Lichens as biomonitors around a coal-fired power station in Israel

In the present study epiphytic lichens were applied as biomonitors of air pollution to determine the environmental impact of a coal-fired power station. Thalli of the lichen Ramalina lacera (With.) J.R. Laund. growing on carob twigs (Ceratonia siliqua L.) were collected with their substrate in July 2000 in a relatively unpolluted forest near HaZorea, Ramoth Menashe, Northeast Israel, and transplanted to 10 biomonitoring sites in the vicinity of the coal-fired power station Oroth Rabin near the town of Hadera. The lichens were retrieved in January 2001. We examined the following parameters of lichen vitality: (a) potential quantum yield of photosynthesis expressed as fluorescence ratio F(v)/F(m), (b) stress-ethylene production, and (c) electric conductivity expressing integrity of cell membranes. Following an exposure of 7 months, the lichens were retrieved and physiological parameters and data of elemental content were analyzed comparatively. Electric conductivity values correlated positively with B, Fe, Mg, Mn, Na, Pb, S, Sn, and Ti content. Concentrations of stress-ethylene correlated positively with Al, Ba, Pb, S, and V content and negatively with Cu and Sn. F(v)/F(m) ratios correlated negatively with S content. Some of the heavy metals reached lower levels than those reported in the relevant literature despite a wind regime that should have blown pollutants toward the biomonitoring sites.