The effects of a range of pollutants on a number of moss species were investigated by field and laboratory experimentation. Effects were demonstrated on growth, reproduction, development, survival, morphology, anatomy and physiology, in particular, pigment and membrane systems. Although a range of response exists within species, which varies with pollutant used, concentration applied, and exposure time, species can be classified into two groups: resistant species which can withstand higher levels and longer exposures to pollutants than the sensitive species which are killed at lower concentrations. This grouping is maintained over gaseous, metallic and fluorine pollution treatments. An investigation of effects on reproduction and development, showed that species fall into the same two groups throughout both sexual and asexual life cycles. Species belonging to the two groups also have initially different patterns and potentials for development, resistant species possessing features which would be advantageous in polluted environments e.g. growth rate and development cycle are fast. Since species vary in their survival ability, they must differ physiologically, Studies of uptake of heavy metals by species from the two groups were made to investigate the site and mechanism of tolerance. Simultaneous measurements of pollutant uptake and moss health showed that resistant species accumulate more pollutant and are damaged at higher internal concentrations of pollutant than sensitive species. This enabled a hypothesis to be set up that the cell wall is the site of the tolerance mechanism. By acting as a "mop" with a finite capacity for absorbing metal ions, especially in resistant species, the wall could keep pollutants away from the metabolic sites, which were found to be equally sensitive in both groups. Once these sites become saturated, damage to membranes and subsequently pigments, occurs . The species demonstrated to be resistant experimentally are the ones commonly in polluted environments, where as sensitive species are not normally found in polluted environments.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:592133 |
| Date | January 1975 |
| Creators | Black, Valerie J. |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU404356 |
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