Hidrológiai Közlöny 1997 (77. évfolyam)

21 Irodalom: (.'<htó Cj., Ki.v C. 1984: A balatoni 1982. évi l/olilás-einelkcdcs okai. Vízügyi Közlemények 64: 580-606. llrrodrk S. 1977: Rccenl resulls of pliytnplaiiklon rcscarch in Uke Halálon. Annál. Biol Tihany. 44:181-198. Hortobágyi T., Kúrpnll I. 1966: Vízvirágzás a Keszthelyi öbölben. Georgikon 114. 12-14. Oláh J., Tólli I,. 1985: A foszfor cs n niliogcn szerepe az culrolizálódásban és a vízminőség védelemben. Hidrológiai Közlöny, 65: 278-282 Piidlsúk J. 1995: l'hyloplanklou cau piovidc eillicr gmdual or licctic rcsponsc lo global climnlc cliangc: casc sludies fioni l\vo large sliallow lakes (Halalon, Hungary, Ncusicdlersec, Auslria/Ilungary) - NATO Procccdings Tólli L.G.; Tadhák J. 1986: Mctcorological Faclors Aflccting Ihc I3loom of Anabacno/isis Raciborskii Wolosz (Cyanophyta, llormogonalcs) in llie Sliallow l^ike Ualalon, Hungary.. J. Plankton Resea/cli, 8:353-363. Vollcnweldcr II. A. 1968: Sciciitiíic fuiidamcntals of llic culrolicalion or lakcs and llowing walers willi pnrticular refcrcncc lo nitrogén and phosphonis as faclors in culropliication. OliCI) OAS/CSI/68 27. Paris Vörös I/. 1995: Kékalgák elszaporodását befolyásoló tényezők cs loxicilásuk kulalása. III.KI Kutatási Jelentés Effecls of liydromclcorological cvents 011 tlic tropliic Icvcl of lakc Balaton, Hungary Kóbor, István Ccntral-Transdanubiaii District ll'ater Authority, Székesfehérvár Analysis of Uic chlorophyll-a dala of lakc Balaton sliows Uial tlic trophic Icvcl of Ihc lakc have incrcascd tcndcntiously sincc 1975 while ils nuLricnt loading dccrcascd in the lasl decadc duc to Ihc incasurcs taken in tlic watershed. The incrcasc in trophic Icvcl is tlic most significant in tlic less ctiliophicatcd liastem hasin (Siófok Basin). At Üic sainc tiinc, Ihc liophic lcvel of the lakc water charactcriscd by chlorophyll-a conccnlralions lluctuatcd in widc rangc year to ycar. Bctwccn 1992 and 1995 the (luctuation incrcascd. Tlie worst water qualily occurrcd in 1994 whilc Ihat of tlic bcst was in 1995. lliis obscrvatioiis, according lo tlic prcccding rcsults, suggested tliat nowadays tlic actual trophic Icvcl of tlic lakc depends on the mctcorological and hydrological faclors, ratlicr than tlic cxtcrnal loading. Tliat mcans Utat tlic laké is not nutricut limited most of tlic tiinc. The cITects of tlic physical cnviioiiincnt (somc mctcorological and hydrological faclors) 011 tlic trophic Icvcl of lakc Balaton wcrc invcsligatcd in tliis study. I hc influciicing paramclcrs wcrc: average and variancc of daily incasurcs of global radiation, water and air temperálnic, wind speed, air pressurc, water Icvcl, prccipitalion. llic chlorophyll-a and growtli ralc wcrc Ihc dcpending trophic parameters. The rcsults suggest, thai Ihc actual trophic Icvcl of tlic lakc depends 011 Uic mctcorological events 011 Uic prcccding 6-10 wecks period. Iligli chlorophyll-a conccnlralions wcrc found if the water, air Icinpcralurc and air prcssiuc wcrc high, tlic wind speed was low und tlic global ladialion was cquablc in Ihc 6-10 wccks period bcl'orc the incasurcincnt. I hc corrclalion was very slrotig. llic corrclalion bctwccn thcsc faclors und Ihc growtli ratc was wcakcr, and depending on shorl (1 or 2 wccks long) periods. Tlic icsulls (accoiding to tlic prcccding rcsults) show Uial nowadays the actual trophic Icvcl of Ihc lakc (cspccially in tlic Western region) depends inainly 011 the mctcorological and hydrological faclors, rallier llian 011 cxtcrnal nulrient loadings. Tliat mcans Ihat the lakc is 110I uutriciit limited inost of tiinc. llic internál nulrient load should bc .significant to mainlain high trophic conditions in suiiiincr nionlhs and tlic incasurcs taken m the watershed did not dccrcasc the cxtcrnal loads lo an appropriatc lcvel.