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I International Conference „ECOLOGY OF URBAN AREAS 2011“, 30th September 2011, Ecka, Serbia
484
I International Conference
„ECOLOGY OF URBAN AREAS“ 2011
STATISTICAL PARAMETERS ON THE CONTENT OF ARSENIC OF
ANTHROPOGENIC ORIGIN IN THE SKOPJE REGION SOIL
Simeon Jancev, Slobodan Bogoevski, Bosko Boskovski*, Blagica Bliznakovska
University “SS Cyril and Methodius”, Faculty of Technology and Metallurgy, Skopje, FYR Macedonia
bboskovski@tmf.ukim.edu.mk
ABSTRACT
Arsenic, as the most common soil contaminant, was the subject of our research, presented in this publication.
Namely, at the previous construction of the geochemical atlas of the presence of heavy toxic metals in the Skopje
region soil, the area of about 300 km
2
has been explored. The analysis has been performed applying a semi
quantitative method of ESA (Emission Spectral Analysis). The minimal detection limit for arsenic of this method
is 100 ppm, so the obtained results did not show any value exceeding the previously pointed. Having in mind the
probability of anthropogenic pollution of some segments of Skopje valley with arsenic, we enlarged our
investigation as second phase of investigation applying the method of ICP-MS (Inductively Coupled Plasma -
Mass Spectrometry). According to this method the minimal detection limit for arsenic is 1 ppm, and four
micro-localities of increased arsenic content were considered. In third phase has been a process of detailed grid
analysis of arsenic contents in the top soil samples of specific micro-localties. With a statistical processing of
data the following values of statistical parametres have been evaluated: number of samples (500), minimal
detected content (< 0,3 ppm), maximal detected content (244,7 ppm), arithmetic mean (19 ppm), geometric
mean ( 16 ppm), median ( 16 ppm), mean ( 16 ppm), standard deviation (1,8 ppm); threshold ( 20 ppm),
threshold’s double value (40 ppm); threshold’s four times value (80 ppm); anomalous mean (> 80 ppm). The
comparative frequency polygon, as well as the comparative diapason diagram were constructed.
Key words: Arsenic, top soil sample, statistical parameters.
INTRODUCTION
Most contaminated regions in the world generally are considered territories with greater population
density i.e. largest cities which represent huge complexes of heterogeneous structures (Bowen, 1979).
The contamination of wider city areas is a result of the intensive traffic, presence of industry,
agrochemical influences inside and around city regions, radioactivity of natural and anthropogenous
origin, as well as other anomalies (Kim, 2000; Alloway, 1990). All these factors are reflected upon the
ecological condition and the contamination in the city and the wider region (Šajn, 1994).
According to the recent investigations, in the Skopsko Pole territory, was determined the
contaminations with heavy toxic metals in the soil. With the aim of getting the idea of the terrain’s real
condition (Bogoevski and Jancev, 2007; Jancev et al., 2007), there has been realized a project for
preparing a geochemical atlas of heavy toxic metals for the territory of Skopsko Pole, with
investigated area of more than 300 km
2
. In this research there has been put a particular accent on
Arsenic (As), as one of the most common soil contaminants (Shacklette et al., 1974), as well as for the
existence of relative assumptions of its increased concentration in some micro-localities (Jancev et al.,
2010).
I International Conference „ECOLOGY OF URBAN AREAS 2011“, 30th September 2011, Ecka, Serbia
485
EXPERIMENTAL AND DISCUSSION
In Phase 1 there have been analyzed samples of the top soil layer of cca 10 - 40 cm in depth.
According to previously defined systematic grid (1 km x 1 km), 300 samples have been taken. Every
sample has a mass of around 1 kg, and it is a represent of 5 separate samples.
Firstly, samples have been dried at room temperature in the period of 3 weeks. The coarse-grained
rock-samples as well as organic relics (roots, leaves etc.), were separated from samples. The dried
samples have been classically treated in the preparation process, i.e. have been sieved (under 63 µm),
and milled. From a total sample was selected cca 0,2 - 0,3 kg representative sample for the further
processing by the squaring treatment method.
Due to the fact that maximum permissible concentration of each metal separately depend of the acidity
of the soil, pH value of the soil has been measured in total of 30 representative samples, within the
value interval between 6 - 6,5.
Analysis of samples has been made by using the semi quantitative method ESA (Emission Spectral
Analysis). There have not been found values of As content, it hasn’t been detected presumably due to
the fact that examined soils of Skopsko Pole are characterized by values under the lower detection
limit (< 100 ppm) for the analyzed microelement.
Due to reasonable doubt of anthropogenous contamination with As in separate micro-localities, there
has been conducted a research of 30 representative samples of analysed soils, with the application of
ICP-MS method (Inductively Coupled Plasma - Mass Spectrometry) with a lower detection limit for
As of 1 ppm. The results are presented in Table 1 and the markings on soil samples taken for analysis
are original and taken from the Phase 1 of the research.
It is evident from the results that As content in the analysed samples is within the limit interval so that
to be a serious pollutant in the soils of Skopsko Pole and for that reason, Phase 2 of the research is
conducted with the application of the ICP-MS method.
Table 1: As - contents in 30 representative samples of analysed soils
In Phase 2 have been taken a total of 300 samples of the top soil layer of cca 10 - 40 cm in depth,
according to a previously defined systematic grid (1 km x 1 km).
Sample
As [g/t]
Sample
As [g/t]
XIII/18 24 XXIV/7 16
XXI/16 31 XXIV/14 11
XX/9 11 XXV/4 46
XV/19 10 XXV/13 27
XII/15 12 XXVI/8 28
XI/17’ 30 XXVII/5 13
XIV/19 26 XXVII/14 19
XVII/18 9 XXVIII/5 23
XIII/16 18 XXVII/11 12
VII/10 13 XXIX/8 15
XX/14’ 13 XXX/6 16
XXII/18 11 XXXI/9 14
XIX/17 34 XXXIV/2 17
XXII/8 16 XXXV/13 27
XXIII/13 8 XXXVI/17 20
I International Conference „ECOLOGY OF URBAN AREAS 2011“, 30th September 2011, Ecka, Serbia
486
Figure 1. Histogram for As - distribution of the Skopje region soil
In compliance with the usual statistic procedure by log - normal methodology, ware evaluated
statistical parameters.
Table 2: As - statistical parameters of the Skopje region soil
Based on the results from Phase 2 for the distribution of As in Skopsko Pole soils, there have been
found indications of anomalous increase in As contents (>> 20 ppm) in particular samples around
separate micro-localities:
1. Rudnici i Zelezarnica Skopje, - v.Smilkovci - v.Stajkovci - v.Arachinovo
2. OHIS factory - v.Gorno Lisiche - v.Dolno Lisiche - v.Drachevo - v.Ognjanci
3. Hipodrom, Skopje - crossroads: Skopje - Veles - Kumanovo
4. OKTA rafinery - v.Miladinovci.
In compliance with this, in Phase 3 there has been conducted more detailed eco-geochemical research
(in a systematic grid of 333 m x 333 m) for determination of As distribution in agricultural soils in the
abovementioned micro localities. According to the semi-detailed systematic grid from the top soil
sample, in depth of around 20 - 30 cm, there have been taken total of 500 samples for analysis.
Based on the analytical data of distribution, i.e. determined As content in separate microlocalities,
there has been made a systematic expatiation upon content and frequencies.
Statistical parameters of 300 samples
As
[ppm]
Minimal detected content 3
Maximal detected content 70,1
Arithmetic mean 15,24
Median 13,4
Mean (by log procedure) 13,05
Standard deviation - σ (by log procedure) 1,56
Threshold (by log procedure) 16,2
Threshold’s double value 32,4
Threshold’s four times value 64,8
Anomalous mean 65
I International Conference „ECOLOGY OF URBAN AREAS 2011“, 30th September 2011, Ecka, Serbia
487
Table 3: As-contents presented in groups with corresponding frequencies
for the treated soil samples of the micro-locality:
Rudnici i Zelezarnica Skopje, - v.Smilkovci - v.Stajkovci - v.Arachinovo
Figure 2. Histogram for As - distribution of the micro-locality:
Rudnici i Zelezarnica Skopje, - v.Smilkovci - v.Stajkovci - v.Arachinovo
Table 4: As-contents presented in groups with corresponding frequencies
for the treated soil samples of the micro-locality:
OHIS factory - v.Gorno Lisiche - v.Dolno Lisiche - v.Drachevo - v.Ognjanci
Figure 3. Histogram for As - distribution of the micro-locality:
OHIS factory - v.Gorno Lisiche - v.Dolno Lisiche - v.Drachevo - v.Ognjanci
Groups
As [ppm] 0-10 11-20 21-30 31-40 41-50 131-140
Frequency
42 97 20 5 0 1 Σ = 165
Groups
As [ppm] 0-10 11-20 21-30 31-40 41-50
Frequency
24 104 74 28 9
Groups
As [ppm] 51-60 71-80 101-110 211-220 241-250
Frequency
4 1 3 1 1 Σ = 249
I International Conference „ECOLOGY OF URBAN AREAS 2011“, 30th September 2011, Ecka, Serbia
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Due to small number of samples, there is absence of graphical figure in the form of a histogram for the
micro-locality of Hipodrom Skopje - crossroad: Skopje - Veles - Kumanovo.
Table 5: As-contents presented in groups with corresponding frequencies
for the treated soil samples of the micro-locality:
Hipodrom, Skopje - crossroads: Skopje - Veles - Kumanovo
Table 6: As-contents presented in groups with corresponding frequencies
for the treated soil samples of the micro-locality:
OKTA rafinery - v.Miladinovci
Figure 4. Histogram for As - distribution of the micro-locality:
OKTA rafinery - v.Miladinovci
In compliance with standard statistical procedures there has been made a statistical evaluation of the
research data (Table 6). A comparative review has been given due to the need of a fuller
comprehension of some statistical parametres of the whole investigated area, as well as comprehension
of the correlation between the same statistical parametres from various micro-localities. There have
been noticed increased values of arithmetic mean, median, mean and threshold for the micro-locality
in the nearest surrounding of OHIS factory, in comparation with a considerably lower values of the
same statistical parametres in the rest of the investigated micro localities.
It can be said about the whole investigated area that As contents up to 20 ppm have the highest
frequencies, and from 21 ppm further, the frequencies considerably decrease (Figure 5). For the micro-
localities under influence of Rudnici i Zelezarnica Skopje and OHIS factory it can be said that their
frequency polygons are similar, so that the frequency polygon of samples under influence of OHIS
factory present higher values of frequencies for As contents in the region of 21 - 30 and 31 - 40 ppm,
which is why it is treated as a contaminated region of a various (higher) contamination degree.
Groups
As [ppm] 0-10 11-20 21-30
Frequency
1 15 6 Σ = 22
Groups
As [ppm] 0-10 11-20 21-30 31-40 41-50 61-70 111-120
Frequency
36 22 2 1 1 1 1 Σ = 64
I International Conference „ECOLOGY OF URBAN AREAS 2011“, 30th September 2011, Ecka, Serbia
489
Table 7: Comparative review of statistical parameters of the investigated micro-localities
1. Rudnici i Zelezarnica Skopje, - v.Smilkovci - v.Stajkovci - v.Arachinovo
2. OHIS factory - v.Gorno Lisiche - v.Dolno Lisiche - v.Drachevo - v.Ognjanci
3. Hipodrom, Skopje - crossroads: Skopje - Veles - Kumanovo
4. OKTA rafinery - v.Miladinovci
5. Whole investigated area
Figure 5. Comparative frequency polygon
Micro-locality
1 2 3 4
Number of samples 165 249 22 64
Minimal detected content < 4 < 4 7,63 < 4
Maximal detected content 131 244,7 27 118
Arithmetic mean 17 25 16,46 17
Geometric mean 12 19 16 11
Median 18 20,5 17,62 9
Mean (by log procedure) 13 20 16,4 9,3
Standard deviation – σ (by log procedure) 1,714 1,97 1,3 2,21
Threshold (by log procedure) 16,4 24 19 14
Threshold’s double value 32 48 38 28
Threshold’s four times value 64 96 76 56
Anomalous mean 64 96 76 56
I International Conference „ECOLOGY OF URBAN AREAS 2011“, 30th September 2011, Ecka, Serbia
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In compliance with the comparative diagram of diapasons of contents with highest frequencies,
arithmetic means and medians, in the whole investigated area and separate micro localities, it could be
concluded that the micro-locality in the nearest surrounding (or under the influence) of OHIS, the area
of maximum frequencies is with the diapason of 3 - 40 ppm and it is almost identical with the whole
investigated area. It is also evident that the values of statistical parameters for the micro-locality near
OHIS, are significantly higher in comparation with the same ones for the micro locality near Rudnici i
Zelezarnica Skopje, Hipodrom and OKTA rafinery.
1. Rudnici i Zelezarnica Skopje, - v.Smilkovci - v.Stajkovci - v.Arachinovo
2. OHIS factory - v.Gorno Lisiche - v.Dolno Lisiche - v.Drachevo - v.Ognjanci
3. Hipodrom, Skopje - crossroads: Skopje - Veles - Kumanovo
4. OKTA rafinery - v.Miladinovci
5. Whole investigated area
Figure 6. Comparative diapason diagram
Based on the data of As distribution from separate micro-localities, there has been conducted a
statistical evaluation of the whole investigated area.
Figure 7. Histogram for As - distribution of the whole investigated area
Based on the standard procedure by the logarithm method, the rest of the statistical parametres have
been evaluated and presented in Table 8.
I International Conference „ECOLOGY OF URBAN AREAS 2011“, 30th September 2011, Ecka, Serbia
491
Table 8: As - statistical parameters of the whole investigated area
CONCLUSION
Based on the above given data and their statistical evaluation for the distribution of As contents in
soils of treated micro-localities, it could be concluded that there are anomalously increased contents of
As (>> 20 ppm) in separate micro localities.
Micro-localities or agricultural alluvial soils around Rudnici i Zelezarnica Skopje, OKTA refinery and
Hipodrom Skopje are considered globally as uncontaminated or low contaminated.
The micro-locality E, NE and SE from the OHIS factory i.e. to v.Gorno Lisiche - v.Dolno Lisiche -
v.Drachevo - v.Ognjanci, due to increased frequencies of As contents in the range of 20 - 40 ppm As
and increased values of statistical parameters is treated as a contaminated area.
The above stated data and regions of most frequent contents point out how a micro-locality with its
high As content (increased values of statistical parameters) can statistically influence and increase the
same values for the whole region.
The contamination of the above stated micro localities is of anthropogenous origin and as a result of:
presumably productive activities of OHIS (a former pesticides manufacturer) Rudnici i Zelezarnica
skopje, OKTA refinery, whereas in agricultural regions presumably and partly due to long - term,
decades long use of agrochemical means (pesticides, artificial fertilizers etc.) in agriculture.
REFERENCES
Bowen, H. J. (1979). Environmental chemistry of elements. Acad. Press, London.
Šajn, R. (1994). Gech. atlas of the Ljubljana urban area, 3
rd
Int. Symp. on Env. Geoch., Krakow.
Shacklette, H.T., Boerngen, J.G., & Keith, J.R. (1974). Selenium, fluorine and arsenic in surficial materials of
the conterminous United States. U.S. Geol. Surv. Circ.
Kim, H. Ten. (2000). Environmental soil science. Univ. of Georgia, Athens, New York, Basel.
Alloway, B. J. (1990). Heavy metals in soils. Printed in G. Britain.
Bogoevski, S., & Jancev, S. (2007). Regional geochemical surveys on heavy-toxic metals (Pb, Zn and Cd) in soil
samples from the Veles city area and its surroundings, Journal of Environmental Protection and
Ecology, JEPE, vol. 8, No 1, 56-66.
Statistical parameters of 500 samples
As
[ppm]
Minimal detected content < 0,3
Maximal detected content 244,7
Arithmetic mean 19
Geometric mean 16
Median 16
Mean (by log procedure) 16
Standard deviation (by log procedure) 1,8
Threshold (by log procedure) 20
Threshold’s double value 40
Threshold’s four times value 80
Anomalous mean 80
I International Conference „ECOLOGY OF URBAN AREAS 2011“, 30th September 2011, Ecka, Serbia
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Jancev, S., Bogoevski, S., & Hristova, E. (2007). Geochemical surveys on toxic heavy metals Pb, Zn and Cd in
agricultural soil samples from Bashino village-Rechani at the Veles city area, Macedonia, Journal of
Environmental Protection and Ecology, JEPE, vol. 8, No 1, 67-76.
Jancev, S., Bogoevski, S., & Bliznakovska, B. (2010). Results of the preliminary regional eco-geochemical
mapping of the agricultural soil samples from the Skopje city area, Journal of Environmental Protection
and Ecology, JEPE, vol. 11, No 3, 854-865.
