Hidrológiai Közlöny 2000 (80. évfolyam)
5-6. szám - XLI. Hidrobiológus Napok: "Vízi ökoszisztémák (taxonómia, biodíverzitás, biomonitorozás, élőhelyek frakmentációja, inváziós fajok biológiája)" Tihany, 1999 október 6-8.
313 1. táblázat. Allatok száma Kipusztult állatok száma 3 nap 6 nap 12 nap Kontrol 45 0 0 0 100pg/l AI 45 0 3 3 500 jig/I Al 45 23 10 10 Si 45 0 1 0 !Q0 tig/l Al és Si 45 0 2 1 500 (rg/1 Al és Si 45 0 6 2 199 «II Sil 499 J99 299 IX I tt i í - ALStSi&D - - - A- - - A14SÍ - M.-AL&D Z 5 08 loot 15»« • •0« SH I rVjf t lffa ; i | » Al 500 —• A1& SiátD • - - A- • AlékSi --M — AliD | l.ábra. A víztömegben mért összaluminium koncentráció (TAI )- A) lOOug/lAl és B) 500 ug/lAI hozzáadás esetén >— I70.J-HU.»« R :-O.t00t v-I7l.5-H4I.Ij R'-O.»:47 Mg/48 óra I I AU500I* D AK500I* Si* D •i AlllOOIiD AKI 001* S.4. P 2. ábra Al koncentráció csökkenési rátája, a regressziós paraméterekkel AllSi ink Al ink Si k • • lr • II 3. ábra Al koncentráció a vándorkagyló lágyszövetében nu 100 A l/L •M 500 •l A l/L ciak Al (Ilk Si kaa trail 4. ábra. Al koncentráció a pseudofaecesben AI*Si ciak Al ctakSi kaalroll 5. ábra. Al koncentráció a kagylók által termelt össz pseudofaeces mennyiségben Irodalom Alexander, G.B. (1953) The reaction of low molecular weight silicic acids with molybdic acid. J.Am.Chem.Soc. 75: 5655-5657. Birchall, J.D., Exley, C„ Chappell, J.S. and Phillips, M.J. (1989) Acute toxocity of aluminium to fish eliminated in silicon-rich acid waters. Nature, 338: 146-148. Elangovan Ä.(1997) Accumulation and distribution of aluminium in two freshwater invertebrates at neutral pH. PhD thesis, University of Manchester, pp 43-45. Golterman, H.L., Clymo, R.S. and Ohnstad, M.AM (1978). Methods for Physical and Chemical Analysis of Fresh Waters. Blackwell Scientific Publications, Oxford;pp 138-139. Jugdaohsingh, R„ Campbell, MM., Thompson, R.P.H., McCrohan, C.R., White, K.N. and Powell, J.J. (1998) Mucus secretion by the freshwater snail Lymnaea stagnalis limits aluminium concentrations of the aqueous environment. Environ. Sei. Tehnol. 32: 2591-2595. Ameliorating effect of monomelic silicic acid on the toxicity of Al to the bivalve Dreissena polymorpha Enikő Kádár, János Salánki, Keith N White * and Cathy McCrohan * Balaton Limnol. Res. Inst, of the Hungarian Academy of Science and Sch. Biol. Sei., Univ crsity of Manchester Abstract: Aluminium (Al) the most abundant metal in the Earth's crust is generally found in an insoluble state, but due to the release of pollutants, i.e. sulphur dioxide and nitrogen oxides, is mobilised, often reaching toxic levels in freshwaters. Previous studies suggest that its bioavailability is reduced to minimum at neutral pH Our research, however, has shown that freshwater bivalves exposed to large amounts of Al due to their feeding behaviour, often remove more Al from the water column than would be expected from the tissue burden. The objective of the present study is to compare the bioavailability of Al in the presence and absence of monomelic silica, by examining the accumulation of Al by the filter-feeder bivalve Dreissena polymorpha Soluble Al concentration in the water containing the animals fell significantly with time over 12 days exposure following addition of two different concentrations 250 and 500 (ig/1 Al as nitrate. This loss was enhanced by the presence of Si (Al:Si 1:15). Al added at 500 ng/1 concentration was lethal (DL50 reached at day 3) in the absence of Si, whereas in its presence only 17 % of the animals died At sublethal concentration Al was well tolerated both in the presence and absence of Si. Al bioaccumulation was not affected by monomelic silica but the production of pseudofaeces incresed significantly m the tanks where Si was added, presumably owing to increased mucus production as deffence mechanism These results suggest that monomenc silica does not reduce significantly the uptake of Al but does reduce its toxicity in correlation to mucus production. Keywds: aluminium toxicity, monomelic silica, pseudofaeces, bioaccumulation.
