Heavy metal accumulation in calcareous soil and sorghum plants

after addition of sulphur-containing waste

as a soil amendment in Turkey

Mustafa Kaplan a,*, Sule Orman a, Imre Kadar b, Jozsef Koncz b

aAkdeniz University, Faculty of Agriculture, Department of Soil Science, 07059 Antalya, TurkeybResearch Institute for Soil Science and Agricultural Chemistry of the Hungarian Academy of Sciences,

H-1022 Budapest, Hermann Otto ut 15. P. Box 1525, Hungary

Received 19 June 2003; received in revised form 1 April 2005; accepted 6 April 2005

Available online 24 June 2005

Abstract

The purpose of this work was to evaluate the effect of sulphur containing industrial waste with respect to heavy metals on

calcareous clay soil and sorghum (Sorghum bicolor L.) plant, as soil amendment. Pot experiment was established with a rate of 0,

20, 40, 60 t ha�1 air dry waste and 0.5, 1.0, 1.5 t ha�1 elemental sulphur and 0.5 t ha�1 sulphur + 20 t ha�1 waste. The use of

waste on the soil with high CaCO3 and clay content did not create heavy metal (Ni, Cr, Co and Cd) build-up or toxicity. Even

after the application of the high level of waste, it could not be seen any important toxic element accumulation in sorghum plant.

Although the sulphur-rich waste, approximately up to 1 million t in the vicinity of Keciborlu Sulphur Factory Isparta/Turkey, can

be considered as amendment product for reclamation of saline-sodic and calcareous soils common in Turkey and other countries,

repeated waste applications would result in different heavy metal accumulation rates. Therefore, it is needed to be examined with

long term field experiments and different crops.

# 2005 Elsevier B.V. All rights reserved.

Keywords: Heavy metals; Industrial wastes; Soil amendment; Sulphur; Sorghum; Sorghum bicolor L.; Ni; Cr; Pb; Cd

www.elsevier.com/locate/agee

Agriculture, Ecosystems and Environment 111 (2005) 41–46

1. Introduction

Heavy metals are natural components of the earth

crust (Wedepohl, 1991). In addition to this native

origin, some heavy metals may be supplied to soils by

atmospheric deposition and by agronomic practices

* Corresponding author. Tel.: +90 242 310 24 62;

fax: +90 242 227 45 64.

E-mail address: mkaplan@akdeniz.edu.tr (M. Kaplan).

0167-8809/$ – see front matter # 2005 Elsevier B.V. All rights reserved

doi:10.1016/j.agee.2005.04.023

such as fertilizer and pesticide applications as well as

the disposal of municipal wastes such as composts and

sewage sludge on agricultural land (Cramer et al.,

1981; Sauerbeck, 1985; Schmidt and Sticher, 1991).

The uptake of heavy metals by plants depend on

their concentration in soil. However, the uptake of

heavy metals from soil is not a simple function of total

soil heavy metal content. Soil factors govern the plant

availability of heavy metals. Some investigations

showed that the availability of heavy metals to plants

.

M. Kaplan et al. / Agriculture, Ecosystems and Environment 111 (2005) 41–4642

depends on several soil characteristics which affect the

binding and mobility of metals in soil. These include

soil pH, ion exchange properties, drainage status as

well as clay and organic matter content (Berrow and

Burridge, 1991; Sauerbeck and Lubben, 1991).

On the other hand some investigations clearly

demonstrated that the plant itself plays an active role

towards mobilizing and uptake of metals bound in soil

with considerable differences among plant species and

cultivars (Helal, 1990; Hinsley et al., 1978; Mench

et al., 1989; Petterson, 1977). Plant characteristics and

activities may affect heavy metal uptake in several

ways. These include the modification of soil properties

related to heavy metal availability, the control of heavy

metal transfer across cell membranes, the binding of

metals in various plant tissues, and the interaction

between the nutritional status of the plant as well as

environmental stress conditions with these activities.

In recent years, the use of various urban and

industrial waste materials for soil reclamation and soil

productivity has attracted an increasing amount of

interest. However, besides the benefits offered by such

waste, it may also incorporate various risks, because of

its heavy metal content. The use of such waste is

recommended under conditions that the risks can be

kept at acceptable levels. This approach is also

considered to be very important for eliminating certain

problems and difficulties created by this kind of waste.

Saline-sodic soils are known to cover 1.5 million ha

in Turkey. These soils have partially or entirely lost

their productivity in time and great amount of

amendment products is needed for their reclamation.

Albeit, the researches are going on about this kind of

amendment products. Number of studies have claimed

that Keciborlu sulphur factory waste, which is

approximately amounting up to 1 million t, can be

used for this purpose (Bahceci, 1989; Sonmez, 1988).

Investigations are still being carried out to recycle

Keciborlu Sulphur Factory waste by evaluating its

reclamation effects on soil productivity but these

investigations do not take into account its heavy metal

content and consequent problems.

On the other hand most of the soils in Turkey are

highly calcareous and as a result has a high pH. 22% of

the soils contain less than 1%, 20.4% of the soils contain

between 1% and 5%, and 57.6% of the soils contain

more than 5% calcium carbonate. Especially, those in

the Mediterranean Region are highly calcareous

(Anonymous, 1984). The use of elemental sulphur or

waste containing sulphur is a potential treatment for

soils with a high pH. In a field experiment conducted by

Kaplan and Orman (1998), sulphur factory flotation

waste was applied to extremely calcareous soil (37.3%

CaCO3) at levels of 20, 40, 60 and 100 t ha�1 and the pH

of the soil was measured on a temporal basis after 5, 10,

38 and 58 weeks. They showed that the pH of the soil

differed from that of the control sample in proportion to

the amount of waste used and the period of time, and

they found that possible reduction of pH is minimum

0.21 and maximum 0.79 units. In the course of

determining potential the use of this waste for both soil

pH reduction and the reclamation of saline-sodic soils,

investigations must consider whether it poses heavy

metal risk or not, which is a matter of economic and

environmental importance.

The aim of this article is to evaluate the use of

sulphur factory waste containing sulphur and heavy

metals in calcareous clay soil, principally with respect

to toxic elements.

2. Materials and methods

Pot experiment was conducted with calcareous clay

soil taken from West Mediterranean Region in Turkey.

The soil was classified as Lithic Xerorthent. Soil was

air dried and passed through a 4 mm sieve. A total of

5 kg of sieved soil was placed in pots with holes at the

bottom. The details of the experiment were previously

reported by Kaplan and Orman (1998).

Basic properties of the soil used in the pot

experiment are as follows; clay 47.4%, CaCO3

37.3%, pHðH2OÞ 7.88, EC 2.49 dS/m, organic matter

2.58%.

The results of the chemical analysis of the sulphur

factory flotation waste used in the experiment are

given in Table 1.

The experiment was carried out according to the

randomized plot design with three replicates in the

greenhouse conditions and eight different treatments

which were applied in the equivalents of 0; 20 (W1),

40 (W2), and 60 (W3) t ha�1 of waste; 0.5 (S1), 1.0

(S2), and 1.5 (S3) t ha�1 of elemental S; and mixture

of 20 t ha�1 (W1) and 0.5 t ha�1 (S1) of waste and S.

Ten weeks after applications, sorghum (Sorghum

bicolor L.) was planted (7–8 seeds pot�1). After

M. Kaplan et al. / Agriculture, Ecosystems and Environment 111 (2005) 41–46 43

Table 1

Mineral composition of sulphur containing waste used (mg kg�1 in air-dry waste)

P K Ca Mg S Fe Zn Mn B Cu Mo

DTPA-extractable 584 1.35 <LDa 1674 74900 64191 107 351 <LD 27.6 <LD

Aqua regia-extractable 779 2210 10700 2630 120600 95250 125 391 4.7 48.4 1.6

Al As Ba Cd Co Cr Hg Ni Se Sr Pb

DTPA-exractable 21131 <LD <LD 0.57 55.87 397 <LD 1061 <LD 2.4 1.22

Aqua regia-extractable 26500 0.59 37.1 0.92 65.10 393 <LD 952 <LD 45.8 3.90

a Limit of detection (LD); DTPA – extractable; Ca: 0.04, B: 0.005, Mo: 0.034, As: 0.013, Ba: 0.001, Hg: 0.02; Se: 0.076; Aqua Regia –

extractable; Hg: 0.5, Se: 0.3.

planting, the seedlings were thinned to 2 pot�1. At the

growing period, each pot received 130 kg N ha�1 as

ammonium nitrate 33% and all the pots were equally

irrigated. During the experiment, soil samples were

taken at the 10 and 30th weeks for measurement of

DTPA-extractable and aqua regia extractable Ni, Cr,

Co, Cd elements. At the 30th week, two plants were

harvested for determination dry matter (g pot�1).

Dried root and straws were analyzed for determination

Ni, Cr, Co and Cd in dry matter.

The extraction for the DTPA-extractable element

contents of soils was made according to Lindsay and

Norwell (1978). For the determination of the total

heavy metal contents of the soils, 1 g air dried soil was

digested in teflon bomb with 4.5 ml HCl (37%), 1.5 ml

HNO3 (65%) and 1 ml H2O2 (30%) in microwave

digestion apparatus (Milestone MLS 1200 Mega). The

microwave technique was also used for the digestion

of plant materials (The Milestone Microwave Acid

Digestion Cookbook, Report Code:17). The element

concentrations of plant and soil samples were

determined by using ICP-OES (Type: JY-238 Ultrace).

All the soil and plant analyses were made in the

Agrochemistry laboratory of the Research Institute for

Soil Science and Agricultural Chemistry of the

Hungarian Academy of Sciences.

The data were analyzed by using standard GLM

procedures and significance were always based on

p < 0.05 level using Duncan’s Multiple Range Test.

3. Results and discussion

As soils in Turkey are calcareous and of high pH, in

particular Fe, Zn and Mn deficiencies are widespread

in agriculture. It is worth noting that the microelement

content (especially Fe) of the waste is important

(Table 1). A significant proportion of the contained

microelements are DTPA-extractable, which is an

important property regarding to their uptake by plants.

The chemical analysis of the waste used in the

experiment showed that it contains not only the

elements with a beneficial effect but also the elements

with high toxicity in terms of soil productivity (Table 1).

Toxic elements limit values for soil amendments in

Hungary and Europe are As 10, Cd 2, Co 50, Cr 100, Cu

100, Hg 1, Ni 50, Pb 100, Se 5 mg kg�1 D.M.

(Anonymous, 2001). As it can be seen in Table 1, most

attention must be paid to nickel, chromium and cobalt,

and cadmium contents of the waste.

3.1. Ni concentrations in soil and sorghum plant

The nickel content within the largest waste applied

to the soil raised the total nickel content of the soil

11% compared to the control sample at the 10th week.

At the 30th week, the total Ni concentration in soil

increased 6.80% but this is not statistically significant

(Table 2). Because of the Ni content of the waste was

entirely in DTPA-extractable form (Table 1), DTPA-

extractable nickel content increasing rate was extre-

mely high which was 376% (from 0.188 to 0.895 mg

kg�1) at 10th week and 465% (from 0.148 to

0.837 mg kg�1) at 30th week (Table 3).

The waste application increased the root nickel

concentration of sorghum plants while it did not make

any significant Ni concentration change in the straw

(Table 4). The root nickel concentration of the control

sample was 14.6 mg kg�1 whereas the Ni concentra-

tion after three different waste applications was

measured as 23.3 mg kg�1 on average which indicated

an increasing rate of 59.6%.

M. Kaplan et al. / Agriculture, Ecosystems and Environment 111 (2005) 41–4644

Table 2

Concentrations of aqua regia-extractable toxic elements after the application of waste and elemental sulphur in soila (mg kg�1)

Treatments Ni Cr Co Cd

10 weeks 30 weeks 10 weeks 30 weeks 10 weeks 30 weeks 10 weeks 30 weeks

Control 155.67 b 156.67 111.00 b 111.00 c 17.47 17.57 0.93 0.85

W1 20 t ha�1 163.00 b 158.67 115.33 b 117.67 bc 18.00 17.90 0.95 0.94

W2 40 t ha�1 162.67 b 168.67 118.67 b 125.00 ab 18.07 18.63 0.88 0.98

W3 60 t ha�1 173.00 a 167.33 128.67 a 131.67 a 18.57 18.27 0.92 0.91

S1 0.5 t ha�1 159.67 b 157.33 115.67 b 113.67 c 17.67 17.37 0.90 0.95

S2 1.0 t ha�1 157.33 b 158.67 117.33 b 113.33 c 17.57 17.77 0.85 0.85

S3 1.5 t ha�1 158.00 b 157.67 112.67 b 111.33 c 17.80 17.80 0.83 0.95

S1 + W1 159.00 b 161.33 114.67 b 117.33 bc 17.70 18.33 0.89 0.94a Different letters in the same column indicate a significant difference at the 0.05 level according to protected Duncan’s Multiple Range Test.

The Ni-content of the above-ground parts of the

plants showed no change after waste application. The

nickel taken up by the sorghum plants was largely

stored in their roots. As a rule, heavy metals are

less accumulated in generative parts of the plants

compared to vegetative ones, and often roots are the

main accumulative organs or sinks for heavy metals

(Hasselbach, 1992). It is not considered that the

application of the waste at the levels of 20, 40, and

60 t ha�1 would create short-term problems relating to

nickel. Because, the plant experiments conducted in

various soils have shown that yield shortfalls only

occur when the plant nickel content is 20–50 mg kg�1

of dry matter (Ozbek et al., 1993). The toxicity of the

nickel, making up as much as 1061 mg kg�1 of the

waste, can be expected to decrease in soil with a high

pH. It has been demonstrated in the literature that the

solubility of nickel is related to soil pH. The Ni

activity was increased when the soil pH was 5.5

(Brummer et al., 1991). The high calcium carbonate

and clay content of the trial soil shows that the

Table 3

Concentrations of DTPA-extractable toxic elements after the application

Treatments Ni Cr

10 weeks 30 weeks 10 weeks 30 we

Control 0.188 e 0.148 e <LDb <LD

W1 20 t ha�1 0.467 c 0.422 c <LD <LD

W2 40 t ha�1 0.697 b 0.625 b <LD <LD

W3 60 t ha�1 0.895 a 0.837 a <LD <LD

S1 0.5 t ha�1 0.196 e 0.171 e <LD <LD

S2 1.0 t ha�1 0.189 e 0.173 e <LD <LD

S3 1.5 t ha�1 0.195 e 0.174 e <LD <LD

S1 + W1 0.430 d 0.362 d <LD <LDa Different letters in the same column indicate a significant difference atb Limit of detection (LD) Cr: 0.005.

treatment on this scale will not create a toxic effect on

plant development. However, when it is considered

that DTPA-extractable Ni values of the soil and the

Ni concentration of root is increased after waste

application, it has to be avoided to grow root

vegetables for the following a few years. Moreover,

it should be realized that an uncontrolled waste

application may cause harmful effects. For this reason,

the waste should be applied at the lowest possible

levels (20 t ha�1) to achieve beneficial results.

3.2. Cr concentrations in soil and sorghum plant

The largest waste applied to the soil raised the total

chromium content of the soil 15.9% at the 10th week

and 18.6% at the 30th week (Table 2). The chromium

contained in the waste was entirely in a DTPA-

extractable form (Table 1). However, after the

application to the soil at the 10 and 30th weeks, the

DTPA-extractable chromium content decreased below

the measurement limit (>0.005 mg kg�1) (Table 3).

of waste and elemental sulphur in soila (mg kg�1)

Co Cd

eks 10 weeks 30 weeks 10 weeks 30 weeks

0.087 c 0.081 0.064 a 0.064 a

0.087 c 0.086 0.063 ab 0.060 b

0.097 abc 0.086 0.060 b 0.060 b

0.10 a 0.094 0.060 b 0.059 b

0.097 abc 0.084 0.063 ab 0.066 a

0.094 bc 0.082 0.064 a 0.066 a

0.104 ab 0.082 0.062 ab 0.066 a

0.091 c 0.085 0.060 b 0.059 b

the 0.05 level according to protected Duncan’s Multiple Range Test.

M. Kaplan et al. / Agriculture, Ecosystems and Environment 111 (2005) 41–46 45

Table 4

Concentrations of toxic elements after the application of waste and elemental sulphur in roots and straws and dry matter yield of the sorghum

plant growna (mg kg�1 in dry matter)

Treatments Ni Cr Co Cd Dry matter (g pot�1)

Root Straw Root Straw Root Straw Root Straw

Control 14.6 b 3.93 12.65 ab 4.05 6.42 ab 0.23 0.62 0.35 bc 5.46 b

W1 20 t ha�1 24.6 a 2.80 15.56 a 6.99 6.57 ab 0.13 0.68 0.33 bc 7.43 b

W2 40 t ha�1 20.7 ab 3.10 12.35 ab 6.79 6.44 ab 0.17 0.62 0.32 c 6.76 b

W3 60 t ha�1 24.7 a 2.99 12.68 ab 6.07 7.23 a 0.23 0.70 0.31 c 6.70 b

S1 0.5 t ha�1 15.0 b 2.70 11.60 b 5.05 3.96 c 0.26 0.61 0.40 ab 10.07 a

S2 1.0 t ha�1 14.5 b 3.37 10.60 b 7.24 4.10 c 0.33 0.64 0.44 a 10.44 a

S3 1.5 t ha�1 14.3 b 2.84 9.39 b 4.19 4.54 bc 0.19 0.61 0.34 bc 8.01 ab

S1 + W1 15.5 b 3.50 9.93 b 7.98 4.88 bc 0.17 0.64 0.36 bc 7.44 ba Different letters in the same column indicate a significant difference at the 0.05 level according to protected Duncan’s Multiple Range Test.

While the plant roots in the control sample had

12.65 mg kg�1 of dry matter chromium, this was

found 13.53 mg kg�1 on average after treated with

waste (Table 4). Increases in the straws relating to the

treatment were found to have no statistical signifi-

cance. Indeed, as observed with nickel, the amount of

chromium reduced as it passed from root to straw. It is

considered that a slight increase in the chromium

content of plants can be viewed in a positive

perspective because it helps to meet human CR III

requirements (Papke, 1981). Bearing in mind that a

very large extent soil in Turkey has a high calcium

carbonate and clay content, and high pH, the levels at

which the waste was applied do not appear to pose a

risk if used occasionally.

3.3. Co concentrations in soil and sorghum plant

The cobalt content within the largest waste applied

to the soil raised the total cobalt content of the soil

6.29% at the 10th week and 3.98% at the 30th week in

comparison to the control sample but it is not

statistically significant (Table 2). The 85.8% of the

cobalt contained in the waste is in DTPA-extractable

form (Table 1). The increase in the DTPA-extractable

cobalt content after treated with waste was 25.3%,

from 0.087 to 0.109 mg kg�1, at the 10th week

(Table 3). When we look at the effects of the cobalt

content within the plant, there was an increase of 5.1%

in the root and reduction of 24.8% in the above-ground

parts compared to the control sample (Table 4). This

reduction may be attributed to a dilution effect owing

to increased plant development. If we evaluate this

data as a whole, it can be said that treatments with

waste under experimental conditions did not pose a

risk and when it is used for reclamation purposes on

one-off basis, it will not create any problems regarding

to cobalt.

3.4. Cd concentrations in soil and sorghum plant

When the waste applied to the soil, the total

cadmium content was not statistically significant both

at the 10th week and at the 30th week (Table 2). The

61.3% of the cadmium in the waste found in DTPA-

extractable form (Table 1). After the application of the

largest waste to the soil, the DTPA-extractable

cadmium content of the 10th and 30th weeks’ samples

exhibited the reduction of 6.7% and 8.47% respectively

compared to the control sample (Table 4). Even though

the applied waste contains cadmium, the increases of

the cadmium in the soil with high calcium carbonate

and clay content may not be evident due to complex

effects caused principally by sulphur on the pH of soil.

Thus, the results of plant analysis show that the effects

of the waste application are to be limited. While it

increased root cadmium content 7.9% compared to the

control sample, it produced 8.0% reduction in the

above-ground parts (Table 4). Anyhow, it appears

unlikely that waste with a total cadmium content of

0.92 mg kg�1 would pose any serious problems

(Table 1). The 61.3% of the cadmium within the waste

is DTPA-extractable form and it may create risky

conditions on use of waste. Nevertheless, this risk is

mostly reduced by insoluble forms occurred in the

calcareous soils after waste application.

M. Kaplan et al. / Agriculture, Ecosystems and Environment 111 (2005) 41–4646

4. Conclusions

Due to its sulphur and iron contents, the waste is able

to create beneficial results in soils with high calcium

carbonate and clay content. The waste applications at

the levels of 20, 40, 60 t ha�1 in this study do not create

a serious heavy metal build-up or toxicity. An important

proviso is that the cultivation of root vegetables (beet,

potatoes, carrots, etc.) is to be avoided in the first

growing season following the waste treatment. Since

this study examined the waste usage with pot

experiments, similar studies should continue to be

carried out in field experiments under various condi-

tions for a long time to exploit beneficial properties of

the waste. However, considering the heavy metals that it

contains, uncontrolled use should be avoided.

Acknowledgements

The Authors would like to express their appreciation

to Research Institute for Soil Science and Agricultural

Chemistry of the Hungarian Academy of Sciences

and Scientific Research Fund of Akdeniz University.

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