Hidrológiai Közlöny 2008 (88. évfolyam)
6. szám - IL. Hidrobiológus Napok: „A Balaton és vízrendszere – a Balaton-kutatás története” és „A Duna-kutatás története” Tihany, 2007. október 3–5.
83 250 300 350 400 450 500 550 600 650 700 750 250 300 350 400 450 500 550 600 650 700 750 Hullámhossz (nm) Hullámhossz (nm) 1. ábra. Az oldott szervesanyagok abszorpciós spektrumainak változása Nap-szimulátorban végzett fotolizis kísérletben a Zala torkolatban (A) és a Balaton Siófoki-medencéjében Balatonfűzfőnél (B) • 0 Nap 3 Nap 7 Nap 250 200 150 100 - 0 Nap 14 Nap - 3 Nap -21 Nap - 7 Nap -28 Nap £ 50 250 200 14 Nap -21 Nap -28 Nap c\i t E LU 150 100 200 250 300 350 400 200 250 300 350 400 Gerjesztési hullámhossz(nm) Gerjesztési hullámhossz(nm) 2. ábra, Az oldott szervesanyagok fluoreszcens spektrumainak változása Nap-szimulátorban végzett fotolizis kísérletben a Zala torkolatban (A) és a Balaton Siófoki-medencéjében Balatonfűzfőnél (B) Köszönetnyilvánítás A munka az NKFP 3B02204 BALÖKO valamint az OTKA K 63296 pályázatok anyagi támogatásával készült. Irodalom Bricaud, A., A. Morei <6 L. Prieur (1981) Absorption by dissolved organic matter of the sea (yellow substance) int he UV and visible domains. Limnol. Oceanogr. 26: 43-53. Cooper, W. J., R. G. Zika, R. G. Petasne & A. M. Ficher( 1989) Sunlight induced photochemistry of humic substances in natural waters: major reactive species. In: Suffet, I. H. & P MacCarthy (Eds) Aquatic humic substances. Influence on fate and treatment of pollutants. America Chemical Society, Washington DC 333-362. Cuthbert, /. D. & P. del Giorgio (1992) Toward a standard method of measuring color in freshwater. Limnol. Oceanogr. 37: 1319-1326 Drischoll, C. T„ M. D. Lehtinen & T. J. Sullivan (1994) Modeling the acidbase chemistry of organic solutes in Adirondack, New York, lakes. Water Resour. Res. 30: 297-306. Karentz, £>., Bothwell, M.L., Coffin, R.B., Hanson, A., Herndl, G.J., Kilham, S.S., Lesser, MP., Lindell, M„ Moeller, R.E., Morris, DP., Neale, P.J., Sanders, R.W., Weiler, CS. & R.G. Wetzel, (1994) Impact of UV-B radiation on pelagic freshwater ecosystems: Report of the working group on bacteria and phytoplankton. Arch. Hydrobio. Ergeb. Limn. 43: 1-226 Kirk, J. T. O. ( 1976) Yellow substance (glebsoff) and its contribution to the attenuation of photosynthetically active radiation in the aquatic environment., In: Allard, B. et al. (Eds.) Humic substances in the aquatic and terrestrial environment. Springer, 369-390. Photochemical degradation of dissolved organic substances in Lake Balaton Keresztes, Zs. Gy. - Fodorpataki, L.- V.Balogh, K. Abstract:The carbon cycle in water systems is largely influenced by the photochemical degradation of dissolved organic substances. The aim of this study was to measure the rate of the photochemical degradation of DOC in Lake Balaton. Water samples, collected in July 2007 in the mouth of River Zala and in different basins of the lake (Keszthelyi, Szigligeti, Szemesi and Siófoki -at Tihany and at Balatonffizfő- basins), were irradiated with the average radiation (UV-B, UV-A and PAR) of a sunny summer day in a sun simulator for 28 days. Samples were taken on day 3, day 7, day 14, day 21, and day 28. Light absorbance (Pt-colour was determined) and fluorescence intensity were measured. The concentration of dissolved organic carbon (DOC) as well as the quantity, degradation rate and half-life of photolitically degradable DOC was measured. The proportion of the DOC contributable to humic substances was measured both at the beginning and at the end of the experiment. The photolysis ran its curse in 21 days. The concentration of photolitically degradable DOC was 3.4 mg f 1 (24%) at the mouth of River Zala, which was an order of magnitude lower (0.2 mg 1"' 1,6 %) in the Siófok basin. The interval of the degradation coefficient ranged between 0.2 and 0.01 day" 1, which equal 3 and 59 days of half-life, respectively. The brown-coloured "Zala-water" discoloured to the Pt-colour value of the Keszthely basin, while the fluorescent spectra showed that the Zala water turned into "Siófok water" as a result of photolysis. Our results suggest that not only the DOC concentration decreases but the quality of organic substances is also transformed during photolysis, whereby they become more resistant to light degradation during residence in the lake. Key words: Lake Balaton, DOC, photolysis, degradation coefficient, half-life Morris, D. P., H. Zagarese, C. E. Williamson, E. G. Belserio, B. R. Hargreaves, B. Modenutti, R. Moeller & C. Queimalinos (1995) The attenuation of solar UV radiation in lakes and the role of dissolved organic carbon. Limnol. Oceanogr. 40: 1381-1391. Perdue, E. M. (1998) Chemical composition, structure, and metal binding properties. In: Hessen, D.O.&L. Tranvik (Eds.) Aquatic humic substances. Ecology and biogeochemistry. Springer-Verlag, Berlin Heidelberg, p. 41-61. Shaw, P. J:, R. I Jones & H. De Haan (2000) The influence of humic substances on the molecular weight distributions of phosphate and iron in epilimnetic lake waters Freshw. Biol. 45: 383-393. Snucins, E. & J. Gunn (2000) Interannual variation in the thermal structure of clear and colored lakes. Limnol. Oceanogr. 45: 1639-1646. Standard Methods (1995) Eaton, A. D„ L. S. Clesceri & A. E. Greenberg (Eds.) 19 l h Edition American Public Health Association, Washington. Srtome, D. J., & M. C. Miller (1948) Photolytic changes in dissolved humic substances. Verh. Internat. Verein. Limnol. 20: 1248-1254. Tóth N. & V.-Balogh K. (2006) Meteorológiai és hidrológiai tényezők hatása a szerves szén frakciók koncentrációjának időbeli változására a Zala folyó torkolatában. Hidrológiai Közlöny 86: 130-132. V.-Balogh, K. L. Vörös, N. Tóth & M. Bokros (2003) Changes of organic matter quality along the longitudinal axis of a large shallow lake (Lake Balaton). Hydrobiologia 506-509: 67-74. V.-Balogh K„ Tóth N„ Somogyi B. & Vörös L. (2007) A Balaton biológiailag hozzáférhető szerves szén terhelése, Hidr. Közlöny 87: 147-149.
