382
for analysis) were taken from the rhizosphere of plant specimens. Viola species collected from six sampling points, plant and soil samples were gathered at the locality
around the abandoned mine described above. It must be mentioned that in the period
when these plants samples were collected, only three samples had seeds. Thymus
species and soil samples were collected at 14 locations in the investigated area,
while the samples of Centaurea leucomalla species from eight sampling points.
During the summer of 2011, Onobrychis degenii, Knautia caroli-rechingeri, and
Centaurea kavadarensis species were collected from one sampling point. All of the
gathered plant samples were washed carefully with redistilled water to remove soil
particles and then separated into different parts (roots, stems, leaves, flowers,
and seeds).
Collected soil samples were dried at room temperature for 5–7 days, and after
extraneous material was removed, soil samples were sown using a plastic sieve with
a 2 mm mesh. A certain amount of the sieved material was grinded into an agate mill
until a powder, having a particle size of 0.125 mm, was obtained (Salminen et al.
2005). Such prepared samples were gathered in polyethylene bags ready for chemical analysis. Digestion of soil samples was performed by taking exact weighted soil
sample (0.2500 g), placed in a PTFE digestion vessel and digested on a hot plate at
about 100 °C. Digestion was performed in three steps. First, HNO3 was added to
remove all organic matter. Then, a mixture of HF and HClO4 was added, and to the
end, HCl and redistilled water were added to dissolve the residue. The digested
solution was transferred quantitatively into 25 ml volumetric flask and then was
analyzed.
Plant material was gathered according to the presence of the plant of the endemic
species (10–20 specimens of plants represent composite material for one sample for
analysis). After gathering, the plants were transferred to the laboratory. The whole
plant was very carefully washed with redistilled water in order to remove the accumulated impurities from the ground and then split into the root, stem, leaf, and
flower. The plant material after drying at room temperature for 7 to 14 days to a
constant mass was pulverized, homogenized, and prepared for total digestion.
A specific mass (0.5000 g) of each plant sample was weighed into PTFE container to which 7 ml of concentrated HNO 3 and 2 ml H 2 O 2 (30%, m/V) were added;
then the PTFE vessels were placed in a microwave digestion system (CEM, Mars).
In the first step of the previously established method, the temperature of 180 °C was
reached for about 15 min and then heated at the same temperature for an additional
20 min. Then, the PTFE vessels were removed from the microwave digestion system when the sample temperature was close to room temperature. The solutions
obtained after the thermal decomposition of the plant tissues were quantitatively
transferred into 25 ml calibrated flasks.
To determine the degree of extraction (bioavailability) of the analyzed soil elements, three different extraction solutions were used (Pansu and Gautheyrou 2006):
– Extraction with water. With this extraction, the natural conditions for extraction
of toxic elements from the soil were simulated, to determine which elements can
be extracted from the soil if it rains in nature under normal conditions.
K. B. Andonovska et al.
for analysis) were taken from the rhizosphere of plant specimens. Viola species collected from six sampling points, plant and soil samples were gathered at the locality
around the abandoned mine described above. It must be mentioned that in the period
when these plants samples were collected, only three samples had seeds. Thymus
species and soil samples were collected at 14 locations in the investigated area,
while the samples of Centaurea leucomalla species from eight sampling points.
During the summer of 2011, Onobrychis degenii, Knautia caroli-rechingeri, and
Centaurea kavadarensis species were collected from one sampling point. All of the
gathered plant samples were washed carefully with redistilled water to remove soil
particles and then separated into different parts (roots, stems, leaves, flowers,
and seeds).
Collected soil samples were dried at room temperature for 5–7 days, and after
extraneous material was removed, soil samples were sown using a plastic sieve with
a 2 mm mesh. A certain amount of the sieved material was grinded into an agate mill
until a powder, having a particle size of 0.125 mm, was obtained (Salminen et al.
2005). Such prepared samples were gathered in polyethylene bags ready for chemical analysis. Digestion of soil samples was performed by taking exact weighted soil
sample (0.2500 g), placed in a PTFE digestion vessel and digested on a hot plate at
about 100 °C. Digestion was performed in three steps. First, HNO3 was added to
remove all organic matter. Then, a mixture of HF and HClO4 was added, and to the
end, HCl and redistilled water were added to dissolve the residue. The digested
solution was transferred quantitatively into 25 ml volumetric flask and then was
analyzed.
Plant material was gathered according to the presence of the plant of the endemic
species (10–20 specimens of plants represent composite material for one sample for
analysis). After gathering, the plants were transferred to the laboratory. The whole
plant was very carefully washed with redistilled water in order to remove the accumulated impurities from the ground and then split into the root, stem, leaf, and
flower. The plant material after drying at room temperature for 7 to 14 days to a
constant mass was pulverized, homogenized, and prepared for total digestion.
A specific mass (0.5000 g) of each plant sample was weighed into PTFE container to which 7 ml of concentrated HNO 3 and 2 ml H 2 O 2 (30%, m/V) were added;
then the PTFE vessels were placed in a microwave digestion system (CEM, Mars).
In the first step of the previously established method, the temperature of 180 °C was
reached for about 15 min and then heated at the same temperature for an additional
20 min. Then, the PTFE vessels were removed from the microwave digestion system when the sample temperature was close to room temperature. The solutions
obtained after the thermal decomposition of the plant tissues were quantitatively
transferred into 25 ml calibrated flasks.
To determine the degree of extraction (bioavailability) of the analyzed soil elements, three different extraction solutions were used (Pansu and Gautheyrou 2006):
– Extraction with water. With this extraction, the natural conditions for extraction
of toxic elements from the soil were simulated, to determine which elements can
be extracted from the soil if it rains in nature under normal conditions.
K. B. Andonovska et al.