Hidrológiai Közlöny 2006 (86. évfolyam)

6. szám - XLVII. Hidrobiológus Napok: Vizeink élővilágát érintő környezeti változások Tihany, 2005. október 5–7.

135 A kapott összefüggések alapján a vízhozam illetve a DOC és Pt-szín koncentráció ismeretében becsülhető a befolyók útján a Balatont érő biológiailag hozzáférhető oldott szerves szénterhelés. A BDOC frakció minden bizonnyal függ a vízhozamtól is, amit nem vizsgáltunk. Mivel Leff & Meyer (1991) azt találták, hogy nagy vízhozamnál kevesebb a hozzáférhető DOC mint kis vízhozamnál, és mivel mi a BDOC meghatározást tavasszal, áradáskor végeztük, a számítás nem jelent majd felülbecslést. Irodalom Cuthbert, 1. D. & P. del Giorgio (1992) Toward a standard method of measuring color in freshwater. Limnol. Oceanogr. 37: 1319-1326. Kalbitz, K„ J. Schmerwitz, D. Schwesi, & E. Matzner (2003) Biodegradation of soil-derived dissolved organic matter as related to its properties. Geoderma, 113: 273-291. Leff L. G. & J. L. Meyer (1991) Biological availability of dissolved organic carbon along the Ogeechee River. Limnol. Oceanogr. 36: 315-323. Servais, P., A. Anzil & C. Ventresque (1989) Simple method for determination of biodegradable dissolved organic carbon in water. Appl. Environ. Microbiol. 55: 2732-2734. S0ndergaard M. & M. Middelboe (1995) A cross-system analysis of labile dissolved organic carbon. Mar. Ecol. Prog. Ser. 118: 283-294 Standard Methods, 1995. Eaton, A. D„ L. S. Clesceri & A. E. Greenberg (Eds.) 19

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h Ed.:American Public Health Assoc., Washington. Tranvik, L. J. (1988) Availability of dissolved organic carbon for planktonic bacteria in oligotrophic lakes of differing humic content. Microb. Ecol. 16: 311-322. Tranvik, L. J. (1998) Degradation of dissolved organic matter in humic waters by bacteria. In: Ecological Studies 133. Hessen, D. O. & L. J. Tranvik (Eds.) Aquatic Humic Substances. SpringerVerlag, Berlin Heidelberg. 259-283. Waiser, M. J. &. R. D. Robarts (2000) Changes in composition and reactivity of allochthonous DOM in a prairie saline lake. Limnol. Oceanogr. 45 763-774. Köszönetnyilvánítás A munka az NKFP által támogatott 3B022 04 BALÖKO projekt keretében készült. Biological availability of allochthonous dissolved organic substances in tributaries of Lake Balaton in Hungary Katalin V.-Balogh, Noémi Tóth, Boglárka Somogyi, Lajos Vörös Balaton Limnological Research Institute of the Hungarian Academy of Sciences, Tihany Abstract: Total organic carbon (TOC), dissolved organic carbon (DOC) and Pt-colour concentrations were measured monthly at the mouth reach of the seven (River Zala, Lesence-nádasmező western outfall, Tapolca creek, Egervíz creek. Nyugati öv canal. Keleti bozót creek, Imremajori canal) tributaries of Lake Balaton in 2005. A laboratory experiment was carried out to measure the biologically available organic carbon (BDOC). Water samples were collected from the tributaries at the time of the spring flood in May. The DOC concentration of nonhumic (NHS) and humic substances (HS) was measured at the start of the experiment. The proportion and degradation rate of BDOC were measured. According to our results, the DOC concentration increased from January to May/ June in all tributaries. The maximum values changed between 10 mg 1"' (Tapolca creek) and 45 mg I ' (Imremajori canal). The BDOC concentration was proportional to the DOC. The minimum value (1.28 mg l"

1) was found in the Tapolca creek, while the maximum one (3.8 mg 1"') in the Imremajori canal, which amounts to 39% and 7% of the total DOC respectively. The breakdown rate of BDOC was the highest in the water of the Imremajori canal, and the smallest in the Egervíz creek, the half-life was found to be 2.1 and 5.4 days respectively. The contribution of humic substances to the total DOC was the highest (69.2%) in the River Zala, and the smallest (53%) in the Tapolca creek. Inverse relationships were found between DOC concentration, colour concentration, percentage HS contribution and percentage BDOC contribution. Our results provide information for a better knowledge of the allochthonous organic matter load of Lake Balaton and for the role of organic substances in the carbon cycling of the lake. Key words: tributaries of Lake Balaton, POC, DOC, BDOC, Pt-colour, HS Klossy Irén alkotása (Fametszet, Magyar tájak sorozat)