84
Li, Mg, Mn, Mo, Na, Ni, P, Pb, Sr, V and Zn. For AES-ICP instrument calibration
and quantitative determination of each element’s contents in digests, a commercial
standard mix solution (11355-ICP Multi Element Standard IV, Merck) was used.
The correlation coefficient of calibration curve for each element was 0.999. In order
to check for possible background contamination, blank samples were used and processed simultaneously with field samples. The method detection limit was calculated based on average measuring of the blank sample (γ ± 3δ). For all laboratory
samples and standard solutions, treated ultra-pure water was used. The QC of the
applied techniques was performed by standard addition method, and it was found
that the recovery for the investigated elements ranges for ICP-AES between 98.5
and 101.2% and for ETAAS between 96.9% and 103.2%.
For this study, M2 and M3 moss samples certified reference materials (Steinnes
et al. 1997) were used to check method accuracy, and for all considered elements,
the difference between measured and certified values was within 15%.
Optimal conditions for the analysis of arsenic and cobalt by ETAAS and mercury
by CV-AAS were given by Balabanova et al. (2010).
3.4 Results and Discussion
Data from the descriptive statistics of the measurements of 23 elements determined
by ICP-AES (Ag, Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni,
P, Pb, Sr, V and Zn) in moss samples collected from 107 sampling locations in
Bitola region are presented in Table 3.1. In Table 3.1 the following statistical parameters are given: N, number of samples; X, arithmetical average; X(BC), arithmetical
average after Box-Cox method; Md, median; Min, minimum; Max, maximum; P 10 ,
10th percentile; P 90 , 90th percentile; P 25 , 25th percentile; P 75 , 75th percentile; Ѕ,
standard deviation; Ѕx, standard error; CV, coefficient of variation; A, skewness; Е,
kurtosis; ВС, Вох-Сох transformed values.
The values of macroelements Al, Ca, Fe, K, Mg and Na are in the following
ranges: 0.008–1.6% Al; 0.02–1.9% Ca; 0.007–1.1% Fe; 0.009–1.2% K; 0.004–0.48%
Mg and 0.003–0.26% P. High matrix content of these elements mostly originated
from plant tissues, and it can be sometimes enriching the actual values from atmospheric distribution of these elements.
In Table 3.2 the comparison of the median, minimal and maximal values for the
content of analysed elements in moss from Bitola region with those for the Republic
of Macedonia and Europe is given. It could be seen that the median values for the
content of almost all analysed elements in moss samples from Bitola region are very
similar to those obtained for the Republic of Macedonia. The only difference is in
the content of copper which in the moss samples from Bitola region is 3.24 times
higher than that in the moss samples from the whole territory of Macedonia. If we
compare the obtained results for the median value for the moss samples from the
area around the thermoelectric power plant and those from wider region of Bitola, it
could be seen that moss samples collected in the vicinity of REK Bitola have higher
T. Stafilov et al.
Li, Mg, Mn, Mo, Na, Ni, P, Pb, Sr, V and Zn. For AES-ICP instrument calibration
and quantitative determination of each element’s contents in digests, a commercial
standard mix solution (11355-ICP Multi Element Standard IV, Merck) was used.
The correlation coefficient of calibration curve for each element was 0.999. In order
to check for possible background contamination, blank samples were used and processed simultaneously with field samples. The method detection limit was calculated based on average measuring of the blank sample (γ ± 3δ). For all laboratory
samples and standard solutions, treated ultra-pure water was used. The QC of the
applied techniques was performed by standard addition method, and it was found
that the recovery for the investigated elements ranges for ICP-AES between 98.5
and 101.2% and for ETAAS between 96.9% and 103.2%.
For this study, M2 and M3 moss samples certified reference materials (Steinnes
et al. 1997) were used to check method accuracy, and for all considered elements,
the difference between measured and certified values was within 15%.
Optimal conditions for the analysis of arsenic and cobalt by ETAAS and mercury
by CV-AAS were given by Balabanova et al. (2010).
3.4 Results and Discussion
Data from the descriptive statistics of the measurements of 23 elements determined
by ICP-AES (Ag, Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni,
P, Pb, Sr, V and Zn) in moss samples collected from 107 sampling locations in
Bitola region are presented in Table 3.1. In Table 3.1 the following statistical parameters are given: N, number of samples; X, arithmetical average; X(BC), arithmetical
average after Box-Cox method; Md, median; Min, minimum; Max, maximum; P 10 ,
10th percentile; P 90 , 90th percentile; P 25 , 25th percentile; P 75 , 75th percentile; Ѕ,
standard deviation; Ѕx, standard error; CV, coefficient of variation; A, skewness; Е,
kurtosis; ВС, Вох-Сох transformed values.
The values of macroelements Al, Ca, Fe, K, Mg and Na are in the following
ranges: 0.008–1.6% Al; 0.02–1.9% Ca; 0.007–1.1% Fe; 0.009–1.2% K; 0.004–0.48%
Mg and 0.003–0.26% P. High matrix content of these elements mostly originated
from plant tissues, and it can be sometimes enriching the actual values from atmospheric distribution of these elements.
In Table 3.2 the comparison of the median, minimal and maximal values for the
content of analysed elements in moss from Bitola region with those for the Republic
of Macedonia and Europe is given. It could be seen that the median values for the
content of almost all analysed elements in moss samples from Bitola region are very
similar to those obtained for the Republic of Macedonia. The only difference is in
the content of copper which in the moss samples from Bitola region is 3.24 times
higher than that in the moss samples from the whole territory of Macedonia. If we
compare the obtained results for the median value for the moss samples from the
area around the thermoelectric power plant and those from wider region of Bitola, it
could be seen that moss samples collected in the vicinity of REK Bitola have higher
T. Stafilov et al.