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Pergamon
Phys. Chem. Earth (A),
Vol.
24, No. 9, pp. 829-835,
1999
0
1999
Elsevier Science Ltd
All rights reserved
1464-I 8951991$ - see front matter
PII: S
1464-l 895(99)00122-2
Magnetic Susceptibility as Indicator of Environmental Pollution
of Soils in Tallinn
L. Bityukova’, R. Scholger’ and M. Birke3
‘Institute of Geology, Tallinn Technical University, 7 Estonia Avenue, Tallinn 10143, Estonia
‘Institute for Geophysics, University of Leoben, Paleomagnetic Laboratory, Gams 45, A-8 130.
Frohnleiten, Austria
3Federal Institute of Geosciences and Natural Resources, Branch Office Berlin, Wilhelmstrasse 25-30.
13593, Berlin, Germany
Received 3 June 1998; accepted I7 December 1998
Abstract.
Low-field magnetic susceptibility
(K)
and
concentration of 40 elements were determined for 531
samples collected from top-soils on the territory of the
biggest industrial centre of Estonia. This study was carried
out during a small-scale geochemical mapping and
monitoring of soils in the frame of the project “Urban
geochemistry of Tallinn” supported by NATO. The main
purpose was to establish the sources of pollution and to study
applicability of
K
for determining geochemical anomalies.
Relationship between
K
and element concentrations in the
topsoil was studied by means of correlation and factor
analyses. Higher than average
K
values were observed in
soils on the territory of phosphorite deposits at Maardu. The
susceptibility anomaly is caused by particular geological
circumstances and can be related to high contents of
ferromagnetic minerals in the host rocks. Strong positive
correlation of magnetic susceptibility with Cr, Pb, Zn and
Cu observed in soils from the central part of the city are
conditioned by industrial contamination mainly by metal-
working factories and by traffic. These heavy metals, known
as the most hazardous elements, are easily extracted by plants
from the soils in the studied area. In addition to traditional
geochemical mapping, the magnetic susceptibility was
successfully applied in determining heavy metal pollution
of soils on the city territories.
0 1999 Elsevier Science Ltd. All rights reserved
1. Introduction
The contamination of urban soils in countries with
developed industry is usually high and the most intensive
Correspondence to: L. Bityukova, e-mail: lida@gi.ee
pollution is usually found nearby the biggest industrial
centres. Very often these soils could not be used for
agriculture. Different geochemical methods such as
geochemical mapping are traditionally used for determining
the contamination, enabling to estimate the background
values of element concentrations in soils, to determine the
total amount of pollution and to trace the source of
pollution.
Detailed geochemical investigations of soils require a great
number of chemical analyses, which are time consuming
and expensive. In our study, the traditional geochemical
methods were complemented by measurements of low-field
magnetic susceptibility
(K),
which may be a fast and
effective alternative method enabling to estimate the
ecological situation and to trace the major sources of heavy
metal pollution (see recent reviews by Oldfield, 1991;
Verosub and Roberts, 1995; Dekkers, 1997).
Magnetic susceptibility is a measure of the iron-bearing
components in the material and can be used to identify the
type of the material and the amount of the iron-bearing
minerals it contains. Iron and steel will also contribute to a
K
reading. The magnetic techniques have been applied by
environmental scientists with demonstrable success in the
pollution studies The major advantages of environmental
magnetism are the high sensitivity and speed of magnetic
techniques. Even minute quantities of magnetic particles in
bulk samples can be measured rapidly. Many
anthropogenic emissions contain fine particles which are
highly magnetic. Therefore,
K
of polluted material can give
a general view of the degree of pollution. Detailed studies
of similar objects were carried out in different regions by
Nulman et al.. 1994; Dann et al., 1994; Georgeaud et al..
1994; Scholger, I997a. Scholger, I997b. These
investigations demonstrated the applicability of w
measurements for estimating the degree of heavy metal
pollution of soils in industrial areas.
829
830 L. Bityukova
et al.:
Magnetic Susceptibility as Indicator of Environmental Pollution of Soils
The magnetic properties depend on the grain size,
concentration and type of the magnetic minerals in the soil.
Ferrimagnetic minerals (such as magnetite) have the
strongest influence on the magnetic properties.
Diamagnetic minerals have low negative susceptibilities,
while paramagnetic minerals show low positive values of
the magnetic susceptibility
(K).
In general, carbonate rocks
are characterised by low
K,
while clay and sandstone
typically exhibit higher values of k.
The main objectives of the study are
:
-
comparing results from geochemical and geophysical
methods for the determination of pollution anomalies in an
industrial territory;
- applying low-field magnetic susceptibility
(K)
for a
small-scale geochemical mapping and monitoring of urban
soils;
- analysing variations of low-field magnetic
susceptibility with the chemical composition of soils;
- using correlation and factor analysis for the
establishment of general factors for soil contamination.
2.
Sampling and methods
The study area comprised the biggest industrial centre of
Estonia, Tallinn, and its suburbs. The geochemical soil
sampling was performed in the frame of a NATO project in
the years 1996 and 1997. A total of 53 I topsoil samples (0 -
20 cm) were collected from an area of 1291,2 km2 for
geochemical monitoring. The grid of sampling sites was
about 2 x 2 km for the territory of Tallinn region, and about
250 x 250 m for urban Tallinn (the territory is about 89,6
square km). Actually the density of sampling varies within
small limits due to difficult sampling conditions in the town
area. The sampling sites were digitised using topographic
maps in the scale
1:
25 000.
At the studied area different types of soils occur. In the
northern part of Tallinn and not far from the seashore they
are represented by different clayey and sandy soils. At the
seashore wet areas (at the peninsulas) and also near the
lakes swamp soils are observed. Sandy soils of small
thickness and bog soils prevail in the south-west part of
Tallinn, in the east part of region gley soils occur. On the
territory of Maardu technogenic soils are usual.
Samples were collected from open space (grass-plots,
parks, meadows), in urban at last in a few meters from the
buildings and roads. Fig.
1
shows the study area with the
sampling sites in Tallinn region (A) and urban Tallinn (B).
Each sample was collected from a square of about 15 x 15
cm. The weight of a sample was typically about
1
kg. The
sample preparation for chemical analyses was carried out in
the Institute of Geology in Tallinn (all samples were air-dried
in the laboratory, desegregated and sieved < 2mm). The soils
were then crushed using a ball mill and chemically analysed
in the Federal Institute of Geosciences and Natural
Resources, Branch Office Berlin. Concentrations of major
elements (Al, Ca, Fe, K, Mg, Na, P, Si and LOI) and
microelements (As, Ba, Bi, Ce, Cl, Co, Cr, Cs, Cu, F, Ga, Hf,
La, Mn, MO, Nb, Ni, Pb, Rb, S, Sb, SC, Sn, Sr, Ta, Th, Ti, U,
V, W, Y, Zn and Zr) were determined by X-ray fluorescence
(RFA) analysis. The reliability of the results were examined
by laboratory standards. Values below the detection level
were indicated as one-half of the detection limit.
The obtained geochemical data base was subdivided in two
data sets with respect to the sampling area. One
multivariate data set consists of 531 topsoil samples from
the Tallinn region. A second data set represents 271 topsoil
samples of urban Tallinn.
Low-field magnetic susceptibility
(K)
was measured in the
Paleomagnetic laboratory of the Institute for Geophysics
(University of Leoben, Austria) using Geofyzika KLY-2
and Exploranium KT-9 instruments.
The data bases were processed mathematically by means of
statistical analysis, correlation and factor analysis (R-mode
factor analysis) using STATISTICA for WINDOWS
software. Statistical distribution parameters of
K
and
element concentrations in soils from urban Tallinn and
Tallinn region are given in Table
1.
The relationships between the measured variables were
investigated by means of R-mode factor analysis (Reyment,
et al., 1993). This method permits to simplify the
interpretation of the obtained data and to replace the
original variables with a smaller number of estimations of
factors. Factors are determined so as to account for
maximum variance of all observed variables. Further
computations include the correlation matrix, extraction of
the factor matrix by principal component method and the
rotation of a factor matrix using the Varimax-normalized
L. Bityukova et al.: Magnetic Susceptibility as Indicator of Environmental Pollution of Soils 831
Table 1 Descriptive statistics of elements distribution in
topsoils of urban Tallinn and Tallinn region
El& Urban Tallinn (n = 271) Tallinn region (n = 53 I)
ment Min Max Std.D. Min Max Med. Std.D.
0 17204 1701 0 17204 460 1504.2
K
SiOz
riOz
A&O,
Ik20!
MnO
MgO
CaO
Na,O
I;,0
P&k
SO;
Cl
1;
LOI
AS
Ba
Ce
Co
Cr
Cs
Cu
Ga
Hf
La
Mo
Nb
NI
Pb
Rb
Sb
SC
Sn
Sr
Ta
Tb
11
V
w
Y
Zn
ZI
14.47
0 08
I 73
0 25
0.01
0 02
0 32
0 I4
0 56
0 04
0 01
0001
091
05
127
05
05
05
05
05
OS
05
0.5
0 5
05
0 5
93.06
0.62
I3 16
8.59
0 47
I
73
23.55
I
33
3 99
2 28
8.30
0.04
0 15
73 24
120
763
156
18
475
469
I6
05
05
0 5
05
23
0.5
OS
04
OS
OF
326
16
I3
205
468
II7
42
I4
71
469
8
I8
I8
200
29
65
1431
I3 14 8.67 94.63 71.10 15.17
0.08 0.04 0 62 0 I9 0 II
I.51 0.71 13.16 448 21
I 07 0 I3 31 26 179 I8
0.05 0.00 0.48 0.04 0.06
0.30 0.01 3 46 0 44 041
3.17 0.10 42.64 2 63 4.27
0.19 0.03 I 81 0 55 0 26
0.44 0.18 3 99 I .49 0 60
0.31 0.02 6 55 0 32 0 55
0.51 0.01 8.30 0 I4 0.39
0.003 0.001 0.038 0 004 0.004
0.03 0.003 0 61 0.003 0.049
IO.56 091 88.8 12 8 II 5
8.7 05 136 5 9.9
748 61 I604 257 101.2
188 0.5 167 40 23.6
23 0.5 I8 0.5 25
42.7 05 475 22 33.2
13 05 6 I I .4
48.4 05 604 I5 46.0
23 0.5 I6 4 2.9
2.1 05 II 3 21
27.2 0.5 326 44 27.6
15 0.5 I7 I I7
2.2 0.5 I3 5 24
14.0 0.5 205 I5 10.7
57.7 2 468 29 48.5
I3 7 0.5 II7 25 19 I
5.2 05 42 I 0 4.8
21 0.5 I4 4 26
7.9 0.5 71 2 6.2
425 I8 771 81 54.9
I .6 0.5 8 05 I6
3.1 0.5 20 I O 3.3
2.5 05 I8 4 2.6
19.4 0 5 200 22 18.5
37 0.5 29 3 3.5
8.5 6 152 I9 14.1
161.7 5 I463 71 148.X
42 368 48.7 10 698 I31 73.2
method. Factor loading and eigenvalues of the major
factors were calculated. Maps of element distributions and
K were processed and printed using SURFER 6.0 for
WINDOWS software.
3. Results and discussion
The composition of the observed soils and especially the
distribution of the microelements were mainly controlled
by technogenous factors. The descriptive statistics of the
statistical distribution of chemical elements and K in the
topsoils of Tallinn region and urban Tallinn are given in
Table
1.
In both data sets, statistical analyses yielded strong
correlation among the major elements. Statistically
significant correlation coefficients (as usual they have the
values 0.4-0.8) indicated a direct relationship between these
elements and source rock material (Palaeozoic terrigenous
and carbonate rocks and quaternary deposits). Due to
variations in the composition of the underlying rocks and
the pollution of soils by industrial sources, relations
between microelements were very complex.
Using factor analysis, six dominant factors were chosen for
further interpretation. They account for 45 % of the element
variation in the soils of Tallinn region and for 55 % in the
soils of urban Tallinn. Tables 2 and 3 show the eigenvalues
of the respective factor scores. In Table 4 the factor
Table 2. Eigenvalues of factors for Tallinn region
Factor Eigenvalur % total Cumulative Cumulative
variance eigenvalues percents
1
7 88 1792 7.88 17.92
2 3.96 8.99 II 84 2h.91
3 3 02 6 87 14.86 33 78
4 I91 4.35 I6 7X 38.13
5 I h8 3 82 1846 41.95
6 I 65 3 76 20.1 I 45 71
Table 3. Eigenvalues of factors for urban Tallinn
Factor Eigenvalue % total Cumulative Cumulative
variance eigenvalues percents
I Y 56 22.76 9 56 22 7h
2 4 53 IO 77 140’) 33 54
3 3.50 8 34 I7 59 41 88
4 2.21 5.26 19.80 47 I4
> I 86 4.42 21 66 51 56
6
I
70 4 06 23.36 55 62
loading of the principal factors for both data sets are shown.
Three groups of factors could be subdivided from the bulk
data set.
The first group combines the first factors for both data sets,
third and sixth factors for urban Tallinn. Typical lithogenic
elements have high loading in this group of factors.
indicating strong influence from the composition of the
underlying rocks and quaternary deposits. The
concentration of the elements (TiO:, Al,O,, KzO, Ga, Rb
and SC) with high loading on the first factors are mostly
connected with the clay content of the soils. Opposite to
them, SiO, shows a high negative factor loading (-0.71) on
the soils of urban Tallinn, which is indicative of an
increase of sand components. The sixth factor for urban
soil (CaO and MgO have high loading) reflects the
influence of the background carbonate rocks on the soil
composition, especially in the eastern part of the city,
where the soils cover platform carbonates.
The second group of factors includes the second factors for
both data sets, the fourth factor for urban Tallinn and the
832 L. Bityukova et al.: Magnetic Susceptibility as Indicator of Environmental Pollution of Soils
fifth factor for Tallinn region. The elements with high
loading on these factors (Cr, Ni, MO, Cu, Pb and Zn)
exhibit the local geochemical anomalies caused by
industrial contamination. Low-field
K
also yields high
loading and correlates with Cr, Ni and MO. On top of this,
K
correlates with Pb, Zn and Cu in both data sets. Anomalies
of the
K
correspond with high concentrations of these
elements.
The third group of elements with high positive factor
loading is represented by P,O,, F, Sr and Y. The
distribution of these elements is very resemble. In general,
concentrations are higher in the north-eastern part of the
study area. The contaminants formed spatial geochemical
anomalies. The concentration of these elements in the soils
of Tallinn region are connected with the contamination by
phosphorite. It is especially high in the area close to the
phosphorite deposits in Maardu. Dictyonema shale,
glauconite sandstone and clay were outcropped in this area
during exploration campaigns for the Maardu phosphorate
deposits. The Dictyonema shale is characterised by high
contents of toxic elements, iron and organic matter.
Table 4. Factor loadings of main factors for topsoils of
urban Tallinn and Tallinn region
Urban Tallinn Tallinn region
Element Factor Element Factor
loadings loadings
I
Factor TiO, 0.90 TiO, 0.92
A1203 0.88 A1203 0.96
K,G 0.88 K,O 0.90
Ga 0.80 Ga 0.90
Rb 0.82 Rb 0.89
SC 0.72 SC 0.85
II Factor Pb 0.78 Cu 0.71
Zn 0.75 Pb 0.79
Zn 0.78
III Factor SiO> -a 71 P,Os 0.93
LOI 0.84 F 0.79
Sr 0.82
Y 0.85
IV Factor K 0.80 SiO, -0.72
Cr 0.74 CaO 0.82
MO 0.74
Ni 0.88
V Factor P,05 0.88 Ni 0.77
Sr 0.71 K 0.65
Y 0.73 MO 0.63
Cr 0.66
VI Factor MgO 0.77
CaO 0.79
Different chemical elements, which polluted the
environment in this region, are concentrated in the dump
(Pihlak et al., 1986). The host material includes various
iron minerals (pyrite, iron hydroxides, glauconite) and an
increase of the concentration of iron is also observed in me
soils on the territory of Maardu.
Factor analysis enables to reveal groups of elements which
correlate with
K
(Cr, Ni and MO). Figures 2 and 3 illustrate
the grouping of elements on the base of their factor loading
values for factors with high loading of
K
and elements
correlating with it. The highest values of factor loading for
Cr, Ni, MO and
K
were calculated for the fifth factor on the
soils of Tallinn region (Fig. 2). The fifth factor accounts for
3.82 % of the total variance. The association of the typical
technogenic elements, which have high loading on this
factor, reflects the intensive industrial contamination of the
topsoils in this area. The fourth factor has high negative
factor loading for SiO, and Na,O and high positive for the
LO1 (loss-in-ignition), indicating the interrelation between
the content of elastic components and organic matter.
Topsoils of Tallinn region
Extraction: Principal components
0.9 1
O=
.s .P
0.7 .
8= f
c10 0.5 M!&
za 0.5. MkIO C*O
;3
z!L
Th
*4O, ““,
Tiq .* &,o,
” 0.1
g.B SiO, . La Zr. Zn.s, ”
??
:
??
. As
i;z-O.’
??
Nap >I .*B2 sr : so,
- -0.3 .
-I -0.6 -0.2
0.2
0.6 1
Underlying rock composition and organic matter
Fourth Factor Loadings
Fig. 2. Factor loading for fourth and fifth factors for topsoils of Tallinn
region. Elements association with highest values of factor loading are shown
inside boxes.
The soils of urban Tallinn establish high loading values for
Cr, Ni, MO and
K
for the fourth factor. The total variance of
this factor is 4.42%. The plot of factor loading (Fig. 3) is
very similar to the Fig. 2, but the values of factor loading
for Cr, Ni, MO and
K
are higher.
1.
0.8
0.6
0.4
Topsoils of urban Tallinn
Extraction. Principal components
-I
-0.6 -0.2 0.2 0.6 1
Underlying rock composition and organic matter
Third Factor Loadings
Fig. 3. Factor loading for third and fourth factors for topsoils of urban
Tallinn. Elements association with highest values of factor loading are
shown inside boxes.
L,. Bityukova
et al.:
Magnetic Susceptibility as Indicator of Environmental Pollution of Soils 833
The soils are more intensively polluted, as indicated by
stronger correlation of these elements with K. The magnetic
susceptibility values range from 0 to 17204 SI*lO-” in the
soils of Tallinn region and urban Tallinn. Mean K in the
soils of Tallinn region was 894 SI* 1O-6 with a median value
of 460 SI*10-6. The soils of urban Tallinn were
characterised by generally higher values (mean
susceptibility = 1089 * 10e6 Sl, median = 598 * 10eh SI).
It should be noted that the vast majority of the samples
were characterised by susceptibility values less than 1200
*IO” SI and that only 28.8% of the samples of Tallinn
region and 29.9 % of the samples from urban Tallinn have
magnetic susceptibilities higher than the respective mean
values.
Maps of low-field magnetic susceptibility for the territory
of Tallinn region and for urban Tallinn are shown in Fig. 4
and Fig. 5.
A generally higher level of K in the soils of urban Tallinn
in comparison with the soils of Tallinn region reflects the
more intensive anthropogenic contamination. Several local
anomalies of K are observed on the territory of urban
Tallinn. In the anomalous zones, susceptibility increases up
to 11000 *10m6 SI. The highest values occurred in areas,
where machine-building factories are located.
5360 5365 5370 5i7s 5580 5385 s3bo 539s
km
Fig. 1. Contour map ofmagnetic susceptibility variation in topsoils ofTallinn region
S368
5369 5370 537 I 5372 5373 537.l 537s 5376 5377 5378 km
Fig. 5. Contour map of Imagnetic susceptibility variation in topsoils of urban Tallinn
834
L. Bityukova
et al.:
Magnetic Susceptibility as Indicator of Environmental Pollution of Soils
In the eastern part of urban Tallinn, susceptibility values of
3000-5000 * 10m6 SI were determined. Various premises of
metal-manufacturing industry are located in this area, and K
increases to 4000-6000*10~6 SI in soils, which were
sampled close to such enterprises. On top of this, relatively
high values of
K
(2000-3000*10’6 SI) were observed near
roads.
On the territory of Tallinn region the variation of
K
was less
intensive. In certain soils
K
reached 6000* 10e6 SI. Again, a
relative increase of the susceptibility (2000-3000* IO’6 SI)
was observed near the major roads. In contrast, samples
from unpolluted areas in the southern, south-eastern and
south-western parts of the study area yielded
susceptibilities very close to the median value. In the
absence of industrial contaminants
K
varied between 0 and
600* lO-6 SI.
Anomalously high concentrations of iron as well as an
increase of
K
was determined in soils at Maardu. The
anomaly is mostly caused by geological circumstances and
most part of the iron is present in form of ferrimagnetic
minerals (magnetite) derived from the Dyctionema shale
and glauconite sandstone, outcropping as a result of the
exploration for phosphorite deposits. The average level
heavy metals in the soils of Maardu is in average two times
higher than the background level. Especially high increase
was determined for Zn.
The relations between K and the concentration of heavy
metals were studied. The magnetic susceptibility correlated
significantly with Ni, Pb, Cu and, less pronounced, Ni, Cr
and MO. The correlation of Ni and the
K is
relatively high
with a correlation coefficient = 0.61 (0.71) for the soils of
Tallinn region and urban Tallinn, respectively. A rather
good correlation (r = 0.51 (0.57)) was determined for Cr.
For Cu, Zn, MO and Pb the following positive correlation
coefficients were calculated: r ,-” = 0.42 (0.41); r Zn = 0.35
(0.27); r Mo = 0.26 (0.45); r rb = 0.29 (0.23).
The association of Cu, Pb and Zn is strongly connected
with industrial contamination of soils. The anomalies of
these elements are very local and are mostly observed in
urban Tallinn. In Tallinn the combination of sources of
contamination in the densely populated and heavily
industrialised areas took place. The areas which show the
highest concentration of Ni, Cr. Pb and Cu elements are
located in urban Tallinn near the major roads and close to
the industrial enterprises which production was connected
with machine-building and metal-reworking.
Concentrations of Zn are also high there (from 400 mg/kg
up to 650 mg/kg). The concentration of these elements in
the soils of Tallinn region is close to the background level
or slightly higher.
Study of soil by consecutive extraction method permitted to
establish that about 40% of the total concentration of Zn,
30% of Mn and 20% of Pb occurred in the studied soils in
the carbonate form. About 40% of Cu and Zn were found in
the forms of
sulfides
and about 50% of Pb was adsorbed
on the amorphous hydroxides. Our earlier investigation
(Bityukova, 1994) showed that Pb, Zn and Cu are easily
extracted by plants.
As Wilson and Bell (1996) indicated in the overview of the
heavy metals mobilisation, Zn is one of the most mobile
elements and it is more mobile than Pb and Cu in the soil
environment. According to Kabata-Pendias
(1994)
and
Chlopecka et al. (1994) the residual (non-available) forms
of Pb and Zn dominate in uncontaminated soils and
anthropogenic metals are more mobile.
The enrichment index was calculated for Pb, Cu, Zn, Cr, Ni
and MO as the sum of the ratios of the element
concentrations in comparison with the world-wide average
Enrichment
5360 5365 5370 5375 5380 5385 5390 5395 km
Fig.6. Contour map ofenrichment index variation ill topsoils ofTallinn region
L. Bityukova
et al.:
Magnetic Susceptibility as Indicator of Environmental Pollution of Soils 835
concentration of these elements in non-contaminated soils deposits also led to an increase of the magnetic
as found by Kabata-Pendias and Pendias (1986). susceptibility.
sum
(C,dK,,,+ C&/K,,+
Cz,IKzn+ &/Kc,+ CNIJKN,+ C,,/K,,)
--
El = n
C4
-
elements concentration in the soil samples, K, -
average concentration of elements in world soils, A-
element. n - is a number of elements analysed.
On the base of the obtained data the map of enrichment
index (El) for the studied soils was plotted (Fig. 6 ). The
highest values of enrichment index were revealed for areas
with the industrial activities. At these areas the El reaches
values some 10-20. The correlation of
K
with the
enrichment index is statistically significant (r = 0.53). In
this calculation, strong correlation between K and element
concentrations was established mostly for values below
2000*l0-h SI. The comparison of the maps showed that at
the areas with the highest level of enrichment index an
increase of the
K
is observed
A correlation of
K
with the summary concentration of
heavy metals was also established for susceptibility values
below 2000 SI* 10Th. The magnetic susceptibility correlated
with the ratios of insoluble residue to iron contents and the
insoluble residue to the enrichment index.
The investigation of the migration forms of heavy metal in
the studied topsoils established that Pb, Zn and Cu have the
highest potential mobility and bioavailability. In the
contaminated soils the more mobile forms dominated.
The level of the
K
is a result of complex influence of
natural ferrimagnetic minerals and the contribution of
magnetic particles into soils as a result of industrial
pollution. The increase in heavy metal concentrations also
take place in the result of emission.
The bulk composition of non-contaminated soils influences
their properties and the adsorption capacity. In the soils of
Tallinn region some increase in magnetic susceptibility was
determined in the soils with higher level of Fe,O,. Some
increase in heavy metal concentrations in these soils is
connected with the great ability of iron compounds to
adsorb heavy metals on their surface.
In the studied soils the higher values of magnetic
susceptibility is observed with increase in the ratios of
insoluble residue to iron content and of the insoluble
residue to enrichment index.
kknowkdgemenu ‘This study was carried out in the rramc of the
collaborative pmject was financed by the Scientifc and Environmental
Affairs Division NATO (Ref. l:NVIR.CRCi 960910). This support is
gratefull) acknowledged. Authors wish to thanks Dr. 7‘. Kiipli from the
Institute of t&logy (Tallinn) for the help in the field work. We are grateful
to colleagues from the Federal Institute of Geosciences and Natural
Resources. Germany (BGR) for the assistance in the sample preparation and
to colleagues from the Federal Institute of Geosciences and Natural their
analysis. ‘The authors are grateful to Prof. P. Rochette for the critical
comments and corrections which significantly improved this manuscript.
We arc also wish to thanks an anonymous reviewer for the constructive
comments on the paper
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Kabata-Pendias. A. Trace elements in soils-an agricultural implication in
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Measurements of the
K
provided complementary
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the environmental situation in the study area. The mapping
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determine groups of elements (heavy metals) which
influenced the variation of low-field magnetic
susceptibility.
The study has shown that variation of the
K
in topsoils of
Tallinn region and urban Tallinn correlated with the
concentration of heavy metals (Ni, Cr, Zn, Cu, Pb and
MO). Concentrations of Pb, Cu and Ni are higher in topsoils
of urban Tallinn than in the soils on the territory of Tallinn
region. The contamination of soils resulting from industrial
activity in the areas near metal-reworking and machine
building factories as well as by traffic led to an increase of
the
K.
At the same time
,
the contamination of soils by iron,
iron minerals and heavy metals in the area near the Maardu
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