<p>U okviru ovog istraživanja ispitani su: 1. Optimalni uslovi&nbsp; za<br />eksperimente biodegradacije policikličnih aromatičnih ugljovodonika sa istim i<br />različitim brojem prstenova; 2. Uticaj struture&nbsp; i matriksa na biodegradaciju<br />policikličnih aromatičnih ugljovodonika sa istim brojem prstenova; 3.<br />Fitotoksičnost biljaka&nbsp; (testovi klijavosti i usvajanje policikličnih aromatičnih<br />ugljovodonika); 4. Procena&nbsp; potencijalne&nbsp; biodostupne frakcije primenom<br />različitih hemijskih sorbenata (HPCD, &beta;CD&nbsp; i&nbsp; MCD, XAD4 i TenaxTA)&nbsp; i 5.<br />Korelacija dobijenih rezultata&nbsp; testovima biodegradacije, testovima klijavosti,<br />testovima fitotoksičnosti i rezultata dobijenih iz eksperimenta procene<br />biodostupnosti hemijskim testovima.&nbsp; Rezultati su pokazali da se&nbsp; optimalni<br />uslovi za biodegradaciju&nbsp; postižu dodatkom mineralnih medijuma, inokuluma i<br />surfaktanata.&nbsp; Posmatrajući uticaj sadržaja gline i organske materije i strukture<br />molekula,&nbsp; najveći stepen biorazgradnje ima fluoranten, &scaron;to je u skladu sa<br />njegovim fizičko-hemijskim osobinama, dok se sadržaj pirena i krizena nije<br />mogao jasno korelirati sa sadržajem organske materije i gline.&nbsp; &Scaron;to se tiče<br />testova fitotoksičnosti,&nbsp; sva semena su proklijala, &scaron;to govori u prilog tome&nbsp; da<br />me&scaron;avina ovih kontaminanata&nbsp; pri ispitivanim koncentracijama&nbsp; nije inhibirala<br />klijanje biljaka.&nbsp; Testovi usvojivosti ispitivanih PAH-ova su pokazali da je<br />najmanji procenat usvojivosti semenom dobijen za benzo(a)piren, &scaron;to se može<br />objasniti njegovom kompleksnijom strukturom. Hemijskim testovima za<br />procenu biodostupnosti je sa druge strane pokazano da se desorpcija u prisustvu<br />MCD, XAD4 smole i Tenaxa može koristiti kao jednostavna metoda za procenu<br />potencijalne biodostupne&nbsp; frakcije organskih jedinjenja u sistemima sediment&nbsp; -voda.</p> / <p>The aim of this study was to investigate: 1. The optimal conditions for&nbsp;the biodegradation of polycyclic aromatic hydrocarbons with the same and&nbsp;different numbers of rings; 2. The impact of structure and matrix&nbsp;biodegradation of polycyclic aromatic hydrocarbons with the same number of&nbsp;rings; 3. Phytotoxicity (germination tests and polycyclic aromatic hydrocarbon&nbsp;uptake); 4. The means for assessing the bioavailable fractions using various&nbsp;chemical sorbents (HPCD, &beta;CD, MCD, XAD4 and &nbsp;TenaxTA) and 5. The&nbsp;correlation between the results of the biodegradation tests, germination tests,&nbsp;phytotoxicity tests and the results obtained from the experiments in the&nbsp;assessment of bioavailability and chemical tests. The results showed that the&nbsp;optimal conditions for biodegradation are achieved by the addition of mineral&nbsp;media, inoculum and surfactants. When considering the effect of the contents of&nbsp;clay and organic matter and the structure of the molecules, the highest degree of&nbsp;biodegradation was observed with fluoranthene,&nbsp; which is in line with its&nbsp;physico-chemical properties. The concentrations of pyrene and chrysene were&nbsp;not clearly correlated with the organic matter and clay contents. During thephytotoxicity tests, all seeds sprouted, which speaks in favor of a mixture of&nbsp;these contaminants not inhibiting the germination of the plants. Tests for the&nbsp;uptake of the investigated PAHs showed that the lowest percentage seed uptake&nbsp;was for benzo(a)pyrene, which is explained by its more complex structure.&nbsp;Chemical tests for evaluating bioavailability have shown that desorption in the&nbsp;presence of MCD, XAD4 and Tenax resins can be used as a simple method for&nbsp;the evaluation of a potential bioavailable fraction of organic compounds in&nbsp;water-sediment systems.</p>

<p>Prirodna organska materija zemlji&scaron;ta/sedimenata predstavlja glavnu oblast<br />za sorpciju hidrofobnih organskih jedinjenja, a njene osobine utiču na stepen<br />retencije i konsekventnu (bio)dostupnost organskih jedinjenja. Da bi se procenio<br />ekotoksikolo&scaron;ki rizik zagađenih zemlji&scaron;ta/sedimenata po okolinu, dizajnirala<br />odgovarajuća strategija remedijacije ili predvidela sudbina i transport organskih<br />polutanata u zagađenim zonama, neophodno je razumevanje mehanizma sorpcije i<br />desorpcije na nivou mehanizma uspostavljenih veza. U radu je izvr&scaron;eno ispitivanje<br />sorpcije i desorpcije odabranih hidrofobnih organskih polutanata, pentahlorbenzena<br />i lindana, na sekvencijalno ekstrahovanim huminskim kiselinama i huminima iz<br />jednog uzorka sedimenta u cilju pronalaženja veze između strukturnih<br />karakteristika izolovanih huminskih kiselina i humina i sorpcionih i desorpcionih<br />parametara. Afinitet za sorpciju, nelinearnost izotermi i prividna sorpciono-desorpciona histereza korelirani su&nbsp; sa osobinama sorbenata dobijenim iz<br />elementarne i FTIR spektroskopske analize. Predloženo je da je mehanizam<br />sorpcije na huminskim kiselinama rezultat odigravanja raspodele i specifične<br />adsorpcije, pri čemu se pri nižim koncentracijama pentahlorbenzena i lindana prvo<br />popune sorpciona mesta u kondenzovanoj aromatičnoj oblasti, a tek potom pri<br />vi&scaron;im koncentracijama sorpciona mesta u amorfnim alifatičnim oblastima.<br />Sveukupno vi&scaron;i koeficijenti nelinearnosti dobijeni za sorpciju pentahlorbenzena na huminskim kiselinama u odnosu na nelinearnost sorpcionih izotermi lindana, ukazuju na to da u ukupnoj sorpciji pentahlorbenzena veći značaj ima mehanizam raspodele i sme&scaron;tanje molekula pentahlorbenzena u hidrofobne &scaron;upljine huminskih kiselina, u odnosu na specifičnu adsorpciju. Ovi zaključci su potvrđeni rezultatima spektroskopskih istraživanja interakcija&nbsp; odabranih organskih jedinjenja i N-metilformamida. Predloženi mehanizam sorpcije ne može objasniti sorpciju pentahlorbenzena i lindana na uzorcima humina, većje pretpostavljeno da nelinearna sorpcija za uzorke humina može biti rezultat ostvarivanja povr&scaron;inskih interakcija, a visoki afinitet za sorpciju rezultat je raspodele organskih jedinjenja u amorfnim alifatičnim oblastima koje pružaju odlično okruženje za sorpciju.</p><p>U cilju daljeg proučavanja mehanizma sorpcije, izvr&scaron;eno je ispitivanje kinetike<br />desorpcije tri odabrana hidrofobna organskajedinjenja, pentahlorbenzena, lindana i<br />pentahloranilina, posredstvom&nbsp; čvrstog adsorbenta, XAD-4 makroporozne<br />jonoizmenjivačke smole. Na osnovu rezultata dobijenih za uzorak sedimenta i<br />frakciju &lt; 125 &micro;m za dva ravnotežna vremena (15 i 90 dana) i za sva odabrana<br />organska jedinjenja može se zaključiti da se za procenu potencijalne (bio)dostupne<br />frakcije organskih jedinjenja može koristiti jednostavna desorpcija u prisustvu<br />XAD-4 makroporozne jonoizmenjivačke smole i to na dva načina: (1) ekstrakcijom<br />sedimenta tokom 24 časa, kada frakcija koja se desorbuje odgovara frakciji<br />jedinjenja koja se nalazi u brzo-desorbujućem domenu organske materije, ili (2)<br />ekstrakcijom tokom 6 časova, kada frakcija koja se desorbuje odgovara polovini<br />one frakcije jedinjenja koja se nalazi u brzo-desorbujućem domenu organske<br />materije.</p> / <p>Natural organic matter of soil/sediment make the main region for&nbsp;sorption of hydrophobic organic compounds, ant its properties influence the degree&nbsp;of retention and, consequently, (bio)availability of organic compounds. In order to&nbsp;assess the ecotoxicological risks of contaminated soils/sediments to the&nbsp;environment and design the appropriate remediation strategy or predict the fate and&nbsp;transport of organic pollutants in contaminated zones, it is necessary to understand&nbsp;the mechanisms of sorption/desorption at the level of the mechanism of established&nbsp;bonds. Study of the sorption and desorption of selected hydrophobic organic&nbsp;pollutants, pentachlorobenzene and lindane, on sequentially extracted humic acids&nbsp;and humins from a single sediment sample with the aim of finding the relationship&nbsp;between the structural characteristics of the isolated humic acids and humin and&nbsp;sorption and desorption parameters. Sorption affinity, nonlinearity of isotherms,&nbsp;and apparent sorption-desorption hysteresis were correlated to the sorbent&nbsp;characteristics obtained from elemental analysis and FTIR spectroscopic data. The&nbsp;proposed sorption mechanism on humic acids assumes that at low concentrations&nbsp;of pentachlorobenzene and lindane the sorption sites in the condensed aromatic&nbsp;region are occupied first, and then, at their higher concentrations, the sorption sites&nbsp;in the amorphous and aliphatic regions. Generally higher nonlinearity coefficient obtained for the sorption of pentachlorobenzene on &nbsp;umic acids compared with the nonlinearity of sorption isotherms for lindane, indicate that in the overall sorption of pentachlorobenzene of higher significance is the &nbsp;echanism of distribution and insertion of pentachlorobenzene molecule into hydrophobic dips of humic acids, compared to specific adsorption. These conclusions were confirmed with the results of spectroscopic investigation of &nbsp;intermolecular interaction of chosen organic compounds and N-methylformamide.Since suggested sorption mechanism could not explain sorption of &nbsp;pentachlorobenzene and lindane onto humin samples, it is supposed that the nonlinearity can be a result of surface interactions, while the high sorption affinity is result of distribution of organic compounds in the amorphous aliphatic regions that offer an excellent environment for sorption.</p><p>With the aim of further insight into the sorption mechanism, investigation of&nbsp;desorption kinetics of three chosen hydrophobic organic compounds,&nbsp;pentachlorobenzene, lindane and pentachloroaniline, in the presence of &nbsp;soild&nbsp;adsorbent XAD-4 macroporous ion-exchange resin was performed. On the basis of&nbsp;the results obtained for sediment sample and fraction &lt; 125 &micro;m at two equilibrium&nbsp;times (15 and 90 days) and for all selected organic compounds, it can be concluded&nbsp;that the assessment of the potential (bio)avialable fraction of organic compounds&nbsp;may be obtained by using simple method of desorption in the presence of XAD-4&nbsp;macroporous ion-exchange resin, performed in two ways: (1) by sediment&nbsp;<br />extraction during 24 hours, when the desorbing fraction corresponds to the fraction&nbsp;of &nbsp;he compound that is found in the fast-desorbing domain of organic matter, or&nbsp;(2) by 6-hour extraction, when the desorbing fraction corresponds to one half of the&nbsp;fraction appearing in the fast-desorbing domain of the organic matter.</p>