![\"\"](\"https:\/\/www.vtei.cz\/wp-content\/uploads\/2018\/06\/ilustracni-fotografie-5_edit.jpg\")
<\/a>\n\u00davod<\/h2>\n
Ke zhor\u0161ov\u00e1n\u00ed kvality vody (my\u0161leny zejm\u00e9na projevy eutrofizace a\u00a0jevy s\u00a0n\u00ed spojen\u00e9) doch\u00e1z\u00ed p\u0159edev\u0161\u00edm vnosem fosforu (P) do n\u00e1dr\u017ee p\u0159\u00edtokem. Na tento negativn\u00ed proces v\u0161ak maj\u00ed \u010dasto aditivn\u00ed vliv tak\u00e9 sedimenty, ze kter\u00fdch se P bu\u010f m\u016f\u017ee uvol\u0148ovat, nebo jej sedimenty m\u00e1lo zadr\u017euj\u00ed. Sedimenty v\u00a0n\u00e1dr\u017e\u00edch tak funguj\u00ed jako dynamick\u00fd z\u00e1sobn\u00edk l\u00e1tek, do kter\u00e9ho se sou\u010dasn\u011b ukl\u00e1daj\u00ed a\u00a0z\u00a0n\u011bj i\u00a0uvol\u0148uj\u00ed v\u00a0z\u00e1vislosti na okoln\u00edch podm\u00ednk\u00e1ch a\u00a0biogeochemick\u00fdch procesech. V\u00fdm\u011bna l\u00e1tek mezi vodou a\u00a0sedimenty je \u0159\u00edzena zejm\u00e9na teplotou vody, p\u0159\u00edsunem l\u00e1tek (koncentrace a\u00a0formy) z\u00a0povod\u00ed, pr\u016ftoky, disturbancemi sediment\u016f (povod\u0148ov\u00e9 epizody, manipulace s\u00a0hladinou, ryby), p\u0159\u00edtomnost\u00ed vazebn\u00fdch prvk\u016f (\u017eelezo, hlin\u00edk, mangan, organick\u00e1 hmota) a\u00a0dal\u0161\u00edmi vlivy.<\/p>\n
P\u0159\u00edtokov\u00e9 \u010d\u00e1sti n\u00e1dr\u017e\u00ed obvykle zachycuj\u00ed nejv\u011bt\u0161\u00ed objemy sediment\u016f, jejich mno\u017estv\u00ed a\u00a0kvalita se v\u0161ak li\u0161\u00ed nejen v\u00a0pod\u00e9ln\u00e9m, ale i\u00a0v\u00a0p\u0159\u00ed\u010dn\u00e9m profilu n\u00e1dr\u017ee v\u00a0z\u00e1vislosti na hydraulick\u00fdch vlastnostech vodn\u00edho sloupce. V\u00a0p\u0159\u00edtokov\u00fdch z\u00f3n\u00e1ch rovn\u011b\u017e doch\u00e1z\u00ed k\u00a0nejmasov\u011bj\u0161\u00edmu rozvoji \u0159as a\u00a0sinic, jejich\u017e biomasa postupn\u011b sedimentuje z\u00a0vodn\u00edho sloupce. Pokud se tak d\u011bje je\u0161t\u011b v\u00a0z\u00f3n\u011b \u00fapln\u00e9ho m\u00edch\u00e1n\u00ed vodn\u00edho sloupce, zpravidla nedoch\u00e1z\u00ed ke kumulaci sestonu na dn\u011b, ale k\u00a0jeho rychl\u00e9mu rozkladu. V\u00a0p\u0159\u00edpad\u011b, kdy m\u00edchan\u00e1 \u010d\u00e1st vodn\u00edho sloupce ji\u017e nedosahuje ke dnu, doch\u00e1z\u00ed ke vzniku lok\u00e1ln\u00edch bezkysl\u00edkat\u00fdch z\u00f3n, k\u00a0nedostate\u010dn\u00e9mu rozkladu sedimentovan\u00fdch \u010d\u00e1stic a\u00a0k\u00a0ukl\u00e1d\u00e1n\u00ed nestabilizovan\u00e9ho, \u017eivinami bohat\u00e9ho sedimentu, schopn\u00e9ho efektivn\u011b uvol\u0148ovat \u017eiviny zp\u011bt do vodn\u00edho sloupce [1]. Z\u00f3ny dna t\u011bchto \u010d\u00e1st\u00ed n\u00e1dr\u017ee se tak \u010dasto m\u011bn\u00ed ve smyslu dostupnosti kysl\u00edku (O2<\/sub>) a\u00a0p\u0159\u00edpadn\u011b dusi\u010dnan\u016f (NO3<\/sub>–<\/sup>), kter\u00e9 maj\u00ed z\u00e1sadn\u00ed vliv na metabolismus bakteri\u00ed a\u00a0ur\u010duj\u00ed chov\u00e1n\u00ed sedimentu.<\/p>\n S\u00a0rostouc\u00ed hloubkou n\u00e1dr\u017ee kles\u00e1 vliv sedimentu jako zdroje \u017eivin k\u00a0rozvoji fytoplanktonu ve vodn\u00edm sloupci, nebo\u0165 P uvol\u0148ovan\u00fd ze sedimentu z\u016fst\u00e1v\u00e1 v\u00a0hypolimnetick\u00e9 \u010d\u00e1sti vodn\u00edho sloupce, tedy pod produk\u010dn\u00ed z\u00f3nou fytoplanktonu. Tyto p\u0159\u00edtokov\u00e9 \u010d\u00e1sti n\u00e1dr\u017ee na rozhran\u00ed m\u00edchan\u00e9ho\/nem\u00edchan\u00e9ho vodn\u00edho sloupce jsou tak nejdynami\u010dt\u011bj\u0161\u00ed a\u00a0maj\u00ed nejv\u011bt\u0161\u00ed vliv na trofii cel\u00e9 n\u00e1dr\u017ee.<\/p>\n Sedimenty obsahuj\u00ed nejen \u010d\u00e1stice, ale tak\u00e9 p\u00f3rovou vodu, kter\u00e1 funguje jako transportn\u00ed spojovatel mezi sedimenty a\u00a0vodou nad sedimenty. Prost\u0159ednictv\u00edm n\u00ed se do sedimentu dost\u00e1vaj\u00ed z\u00a0vodn\u00edho sloupce l\u00e1tky, kter\u00e9 jsou zde v\u00a0n\u00edzk\u00fdch koncentrac\u00edch a\u00a0jsou spot\u0159ebov\u00e1v\u00e1ny (zejm\u00e9na rozpu\u0161t\u011bn\u00fd O2<\/sub>, NO3<\/sub>–<\/sup>, SO4<\/sub>2-<\/sup>). Naopak ze sedimentu jsou transportov\u00e1ny l\u00e1tky, kter\u00e9 se vlivem chemick\u00fdch a\u00a0mikrobi\u00e1ln\u00edch proces\u016f na \u010d\u00e1stic\u00edch rozpou\u0161t\u011bj\u00ed do p\u00f3rov\u00e9 vody (nap\u0159. P, NH4<\/sub>+<\/sup>, CO2<\/sub> a\u00a0dal\u0161\u00ed).<\/p>\n Rozpu\u0161t\u011bn\u00e9 l\u00e1tky v\u00a0p\u00f3rov\u00e9 vod\u011b, v\u010detn\u011b P, se dost\u00e1vaj\u00ed ze sedimentu do vody v\u00a0n\u00e1dr\u017ei bu\u010f p\u0159\u00edmou dif\u00faz\u00ed, nebo rychleji d\u00edky rozru\u0161ov\u00e1n\u00ed cel\u00e9ho sedimentu bioturbac\u00ed bezobratl\u00fdch \u017eivo\u010dich\u016f (nap\u0159. larvy pakom\u00e1r\u016f) a\u00a0ryb, produkc\u00ed a\u00a0n\u00e1sledn\u00fdm vybubl\u00e1n\u00edm plyn\u016f nebo resuspenz\u00ed sedimentu d\u00edky pohyb\u016fm vody [2]. Biogeochemick\u00e9 zm\u011bny \u010d\u00e1stic pak z\u00e1visej\u00ed na parametrech, jako je teplota, kter\u00e1 d\u00e1le ovliv\u0148uje rychlosti chemick\u00fdch a\u00a0zvl\u00e1\u0161t\u011b mikrobi\u00e1ln\u00edch aktivit, dostupnost tzv. akceptor\u016f elektron\u016f O2<\/sub>, NO3<\/sub>-, <\/sup>SO4<\/sub>2-<\/sup> a\u00a0n\u00e1sledn\u011b oxida\u010dn\u011b-reduk\u010dn\u00ed potenci\u00e1l (Eh) a\u00a0pH, formy organick\u00fdch l\u00e1tek, a\u00a0d\u00e1le pak sorp\u010dn\u011b desorp\u010dn\u00ed rovnov\u00e1hy. Akceptory elektron\u016f jsou d\u016fle\u017eit\u00e9 pro proces oxidace organick\u00fdch slou\u010denin bakteriemi. Pokud je sediment anoxick\u00fd a\u00a0jsou vy\u010derp\u00e1ny v\u00fd\u0161e zm\u00edn\u011bn\u00e9 akceptory (zejm\u00e9na O2<\/sub> a\u00a0NO3<\/sub>–<\/sup>), doch\u00e1z\u00ed k\u00a0redukci slou\u010denin MnIV <\/sup>na MnII<\/sup> a\u00a0zejm\u00e9na v\u00edce zastoupen\u00e9ho FeIII<\/sup> na FeII<\/sup>, kter\u00e9 se tak rozpou\u0161t\u011bj\u00ed do p\u00f3rov\u00e9 vody. FeIII<\/sup> slou\u010deniny a\u00a0zejm\u00e9na jeho (hydr)oxidy jsou hlavn\u00edm vazebn\u00fdm partnerem pro P, proto doch\u00e1z\u00ed k\u00a0sou\u010dasn\u00e9mu rozpou\u0161t\u011bn\u00ed P do p\u00f3rov\u00e9 vody. Pokud obsahuje p\u00f3rov\u00e1 voda vy\u0161\u0161\u00ed koncentrace rozpu\u0161t\u011bn\u00e9ho Fe, m\u016f\u017eeme s\u00a0jistotou \u0159\u00edci, \u017ee doch\u00e1z\u00ed k\u00a0reduk\u010dn\u00edmu rozpou\u0161t\u011bn\u00ed Fe (hydr)oxid\u016f a\u00a0sou\u010dasn\u011b k\u00a0p\u0159em\u011bn\u011b P z\u00a0pevn\u00e9 formy do rozpu\u0161t\u011bn\u00e9 a\u00a0zp\u0159\u00edstupn\u011bn\u00ed tohoto P pro p\u0159echod do vodn\u00edho sloupce. Sedimenty s\u00a0vysok\u00fdmi koncentracemi P v\u00a0p\u00f3rov\u00e9 vod\u011b maj\u00ed tak vysok\u00fd eutrofiza\u010dn\u00ed potenci\u00e1l.<\/p>\n V\u00a0tomto p\u0159\u00edsp\u011bvku bude uk\u00e1z\u00e1n zp\u016fsob zji\u0161t\u011bn\u00ed potenci\u00e1ln\u00edho vlivu sedimentu z\u00a0p\u0159\u00edtokov\u00e9 \u010d\u00e1sti n\u00e1dr\u017ee Vranov na kvalitu vody v\u00a0n\u00e1dr\u017ei za p\u0159\u00edtomnosti \u010di nep\u0159\u00edtomnosti kysl\u00edku, dostupnosti NO3<\/sub>–<\/sup> a\u00a0vysv\u011btlen mechanismus uvol\u0148ov\u00e1n\u00ed P ze sedimentu.<\/p>\n Studovan\u00fd sediment byl odebr\u00e1n na n\u00e1dr\u017ei Vranov v\u00a0lokalit\u011b mezi \u201eFar\u00e1\u0159kou\u201c a\u00a0\u201eM. Lou\u010dky\u201c 23. 8. 2016. V\u00a0dob\u011b a\u00a0m\u00edst\u011b odb\u011bru byla koncentrace O2<\/sub> 4\u2008mg\u2219l-1<\/sup> v\u00a0hloubce 0,5\u2008m nade dnem. Celkem \u010dty\u0159i paraleln\u00ed vzorky sediment\u016f z\u00a0identick\u00e9 lokality byly odebr\u00e1ny inovovan\u00fdm gravita\u010dn\u00edm odb\u011br\u00e1kem do plexisklov\u00fdch trubic o\u00a0pr\u016fm\u011bru 20\u2008cm a\u00a0v\u00fd\u0161ce 40\u2008cm. Takto odebran\u00e9 vzorky umo\u017enily zachov\u00e1n\u00ed svrchn\u00ed vrstvy sedimentu s\u00a0neporu\u0161en\u00fdm vertik\u00e1ln\u00edm profilem, kter\u00fd odpov\u00eddal stavu sediment\u016f v\u00a0n\u00e1dr\u017ei (vzorky z\u00a0pr\u016fb\u011bhu inkubace viz obr.<\/em>\u00a01<\/em>). Sou\u010dasn\u011b byla z\u00a0vodn\u00edho sloupce nade dnem odebr\u00e1na voda do 25 l barel\u016f, kter\u00e1 slou\u017eila n\u00e1sledn\u011b b\u011bhem inkuba\u010dn\u00edho sledov\u00e1n\u00ed jako z\u00e1sob\u00e1rna vody. Tento objem (spole\u010dn\u011b s\u00a0vodou nad sedimentem v\u00a0odb\u011brov\u00e9 trubici) odpov\u00eddal v\u00fd\u0161ce vodn\u00edho sloupce 1\u2008m nad plochu sedimentu vzork\u016f v\u00a0trubic\u00edch.<\/p>\n K\u00f3ry sediment\u016f byly um\u00edst\u011bny do inkuba\u010dn\u00edho boxu temperovan\u00e9ho na 12\u2008\u00b0C, napojeny na syst\u00e9m kontinu\u00e1ln\u00ed v\u00fdm\u011bny vody mezi vodou nad sedimentem v\u00a0k\u00f3ru a\u00a0z\u00e1sobn\u00ed vodou v\u00a0barelu. Nad sediment byly n\u00e1sledn\u011b um\u00edst\u011bny m\u00edchac\u00ed vrtule simuluj\u00edc\u00ed pomal\u00e9 proud\u011bn\u00ed vody nad sedimentem (obr.\u00a01<\/em>). Byly simulov\u00e1ny t\u0159i varianty podm\u00ednek ve vodn\u00edm sloupci:<\/p>\n Ka\u017ed\u00fd t\u00fdden byl monitorov\u00e1n ve v\u0161ech variant\u00e1ch v\u00fdvoj koncentrac\u00ed rozpu\u0161t\u011bn\u00fdch l\u00e1tek v\u00a0p\u00f3rov\u00e9 vod\u011b vertik\u00e1ln\u00edho profilu sedimentu. Pro vzorkov\u00e1n\u00ed p\u00f3rov\u00e9 vody byla pou\u017eita upraven\u00e1 technika DET (Diffusive Equilibrium in Thin Film). Minipeeper s\u00a0aktivn\u00ed gelovou \u010d\u00e1st\u00ed o\u00a0celkov\u00e9 d\u00e9lce 9\u2008cm byl zasunut do sedimentu a\u00a0exponov\u00e1n zde 24\u00a0hodin. Tato m\u00e1lo invazivn\u00ed metoda a\u00a0velk\u00fd pr\u016fm\u011br k\u00f3r\u016f n\u00e1m umo\u017enila vzorkov\u00e1n\u00ed p\u00f3rov\u00e9 vody ve stejn\u00e9m k\u00f3ru, pouze na v\u017edy jin\u00e9m m\u00edst\u011b. Pro informace ohledn\u011b t\u00e9to techniky viz [3, 4].<\/p>\n Pro sledov\u00e1n\u00ed zm\u011bn slo\u017een\u00ed \u010d\u00e1stic sediment\u016f vyvolan\u00fdch v\u00fdvojem sedimentu za r\u016fzn\u00fdch podm\u00ednek inkubace byl vzorek sedimentu analyzov\u00e1n pomoc\u00ed frakcionace P. Jeden k\u00f3r byl v\u00a0dob\u011b za\u010d\u00e1tku inkubace (pou\u017eit \u010dtvrt\u00fd neinkubovan\u00fd replik\u00e1t) roz\u0159ez\u00e1n ve vertik\u00e1ln\u00edm profilu do vrstev o\u00a0v\u00fd\u0161ce 1\u2008cm. V\u00a0t\u011bchto vrstv\u00e1ch byl stanoven obsah (105\u2008\u00b0C, 2 hod) a\u00a0ztr\u00e1ta \u017e\u00edh\u00e1n\u00edm, kter\u00e1 odpov\u00edd\u00e1 obsahu organick\u00e9 slo\u017eky v\u00a0\u010d\u00e1stic\u00edch sedimentu (550\u2008\u00b0C, 2 hod). Vzorky z\u00a0jednotliv\u00fdch vrstev byly analyzov\u00e1ny pomoc\u00ed frakcionace podle Jan a kol. [5], ke stanoven\u00ed forem P a\u00a0jeho vazebn\u00fdch partner\u016f (tabulka 1<\/em>). Stejn\u011b byly roz\u0159ez\u00e1ny a\u00a0zanalyzov\u00e1ny t\u0159i inkubovan\u00e9 k\u00f3ry po ukon\u010den\u00ed inkuba\u010dn\u00edho sledov\u00e1n\u00ed, ke stanoven\u00ed zm\u011bn slo\u017een\u00ed \u010d\u00e1stic zp\u016fsoben\u00fdch r\u016fzn\u00fdmi podm\u00ednkami ve \u201evodn\u00edm sloupci nad sedimentem\u201c.<\/p>\n Z\u00e1kladn\u00ed parametry sedimentu p\u0159ed zah\u00e1jen\u00edm inkubac\u00ed jsou vyobrazeny na obr.\u00a02<\/em>. Sediment obsahoval 86 % vody v\u00a0nejsvrchn\u011bj\u0161\u00ed vrstv\u011b 0\u20131\u2008cm a\u00a0postupn\u011b klesal a\u017e na 57 % ve vrstv\u011b 8\u20139\u2008cm. \u010c\u00e1stice sedimentu, kter\u00e9 tvo\u0159ily zbytek sedimentu, pak obsahovaly p\u0159ibli\u017en\u011b 14 % organick\u00e9 slo\u017eky (stanoveno jako ztr\u00e1ta \u017e\u00edh\u00e1n\u00edm p\u0159i 550\u2008\u00b0C) a\u00a0klesaly s\u00a0hloubkou sedimentu na 12 % ve spodn\u00ed sledovan\u00e9 vrstv\u011b. Zjevn\u011b vy\u0161\u0161\u00ed zastoupen\u00ed organick\u00e9 slo\u017eky v\u00a0nejsvrchn\u011bj\u0161\u00ed vrstv\u011b je zp\u016fsoben nasedimentovanou organickou hmotou v\u00a0pr\u016fb\u011bhu produk\u010dn\u00ed sezony fytoplanktonu. Pokud se pak zam\u011b\u0159\u00edme na pom\u011br mezi obsahem P rozpu\u0161t\u011bn\u00e9ho v\u00a0p\u00f3rov\u00e9 vod\u011b a\u00a0celkov\u00fdm obsahem P v\u00a0jednotliv\u00fdch vrstv\u00e1ch (rozpu\u0161t\u011bn\u00fd + \u010d\u00e1sticov\u00fd), vid\u00edme, \u017ee p\u00f3rov\u00e1 voda na po\u010d\u00e1tku inkubace obsahovala pouze m\u00e9n\u011b ne\u017e 1 % z\u00a0celkov\u00e9ho mno\u017estv\u00ed P v\u00a0sedimentu a\u00a0klesala s\u00a0hloubkou a\u017e na 0,5 %. A\u010dkoli se zd\u00e1 toto procento velice n\u00edzk\u00e9, hraje p\u00f3rov\u00e1 voda v\u00fdznamnou roli nejenom z\u00a0hlediska mno\u017estv\u00ed P v\u00a0n\u00ed, ale tak\u00e9 jako transportn\u00ed m\u00e9dium mezi sedimentem a\u00a0vodou nad n\u00edm viz d\u00e1le.<\/p>\n V\u00fdsledky monitoringu vody nad sedimentem v\u00a0pr\u016fb\u011bhu inkuba\u010dn\u00edho pokusu uk\u00e1zaly v\u00fdrazn\u00fd vliv podm\u00ednek b\u011bhem inkubace (obr.\u00a03<\/em>). Zat\u00edmco sediment inkubovan\u00fd za anoxick\u00fdch podm\u00ednek vody nad sedimentem (anox) vykazoval kontinu\u00e1ln\u00ed uvol\u0148ov\u00e1n\u00ed P ze sedimentu, u\u00a0obou oxick\u00fdch variant, jak bez p\u0159\u00eddavku NO3<\/sub>–<\/sup> (ox), tak i\u00a0s\u00a0p\u0159\u00eddavkem NO3<\/sub>–<\/sup> (NO3<\/sub>), k\u00a0uvol\u0148ov\u00e1n\u00ed P ze sedimentu nedoch\u00e1zelo. Sediment o\u00a0plo\u0161e 1\u2008m2<\/sup> tak v\u00a0anoxii uvolnil celkem 435\u2008mg P b\u011bhem 35\u00a0dn\u00ed inkubace, vyj\u00e1d\u0159eno na koncentrace, zat\u00edmco po\u010d\u00e1te\u010dn\u00ed stav byl 70\u2008mg\u2219m3<\/sup> P, koncov\u00fd stav 505\u2008mg\u2219m3<\/sup> P, co\u017e znamen\u00e1, \u017ee 1\u2008m2<\/sup> sedimentu ka\u017ed\u00fd den obohatil 1 l vody ve vodn\u00edm sloupci o\u00a0v\u00fd\u0161ce 1\u2008m o\u00a012,4 \u00b5g P. Toto anoxick\u00e9 uvol\u0148ov\u00e1n\u00ed P nebylo doprov\u00e1zeno uvol\u0148ov\u00e1n\u00edm Fe do vodn\u00edho sloupce, jak je vid\u011bt na obr.\u00a03<\/em>, a\u00a0koncentrace rozpu\u0161t\u011bn\u00e9ho Fe z\u016fstala na stabiln\u00ed n\u00edzk\u00e9 koncentraci. V\u00a0oxick\u00fdch variant\u00e1ch do\u0161lo k\u00a0dal\u0161\u00edmu poklesu koncentrace Fe, tedy k\u00a0vysr\u00e1\u017een\u00ed z\u00a0vodn\u00edho sloupce do \u010d\u00e1stic. Reduk\u010dn\u00ed rozpou\u0161t\u011bn\u00ed pak bylo patrn\u00e9 u\u00a0dal\u0161\u00edho redox labiln\u00edho prvku, manganu (Mn). Z\u00a0t\u011bchto v\u00fdsledk\u016f se m\u016f\u017ee zd\u00e1t, \u017ee za uvol\u0148ov\u00e1n\u00ed nen\u00ed zodpov\u011bdn\u00e9 rozpou\u0161t\u011bn\u00ed \u017eelezit\u00fdch slou\u010denin s\u00a0P, opak je v\u0161ak pravdou, jak potvrzuj\u00ed v\u00fdsledky anal\u00fdzy p\u00f3rov\u00e9 vody a\u00a0frakcionace.<\/p>\n Z\u00a0anal\u00fdz p\u00f3rov\u00fdch vod (obr.\u00a04<\/em>) je patrn\u00e9, \u017ee na po\u010d\u00e1tku inkubace (den 0) byl vysok\u00fd obsah celkov\u00e9ho rozpu\u0161t\u011bn\u00e9ho P v\u00a0jednotliv\u00fdch vrstv\u00e1ch sedimentu v\u010detn\u011b nejsvrchn\u011bj\u0161\u00ed vrstvy 0-0,5\u2008cm (c = 3,3\u00b10,5\u2008mg\u2219l-1<\/sup> P). Tato koncentrace byla t\u00e9m\u011b\u0159 50\u00d7 vy\u0161\u0161\u00ed oproti koncentraci P ve vodn\u00edm sloupci na po\u010d\u00e1tku inkubace (70 \u00b5g\u2219l-1<\/sup> P). D\u00edky tomuto vysok\u00e9mu koncentra\u010dn\u00edmu gradientu P na rozhran\u00ed sediment\/voda doch\u00e1zelo k\u00a0difuzn\u00edmu transportu P p\u00f3rovou vodou ven ze sedimentu. Jak je pak patrn\u00e9 z\u00a0dal\u0161\u00edch dvou sledov\u00e1n\u00ed po 14 a\u00a028 dnech, vysok\u00e9 mno\u017estv\u00ed P je st\u00e1le ve svrchn\u00edch vrstv\u00e1ch p\u0159\u00edtomno. Tento obsah P v\u00a0p\u00f3rov\u00e9 vod\u011b je tedy v\u00fdsledkem dvou proces\u016f: i) transportem P ven ze sedimentu (viz akumulace P ve vodn\u00edm sloupci) a\u00a0generov\u00e1n\u00edm rozpu\u0161t\u011bn\u00e9ho P uvnit\u0159 sedimentu d\u00edky p\u0159em\u011bn\u011b\/rozpou\u0161t\u011bn\u00ed \u010d\u00e1stic obsahuj\u00edc\u00edch P, jak bude uk\u00e1z\u00e1no d\u00e1le. V\u00a0p\u0159\u00edpad\u011b oxick\u00e9 varianty (ox) v\u00a0pr\u016fb\u011bhu inkubace doch\u00e1zelo k\u00a0v\u00fdrazn\u00e9mu poklesu P ve vrstv\u011b 0\u20133\u2008cm a\u00a0zejm\u00e9na nejv\u00edce ve svrchn\u00edch vrstv\u00e1ch pod povrchem sedimentu. Tento pokles byl je\u0161t\u011b v\u00fdrazn\u011bj\u0161\u00ed u\u00a0inkubovan\u00e9ho sedimentu s\u00a0vy\u0161\u0161\u00ed koncentrac\u00ed NO3<\/sub>–<\/sup> ve vodn\u00edm sloupci (NO3<\/sub>). N\u00edzk\u00fd obsah P tak zap\u0159\u00ed\u010dinil, \u017ee sedimenty P neuvol\u0148ovaly.<\/p>\n Pokud se zam\u011b\u0159\u00edme na profily rozpu\u0161t\u011bn\u00e9ho Fe v\u00a0p\u00f3rov\u00e9 vod\u011b (obr.\u00a04<\/em>), je patrn\u00e9, \u017ee maj\u00ed stejn\u00fd pr\u016fb\u011bh, jako u\u00a0P. Znamen\u00e1 to, \u017ee v\u00a0sedimentu nedoch\u00e1zelo k\u00a0rozpou\u0161t\u011bn\u00ed \u017eelezit\u00fdch slou\u010denin s\u00a0P, naopak d\u00edky p\u0159\u00edtomnosti oxick\u00e9 vody nade dnem doch\u00e1zelo k\u00a0postupn\u00e9mu \u201eprooxidov\u00e1v\u00e1n\u00ed\u201c svrchn\u00ed vrstvy sedimentu a\u00a0ke sr\u00e1\u017een\u00ed nov\u00fdch Fe~P slou\u010denin. Ke stejn\u00e9mu efektu doch\u00e1zelo, pokud byly p\u0159\u00edtomny ionty NO3<\/sub>–<\/sup> v\u00a0sedimentu, kter\u00e9 nav\u00edc pronikaly do v\u011bt\u0161\u00edch hloubek sedimentu a\u00a0ke sr\u00e1\u017een\u00ed rozpu\u0161t\u011bn\u00e9ho Fe a\u00a0sou\u010dasn\u011b P doch\u00e1zelo je\u0161t\u011b efektivn\u011bji. Z\u00a0pr\u016fb\u011bhu koncentrac\u00ed Fe na po\u010d\u00e1tku inkubac\u00ed a\u00a0d\u00e1le v\u00a0anoxick\u00e9 variant\u011b by ov\u0161em m\u011blo doch\u00e1zet k\u00a0uvol\u0148ov\u00e1n\u00ed Fe do anoxick\u00e9 vody. Tento proces v\u0161ak nebyl zaznamen\u00e1n p\u0159i monitoringu slo\u017een\u00ed vody nad sedimentem a\u00a0byl zp\u016fsoben sr\u00e1\u017een\u00edm redukovan\u00e9 formy Fe do formy sulfid\u016f FeSx<\/sub> na povrchu sedimentu d\u00edky soub\u011b\u017en\u00e9 redukci s\u00edran\u016f.<\/p>\n Obsah P v\u00a0p\u00f3rov\u00e9 vod\u011b jednotliv\u00fdch vrstev lze rozd\u011blit do dvou \u010d\u00e1st\u00ed i) H2<\/sub>O frakce (modr\u00e1 slo\u017eka) odpov\u00edd\u00e1 P, kter\u00fd se p\u0159i p\u0159echodu do oxick\u00e9 vody d\u00edky disturbanc\u00edm sedimentu (hydraulick\u00e1 resuspenze, aktivita ryb a\u00a0dal\u0161\u00ed) nen\u00ed schopen srazit s\u00a0rychle oxidovan\u00fdm Fe poch\u00e1zej\u00edc\u00edm ze stejn\u00e9 p\u00f3rov\u00e9 vody a\u00a0vytvo\u0159it nov\u00e9 \u010d\u00e1stice a\u00a0ii) HNO3<\/sub> frakce (oran\u017eov\u00e1 \u010d\u00e1st), kter\u00e1 je s\u00a0t\u00edmto rozpu\u0161t\u011bn\u00fdm Fe potencion\u00e1ln\u011b sraziteln\u00e1 v\u00a0oxick\u00fdch podm\u00ednk\u00e1ch. H2<\/sub>O \u010d\u00e1st P p\u00f3rov\u00e9 vody je tedy v\u00a0p\u0159\u00edpad\u011b resuspenze okam\u017eit\u011b v\u00a0rozpu\u0161t\u011bn\u00e9 form\u011b dostupn\u00e1 pro organismy ve vodn\u00edm sloupci a\u00a0p\u0159edstavuje nejv\u011bt\u0161\u00ed riziko z\u00a0celkov\u00e9ho obsahu P v\u00a0sedimentu. Pokud by do\u0161lo k\u00a0resuspenzi sedimentu do hloubky 3\u2008cm u\u00a0sedimentu na po\u010d\u00e1tku inkubace, uvolnilo by se v\u00a0pr\u016fm\u011bru 90\u2008mg P z\u00a0jednoho \u010dtvere\u010dn\u00edho metru sedimentu, z\u00a0\u010deho\u017e 18\u2008mg by se v\u00a0p\u0159\u00edpad\u011b oxick\u00e9 vody nebylo schopno srazit s\u00a0Fe, a\u00a0stalo se tak okam\u017eit\u011b dostupn\u00fdm.<\/p>\n Sediment obsahoval na po\u010d\u00e1tku inkuba\u010dn\u00edho pokusu v\u00a0horn\u00edch 9\u2008cm celkem 35\u2008g\u2219m-2<\/sup> P. Celkov\u00e9 mno\u017estv\u00ed r\u016fzn\u00fdch forem P a\u00a0Fe stanovovan\u00fdch frakciona\u010dn\u00ed anal\u00fdzou, stejn\u011b jako jejich procentu\u00e1ln\u00ed zastoupen\u00ed v\u00a0r\u016fzn\u00fdch vrstv\u00e1ch je zobrazeno na obr.\u00a05<\/em>. Pr\u016fm\u011brn\u011b 29\u00b13\u00a0% P bylo v\u00e1z\u00e1no ve vysoce reduk\u010dn\u011b labiln\u00edch slou\u010denin\u00e1ch Fe a\u00a0Mn (frakce BD-I), 30\u00b13 v\u00e1z\u00e1no na stabiln\u011bj\u0161\u00ed a\u00a0m\u00e9n\u011b bakteri\u00e1ln\u011b a\u00a0chemicky redukovateln\u00e9 slou\u010deniny Fe a\u00a0Mn (frakce BD-II), 26\u00b14\u00a0% P v\u00e1zan\u00e9ho na amorfn\u00ed (hydr)oxidy Al a\u00a0v\u00a0organick\u00fdch form\u00e1ch (frakce NaOH-I), 11\u00b12 % ve stabiln\u00edch organick\u00fdch form\u00e1ch a\u00a0krystalick\u00fdch oxidech Al (frakce NaOH-II), 4\u00b11 % P ve slou\u010denin\u00e1ch labiln\u00edch v\u00a0n\u00edzk\u00fdch hodnot\u00e1ch pH. Fosfor je v\u00a0tomto typu sedimentu p\u0159ev\u00e1\u017en\u011b v\u00e1z\u00e1n v\u00a0\u017eelezit\u00fdch (hydr)oxidech, jejich nejv\u011bt\u0161\u00ed zastoupen\u00ed je pak ve svrchn\u00edch 3 centimetrech.<\/p>\n Zm\u011bny, kter\u00e9 se odehr\u00e1ly b\u011bhem sledovan\u00e9ho obdob\u00ed, byly nejv\u00fdznamn\u011bj\u0161\u00ed ve svrchn\u00edch 3\u2008cm sedimentu, a\u00a0byly t\u00e9m\u011b\u0159 v\u00fdhradn\u011b zp\u016fsobeny zm\u011bnami mno\u017estv\u00ed P v\u00e1zan\u00e9ho na redox labiln\u00ed (hydr)oxidy Fe a\u00a0n\u00e1sledn\u011b Mn, kter\u00fd m\u011bl ov\u0161em men\u0161\u00ed v\u00fdznam vzhledem k\u00a0jeho mal\u00e9mu mno\u017estv\u00ed v\u00a0sedimentu (obr.\u00a06<\/em>). Uvol\u0148ovan\u00fd P ze sedimentu pod anoxick\u00fdm vodn\u00edm sloupcem byl zp\u016fsoben rozpou\u0161t\u011bn\u00edm snadno dostupn\u00fdch (hydr)oxid\u016f Fe, kter\u00e9 slou\u017e\u00ed jako termin\u00e1ln\u00ed akceptor elektron\u016f p\u0159i mikrobi\u00e1ln\u00edm rozkladu organick\u00fdch l\u00e1tek, a\u00a0na nich v\u00e1zan\u00e9ho P (frakce BD-I). Pokles jejich mno\u017estv\u00ed byl patrn\u00fd zejm\u00e9na v\u00a0nejsvrchn\u011bj\u0161\u00ed vrstv\u011b 0\u20131\u2008cm (pokles P o\u00a048 %, pokles Fe o\u00a038 %, viz tabulka 2<\/em>). Jak bylo uk\u00e1z\u00e1no d\u0159\u00edve, Fe se ze sedimentu v\u00a0anoxick\u00e9 variant\u011b neuvol\u0148ovalo, nebo\u0165 doch\u00e1zelo ke sr\u00e1\u017een\u00ed FeSx<\/sub> d\u00edky siln\u00fdm anoxick\u00fdm podm\u00ednk\u00e1m a\u00a0redukci s\u00edran\u016f (stanoveno jako AVS \u2013 acid volatile sulfur a\u00a0p\u0159epo\u010d\u00edt\u00e1no s\u00a0mol\u00e1rn\u00edm pom\u011brem S : Fe \u2013 1 : 1). Naopak v\u00a0obou oxick\u00fdch variant\u00e1ch do\u0161lo k\u00a0nabohacen\u00ed P v\u00a0BD-I\u00a0frakc\u00edch, a to o des\u00edtky procent (obr. 6, tabulka 2<\/em>). Tento efekt byl zp\u016fsoben jednak vysr\u00e1\u017een\u00edm rozpu\u0161t\u011bn\u00e9ho P a Fe z p\u00f3rov\u00e9 vody a pravd\u011bpodobn\u011b tak\u00e9 d\u00edky p\u0159em\u011bn\u011b p\u016fvodn\u00edch h\u016f\u0159e dostupn\u00fdch (hydr)oxid\u016f Fe. Zat\u00edmco p\u0159i dostupnosti rozpu\u0161t\u011bn\u00e9ho O2 a NO3\u00a0<\/sub>–<\/sup> doch\u00e1zelo k nabohacen\u00ed mno\u017estv\u00ed P a Fe v BD-I frakci, do\u0161lo k ochuzen\u00ed P a \u010d\u00e1ste\u010dn\u011b Fe v h\u016f\u0159e dostupn\u00fdch form\u00e1ch (BD-II). Tento fakt byl zap\u0159\u00ed\u010din\u011bn bu\u010f oxidac\u00ed a uvoln\u011bn\u00edm organick\u00fdch l\u00e1tek nasorbovan\u00fdch na povrchu \u017eelezit\u00fdch (hydr)oxid\u016f nebo oxidac\u00ed redukovan\u00fdch FeII<\/sup> iont\u016f takt\u00e9\u017e na povr\u0161\u00edch t\u011bchto slou\u010denin. Oba mechanismy v sedimentech znep\u0159\u00edstup\u0148uj\u00ed bakteri\u00edm p\u0159en\u00e1\u0161et elektrony na FeIII<\/sup> (hydr)oxidy [6, 7]. V BD-II frakci jsou nav\u00edc P\u0159es ve\u0161kerou snahu se p\u0159i inkubaci p\u0159ibl\u00ed\u017eit podm\u00ednk\u00e1m v n\u00e1dr\u017ei, v\u010detn\u011b pou\u017eit\u00ed nejlep\u0161\u00edch dostupn\u00fdch postup\u016f, bude v\u017edy obt\u00ed\u017en\u00e9 extrapolovat v\u00fdsledky do v\u011bt\u0161\u00edho m\u011b\u0159\u00edtka. I p\u0159esto se n\u00ed\u017ee pokus\u00edme o vyj\u00e1d\u0159en\u00ed vztahu mezi nam\u011b\u0159en\u00fdmi v\u00fdsledky a situac\u00ed v n\u00e1dr\u017ei.<\/p>\n Na z\u00e1klad\u011b p\u0159edchoz\u00edho monitoringu lze p\u0159edpokl\u00e1dat:<\/p>\n Sedimenty z\u00a0p\u0159\u00edtokov\u00fdch \u010d\u00e1st\u00ed n\u00e1dr\u017e\u00ed maj\u00ed velk\u00fd vliv na trofick\u00fd stav n\u00e1dr\u017e\u00ed vzhledem k\u00a0jejich bl\u00edzk\u00e9mu kontaktu s\u00a0epilimnetickou vodou. Uvol\u0148ovan\u00fd P ze sediment\u016f tak snadno p\u0159ech\u00e1z\u00ed do produk\u010dn\u00ed z\u00f3ny fytoplanktonu ve vodn\u00edm sloupci a\u00a0zvy\u0161uje dostupnost \u017eivin i\u00a0v\u00a0hlub\u0161\u00edch ji\u017e stratifikovan\u00fdch \u010d\u00e1stech n\u00e1dr\u017ee. Sediment z\u00a0n\u00e1dr\u017ee Vranov je zna\u010dn\u011b z\u00e1visl\u00fd na dostupnosti rozpu\u0161t\u011bn\u00e9ho O2<\/sub> a\u00a0tak\u00e9 NO3<\/sub>–<\/sup>, kter\u00e9 zabra\u0148uj\u00ed p\u0159i jejich dostupnosti uvol\u0148ov\u00e1n\u00ed P ze sediment\u016f. V\u00a0p\u0159\u00edpad\u011b jejich nedostatku jsou vyu\u017e\u00edv\u00e1ny (hydr)oxidy Mn a\u00a0zejm\u00e9na pak Fe p\u0159i mikrobi\u00e1ln\u00ed mineralizaci nasedimentovan\u00e9ho organick\u00e9ho materi\u00e1lu. Rozpou\u0161t\u011bn\u00ed t\u011bchto (hydr)oxid\u016f s\u00a0nasorbovan\u00fdm P pak vede k\u00a0uvol\u0148ov\u00e1n\u00ed velk\u00e9ho mno\u017estv\u00ed P ze sedimentu. Rychlost uvol\u0148ov\u00e1n\u00ed P za anoxick\u00fdch podm\u00ednek odpov\u00eddala 12,4\u2008mg P na m2<\/sup> za den. Toto mno\u017estv\u00ed tak v\u00fdrazn\u011b p\u0159isp\u00edv\u00e1 k\u00a0dostupnosti \u017eivin v\u00a0n\u00e1dr\u017ei. Za p\u0159\u00edtomnosti rozpu\u0161t\u011bn\u00e9ho O2<\/sub> a\/nebo NO3<\/sub>–<\/sup> jsou naopak tyto (hydr)oxidy schopn\u00e9 P zadr\u017eovat\u00a0a\u00a0kumulovat se v\u00a0horn\u00edch vrstv\u00e1ch sedimentu. Toto zadr\u017een\u00ed v\u0161ak nen\u00ed trval\u00e9 a\u00a0p\u0159i zm\u011bn\u011b nestabiln\u00edch oxick\u00fdch podm\u00ednek ve vod\u011b nad sedimentem nebo p\u0159ekryt\u00ed nov\u00fdm organick\u00fdm materi\u00e1lem m\u016f\u017ee doch\u00e1zet k\u00a0jejich uvoln\u011bn\u00ed. Fosfor obsa\u017een\u00fd v\u00a0p\u00f3rov\u00e9 vod\u011b se tak\u00e9 stane rychle dostupn\u00fdm pro vodn\u00ed sloupec, pokud dojde k\u00a0naru\u0161en\u00ed povrchu sedimentu a\u0165 ji\u017e zv\u00fd\u0161en\u00fdmi pr\u016ftoky a\u00a0resuspenz\u00ed, \u010di naru\u0161en\u00edm zp\u016fsoben\u00fdm aktivitou ryb.<\/p>\n Tato pr\u00e1ce vznikla za podpory Technologick\u00e9 Agentury \u010cesk\u00e9 Republiky (projekt \u010d.\u00a0TA04021342) a\u00a0M\u0160MT (projekt \u010d. LM2015075 a\u00a0EF16_013\/0001782 \u2013 SoWa Ecosystems Research).<\/em><\/p>\n \u00a0<\/em><\/p>\n P\u0159\u00edsp\u011bvek byl publikov\u00e1n ve sborn\u00edku konference Vodn\u00ed n\u00e1dr\u017ee 2017, ISBN 978-80-905368-5-2.<\/p>\n","protected":false},"excerpt":{"rendered":" The inflow parts of eutrophic reservoirs typically exhibit exacerbated rates of primary production, with concomitant increase in organic matter sedimentation. Its microbial remineralization leads to the consumption of electron acceptors.<\/p>\n","protected":false},"author":8,"featured_media":4780,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[87],"tags":[1189,1239,1238,453],"coauthors":[1201,1207,1208,1220,1209,1210],"class_list":["post-4823","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-hydrochemistry-radioecology-microbiology","tag-eutrophication","tag-iron","tag-oxygen","tag-phosphorus"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/4823","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/comments?post=4823"}],"version-history":[{"count":2,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/4823\/revisions"}],"predecessor-version":[{"id":30459,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/4823\/revisions\/30459"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media\/4780"}],"wp:attachment":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media?parent=4823"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/categories?post=4823"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/tags?post=4823"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/coauthors?post=4823"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}<\/a>\nObr.\u00a01. Inkuba\u010dn\u00ed box umo\u017e\u0148uj\u00edc\u00ed paraleln\u00ed inkubaci vzork\u016f sediment\u016f (k\u00f3ry s\u00a0neporu\u0161en\u00fdm vertik\u00e1ln\u00edm profilem) ke sledov\u00e1n\u00ed vlivu slo\u017een\u00ed vody nad sedimentem (koncentrace O2<\/sub>, NO3<\/sub>–<\/sup>); syst\u00e9m obsahuje z\u00e1sobn\u00edk vody, kter\u00fd zvy\u0161uje objem vody nad sedimentem zapojen\u00fd do cirkuluj\u00edc\u00edho ob\u011bhu zaji\u0161\u0165ovan\u00fd peristaltick\u00fdmi pumpami, syst\u00e9m m\u00edch\u00e1n\u00ed vody nad sedimentem (m\u00edchac\u00ed vrtule s\u00a0jednotnou rychlost\u00ed m\u00edch\u00e1n\u00ed) a\u00a0box umo\u017e\u0148uj\u00edc\u00ed simulaci bezkysl\u00edkat\u00fdch podm\u00ednek (plexisklov\u00e1 komora s\u00a0pr\u016ftokem \u010dist\u00e9ho plynn\u00e9ho N2<\/sub>)
\nFig. 1. Incubation box allowing parallel incubation of sediment samples (kori with intact vertical profile) to monitor the effect of water composition over sediment (O2<\/sub>, NO3<\/sub>–<\/sup> concentration); the system includes a\u00a0water reservoir which increases the volume of water above the sediment involved in circulating circulation provided by peristaltic pumps, a\u00a0stirring system over the sediment (a\u00a0stirring propeller with a\u00a0uniform mixing rate) and a\u00a0box allowing simulation of oxygen free conditions (a\u00a0plexiglass chamber with a\u00a0flow of pure N2<\/sub> gas)<\/h6>\nMateri\u00e1l a\u00a0metody<\/h2>\n
Odb\u011br sediment\u016f<\/h3>\n
Inkubace k\u00f3r\u016f a\u00a0sledov\u00e1n\u00ed zm\u011bn koncentrac\u00ed ve vod\u011b nad sedimentem<\/h3>\n
\n
Tabulka 1. Ozna\u010den\u00ed jednotliv\u00fdch extrahovan\u00fdch frakc\u00ed a\u00a0popis nejd\u016fle\u017eit\u011bj\u0161\u00edch forem P, Mn, Fe a\u00a0Al extrahovan\u00fdch v\u00a0jednotliv\u00fdch extrak\u010dn\u00edch kroc\u00edch
\nTable 1. Labeling of individual extracted fractions and description of the most important forms of P, Mn, Fe and Al extracted in individual extraction steps<\/h5>\n<\/a>\nAnal\u00fdza p\u00f3rov\u00e9 vody<\/h3>\n
Formy P v\u00a0sedimentu a\u00a0sledov\u00e1n\u00ed zm\u011bn slo\u017een\u00ed \u010d\u00e1stic<\/h3>\n
V\u00fdsledky a\u00a0diskuse<\/h2>\n
Obecn\u00e9 vlastnosti sedimentu<\/h3>\n
<\/a>\nObr. 2. Z\u00e1kladn\u00ed charakteristika slo\u017een\u00ed studovan\u00e9ho sedimentu z p\u0159\u00edtokov\u00e9 \u010d\u00e1sti n\u00e1dr\u017ee Vranov; vlevo \u2013 procentu\u00e1ln\u011b vyj\u00e1d\u0159en\u00e9 hmotnostn\u00ed zastoupen\u00ed p\u00f3rov\u00e9 vody a \u010d\u00e1stic, uprost\u0159ed \u2013 ztr\u00e1ta \u017e\u00edh\u00e1n\u00edm \u010d\u00e1stic p\u0159i 550 \u00b0C, vpravo \u2013 procentu\u00e1ln\u00ed vyj\u00e1d\u0159en\u00ed obsahu P v p\u00f3rov\u00e9 vod\u011b v\u016f\u010di celkov\u00e9mu obsahu P v jednotliv\u00fdch vrstv\u00e1ch sedimentu
\nFig. 2. Basic characteristics of the composition of the studied sediment from the inlet part of the Vranov reservoir; left \u2013 percentage weight of porous water and particles, middle \u2013 loss of particle annealing at 550 \u00b0C, right \u2013 percentage of content of P in pore water to total P content in individual layers of sediment<\/h6>\nZm\u011bny koncentrac\u00ed ve vod\u011b nad sedimentem<\/h3>\n
<\/a>\nObr. 3. Pr\u016fb\u011bh zm\u011bn koncentrac\u00ed P, Fe a Mn ve vod\u011b nad sedimentem o plo\u0161e 1 m2\u00a0<\/sup>a v\u00fd\u0161ce vodn\u00edho sloupce 1 m vyj\u00e1d\u0159en\u00e1 v jednotk\u00e1ch g\u2219m-3<\/sup>
\nFig. 3. The course of variations in P, Fe and Mn concentrations in water above the sediment area of 1 m2<\/sup> and the height of the water column 1 m, expressed in units of g\u2219m-3<\/sup><\/h6>\nAnal\u00fdza p\u00f3rov\u00e9 vody<\/h3>\n
<\/a>\nObr. 4. Anal\u00fdza zm\u011bn koncentrac\u00ed P a Fe v p\u00f3rov\u00e9 vod\u011b jednotliv\u00fdch inkubovan\u00fdch variant sediment\u016f v pr\u016fb\u011bhu inkubace (den 0, den 14 a den 28); jsou zde zv\u00fdrazn\u011bny nejaktivn\u011bj\u0161\u00ed prvn\u00ed 3 cm sedimentu vykazuj\u00edc\u00ed zm\u011bny v koncentrac\u00edch
\nFig. 4. Analysis of changes in P and Fe concentrations in the porous water of individual incubated sediment variants during incubation (day 0, day 14 and day 28); there are highlighted the most active first 3 cm of sediment exhibiting changes in concentrations<\/h6>\nFormy P v\u00a0sedimentu a\u00a0zm\u011bny slo\u017een\u00ed \u010d\u00e1stic<\/h3>\n
<\/a>\nObr. 5. Obsah jednotliv\u00fdch forem P a Fe a jejich procentu\u00e1ln\u00edho zastoupen\u00ed v sedimentu stanoven\u00fdch pomoc\u00ed frakciona\u010dn\u00ed anal\u00fdzy
\nFig. 5. Content of individual P and Fe forms and their percentages in sediment determined by fractionation analysis<\/h6>\n
\nextrahov\u00e1ny krystalick\u00e9 (hydr)oxidy Fe, kter\u00e9 maj\u00ed ni\u017e\u0161\u00ed sorp\u010dn\u00ed schopnosti pro P. Tyto miner\u00e1ly tak z\u016fstaly beze zm\u011bny, co\u017e nazna\u010duj\u00ed zv\u00fd\u0161en\u00e9 mol\u00e1rn\u00ed pom\u011bry Fe\/P v t\u00e9to frakci v obou oxick\u00fdch variant\u00e1ch (tabulka 2<\/em>).<\/p>\n<\/a>\nObr. 6. Obsah P, Fe a Mn ve svrchn\u00edch 3 cm sedimentu extrahovan\u00fdch ve frakc\u00edch BD-I a BD-II p\u0159ed inkubac\u00ed (varianta start) a po inkubac\u00edch jednotliv\u00fdch variant
\n(varianta anox, ox a NO3<\/sub>); AVS-Fe bylo stanoveno jako sulfidick\u00e1 s\u00edra p\u0159epo\u010d\u00edt\u00e1na na Fe v mol\u00e1rn\u00edm pom\u011bru 1 : 1
\nFig. 6. P, Fe and Mn content in the upper 3 cm sediment extracted in BD-I and BD-II fractions prior to incubation (start option) and after incubation of individual variants (anox, ox and NO3<\/sub> variant); AVS-Fe was determined as sulphide sulfur converted to Fe in a molar ratio of 1 : 1<\/h6>\nPotencion\u00e1ln\u00ed v\u00fdznam P ze sedimentu pro p\u0159\u00edtokovou \u010d\u00e1st n\u00e1dr\u017ee<\/h3>\n
\n
Tabulka 2. Procentu\u00e1ln\u00ed zm\u011bny P a\u00a0Fe b\u011bhem inkubace v\u00a0BD-I\u00a0a\u00a0BD-II frakc\u00edch v\u016f\u010di hodnot\u00e1m p\u0159ed po\u010d\u00e1tkem inkubac\u00ed a\u00a0mol\u00e1rn\u00ed pom\u011bry Fe\/P v\u00a0jednotliv\u00fdch frakc\u00edch a\u00a0vrstv\u00e1ch sediment\u016f
\nTable 2. Percent changes of P and Fe during incubation in BD-I\u00a0and BD-II fractions relative to pre-incubation and molar Fe\/P ratios in individual fractions and sediment layers<\/h5>\n<\/a>\nZ\u00e1v\u011br<\/h2>\n
Pod\u011bkov\u00e1n\u00ed<\/h3>\n