Handbook of Vitamin C Research

Vitamin C as a Stress Bioindicator of Norway Spruce 315indirectly, all of the damaging free radicals commonly encountered in plant cell (Foyer,1993). As primary antioxidant it reacts with hydrogen peroxide (H 2 O 2 ), with superoxid (O 2 - ),hydroxil radical (OH - ), and lipid hydroperoxides (Yu, 1994), respectively; furthermore, it isalso important secondary antioxidant since it maintenance the α-tocopherol (vitamin E) poolto cope with radicals in deeper layer of membranes. Vitamin E is an efficient lipophilicantioxidant which is incorporated into photosynthetic membranes, and serves to reduce thepossibility of damages caused by singlet oxygen or lipid peroxides (Foyer, 1993; Hofer et al.,2008).In last two decades, permanent survey (biomonitoring) has been performing in northernSlovenia with the aim to assess the forest health condition in the emission area of the largestSlovenian thermal power plant of Šoštanj (ŠTPP) by using the Norway spruce (Picea abies(L.) Karst.) needles as bioindicator. In the present paper, a particular attention is focused onthe determination antioxidant defence mechanisms (e.g. content of vitamin C) against thepollution stress in Norway spruce, and on assessing the bioindicative value of vitamin C as asensitive and early-warning bioindicator of environmental pollution with inorganicsubstances.2. Material and Methods2.1. Study Area and Sampling ProceduresThe study area is (used to be) exposed to huge amounts of pollutants due to its closevicinity to the largest Slovene thermal power plant of Šoštanj. It has been emitting hugeamounts of SO 2 , NO x and CO 2 (Table 1); moreover, annual emissions of heavy metalsreached up to 298 t of Zn, 60.6 t of Cr, 22.1 t of Pb, 4.5 t of As, 0.3 t of Hg, and 0.2 t of Cdbefore installation of desulphurization devices in 1995 and 2000, respectively. A pronouncedimpact of air pollution was observed in many environmental segments in the study area (e.g.soils and vegetables: Kugonič & Stropnik, 2001; forest stands: Ribarič Lasnik et al., 2001; AlSayegh Petkovšek et al., 2008; mushrooms: Al Sayegh Petkovšek et al., 2002; lichens:Poličnik et al., 2004, 2008; aquatic organisms: Mazej & Germ, 2009; wild-living ruminants:Pokorny, 2000, 2006; Pokorny et al., 2004).ŠTPP is located at the bottom of the Šalek Valley, at an altitude of 370 m, in the centralnorthern part of Slovenia (Figure 1), in the apline and pre-alpine vegetation province withmoderate continental climate. Prevailing winds are from the west and east, which has animportant impact on the distribution of pollutants in the area. In this respect it is importantthat the ground layer of the frequent thermal inversions usually does not exceed 100 m,which is far below the height of the power station chimneys. Therefore, pollutants are spreadover the hilly margins up to 1100 m above sea level, where the upper inversion layer occurs(Šalej, 1999).