79
Metals are non-degradable and once released into the environment become an
integral part of the habitat. Bryophytes are able to concentrate heavy metals in large
amounts than that of vascular plants. Heavy metals are absorbed either from the
atmosphere or from the substrate or from both the sources. The older tissues of the
plant have higher concentrations of the metallic ions as compared to the younger
portions (Fernandez et al. 2012). The ability of mosses to accumulate heavy metals
depends upon the total leaf surface and the number of thin-walled parenchyma cells.
The use of carpet-forming bryophytes has proved to be rapid and inexpensive
method for surveying heavy metal deposition in the terrestrial ecosystem (Rühling
and Tyler 1968). The concentration of airborne material decreases in the plant tissues with distance from the source of pollution, and there is a wide variation in
metal accumulation from species to species and from habitat to habitat under different microclimate conditions (Žibret and Šajn 2008). Among mosses the profusely
branched and ramifying pleurocarps and the densely packed acrocarps are more
efficient entrappers and absorbers of metal particles than the unbranched and erect
acrocarps.
Mosses have been frequently used to monitor time-integrated bulk deposition of
metals as a combination of wet, cloud and dry deposition, thus eliminating some of
the complications of precipitation analysis due to the heterogeneity of precipitation
(Markert et al. 2003). Ectohydric mosses in particular draw negligible amounts of
water and minerals from the soil and instead depend almost entirely on atmospheric
inputs of nutrients (Rühling and Tyler 1968). Because mosses have a high cation
exchange capacity (CEC), they act as hyper-accumulators of metals and metal complexes. The metals are bound to the tissue with minimal translocation within the
plant due to a lack of vascular tissue (Rühling and Tyler 1968). This results in biological tissue that can be analysed to reveal time-integrated deposition (Zechmeister
et al. 2003). Additional advantages of using mosses as heavy metal biomonitors
include their stationary nature, widespread geographic distribution and low genetic
variability between populations. It has been shown that there is some experimental
error due to heterogeneity in morphological characteristics and microenvironments
among different populations (Zechmeister et al. 2003). There is also an incomplete
understanding of the degree of mineral uptake by ectohydric mosses in direct contact with substrate (Gjengedal and Steinnes 1990). Despite the accuracy and precision of precipitation analysis techniques, however, mosses offer an efficient,
low-cost complement for determining metal concentrations at a large number of
locations and offer analyses of biologically relevant fluxes at multiple scales.
Harmens and his European colleagues (Harmens et al. 2008, 2010) have found
that mosses are reliable indicators of air pollution risks to ecosystems, because they
get most of their nutrients direct from the air and rain, rather than the soil. Since
2000 the European moss survey has been conducted by a special international programme (ICP Vegetation). Moss data provides a better geographic coverage than
measured deposition data and can reveal more about actual atmospheric pollution at
a local level (http://icpvegetation.ceh.ac.uk/).
3 Moss Biomonitoring of Air Pollution Around the Coal Mine and Bitol…
Metals are non-degradable and once released into the environment become an
integral part of the habitat. Bryophytes are able to concentrate heavy metals in large
amounts than that of vascular plants. Heavy metals are absorbed either from the
atmosphere or from the substrate or from both the sources. The older tissues of the
plant have higher concentrations of the metallic ions as compared to the younger
portions (Fernandez et al. 2012). The ability of mosses to accumulate heavy metals
depends upon the total leaf surface and the number of thin-walled parenchyma cells.
The use of carpet-forming bryophytes has proved to be rapid and inexpensive
method for surveying heavy metal deposition in the terrestrial ecosystem (Rühling
and Tyler 1968). The concentration of airborne material decreases in the plant tissues with distance from the source of pollution, and there is a wide variation in
metal accumulation from species to species and from habitat to habitat under different microclimate conditions (Žibret and Šajn 2008). Among mosses the profusely
branched and ramifying pleurocarps and the densely packed acrocarps are more
efficient entrappers and absorbers of metal particles than the unbranched and erect
acrocarps.
Mosses have been frequently used to monitor time-integrated bulk deposition of
metals as a combination of wet, cloud and dry deposition, thus eliminating some of
the complications of precipitation analysis due to the heterogeneity of precipitation
(Markert et al. 2003). Ectohydric mosses in particular draw negligible amounts of
water and minerals from the soil and instead depend almost entirely on atmospheric
inputs of nutrients (Rühling and Tyler 1968). Because mosses have a high cation
exchange capacity (CEC), they act as hyper-accumulators of metals and metal complexes. The metals are bound to the tissue with minimal translocation within the
plant due to a lack of vascular tissue (Rühling and Tyler 1968). This results in biological tissue that can be analysed to reveal time-integrated deposition (Zechmeister
et al. 2003). Additional advantages of using mosses as heavy metal biomonitors
include their stationary nature, widespread geographic distribution and low genetic
variability between populations. It has been shown that there is some experimental
error due to heterogeneity in morphological characteristics and microenvironments
among different populations (Zechmeister et al. 2003). There is also an incomplete
understanding of the degree of mineral uptake by ectohydric mosses in direct contact with substrate (Gjengedal and Steinnes 1990). Despite the accuracy and precision of precipitation analysis techniques, however, mosses offer an efficient,
low-cost complement for determining metal concentrations at a large number of
locations and offer analyses of biologically relevant fluxes at multiple scales.
Harmens and his European colleagues (Harmens et al. 2008, 2010) have found
that mosses are reliable indicators of air pollution risks to ecosystems, because they
get most of their nutrients direct from the air and rain, rather than the soil. Since
2000 the European moss survey has been conducted by a special international programme (ICP Vegetation). Moss data provides a better geographic coverage than
measured deposition data and can reveal more about actual atmospheric pollution at
a local level (http://icpvegetation.ceh.ac.uk/).
3 Moss Biomonitoring of Air Pollution Around the Coal Mine and Bitol…