within a 5–20 cm thick region known as the surface mixing layer (Nittrouer et al.
2007); therefore, the upper 20 cm of sediment was taken with a grab corer. Before
chemical analysis, samples from stream sediments were dried at 40
C and passed
through a 0.125 mm mesh. A fraction with the particle size <0.125 mm was then
ground in an agate mortar to fine powder <0.09 mm. Soil samples were collected at a
depth of 0–20 cm. Under laboratory conditions, soil was air-dried, homogenized by
quartering, sieved through a 2-mm mesh and subsequently processed as given above.
The batch extraction experiments were conducted at a sample to extracting
solution ratio of 1:5 (5 g of soil, 25 ml of extracting solution). Five g of the sample
was weighed and placed in a 100 ml high-density polyethylene (HDPE) bottle, 25 ml
of the extracting solution were then added and the bottle was sealed with a HDPE
top. Each bottle was hand-shaken for about 1 min to ensure the sample was fully
saturated with solution, and the bottles were subsequently shaken in a mechanical
shaker (Unimax 2010, Heidolph, Germany) at 250 rpm for 24 h. After shaking, the
soil-solution mixture was centrifuged (MPW-360 centrifuge, Mechanika
Precyzyjna, Warsaw, Poland) at 4000 rpm for 30 min. The supernatant was then
poured through a glass funnel holding a Whatman 42 filter to remove any floating
particles or debris, and the concentration of heavy metals (Cu, Pb, Ni, and Zn) was
determined by flame atomic absorption spectrometry (FAAS) carried out on a
Perkin-Elmer 1100B spectrometer (USA) with air-acetylene flame (air 8 L min
À1 ,
acetylene 3.5 L min
À1 ). The batch extractions were performed in triplicates to ensure
reproducibility of the results.
Total concentrations of Cu, Pb, Ni and Zn in samples were determined after
decomposition as follows. 0.5 g of sample in a polytetrafluoroethylene (PTFE)
vessel with a mixture of mineral acids (15 ml of 48% HF, 1 ml of 65% HNO 3 and
1 ml of 70% HClO 4 ) was heated in a water bath at 80
C for 2 h. The mixture was
then allowed to settle down overnight. Next day, the samples were evaporated to wet
salts, 5 ml of HF were added and heated until the fumes of HClO 4 were formed.
Then, 1 ml of HNO 3 , 1 ml of HClO 4 and 10 ml of H 3 BO 3 (saturated solution) were
added and samples were heated to dryness. The dried mass was heated again with an
addition of 10 ml of deionized water in a water bath for 1–2 h. To purify the solution,
3 ml of HNO 3 and 3–5 drops of 30% H 2 O 2 were added and the solution was allowed
to digest in a water bath until dissolving the residues. Then, the sample solution was
transferred into a 25 ml volumetric flask and filled up to the mark with deionized
water (Medveď et al. 1998, 2003). Total contents of heavy metals in contaminated
soils and sediments were determined by FAAS and are presented in Table 5.3.
In soil samples, the total contents of Cu and Zn exceed limit values. Furthermore,
the Šobov soil is contaminated also by Pb and soil around the Pezinok deposit shows
an inadmissible degree of Zn pollution. The analysis of river sediments for Cu, Pb,
Ni and Zn indicates high levels of contamination, except for Pb in Jaklovce sediment
which does not exceed permitted limit value. It should be pointed out that Slovak
threshold values for contaminants in sediments are unbelievably lenient, therefore,
the limit concentrations established in European Union directive (EU WFD 2000)
that are far more strict and closer to common standards than limits set by Slovak
legislation are listed as well (see Table 5.3). Based on these limits and on the data
5 The Recent Strategies Employed in Chemical Analysis of Contaminated Waters,. . .
159
2007); therefore, the upper 20 cm of sediment was taken with a grab corer. Before
chemical analysis, samples from stream sediments were dried at 40
C and passed
through a 0.125 mm mesh. A fraction with the particle size <0.125 mm was then
ground in an agate mortar to fine powder <0.09 mm. Soil samples were collected at a
depth of 0–20 cm. Under laboratory conditions, soil was air-dried, homogenized by
quartering, sieved through a 2-mm mesh and subsequently processed as given above.
The batch extraction experiments were conducted at a sample to extracting
solution ratio of 1:5 (5 g of soil, 25 ml of extracting solution). Five g of the sample
was weighed and placed in a 100 ml high-density polyethylene (HDPE) bottle, 25 ml
of the extracting solution were then added and the bottle was sealed with a HDPE
top. Each bottle was hand-shaken for about 1 min to ensure the sample was fully
saturated with solution, and the bottles were subsequently shaken in a mechanical
shaker (Unimax 2010, Heidolph, Germany) at 250 rpm for 24 h. After shaking, the
soil-solution mixture was centrifuged (MPW-360 centrifuge, Mechanika
Precyzyjna, Warsaw, Poland) at 4000 rpm for 30 min. The supernatant was then
poured through a glass funnel holding a Whatman 42 filter to remove any floating
particles or debris, and the concentration of heavy metals (Cu, Pb, Ni, and Zn) was
determined by flame atomic absorption spectrometry (FAAS) carried out on a
Perkin-Elmer 1100B spectrometer (USA) with air-acetylene flame (air 8 L min
À1 ,
acetylene 3.5 L min
À1 ). The batch extractions were performed in triplicates to ensure
reproducibility of the results.
Total concentrations of Cu, Pb, Ni and Zn in samples were determined after
decomposition as follows. 0.5 g of sample in a polytetrafluoroethylene (PTFE)
vessel with a mixture of mineral acids (15 ml of 48% HF, 1 ml of 65% HNO 3 and
1 ml of 70% HClO 4 ) was heated in a water bath at 80
C for 2 h. The mixture was
then allowed to settle down overnight. Next day, the samples were evaporated to wet
salts, 5 ml of HF were added and heated until the fumes of HClO 4 were formed.
Then, 1 ml of HNO 3 , 1 ml of HClO 4 and 10 ml of H 3 BO 3 (saturated solution) were
added and samples were heated to dryness. The dried mass was heated again with an
addition of 10 ml of deionized water in a water bath for 1–2 h. To purify the solution,
3 ml of HNO 3 and 3–5 drops of 30% H 2 O 2 were added and the solution was allowed
to digest in a water bath until dissolving the residues. Then, the sample solution was
transferred into a 25 ml volumetric flask and filled up to the mark with deionized
water (Medveď et al. 1998, 2003). Total contents of heavy metals in contaminated
soils and sediments were determined by FAAS and are presented in Table 5.3.
In soil samples, the total contents of Cu and Zn exceed limit values. Furthermore,
the Šobov soil is contaminated also by Pb and soil around the Pezinok deposit shows
an inadmissible degree of Zn pollution. The analysis of river sediments for Cu, Pb,
Ni and Zn indicates high levels of contamination, except for Pb in Jaklovce sediment
which does not exceed permitted limit value. It should be pointed out that Slovak
threshold values for contaminants in sediments are unbelievably lenient, therefore,
the limit concentrations established in European Union directive (EU WFD 2000)
that are far more strict and closer to common standards than limits set by Slovak
legislation are listed as well (see Table 5.3). Based on these limits and on the data
5 The Recent Strategies Employed in Chemical Analysis of Contaminated Waters,. . .
159