Effects of Air Pollutants on Cold-Desert Cyanobacterial-Lichen Crusts and Rock Lichens: Chlorophyll Degradation, Electrolyte Leakage and Nitrogenase Activity
Citation
Jayne Belnap, Effects of Air Pollutants on Cold-Desert Cyanobacterial-Lichen Crusts and Rock Lichens: Chlorophyll Degradation, Electrolyte Leakage and Nitrogenase Activity: .
Summary
Exposure of cold-desert cyanobacteral-lichen crusts on three different substrates (sandstone, limestone and gypsum) to different pollution sources showed that while urban pollutants in the Los Angeles basin, especially particulates, significantly degraded chlorophyll on all three substrates, simulated acid rain (pH 3.5, 4.5, 5.5 and 6.5; 1:1 sulfuric and nitric acid) had an opposite, fertilizing effect on sandstone and limestone crusts. Studies around a coal-fired power plant, comparing sites 9 and 12 k, away from the plant with a control site 42 km away, showed the same fertilizing effect on surrounding sandstone crusts. However, less pH-buffered rock lichens had significantly increased electrolyte leakage and chlorophyll degradation [...]
Summary
Exposure of cold-desert cyanobacteral-lichen crusts on three different substrates (sandstone, limestone and gypsum) to different pollution sources showed that while urban pollutants in the Los Angeles basin, especially particulates, significantly degraded chlorophyll on all three substrates, simulated acid rain (pH 3.5, 4.5, 5.5 and 6.5; 1:1 sulfuric and nitric acid) had an opposite, fertilizing effect on sandstone and limestone crusts. Studies around a coal-fired power plant, comparing sites 9 and 12 k, away from the plant with a control site 42 km away, showed the same fertilizing effect on surrounding sandstone crusts. However, less pH-buffered rock lichens had significantly increased electrolyte leakage and chlorophyll degradation at the nearer sites; nitrogenase activity in a crustal soil lichen was depressed as well. When exposed to power plant effluents or simulated acid rain, the degree of contact with the pH-buffering substrate was important: cyanobacteria, embedded in soils that buffered acidity, may use nitrates and sulfates as fertilizers. Rock and soil lichens, with less contact and less buffering, showed opposite effects. Chlorophyll degradation in crusts by urban pollutants, especially particulates, suggests that pollutants other than acid-producing or gaseous ones injure crusts as well. Combined, these data suggest that the deleterious effects seen in this study from power plant emissions and simulated acid rain are caused by different agents than those injuries due to urban pollutants.
Published in Measurement of Toxic and Related Air Pollutants: Proceedings of the 1990 EPA/A&WMA International Symposium, in 1990.
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Effects of Air Pollutants on Cold-Desert Cyanobacterial-Lichen Crusts and Rock Lichens: Chlorophyll Degradation, Electrolyte Leakage and Nitrogenase Activity
