similar to the value obtained by the extraction with saponin. It indicates that the most
mobile fractions (water soluble and acid extractable) were easily released in the
presence of selected biosurfactant. Regarding Pb, no presence of this element was
detected in the first two steps of SEP. The maximum recovery yields were attained in
step three of SEP (0.1 mol L
À1 NH 2 OH.HCl), reaching about 50–80% of total Pb
content in sediment samples; such a finding is consistent with the ability of Pb to
co-precipitate with Mn and Fe oxides (reducible sediment fraction) (Vojteková et al.
2008) and thereby remain stable for a relatively long period of time. Saponin was not
able to release Pb from such structures.
The hazard level associated with a heavy metal-contaminated site depends significantly on the chemical form and speciation of the metal. It can be concluded that if
the most mobile fractions pose an increased risk of contamination and re-entering
biogeochemical cycles, the current risk of Pb contamination in Richňava and
Jaklovce is low. It can be also mentioned that the sites in which metal ions exist
mainly in residual forms, such as Pb in phosphates (e.g. Pb 3 (PO 4 ) 2 , PbHPO 4 ,
Pb 5 (PO 4 ) 3 Cl), PbS and PbSO 4 , present little or no hazard to the environment and
living organisms (Ogundiran and Osibanjo 2009).
5.6
Conclusions
The residues of organic and inorganic substances found in soils, sediments, waters
and aquatic biota have been of environmental concern since the 1960–1970s.
Although production of many hazardous chemicals has been gradually banned
across the world since the 1970s, the amounts released in the environment can be
counted in millions of tons. Moreover, new substances that are harmful to living
organisms are being produced by polluting industries every day; they are commonly
used in agriculture; worldwide, companies routinely pollute our natural resources
with their waste. Many of these compounds are resistant to biological and chemical
degradation, thus persisting in the environment for a long period of time. For their
determination in different environmental matrices, sample preparation can be timeconsuming and challenging but still an essential part of the whole contaminant
analysis process. Due to a low concentration of pollutants and often a complex
nature of collected samples, separation and pre-concentration prior to analysis
become even more important. Among sample preparation methods, liquid-liquid
extraction and solid-phase extraction are reported to be the most frequently used for
isolation and clean-up, sample preconcentration and derivatization. Both techniques
are available in different modifications and both are applicable for an extraction of
organic and inorganic pollutants. It is evident that much effort has been devoted to
improving extraction procedures in order to make the process more effective, faster,
simpler, less expensive and eco-friendly. In this context, conventional surfactants are
gradually being replaced with substances of biological origin that are equally or even
more efficient and are not harmful to the environment and human health. In our study
on extraction of metal ions from solid materials using liquid solvent, we tested plantderived surfactant saponin for the recovery of selected heavy metals from soils and
162
L. Nemček and I. Hagarová
mobile fractions (water soluble and acid extractable) were easily released in the
presence of selected biosurfactant. Regarding Pb, no presence of this element was
detected in the first two steps of SEP. The maximum recovery yields were attained in
step three of SEP (0.1 mol L
À1 NH 2 OH.HCl), reaching about 50–80% of total Pb
content in sediment samples; such a finding is consistent with the ability of Pb to
co-precipitate with Mn and Fe oxides (reducible sediment fraction) (Vojteková et al.
2008) and thereby remain stable for a relatively long period of time. Saponin was not
able to release Pb from such structures.
The hazard level associated with a heavy metal-contaminated site depends significantly on the chemical form and speciation of the metal. It can be concluded that if
the most mobile fractions pose an increased risk of contamination and re-entering
biogeochemical cycles, the current risk of Pb contamination in Richňava and
Jaklovce is low. It can be also mentioned that the sites in which metal ions exist
mainly in residual forms, such as Pb in phosphates (e.g. Pb 3 (PO 4 ) 2 , PbHPO 4 ,
Pb 5 (PO 4 ) 3 Cl), PbS and PbSO 4 , present little or no hazard to the environment and
living organisms (Ogundiran and Osibanjo 2009).
5.6
Conclusions
The residues of organic and inorganic substances found in soils, sediments, waters
and aquatic biota have been of environmental concern since the 1960–1970s.
Although production of many hazardous chemicals has been gradually banned
across the world since the 1970s, the amounts released in the environment can be
counted in millions of tons. Moreover, new substances that are harmful to living
organisms are being produced by polluting industries every day; they are commonly
used in agriculture; worldwide, companies routinely pollute our natural resources
with their waste. Many of these compounds are resistant to biological and chemical
degradation, thus persisting in the environment for a long period of time. For their
determination in different environmental matrices, sample preparation can be timeconsuming and challenging but still an essential part of the whole contaminant
analysis process. Due to a low concentration of pollutants and often a complex
nature of collected samples, separation and pre-concentration prior to analysis
become even more important. Among sample preparation methods, liquid-liquid
extraction and solid-phase extraction are reported to be the most frequently used for
isolation and clean-up, sample preconcentration and derivatization. Both techniques
are available in different modifications and both are applicable for an extraction of
organic and inorganic pollutants. It is evident that much effort has been devoted to
improving extraction procedures in order to make the process more effective, faster,
simpler, less expensive and eco-friendly. In this context, conventional surfactants are
gradually being replaced with substances of biological origin that are equally or even
more efficient and are not harmful to the environment and human health. In our study
on extraction of metal ions from solid materials using liquid solvent, we tested plantderived surfactant saponin for the recovery of selected heavy metals from soils and
162
L. Nemček and I. Hagarová