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Epicuticular wax of subarctic Scots pine needles: response to sulphur and heavy metal deposition

Published online by Cambridge University Press:  01 March 1997

M. TURUNEN
Affiliation:
Arctic Centre, University of Lapland, P.O. Box 122, FIN-96101 Rovaniemi, Finland
S. HUTTUNEN
Affiliation:
Department of Biology/Botany, University of Oulu, FIN-90570 Oulu, Finland
K. E. PERCY
Affiliation:
Natural Resources Canada, Canadian Forest Service – Atlantic Forestry Centre, P.O. Box 4000, Fredericton, N.B. Canada E3B 5P7
C. K. MCLAUGHLIN
Affiliation:
Natural Resources Canada, Canadian Forest Service – Atlantic Forestry Centre, P.O. Box 4000, Fredericton, N.B. Canada E3B 5P7
J. LAMPPU
Affiliation:
Department of Biology/Botany, University of Oulu, FIN-90570 Oulu, Finland
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Abstract

The response of epicuticular wax of Scots pine (Pinus sylvestris L.) needles to dry- and wet- deposited sulphur and heavy metals was investigated at six sites located 10–110 km from the Monchegorsk Cu-Ni smelter on the Kola Peninsula, North-West Russia, and in a long-term irrigation experiment where pines were exposed over four growing seasons (1991–1994) to either acid rain treatment at pH 3·1 (H2SO4), metal treatment at pH 5·7 (Cu and Ni) or a combination of these at pH 3·1. Needle wettability exhibited a closer relationship with epistomatal wax tube distribution (WTD) than with chemical composition of epicuticular wax. Water droplet contact angles (DCA) decreased towards the smelter, and significant differences due to site were noted for 26-month-old and 38-month-old needles. Significant differences due to site were determined for secondary alcohols, dehydroabietic acid and hydroxy fatty acids, the proportions of which ranged from 22·5 to 48·9%, 6·2 to 22·4% and 0·6 to 2·6% respectively, depending on site and needle age class. The proportion of dehydroabietic acid increased towards the smelter, but no gradient was observed in the proportion of secondary alcohols or hydroxy fatty acids. No major effect of experimentally applied pollutants on the chemical composition or structure of the epicuticular wax was observed. The effect of treatment on DCA was significant in 1993 and 1994 due to a 6·5–13·2 degree greater wettability of the 37–49-month-old acid-treated needles relative to the irrigated or dry controls. Sulphuric acid at pH 3·1 did not increase needle wettability when combined with copper and nickel sulphate in similar concentrations. These data indicate that S deposition, especially H2SO4, plays a more important role in needle surface deterioration than Cu and Ni. Pollutant-induced changes in epicuticular wax structure and needle wettability mimic natural wax ageing, but at an accelerated rate. Changes in wax chemical composition might also be caused by pollutant-induced metabolic changes in elongating needles.

Type
Research Article
Copyright
© Trustees of The New Phytologist 1997

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