Concentrations and among-compound correlations of individual phenolics in white birch leaves under air pollution stress

To detect early symptoms of heavy metal pollution in birch (Betula pubescens Ehrh.) trees, we studied foliar concentrations of phenolic compounds in polluted and control areas around the Harjavalta copper-nickel smelter, SW Finland. Phenolic compounds were quantified by analytical high performance liquid chromatography. The total content of individual phenolics was 21% higher in samples from the heavily polluted (400–500 m from the smelter) area than on the control area. Differences in foliar concentrations of individual compounds between the study areas were significant for (+)-catechin, trans-3-p-coumaroylquinic acid, quercetin-3-O-β-D-galactopyranoside and one gallotannin. Variation in contents of phenolics was quite large. Among tree variances of individual phenolics between control and polluted area differed significantly in the case of seven compounds: 1-O-galloyl-β-D-(2-O-acetyl)-glucopyranose, four gallotannins, neochlorogenic acid and quercetin-3-O-α-L-(4″-O-acetyl)-rhamnopyranoside. Differences in pairwise correlations between phenolic compounds in polluted and control areas indicated competition between some gallotannins and p-coumaroylquinic acids on the polluted but not on control site. Concluding, in strongly polluted areas atmospheric stress factors appear to affect accumulation of some plant phenolics in birch leaves, their variability as well as between-compound correlations.