Ekofiziološke adaptacije odabranih vrsta zeljastih biljaka na deponiji pepela termoelektrane 'Nikola Tesla - A' u Obrenovcu

Abstract

Zasnivanje biljnog pokrivača na odlagalištima pepela obezbeđuje fizičku i hemijsku stabilizaciju pepela, sprečava eroziju vetrom i smanjuje disperziju toksičnih hemijskih elemenata u životnu sredinu. Istraživanja u okviru ove disertacije su obavljena na području deponije pepela termoelektrane 'Nikola Tesla – A' u Obrenovcu i to na pasivnim kasetama (K3 – stara tri godine i K2 – stara jedanaest godina), kao i na kontrolnim staništima (KKo - nasip reke Kolubare; KBb – Botanička bašta „Jevremovac“ u Beogradu i KBk – naselje Bežanijska kosa u Beogradu), a obuhvatala su analize biljaka, kao i supstrata na kojima one rastu. Za ekofiziološka istraživanja bile su odabrane zeljaste biljke koje se obično koriste za biorekultivaciju pepelišta: Festuca rubra L. (K3, K2 i KBb) i Dactylis glomerata L. (K3 i KKo), kao i vrste koje spontano kolonizuju prostor na deponiji pepela: Calamagrostis epigejos (L.) Roth. (K3, K2 i KKo) i Oenothera biennis L. (K3, K2 i KBk). Osnovni cilj doktorske disertacije je utvrđivanje limitirajućih faktora staništa za nesmetani razvoj biljnog pokrivača, kao i ustanovljavanje ekofizioloških adaptivnih strategija ispitivanih biljaka koje opstaju u uslovima višestrukog stresa na deponiji pepela. Fitocenološka analiza deponije pepela TENT – A u Obrenovcu je pokazala da su na K3 najveću brojnost i pokrovnost imale sejane vrste F. rubra i D. glomerata, dok su na K2 bile dominantne spontano kolonizovane vrste C. epigejos i O. biennis. Tokom vremena na K2 se stvaraju povoljni fizičko - hemijski uslovi za rast i opstanak biljaka na pepelu, što se ogleda u smanjenju procenta ukupnog peska, a povećanju frakcije gline i glina+prah, smanjenju koncentracije rastvorljivih soli, slabo bazne reakcije pepela i povećanju kiselih katjona u adsorptivnom kompleksu, što je u velikoj meri uslovljeno aktivnošću biljaka koje su kolonizovale ovu kasetu. Količina dostupnih oblika K2O je bila najveća na K2, a P2O5 na K3, dok je količina N bila generalno mala. Na deponiji pepela, koncentracije As, B i Cu su bile toksične, (izuzev B na K2), dok su koncentracije Mn i Zn (K2) bile deficitarne. Na deponiji pepela, DTPA – As i DTPA – B, kao i udeo DTPA – dostupnih frakcija u odnosu na ukupan sadržaj ovih elemenata je bio velik, što ukazuje na potencijalna strukturna i funkcionalna oštećenja biljaka vezana za njihovu toksičnost. Količina DTPA – Cu, DTPA – Mn i DTPA – Zn, kao i udeo DTPA – dostupnih frakcija u odnosu na ukupan sadržaj istih je bio mali, te rastvorna količina koja je dostupna biljkama može biti odgovorna za metabolička oštećenja vezana za njihov deficit. Na deponiji pepela u listovima ispitivanih biljaka bile su izmerene toksične koncentracije As i B, izuzev B kod C. epigejos. Koncentracije Mn i Zn u listovima svih biljaka su bile u deficitu, dok je Cu bio na granici deficita, osim kod O. biennis. Sejane vrste F. rubra i D. glomerata se odlikuju smanjenim kapacitetom transporta As, Cu i Mn iz korenova u listove (BCF<1, TF<1), osim Mn kod F. rubra (K3). Međutim, spontano kolonizovane vrste C. epigejos i O. biennis pokazuju veću sposobnost translokacije As, Cu, Mn iz korena u listove (BCF<1, TF >1). Se se kod F. rubra i O. biennis (K2) akumulira u korenu (BCF>1, TF<1), dok se kod ostalih vrsta efikasno transportuje u listove (BCF>1, TF>1). Zn se kod svih ispitivanih biljaka na deponiji pepela nalazi u većoj količini u korenu u odnosu na listove (izuzev kod O. biennis, K2), dok se B i Mo efikasno transportuju u listove. Efikasnost fotosinteze kod svih biljaka na deponiji pepela je bila ispod optimalnog opsega, što ukazuje na fotoinhibiciju fotosistema II (PSII) i smanjenu vitalnost. Količina hlorofila i karotenoida je u listovima svih ispitivanih biljaka bila manja u odnosu na kontrolna staništa, dok je količina antocijana u listovima F. rubra bila najveća na K3. Količina malondialdehida (MDA) je bila veća u listovima svih ispitivanih biljaka na deponiji pepela, što ukazuje da su one izložene oksidativnom stresu. Količina fenola, askorbinske kiseline (AsA) i ukupna DPPH antioksidativna aktivnost bile su velike kod svih biljaka koje rastu na pepelištu, što ukazuje na sposobnost aktivacije adaptivnih mehanizama zaštite. Na deponiji pepela, vrsta O. biennis se najviše razlikuje od ostalih biljaka po većoj količini vezanih fenola (VF) i ukupnoj DPPH antioksidativnoj aktivnosti. Morfološke promene listova biljaka bile su izražene u vidu hloroza i nekroza izazvanih toksičnim sadržajem As i B, kao i deficitarnim koncentracijama Cu, Mn i Zn. Sejane vrste F. rubra i D. glomerata su značajne tokom prve faze biološke rekultivacije, jer stabilizuju pepeo dobro razvijenim korenovim sistemom i u uslovima stresa poseduju potencijal aktivacije antioksidativne zaštite. Međutim, tokom vremena spontano kolonizovane vrste C. epigejos i O. biennis osvajaju prostor deponije pepela, zahvaljujući dobro razvijenom multirizomskom sistemu, velikoj količini viabilnih semena i ekofiziološkim adaptacijama koje im omogućavaju rast i opstanak u nepovoljnim uslovima sredine, što ih čini pogodnim za revitalizaciju pepelišta.

Establishment of plant cover on fly ash deposits provides the physical and chemical stabilization of ash, prevents wind erosion and reduces dispersion of toxic chemical elements in the environment. Research within this thesis was carried out in the area of the fly ash deposits thermoelectric plant 'Nikola Tesla - A' in Obrenovac: passive cassette (K3 - three years old and K2 - eleven years old), as well as the control sites (KKo - embankment of the river Kolubara; KBb - Botanical Gardens "Jevremovac" in Belgrade and KBK - settlement Bežanijska kosa in Belgrade), and included analysis of plants, as well as the substrate on which they grow. For ecophysiological studies were selected herbaceous plants which are commonly used for the biorecultivation on the fly ash: Festuca rubra L. (K3, K2 and KBb) and Dactylis glomerata L. (K3 and KKo), as well as species that spontaneously colonized space in fly ash deposits: Calamagrostis epigejos (L.) Roth. (K3, K2 and KKo) and Oenothera biennis L. (K3, K2 and KBk). The main objective of the doctoral dissertation is to determine the limiting factors of site for the smooth development of the vegetation cover, as well as the establishment of ecophysiological adaptive strategies of examined plants that survive in conditions of multiple stress on the fly ash. Phytocoenological analysis of the fly ash deposit TENT - A in Obrenovac showed that on the K3, the largest number and coverage had sown species F. rubra and D. glomerata, while on the K2 were spontaneously colonized dominant species C. epigejos and O. biennis. Over time, on the K2 to create good physico - chemical conditions for the growth and survival of plants in the fly ashes, which is reflected in the reduction of the percentage of total sand, and increasing fractions of clay and clay + powder, reducing the concentration of soluble salts, weak base reactions of fly ash and increasing acidic cation of the adsorptive complex, which is largely conditioned by the activity of the plants that have colonized this disposal site. The content of available forms of K2O was the highest on the K2, and P2O5 on the K3, while the content of N was generally small. On the fly ash deposit sites, the concentrations of As, B and Cu were toxic (except B on the K2), while concentrations of Mn and Zn (K2) were in deficiency. On the fly ash deposit sites, DTPA - As and DTPA - B, and the percentage of DTPA - available fraction of the total content of these elements was large, indicating the potentialy structural and functional damage to plants related to their toxicity. The content of DTPA - Cu, DTPA - Mn, DTPA - Zn as well as the percentage of DTPA - the available fraction of Cu, Mn and Zn of the total content was small, and the soluble content which is accessible to the plants may be responsible for the metabolic disorders related to their deficiency. Thus, on the fly ash deposit sites, toxic concentrations As and B in leaves of examined plants were measured, with the exception of B in C. epigejos. The concentrations of Mn and Zn in the leaves of all plants were deficient, while Cu was on the deficiency limit, except for O. biennis. Sown species F. rubra and D. glomerata are characterized by a reduced transport capacity of As, Cu and Mn from roots to leaves (BCF<1, TF<1), except for Mn in F. rubra (K3). However, spontaneously colonized species C. epigejos and O. biennis showed greater ability of translocation of As, Cu and Mn from the roots to the leaves (BCF<1, TF>1). In F. rubra and O. biennis (K2), Se is accumulated in the roots (BCF>1, TF>1), while in other species, Se is efficiently transported to the leaves (BCF>1, TF>1). In all the species examined at the disposal site, greater amount of Zn is retained in the roots (except in O. biennis, K2), while B and Mo are efficiently transported to the leaves. Photosynthetic efficiency of all plants which grow on fly ash deposits was below the optimum range, which indicates on photoinhibition of photosytem II (PSII) and decreased vitality. The chlorophyll and carotenoids content in leaves of all plants was lower compared to the control site, while the anthocyanins content in leaves of F. rubra was the highest on the K3. The malondialdehyde (MDA) content was higher in leaves of all plants at fly ash deposits, indicating that they were exposed to oxidative stress. The phenolics content, ascorbic acid (AsA) and total DPPH antioxidant activity was high in all plants, indicating the ability to activate the protective adaptive mechanisms. Species O. biennis is the most different from the other species by the higher content of bound phenolics (BPh) and the total DPPH antioxidant activity. Morphological changes in plant leaves were expressed in the form of chlorosis and necrosis caused by toxic levels of As and B, as well as deficient concentrations of Cu, Mn and Zn. Sown species F. rubra and D. glomerata are important in the first stage of biological cultivation, because their well-developed root system stabilizes the substrate. Furthermore, under conditions of stress they have the potential to activate antioxidant protection. However, over time, spontaneously colonized species C. epigejos and O. biennis have conquered the area of fly ash. This was made possible by their welldeveloped multirhizome system, large amount of viable seeds and ecophysiological adaptations that enable them to grow and survive in adverse environmental conditions. These traits make them suitable for the revitalization of fly ash.