The Use of Lichen Fumigation Studies to Evaluate the Effects of New Emission Sources on Class I Areas

Abstract

Allowable increments of SO/sub 2/ from new emission sources near Class I areas are severely limited by the PSD provisions of the Clean Air Act, unless the applicant can prove that the expected emissions will not adversely affect the air quality related values of Class I area. Lichens are considered to be the resource that is most sensitive to SO/sub 2/. If projected concentrations will not injure lichens, other resources should not be affected. Four lichen species native to two Class I area, Cape Romain National Wildlife Refuge and Everglades National Park, were fumigated in the laboratory with SO/sub 2/ doses that simulated the frequencies, duration, and concentrations expected from potential new sources. Lichens from Cape Romain were fumigated with 240 ..mu..g/m/sup 3/, 400 ..mu..g/m/sup 3/, and ambient air 3 hours/week for 6 weeks. No differences in biomass gain, percent electrolyte leakage in solution (an indicator of membrane damage) or /sup 14/CO/sub 2/ assimilation were observed among treatments. Lichens from Everglades National Park were fumigated with 100 ..mu..g/m/sup 3/, 200 ..mu..g/m/sup 3/, 400 ..mu..g/m/sup 3/, and ambient air 6 hours/week for 10 weeks. Percent electrolyte leakage of Parmotrema tinctorum was greater at the two high concentrations, but there was nomore » significant effect on biomass gain or /sup 14/CO/sub 2/ assimilation. Percent electrolyte leakage increased and biomass gain and /sup 14/CO/sub 2/ assimilation decreased in Ramalina denticulata at 400 ..mu..g/m/sup 3/ SO/sub 2/ in comparison with lower concentrations. Studies of fumigation effects on lichens are a useful technique for the evaluation of impacts of emission sources on air quality related values in Class I areas.« less