LEAD BEHAVIOR IN A SOIL - PLANT SYSTEM FROM POLLUTED AND
UNPOLLUTED AREAS IN ROMANIA
Radu Lăcătuşu1, 3, Mihaela Lungu1, Anca Rovena Lăcătuşu1, Carmen Burtea2,
Iuliana Gabriela Breabăn3
1
National Research and Development Institute for Soil Science, Agrochemistry and Environment
Protection (RISSA) Bucharest
2
„Dunărea de Jos” University Galaţi, Faculty of Engineering Brăila
3
„Al. I. Cuza” University Iassy
Correspondence to Mr. Radu Lăcătuşu, Research and Development National Institute for Soil
Science, Agrochemistry and Environment Protection (RISSA), Bucharest,
Bd. Mărăşti,
nr.61, Sector 1, Postal code 011464; Fax +040 21 3184349; e-mail: radu@icpa.ro
Abstract
Data regarding total and mobile Pb abundance in the A horizon of Romanian soils are presented. A
Pb distribution map highlights the Pb polluted areas. Studies were carried out in three of these areas
regarding total and mobile Pb abundance, total Pb fractions, and Pb accumulation in plants used as
vegetal food for people and animals. Pb flow in the soil, plant, animal system is presented in
polluted and unpolluted areas. The total Pb content from the A horizon of the Romanian soils
ranges between 0.6 and 498 mg·kg-1, with a geometric mean of 28 mg·kg-1. The high Pb
concentrations, over 100 mg·kg-1, belong to the geogenic or anthropogenic polluted areas. In
unpolluted soils, over 50% of the total Pb belongs to hard to mobilize fractions, while in polluted
soils most of the total Pb belongs to mobile fractions. In the polluted areas, vegetables and pasture
plants accumulated Pb in quantities that exceed up to ten times the maximum allowable limit. Pb
flow in the soil – plant – animal system from heavy metal polluted areas takes place at values up to
12 times higher, as compared to an unpolluted area.
Key words: Pb, pollution, soils, Romania
Introduction
The total Pb content in soils oscillates in a large interval, usually between 5 and 80 mg·kg-1, with an
average value of 32 mg·kg-1 (Kabata-Pendias and Pendias, 2001). For areas polluted industrially,
from agricultural activities or as a consequence of traffic, the same authors frequently signalate
values intervals between 100 and 18,500 mg·kg-1.
In Pb polluted soils, a great part of this chemical element is to be found in potentially mobile forms,
bound to the exchangeable fraction, the organic matter and in the soil solution. Plants grown on
such soils accumulate high Pb quantities which can reach the animal and human organisms, causing
toxic phenomena, some of them most severe. Such phenomena were signaled in different countries,
such as: Poland, Germany, Japan, Canada and others (Kabata-Pendias and Pendias, 2001).
In this paper total and mobile Pb abundance is presented in Romania’s soils, in polluted and
unpolluted areas, as well as its accumulation in plants and animal organisms.
Material and Methods
Total Pb content from the A horizon was determined in 990 samples from all over Romania, using a
relatively sampling uniform network. Over 100 samples were obtained from three areas polluted
with heavy metals (Baia Mare, Zlatna, and Copşa Mică, Fig. 1). A mixture of HNO3 and HClO4 was
used to digest soil samples. Total Pb was fractioned by soil components, using a method developed
by Lăcătuşu and Kovacsovics (1994).
Soil mobile Pb was extracted with an EDTA-CH3COONH4 solution at pH 7.0.
Pb content was also determined in the hydrochloric solution obtained by solubilization of the ashes
of the biological samples (plants, animal organs).
All Pb determinations were performed by means of absorption spectrometry in air-acetylene flame.
Results were analyzed statistically, for grouping centre parameters (arithmetic mean, geometric
mean, median), and scattering parameters (standard deviation, minimum and maximum values).
Correlations were calculated between Pb contents in vegetables and pasture plants and mobile Pb
contents in soils.
Results and discussion
General abundance of total Pb in Romania soils
Data from 990 soil samples from the upper horizon of Romania soils pointed to a Pb content
ranging between 0.6 and 498 mg·kg-1, with an arithmetic mean of 32 mg·kg-1, geometric mean of
28 mg·kg-1, and median 29 mg·kg-1. The standard deviation, 27 mg·kg-1, indicates a high scattering
degree of the values.
The value of the geochemical abundance index, 2, shows that the soils in Romania have double the
lead content as compared to its lithosphere abundance.
The map of Pb distribution in Romania’s soils (Fig. 1) highlights the fact that the Pb content in the
upper horizons of the soils ranges up to 50 mg·kg-1. Higher values belonging to the 50-150 mg·kg-1,
150-600 mg·kg-1 intervals or greater usually occur in the mountainous zone as pedo-geochemical
specific areas, or in areas in which heavy metal pollution, including Pb, has been taking place over
an extended period of time. This is the case for the Baia Mare, Copşa Mică and Zlatna areas.
Total Pb abundance in soils resulting from complex sulphides ores processing industries
In the three areas mentioned above, complex sulphide ores containing different chemical elements,
including Pb, are processed through flotation and melting. The resulting emissions of chemical
elements have polluted the environment, including the soil which became, over time, a polluting
chemical elements depositary. Total Pb contents in the soils of these areas (table 1) have been
showing values that exceed the normal Pb content of soils as well as the maximum allowable limits.
Taking into account the geometric mean x of the value intervals specific to Baia Mare, Copşa
Mică, and Zlatna, Pb exceeds normal values by: 12, 11, and 15 times respectively, and: 1.8; 1.7 and
1.1 times respectively as compared to the maximum allowable limits.
Similarly, the mobile Pb quantities from the soils of the three areas exceed the maximum allowable
limit value for this form (18 mg·kg-1) by 5 times.
The fractions of total Pb content from unpolluted and polluted soils
The percentage mean values of total Pb fractions, represented by Pb in soil solution, Pb adsorbed by
exchange on the surface of colloidal particles, Pb bounded to the organic matter, free oxides and Pb
from the crystallin mineral lattice show significant differences between unpolluted soils and the
polluted ones from Baia Mare and Copşa Mică (figure 2).
Not only overall differences occur between the three soil categories, but also in the fractions
abundance. Thus, if in the unpolluted soils Pb in hard to mobilize fractions, bound to free oxides,
and in the fraction bound to the minerals crystalline lattice is predominant (69%), then in the
polluted soils Pb in mobile fractions is predominant. The mobile fractions define soil mobile Pb,
namely Pb in soil solution, exchangeable Pb, and organically bound Pb. Their average percentage
value is 54% for Baia Mare soils and 57% for Copşa Mică soils.
When comparing these percentages to overall Pb values, the polluted soils have an average quantity
of mobile soil Pb of 94 mg·kg-1 at Baia Mare and 97 mg·kg-1 at Copşa Mică, as compared to only
9.9 mg·kg-1 in unpolluted soil. The polluted soils provide plants with quantities almost ten times
higher than the unpolluted soil.
Pb accumulation in vegetables, fruits, and strawberry plants grown in polluted areas
In general, only 0.005% of the total soil Pb is absorbed by plants (Gerhardsson, 2004). The high Pb
quantity in the polluted soil solution, however, leads to passive accumulation of the chemical
element in edible plants.
Table 2 contains the average mean values of Pb content in the edible parts (fresh material) of some
vegetables and fruits. When comparing the maximum allowable limit to the average values
registered in the vegetables and fruits, Pb limits were exceeded ten times, as is the case with carrots
grown on the polluted soil at Baia Mare. All the registered values are higher than the maximum
allowable limit.
A similar order of magnitude was also registered for vegetables analyzed as dry matter, such as:
lettuce, dill, parsley, orache, and onion (Table 2).
In the plants of pastures from these three regions, in the areas with polluting industries, Pb contents
were recorded much higher than the normal ones, entering the phyto-toxicity and toxicity level for
animals (Table 3).
Pb flow in the soil – plant – animal system
Pb was determined in soil, pasture plants and in animals in the polluted areas from Copşa Mică and
Baia Mare, and from an unpolluted area. This permitted the assessment of Pb flow between three
environment components: soil, plant, animal (Figure 3).
Analytical data and the values of the transfer coefficients have highlighted the fact that the Pb
transfer intensity and capacity from one environment component to another is, on an average, 8
times higher in Copşa Mică and 12 times higher in Baia Mare, as compared to the non-polluted area
(Lăcătuşu, 2001). This explains the intoxications and saturnism of animals and people from the
heavy metals polluted areas.
Conclusions
1. The total Pb content from the A horizon of the Romanian soils ranges between 0.6 and
498 mg·kg-1, with a geometric mean of 28 mg·kg-1. The high Pb concentrations, over
100 mg·kg-1, belong to the geogenic or anthropogenic polluted areas.
2. In unpolluted soils, over 50% of the total Pb belongs to hard to mobilize fractions, while in
polluted soils most of the total Pb belongs to mobile fractions.
3. In the polluted areas, vegetables and pasture plants accumulated Pb in quantities that exceed
up to ten times the maximum allowable limit.
4. Pb flow in the soil – plant – animal system from heavy metal polluted areas takes place at
values up to 12 times higher, as compared to an unpolluted area.
References
1. Alloway B. J., Ayers D. C., 1993, Chemical Principles of Environmental Pollution, Blackie
Academic and Professional, London, New York, Tokyo.
2. Ewers U., 1991, Standards, guidelines and legislative regulations concerning metals and
their compounds, In: Metals and their compounds in the Environment, Ed. E. Merian, VCH,
Weinheim, New York, Basel, Cambridge, 687-711.
3. Fiedler H. J., Rösler H. J., 1988, Spurenelemente in der Umwelt, Ferdinand Enke Verlag,
Stuttgart.
4. Fritz P. D., Forughi M., Venter P., 1977, Schwermetallgehalte in einigen Gemüssenarten,
Landw. Forsch., Sonderh., 33, 335-343.
5. Gerhardsson L., 2004, Lead, In: Elements and their Compounds in the Environment, 2nd
Edition. Ed. Merian, Anke, Ihnat, Stoeppler, vol.2, 879-900.
6. Kabata-Pendias Alina, Pendias H., 2001, Trace Elements in Soils and Plants, 3rd Edition,
CRC Press, Boca Raton, London, New York, Washington D.C.
7. Kloke A., 1980, Richwerte ‘80, Orientierungsdaten für tolerierbare Gesamtgehalte einiger
Elemente in Kulturböden, Mitt. VDLUFA, H.2, 9-11.
8. Lăcătuşu R., Răuţă C., Mihăilescu A., Neda C., Medrea N., Koacsovics Beatrice,
Lungu Mihaela, 1987, Researches regarding the soil – plant – animal system of the
iunfluence area of the Turnu Măcurele pyrite ash valorization plant, Analele ICPA,
vol.XLVIII, 281-294 (in Romanian).
9. Lăcătuşu R., Kovacsovics Beatrice, 1994, Method for fractionation of heavy metals from
soil, Pub. SNRSS, vol. 28A, 187-194 (in Romanian).
10. Lăcătuşu R., 2001, Contributions regarding heavy metals flow within soil – plant – animal
system in polluted areas, In: Proc. of the 12th Int. Symp. of CIEC, 217-229.
Figure caption
Figure 1
Lead distribution in Romanian soils
Figure 2
Average values of Pb fractions in an unpolluted soil (A) and in the polluted soils from Baia Mare (B) and
Copşa Mică (C)
Figure 3
Pb flow chart of a soil-plant-animal system within a non-polluted area (A) and the Copşa Mică (B) and Baia
Mare (C) polluted areas
The units of measurement are: g·l-1 for blood serum, mg·l-1 for milk and mg·kg-1 for the other sample
types
The transfer values from one environmental component to another are expressed in mg per day
Tables
Table 1
-1
Statystical parameters of the total and mobile Pb content (mg·kg ) in the soils of the
polluted areas from Baia Mare, Copşa Mică, and Zlatna, as compared to the normal
values (NV) and the maximum allowable limits (MAL)
xmin – minimum value; xmax – maximum value; x - average value;  - standard
deviation; xg – geometric mean; Me - median
Statistical
parameter
xmin
xmax
x

xg
Me
NV *
MAL **
*
**
Baia Mare
t
m
20
400
184
94
174
181
15
100
Copşa Mică
t
m
14
288
89
62
72
81
37
476
171
158
149
141
18
15
100
Zlatna
t
m
13
296
84
98
79
85
17
416
223
98
103
98
11
291
107
79
96
101
18
15
100
18
After Fiedler and Rösler (1988)
After Kloke (1980) for the total content and Lăcătuşu et al. (1987) for
mobile Pb
Table 2
Average Pb content in the edible parts of some vegetables an fruits sampled from the
polluted areas Copşa Mică, Zlatna, and Baia Mare, as compared to the maximum
allowable limits (*) and normal (**) values
Vegetables and fruits
nature
Copşa Mică
Zlatna
Baia Mare
-1
Tomatoes
Cucumbers
Carrots
Radishes
Potatoes
Cherry
Apple
Pear
Lettuce
Dill
Parsley
Orache
Onion
Fresh vegetables (mg·kg )
0.4  0.1
0.6  0.3
5.5  1.0
0.7  0.5
1.0  0.8
0.5  0.2
0.6  0.1
Fresh fruits (mg·kg-1)
3.2  3.5
0.6  0.3
1.7  2.0
0.5  0.1
0.9  0.6
0.7  0.4
Vegetables, dry matter (mg·kg-1)
251  118
56.8  26.6
56.6  35.6
130.4  29.1
90.7  56.2
36.5  20.2
95.9  51.2
10.7  5.9
2.5  1.9
1.9  0.8
1.5  0.9
1.0  0.7
2.0 0.8  0.6
43.5  24.1
37.2  20.8
49.1  35.4
12.8  7.3
* Maximum allowable limits for fresh vegetables: 0.5 mg·kg-1, 0.25 mg·kg-1 for
potatoes (from Evers, 1991)
** Normal contents for vegetables, dry matter: 10-15 mg·kg-1, (after Fritz et al., 1977)
Table 3
Statistical parameters of Pb content (mg·kg-1) in pasture plants from the polluted areas
of Baia Mare, Zlatna, and Copşa Mică, as compared to the normal content (NC) and
phyto-toxicity level (PTL) values
xmin – minimum value; xmax – maximum value; x - average value;  - standard
deviation; xg – geometric mean; Me - median
Statistical
parameter
xmin
xmax
x

xg
Me
Baia Mare
15
338
106
80
97
88
Zlatna
5
1129
130
207
107
86
Copşa Mică
40
211
134
55
130
121
Normal values = 5-10 mg·kg-1 and PTL = 30-300 mg·kg-1 (after Alloway and Ayers,
1993)
Table 4
The values of the correlation ratios and coefficients between Pb content in vegetables
and pasture plants from the polluted areas of Baia Mare, Zlatna, and Copşa Mică
Area
Baia Mare
Zlatna
Copşa
Mică
Vegetables
Pasture plants

r
0.659 *
0.732**
0.542*

r
0.412
0.532
0.618
0.724**
0.802**
0.642*
* Significant for a 5% probability with degree of freedom = 12
** Significant for a 1% probability with degree of freedom = 12
0.324
0.419
0.523
Figures
Figure 1
Figure 2.
1 – the fraction soluble in the soil solution and the exchangeable fraction
2 – the fraction bound to the organic matter
3 – the fraction bound to iron and manganese oxydes
4 – the anorganic residual fraction
Figure 3