–2) 25 (,1–700) 19 (,10–700) 60 (,5–2900) 7.2 (0.1–97)

BDL ¼ below detection limit (,0.002 ppm).a Natural contents in soils from US Geological Survey Professional Paper 1270 (1984).

Geosystem Engineering 13

plant roots. However, a significant correlation was not

observed in the other plant parts. This is because plant

roots can directly contact with soil surface. Average R 2

values of heavy metals between soil and plant roots were

around 0.83 except As (Figure 3). Especially, R 2 values

for Pb were significantly higher than those of the others

(Pb-R 2 ¼ 0.94). According to those results, the heavy

metals that the plant can uptake is significantly related to

exchangeable fraction in soil. In the case of As, there

was no relationship between As concentration in roots

and that in non-specifically sorbed phase of soil (step 1)

from the sequential extraction. However, the correlation

was observed in the sum of step 1 and step 2 (Figure 3).

It implies that when exchangeable heavy metals and As

in soil increased, that in the plant can also increase. In

other words, Brassica napus can accumulate heavy

metals as much as phyto-available fraction of heavy

metals in soil.

Flower Leave Shoot Root Flower Leave Shoot Root

Flower Leave Shoot RootFlower Leave Shoot Root

Flower Leave Shoot Root

As

ZnPb

Cd Cu

ControlJangHang

ControlJangHang

ControlJangHang

ControlJangHang

ControlJangHang

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

2.5

2.0

1.5

1.0

0.5

0.0

140

120

100

80

60

40

20

0

25

20

15

10

5

0

1.0(a) (b)

(c)

(e)

(d)

0.8

0.6

0.4

0.2

0.0

Cd

conc

.in p

lant

(µg

g–1

D.W

.)

Cu

conc

.in p

lant

(µg

g–1

D.W

.)Z

n co

nc.in

pla

nt (

µg g

–1 D

.W.)

Pb

conc

.in p

lant

(µg

g–1

D.W

.)A

s co

nc.in

pla

nt (

µg g

–1 D

.W.)

Figure 2. Comparison of heavy metal concentrations in plants between from Jang-Hang and control areas. D.W. ¼ Distilled Water.

Jiyeon Park et al.14

The interactions of Zn and Cd on the heavy metal

accumulation in plants

Behavior of a heavy metal can be affected by other heavy

metals that have similar geochemical properties. Cadmium

and Zn are typical associated metals in geochemical and

environmental characteristics. Due to 0.1 , 5%ofCd inZn

ores, Cd is also released into the environment during the

process and release of Zn (Adriano, 1986). Their interaction

3.0

2.5

2.0

1.5

1.0

0.5

0.0

–0.5

35

30

25

20

15

10

5

0

0

4

3

2

1

0

0.00 0.05 0.10 0.15 0.20 0.25 0.30

Non-specifically sorbed As (mg kg–1) Non-specifically sorbed + Specificallysorbed pahse (mg kg–1)

Exchangeable Zn in soil (mg kg–1)Exchangeable Pb in soil (mg kg–1)

Exchangeable Cd in soil (mg kg–1) Exchangeable Cu in soil (mg kg–1)

10 20 30 40 50

0.0 0.2 0.4 0.6

Pb

Cd(a) (b)

(c) (d)

(f) (e)

CuC

d co

nc.in

pla

nt r

oot (

µg g

–1 D

.W.)

Cu

conc

.in p

lant

roo

t (µg

g–1

D.W

.)

Pb

conc

.in p

lant

roo

t (µg

g–1

D.W

.)

Zn

conc

.in p

lant

roo

t (µg

g–1

D.W

.)

As

conc

.in p

lant

roo

t (µg

g–1

D.W

.)

4

3

2

1

0

As

conc

.in p

lant

roo

t (µg

g–1

D.W

.)

60

50

40

30

20

10

00 1 2 3 4 5 6

60

50

40

30

20

10

00 2 4 6 8

0.0 0.5 1.0 1.5

AsAs

Zn

R2 = 0.78R2 = 0.90

R2 = 0.94R2 = 0.99

R2 = 0.85R2 = 0.97

R2 = 0.73R2 = 0.84

Figure 3. Relationship between exchangeable heavy metals in soil and plant roots.

Geosystem Engineering 15

in soil and plants can cause meaningful consequences. The

results show a significant positive correlation between Cd

and Zn in plant shoots as well as those in the roots (R 2 ¼ 0.

95 and 0.96, respectively). When Zn concentration

increases in the plant part, Cd concentration also increased

in the same part, as shown in Figure 4. Dudka, Piotrowska

and Chlopecka (1993) also showed that the level of Cd in

plants was significantly increased by the presence of a high

concentration of Zn in the soil.

According to the results, it was caused by reducing the

ability of the Zn-poisoned plants to control Cd uptake. As

shown in Figure 5, a correlation was also found between

Zn concentration in the soil and Cd concentration in

Brassica napus in this experiment. With the increase of Zn

concentration in the soil, Cd concentration in plant tissues

also increased.

Feasibility of biodiesel extraction from rape seed grownin the contaminated area

Oil extracted from seed grown in contaminated soil can

cause air pollution by using the gas for car and industrial

activities. For this reason, attention should be given to

heavy metal concentrations in seeds. When heavy metal

concentration in seeds is high, it is apparent that high

concentrations of heavy metals will be contained in oil

from that seed. According to the results, the seed contains

very low concentrations of heavy metal contents in soil

(Table 4). In the case of Zn, concentrations in seeds were

not affected by Zn concentration in the soil. Zinc is an

essential element for seed germination and growth

(Grewal & Graham, 1997). However, Cd, Cu, Pb and As

contained almost similar concentrations without variation

from the soil. It means that rape seed can accumulate

heavy metals in limited levels.

Heavymetal concentration in seedsmight be affected by

concentrations in the shoots. The translocation factor (TF),

which can be defined as the ratio of concentrations of heavy

metals in shoots to that in seeds, was calculated to estimate

the amount of translocating fraction of heavy metals from

shoots to roots (modified from Marchiol, Assolari, Sacco &

Zerbi, 2004). Zinc was recorded as the highest TF value

followed by Cu. The TF for Zn and Cu was significantly

higher than other metals (Figure 6) and TF for Cd and As

was almost similar in most plants. This means that there is

no significant effect of heavy metal concentrations in soil or

those in seeds. According to Scora and Chang (1997),

extracted oil from peppermint (Mentha X Piperita L.)

contained a limited amount of several heavy metals, which

were removed from the leaf. Heavy metal concentrations

were also compared between residues (the remaining part of

the seed after extracting the oil) and the oil. As was

60(a) (b)

50

40

30

20

10

00.0 0.5 1.0

Cd conc. in root (µg g–1 D.W.) Cd conc. in shoot (µg g–1 D.W.)

Zn

conc

. in

root

(µg

g–1

D.W

.)100

80

60

40

20

0

Zn

conc

. in

shoo

t (µg

g–1

D.W

.)

1.5 2.0

Cd - Zn Cd - Zn

R2 = 0.96 R2 = 0.95

2.5 3.0 0 1 2 3 4

Figure 4. Relationship between Cd and Zn in plant roots and shoots.

4

Zn soil - Cd root

Zn soil - Cd shoot

R2 = 0.86

R2 = 0.81

3

Cd

conc

. in

plan

t (µg

g–1

D.W

.)

2

1

0

0 1 2 3 4 5

Exchangeable Zn conc. in soil (mg kg–1)

6 7 8

Figure 5. Correlation coefficients between exchangeable Zn insoil and total Cd in plant parts (shoots and roots).

Jiyeon Park et al.16

expected, concentrations in seeds are significantly higher

than those in oil (Figure 7). This indicates that more than

half of the heavy metals are left in the residues during the

extraction procedure of oil from seed and the use of oil from

rape seeds from contaminated soil is acceptable.

Conclusion

Heavy metal contamination of an agricultural area in the

vicinity of the Jang-Hang smelter was investigated using

total digestion and sequential extraction analysis. From the

comparison of heavy metal concentrations between Jang-

Hang and the control areas, it was found that Brassica

napus can accumulate a high amount of heavy metals.

Using sequential extraction analysis, the phyto-available

fraction of heavy metals in soil was examined and it was

found that concentrations in plants increased with the

elevating phyto-available fraction of heavy metals in soil.

This indicates that Brassica napus may have no limitation

of heavy metal absorption until heavy metals cause

significant damage to plants.

Zinc and Cd showed a high positive correlation in the

shoots and roots (R 2 ¼ 0.95 and 0.96, respectively) of the

plant. Seeds contain significantly low concentrations of

heavy metals from soil except Zn, which is essential for

seed growth. Heavy metal concentrations in seeds may be

affected by translocation of heavy metals from the shoots.

More than half the amount of heavy metals is left in

residues during the extraction process of oil from the seed

and this oil produced from Brassica napus in contaminated

soil is acceptable as a future energy source.

Notes on contributors

Jiyeon Park received her master degreefrom the School of EnvironmentalScience and Engineering (SESE) atGwangju Institute of Science andTechnology (GIST). She has worked atEcofrontier (Environmental consultingcompany) and Korea EnvironmentInstitute (KEI) as a researcher. (Email:tomboyjy@gmail.com)

Table 4. Total heavy metal concentrations in the set of soil and seed samples (n ¼ 3).

Cd Cu Pb Zn As

C Soil(mg kg21) 1.6 ^ 0.16 78.4 ^ 3.26 200.5 ^ 6.65 101.2 ^ 4.09 84.2 ^ 3.97Seed(m g21) 0.05 3.9 0.14 41.3 0.05

D Soil(mg kg21) 1.4 ^ 0.09 65.7 ^ 2.61 176.1 ^ 7.94 87.4 ^ 4.23 70.7 ^ 6.58Seed(m g21) 0.10 5.3 0.14 49 0.10

I Soil(mg kg21) 0.8 ^ 0.05 35.2 ^ 1.96 55.5 ^ 2.04 57.5 ^ 1.85 27.01 ^ 6.90Seed(m g21) 0.02 2.9 0.09 34.0 0.04

J Soil(mg kg21) 0.8 ^ 0.03 43.6 ^ 2.84 72.3 ^ 2.42 88.5 ^ 2.36 27.6 ^ 3.49Seed(m g21) 0.02 5.0 0.46 47.8 0.05

K Soil(mg kg21) 1.04 ^ 0.09 38.02 ^ 4.8 76.8 ^ 6.53 78.4 ^ 5.16 26.5 ^ 6.49Seed(m g21) 0.04 8.7 0.69 67.0 0.12

10Translocation Factor (TF)

Palnt CPalnt DPalnt IPalnt JPalnt KPalnt L

TF

val

ue

8

6

4

2

0

Cd Cu Pb Zn As

Figure 6. TF, which is the ratio of elemental concentrations inshoots to those in roots.

Oil-Dregs

Oil

100

Hea

vy m

etal

con

c.

80

60

40

20

0Cd Cu Pb Zn As

Dregs

Figure 7. Heavy metal concentrations in oil and dregs, theresidual part of the seed after extraction of the oil.

Geosystem Engineering 17

Ju-yong Kim is research professor atGwangju Institute of Sicence & Tech-nology(GIST). He holds a BS degree, aMS degree and a PhD degree in Mineral& Petroleum Engineering from SeoulNational University. (Email: jykim@gist.ac.kr)

Kyoung-Woong Kim received his PhDfrom the Imperial College, University ofLondon. He is a Professor of Environ-mental Geochemistry and Dean ofSchool of Environmental Science andEngineering at Gwangju Institute ofScience and Technology, Korea. Hisresearch interests are environmentalmonitoring & risk assessment and theremediation of contaminated soil andgroundwater. Professor Kim has morethan 120 papers in the international SCI

journal and is currently a member of the editorial board of severalinternational journals. (Email: kwkim@gist.ac.kr)

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