Heavy Metals Accumulation Effects on The Photosynthetic Performance of Geophytes in Mediterranean Reserve

Abstract

In Bentael natural reserve, Byblos-Lebanon, a recently constructed road, adjacent to its Southside, is threatening the wildlife of the reserve. The first source of this pollution is a vehicle derived contamination of soil, air and plants. This study determines heavy metals contamination levels evaluated by a rare plant species “Urginea maritima”, which is used as a biomonitor of airborne pollution. Four heavy metals were chosen for their toxic effects on the floral species. Lead, cadmium, aluminium and chromium were studied in plant leaves. The analysis of heavy metals is completed by a measurement of the photosynthetic activity of the plant. Two years period study showed lead upgrade in leaves versus a chromium decrease of plant uptake from the first year of road inauguration. Aluminium and cadmium levels increase for the first months after road works beginning then decreased sharply. As for photosynthetic pigments, the study showed an adverse effect of heavy metals on ordinary photosynthetic activities of the plants. Chlorophyll revealed primarily a decline in activities the first year but then amplification, in contrast of pheophytin which concentrations displayed a sharp rise especially in the most closely site to the road. These results indicated that landscape activities near natural reserves initiate heavy metals pollution for plants with a high risk of accumulation. Keywords: Heavy metals, Photosynthetic activity, Contamination, Accumulation, Biomonitor