Temporal and spatial fluctuations of ethylene production and concentrations of sulfur, sodium, chlorine and iron on/in the thallus cortex in the lichen Ramalina duriaei (De Not.) Bagl.

Abstract

Thalli of the lichen Ramalina duriaei (De Not.) Bagl., growing on carob twigs, were taken from an unpolluted forest area and transplanted within the original forest and to an industrial area in Northwest Israel. The production of ethylene by transplanted and nontransplanted lichen thalli left in the original forest and by transplanted thalli in the industrial area was measured after various periods of exposure of the thalli to their surroundings. Lichens produced larger amounts of ethylene in the polluted industrial sites than in the control site within their original unpolluted forest area. Changes in the production of ethylene were observed rather quickly under certain pollution conditions. Temporal and spatial fluctuations in the production of ethylene of a sensitive lichen, rather than the absolute amounts of ethylene produced by transplanted thalli, were deemed to reflect environmental stress in the lichen and were used a bioindicator of air pollution. Thalli retrieved in the vicinity of a steel smelter bore on/in their cortex large amounts of S and Fe, as detected with a scanning electron microscope (SEM) combined with energy dispersive X-ray analysis (EDX). Such thalli also showed large amounts of Na and Cl on/in the cortex. Probable correlations between fluctuations in ethylene production by lichens and environmental factors are discussed.