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Unpolluted Sites (unpolluted + site)

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Life Sciences100%

Selected Abstracts

Calcium oxalate and sulphate-containing structures on the thallial surface of the lichen Ramalina lacera: response to polluted air and simulated acid rain

PLANT CELL & ENVIRONMENT, Issue 12 2002
J. GARTY
Abstract The formation of calcium-containing structures on the thallial surface of the lichen Ramalina lacera (With.) J.R. Laund. in response to air pollution and to simulated acid rain, was studied in in situ and transplanted thalli. In situ thalli were collected from an unpolluted site and transplanted to heavily polluted and less polluted sites for a 10 month period. Additional thalli were treated either with double distilled water or with simulated acid rain. Scanning electron microscopy and infrared spectrometry revealed that thallial surfaces of in situ R. lacera samples collected in unpolluted sites were covered with two kinds of calcium oxalate crystals: whewellite and weddellite. These aggregates of calcium oxalate crystals appear to disintegrate and provide a crystal layer on the thallial surface. Infrared spectroscopy of powder scraped from thallial surfaces of transplants, retrieved from non-polluted sites, showed the presence of whewellite and weddellite, whereas powders obtained from thalli retrieved from polluted sites contained whewellite, weddellite and gypsum. It is suggested that a certain fraction of the gypsum detected in crater-like structures in transplants from polluted sites and in thalli treated with simulated acid rain is endogenous and should be considered a biomineral. [source]

Changes in the potential quantum yield of photosystem II and the integrity of cell membranes relative to the elemental content of the epilithic desert lichen Ramalina maciformis

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2002
Jacob Garty
Abstract The present study used the epilithic fruticose lichen Ramalina maciformis to investigate the occurrence of mineral elements, including heavy metals, at a distance of up to 50 km from the industrial region in Ramat Hovav in the Negev Desert, Israel. The major objective of this study was an analytical comparison of elemental content and physiological parameters of lichen vitality, apart from a test of the applicability of this specific lichen in investigations of air pollution. The Ca, Cr, Cu, K, Mg, Na, Pb, S, Sr, and Zn content of thalli from the unpolluted Tellalim site collected in August 1997, transferred to 24 biomonitoring sites, and retrieved in April 1998 was analyzed in comparison with the following parameters: The potential quantum yield of photosystem II (PSII), and the integrity of cell membranes. Transplanted thalli in several sites at Ramat Hovav accumulated large amounts of most of the elements. The K content of the transplants located in the polluted sites indicated a leakage of this element, because this content was lower than that of thalli in unpolluted sites. Calcium, Cu, Mn, and Na showed an inverse correlation with the K content of the lichen. Calcium, Cu, and Sr showed an inverse correlation with the Fv/Fm ratio expressing the potential quantum yield of PSII. Calcium, Cr, Cu, Mg, Na, S, and Sr showed a positive correlation with the electrical conductivity corresponding with cell-membrane disintegration. The present study demonstrated a meaningful connection between enlarged concentrations of certain elements and physiological phenomena. The capability of the lichen to detect air pollution was found to be satisfactory. The dispersion of airborne heavy metals was found, however, to be local and limited to a few hundred meters from the source of pollution. [source]

Needle cytokinin content as a sensitive bioindicator of N pollution in Sitka spruce

PLANT CELL & ENVIRONMENT, Issue 12 2003
M. D. COLLIER
ABSTRACT Previous work has shown that conifers growing on sites exposed to aerial pollution exhibit a different pattern of vegetative development in comparison with those on unpolluted sites, and have higher needle cytokinin contents (von Schwartzenberg & Hahn, Journal of Plant Physiology 139, 218,223, 1991). Physiologically mature Sitka spruce (Picea sitchensis[Bong.] Carr) trees growing in a commercial plantation were sprayed with combinations of S, N and acidity from bud burst until December, for a 3 year period, in order to factor out the effects of individual pollutants and identify the specific component responsible for the high cytokinin content. Cytokinins were monitored using high-performance liquid chromatography/enzyme-linked immunosorbent assay techniques. After 3 years of treatment only needles of neutral N-treated trees contained significantly higher levels of cytokinin than those of trees receiving no spray. The addition of acid S could suppress the effects of added N. Needles from neutral N treatments also contained significantly higher levels of biologically active cytokinins and forms that can be transported in the xylem/phloem. Significantly lower levels of active cytokinins were present in needles sprayed with N in combination with acid sulphate. The results demonstrate that the needle cytokinin content may be used as a sensitive and selective bioindicator of the early stages in N perturbation in coniferous trees. [source]

Calcium oxalate and sulphate-containing structures on the thallial surface of the lichen Ramalina lacera: response to polluted air and simulated acid rain

PLANT CELL & ENVIRONMENT, Issue 12 2002
J. GARTY
Abstract The formation of calcium-containing structures on the thallial surface of the lichen Ramalina lacera (With.) J.R. Laund. in response to air pollution and to simulated acid rain, was studied in in situ and transplanted thalli. In situ thalli were collected from an unpolluted site and transplanted to heavily polluted and less polluted sites for a 10 month period. Additional thalli were treated either with double distilled water or with simulated acid rain. Scanning electron microscopy and infrared spectrometry revealed that thallial surfaces of in situ R. lacera samples collected in unpolluted sites were covered with two kinds of calcium oxalate crystals: whewellite and weddellite. These aggregates of calcium oxalate crystals appear to disintegrate and provide a crystal layer on the thallial surface. Infrared spectroscopy of powder scraped from thallial surfaces of transplants, retrieved from non-polluted sites, showed the presence of whewellite and weddellite, whereas powders obtained from thalli retrieved from polluted sites contained whewellite, weddellite and gypsum. It is suggested that a certain fraction of the gypsum detected in crater-like structures in transplants from polluted sites and in thalli treated with simulated acid rain is endogenous and should be considered a biomineral. [source]