Metal Pollution and Forest Decline
Human activities influence the natural distribution and biogeochemical cycling of elements, thus changing the chemical environment where plants develop (Nriagu and Pacyna 1988). Among the elements which could affect plants, heavy metals are not naturally
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Forstbotanisches Institut, Abteilung Technische Mykologie, Universitat G6ttingen, D-37077 G6ttingen, Germany Dipartimento di Agronomia e Gestione dell' Agro-Ecosistema, Universitl degli Studi Pisa, Via S. Michele degli Scalzi 2, 56124, Pisa, Italy School of Agricultural and Forest Sciences, University of Wales, Bangor, Gwynedd LL57 2UW, UK
12.1 Sources and Pattern of Heavy Metal Pollution Human activities influence the natural distribution and biogeochemical cycling of elements, thus changing the chemical environment where plants develop (Nriagu and Pacyna 1988). Among the elements which could affect plants, heavy metals are not naturally removed or degraded and therefore progressively accumulate in soil or water sediments (Bussotti et al. 1983; Hunter et al. 1987). In forest ecosystems different sources of heavy metal contamination are prevalent. A natural source is the background load from the parent rocks which on the whole is rather low (Table 12.1) , but may be distributed unevenly. Human activities have resulted heaps and spoils from mining, short-range emissions from smelters, and long-range emissions from high stacks and the lead from automobiles. Special sources of heavy metal contamination may be of local importance, like the treatment of soils with manure from intensive animal husbandry, which may lead to wide-range contamination with copper (Ernst 1985) or polluted rivers which contaminate cosystems via aerosols (Bussotti et al. 1983).
12.1.1 Short-Range Pollution Owing to Mining Activities
The sources of pollution which are directly connected with mining result in small areas with very different concentrations of heavy metals. Mountain regions with local concentrations of heavy metals are found in Europe, especially in Scandinavia (The Fenno-Scandic Shield) and in the temperate humid zone of Central M. N. V. Prasad et al., Heavy Metal Stress in Plants © Springer-Verlag Berlin Heidelberg 1999
254 Table 12.1. Trace elements in main soil-parent rocks (Values commonly found, mg/kg, Dryweight basis) (Kabata-Pendias et al. 1992) Magmatic Rocks Element Mafic Intermediate Acid
Cd Co Cr Cu Hg Mn Mo Ni Ph V Zn
0.13-0.22 35-50 170-200 60-120 O.OX 1200-2000 1.0-1.5 130-160 3-8 200-250 80-120
0.13 1.0-10 15-50 15-80 O.OX 500-1200 0.6-1.0 5-55 12-15 30-100 40-100
0.09-0.20 1-7 4-25 10-30 0.08 350-600 1-2 5-15 15-24 40-90 40-60
Argillaceous and shales
Sedimentary Rocks Sandstones Limestones, dolomites
0.22-0.30 11-20 60-100 40 0.18-0.40 500-850 0.7-2.6 50-70 18-25 100-130 80-120
0.05 0.3-10 20-40 5-30 0.04-0.10 100-500 0.2-0.8 5-20 5-10 10-60 15-30
0.035 0.1-3.0 5-16 2-10 0.04-0.05 200-1000 0.16-0.40 7-20 3-10 10-45 10-25
and Eastern Europe, with a Cambrian mountain ridge stretching from the Ore Mountains in Germany to Romania. In these regions mining and ore processing activities started several centuries ago, and a very complex emission pattern has evolved. Past mining activities have resulted in short range transported highly concentrated pollution such as mine heaps and emissions from small s
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