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Arctic research reveals unexpected effect of ozone depletion 8/3/2002
Welsh scientists studying the effect of increased UV-B radiation (as a result of the ozone hole above the North Pole) on sub-arctic plants have discovered that microbes living below ground are significantly affected, even though they are not exposed directly to sunlight themselves.
Dr Dylan Gwynn-Jones from the Institute of Biological Sciences at the University of Wales, Aberystwyth, and a member of the team whose findings are published in this weeks edition of the science journal Nature, believes that this completely changes our viewpoint about the impacts of ozone depletion in terrestrial ecosystems.
According to Dr Gwynn-Jones, ozone depletion is a reality caused by man’s production and release of CFC aerosol propellants into the atmosphere and indirectly by global warming. The ozone layer is particularly depleted at higher latitudes, for example the current ozone hole above Antarctica is twice the size of Europe. Ozone depletion in the Arctic is equally pronounced reaching depletion rates of up to 60% over the last two winters.
Ozone depletion raises concerns about increases in the intensity of harmful UV-B radiation which can affect humans directly (e.g. via melanoma and catarrhs) and indirectly via the food we eat and the natural environments that we enjoy, he said. The work we have been doing in Arbisko, in northern Sweden, concentrates on these natural environments, investigating pristine sub-arctic heath communities, and how they would be affected in future by ozone depletion.
Before the era of ozone depletion, organisms living at such latitudes were accustomed to low levels of UV-B radiation due to i.) A naturally thicker ozone layer as you move from the equator towards the poles ii.) A longer travel distance for radiation through the ozone layer due to solar angle and iii.) A low solar angle (cf. equator). Plant communities cannot move, hence they will be very vulnerable to future increases in UV-B consequent of ozone depletion. In addition to enhancement of UV-B at ground layer future Arctic ecosystems will also be exposed to elevated concentrations of Carbon Dioxide, a consequence of increased fossil fuel burning.
The researchers exposed a sub-artic heath community to enhanced levels of UV-B (the direct result of ozone depletion) and elevated concentrations of Carbon Dioxide. Such heath communities contain several characteristic species such as reindeer lichen (Cladonia rangiferina), feather moss (Hylocomium spledens), bilberry (Vaccinium myrillus) and other dwarf species.
Following exposure to the treatments for five years, below ground microbial responses were investigated. The research revealed very striking impacts of enhanced UV-B on the nutrient budgets and microbial populations belowground. This is particularly striking given the microbial communities are not directly exposed to UV-B radiation, said Dr Gwynn-Jones.
The results importantly show that ongoing and future ozone depletion could affect microbial communities belowground in the Arctic. More importantly, the emission of pollutants could have future consequences to pristine Arctic ecosystems which are thousands of miles away from their source, he added.
The team of researchers working on the project are currently looking at a possible future scenario where 50 years from now, the concentration of Carbon Dioxide in the environment has increased from 360 parts per million (ppm) to 600 ppm, and where there has been a 15% reduction in the ozone layer.
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