Urban Air Pollution, Bioindication and Environmental AwarenessTaschenbuch
This paper describes past and current work on air pollution in London, with emphasis on impacts on vegetation and biomonitoring. Much of the current research is under the auspices of the Air Pollution Research in London ( A P R I L) network which brings together a wide range of interested parties. The Mayor of London has published his Air Quality Strategy aimed at reducing pollutants to levels not damaging to human health. Current N Ox levels across London exceed the Objective for sensitive vegetation and ecosystems. Major studies on epiphytic lichens have indicated increases in nitrophilic species and S O2 no longer appears to be a major factor contributing to lichen distribution in London. A P R I L projects include lichen transplant studies, measurements of nitrogen levels in Calluna and analysis of bird population data in relation to air pollution. In the days when London was heavily polluted with coal smoke and S O2 there were severe effects on many higher plant species. However, even with the major improvements in air quality, filtration and transect studies in the 1980s still indicated adverse impacts of ambient pollution on plant health. Recent work has examined impacts of diesel exhaust on native plant species and shown adverse growth and physiological effects at ambient levels. An ongoing long-term transect study has shown that lichens growing on oaks are only slowly recolonising London. The highly S O2-tolerant lichen, Lecanora conizaeoides, has effectively disappeared from this transect, providing evidence of falling S O2 concentrations. Two fungal pathogens, Rhytisma acerinum (cause of tarspot of sycamore) and Diplocarpon rosae (cause of blackspot of roses) have reinvaded areas of the U K where S O2 had previously prevented infection, but the former is still absent from London, probably due to prevailing N Ox levels. Research at Imperial College has demonstrated clearly that ambient pollution in London can markedly stimulate the performance of aphids.
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