1. Campbell, P.G.C., Stokes, P.M. and Galloway, J.N.: 1985, Acid deposition: Effects on geochemical cycling and biological availability of trace elements. Subgroup on metals of the Tri-Academy Committee, on Acid Deposition. National Academy Press, Washington, DC.
2. Dauvalter, V.: 1994, Sci. Total Environ. 158, 51?61.
3. Moiseenko, T.I.: 1991, Acidification and pollution by heavy metals of surface waters of Kola North. Apatity, 48 pp.
4. Nelson, W.O. and Campbell, P.G.C.: 1991, Environ. Pollut., 71, 91?130.
5. Norton, S.A.: 1974, Geol. Soc. Am. 844, 159?160.