137
(containing carboxyl groups) in the cell walls compared to cellulose and
hemicellulose (having hydroxyl groups) could explain the higher heavy metal binding affinity of the plants cultured in the laboratory than that of the field-grown
mosses observed by Wells and Brown (1987). The dominance of carboxyl and phosphoryl groups in the cell walls of different mosses could also explain the similar
patterns of heavy metal adsorption in different bryophyte species seen in some studies (González and Pokrovsky 2014; Stankovic et al. 2018). However, it has been
observed that adsorbing properties and uptake efficiencies for the same metals may
vary significantly between the mosses and liverworts (Shakya et al. 2008). This
could be a result of the different cell wall composition of these two bryophyte
groups, where uronic acid is a characteristic component of the cell wall of mosses
and mannuronic acid in that of the liverworts. Other studies, performed by Rühling
and Tyler (1970), have shown that different heavy metals may follow the same order
in maximum concentrations reached in the extracellular fractions regardless of the
moss species, suggesting that this property depends mainly on the type of the metal.
On the other hand, the affinity of extracellular binding sites for different metals may
vary significantly among the species. Heavy metals adsorbed on the moss surface
can reach the interior of the cell by specific membrane transport proteins or via
channels present in the cell membrane (Basile et al. 2012). While the extracellular
fraction of heavy metals in mosses is usually easily exchangeable and tends to
reflect the current environmental conditions and sporadic peaks in contamination,
the intracellular fraction is usually a result of the integration of metals during the
longer period of time and thus represents the average situation in the environment
(Fernandez et al. 2012). It has been shown, as in other organisms, that the intracellular metal ion uptake by bryophytes displays saturation kinetics (Wells and Brown
1987; Basile et al. 2012). Though it is hypothesized that uptake is a slow metabolically controlled process, the study of Fernandez et al. (2012) revealed that when the
bioavailability of heavy metals in the environment is high, intracellular uptake can
be rather quick, leading to an accumulation of large amounts of the metals inside the
cell in a short period of time. Nevertheless, in this study, the high velocity of heavy
metal accumulation inside the cells of the aquatic moss Fontinalis antipyretica
Hedw. resulted in a quick onset of the release of the same elements into the exterior,
suggesting the existence of saturating concentrations inside cells (Fernandez et al.
2012; González and Pokrovsky 2014). Interestingly, in the study of Basile et al.
(2012) on different mosses, intracellular concentrations of heavy metals that act as
micronutrients, such as Cu and Zn, remained rather constant regardless of their
extracellular concentrations, while the accumulation of the elements with no metabolic function, such as Pb and Cd, increased with increasing metal supply in the
environment. A similar relationship between the extracellular and intracellular concentrations of Cd was also observed in the moss Pseudoscleropodium purum
(Hedw.) M. Fleisch. by Fernandez et al. (2012).
One of the potential reasons for the lack of control of non-essential metal input
could be the absence of the specific transporters for these metals (Basile et al.
2012). Instead, they could be using channels and transporters of the plasma membrane that normally function in the uptake of essential ions (Wells and Brown 1987;
5 Proposing Chemometric Tool for Efficacy Surface Dust Deposition Tracking…
(containing carboxyl groups) in the cell walls compared to cellulose and
hemicellulose (having hydroxyl groups) could explain the higher heavy metal binding affinity of the plants cultured in the laboratory than that of the field-grown
mosses observed by Wells and Brown (1987). The dominance of carboxyl and phosphoryl groups in the cell walls of different mosses could also explain the similar
patterns of heavy metal adsorption in different bryophyte species seen in some studies (González and Pokrovsky 2014; Stankovic et al. 2018). However, it has been
observed that adsorbing properties and uptake efficiencies for the same metals may
vary significantly between the mosses and liverworts (Shakya et al. 2008). This
could be a result of the different cell wall composition of these two bryophyte
groups, where uronic acid is a characteristic component of the cell wall of mosses
and mannuronic acid in that of the liverworts. Other studies, performed by Rühling
and Tyler (1970), have shown that different heavy metals may follow the same order
in maximum concentrations reached in the extracellular fractions regardless of the
moss species, suggesting that this property depends mainly on the type of the metal.
On the other hand, the affinity of extracellular binding sites for different metals may
vary significantly among the species. Heavy metals adsorbed on the moss surface
can reach the interior of the cell by specific membrane transport proteins or via
channels present in the cell membrane (Basile et al. 2012). While the extracellular
fraction of heavy metals in mosses is usually easily exchangeable and tends to
reflect the current environmental conditions and sporadic peaks in contamination,
the intracellular fraction is usually a result of the integration of metals during the
longer period of time and thus represents the average situation in the environment
(Fernandez et al. 2012). It has been shown, as in other organisms, that the intracellular metal ion uptake by bryophytes displays saturation kinetics (Wells and Brown
1987; Basile et al. 2012). Though it is hypothesized that uptake is a slow metabolically controlled process, the study of Fernandez et al. (2012) revealed that when the
bioavailability of heavy metals in the environment is high, intracellular uptake can
be rather quick, leading to an accumulation of large amounts of the metals inside the
cell in a short period of time. Nevertheless, in this study, the high velocity of heavy
metal accumulation inside the cells of the aquatic moss Fontinalis antipyretica
Hedw. resulted in a quick onset of the release of the same elements into the exterior,
suggesting the existence of saturating concentrations inside cells (Fernandez et al.
2012; González and Pokrovsky 2014). Interestingly, in the study of Basile et al.
(2012) on different mosses, intracellular concentrations of heavy metals that act as
micronutrients, such as Cu and Zn, remained rather constant regardless of their
extracellular concentrations, while the accumulation of the elements with no metabolic function, such as Pb and Cd, increased with increasing metal supply in the
environment. A similar relationship between the extracellular and intracellular concentrations of Cd was also observed in the moss Pseudoscleropodium purum
(Hedw.) M. Fleisch. by Fernandez et al. (2012).
One of the potential reasons for the lack of control of non-essential metal input
could be the absence of the specific transporters for these metals (Basile et al.
2012). Instead, they could be using channels and transporters of the plasma membrane that normally function in the uptake of essential ions (Wells and Brown 1987;
5 Proposing Chemometric Tool for Efficacy Surface Dust Deposition Tracking…