Handbook of Vitamin C Research

322Samar Al Sayegh Petkovšek and Boštjan PokornyFigure 6. Correlation between mean annual emissions of SO 2 and mean annual concentration αtocopherol (vitamin E) in spruce needles.Table 4. Correlations between mean annual concentrations of selected parameters,in spruce needles in the emission area of ŠTPPvitamin E chlorophyll (a + b) emission of SO 2vitamin C ns ns nsα tocopherol - ns R = -0.68; p = 0.02chlorophyll (a + b) - - R = -0.51; p = 0.04Note: ns: not significant.The impact of altitude on vitamin C content in spruce needles was tested per every singleyear. It was established that in study area altitude does not affected the content of vitamin Cin spruce needles. Normally (e.g. in areas, where the impacts of air pollution is absent), thecontent of vitamin C increase with rising altitude. For northern Slovenia, however, it isevident that stress caused by higher altitude does not prevail over the stress caused by airpollution. Indeed, the locations at lower altitudes are more exposed to the emissions from theŠTPP, that is indicated by mean annual contents of total sulphur in spruce needles (Table 6).Total sulphur in spruce needles could reflect the exposure of spruce trees to SO 2 emissions,since mean annual total sulphur content in needles was directly correlated with the meanannual SO 2 emissions in the period of 1991– 2007 (R = 0.91; p = 0.000001; n = 16).Analyses of single year needles indicated that sulphur content in spruce needles is highest atsites close to the power plant (Veliki Vrh, Topolšica, Lajše) and where altitude coincideswith that of frequent thermic inversions (Zavodnje) (Ribarič Lasnik et al., 2001; Tausz et al.,2002).