Biogeochemical cycling of vanadium (+IV i +V) in aquatic systems and sediments

doctoral thesis

• Title (croatian): Biogeokemijsko kruženje vanadija (+IV i +V) u vodenim sustavima i sedimentima
• Author: Lucija Knežević
• Mentor: Elvira Bura-Nakić (mentor)
• Committee member: Dario Omanović (predsjednik povjerenstva)
• Committee member: Neven Cukrov (član povjerenstva)
• Committee member: Kristina Pikelj (član povjerenstva)
• Committee member: Hana Fajković (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Geology); Zagreb
• Defense date and country: 2023-05-10, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Interdisciplinary Natural Sciences; Marine Science
• Universal decimal classification (UDC): 55 - Geology. Meteorology. Hydrology

Abstract

The PhD thesis is based on the developed and adapted specific analytical methods for determination of vanadium redox species concentration in the water samples and bioavailable phase of surface sediment of Krka River esturay. The results show that V is predominantly present in the form of V(+V) species in the oxic water column of Krka River estuary, while determined presence of V(+IV) was linked with oxygen depletion in the water layer at the head of estuary, and stabilisation with organic ligands in the anthropogenic burdened sampling site. Determined slight V enrichment is mostly accompanied with retention of V to less mobile sediment phases, possibly due to the low mobility of reduced species and their binding to organic matter. Redox speciation in the bioavailable fraction of surface sediments of Krka River estuary showed that V is present in the form of V(+IV), thus it is not presenting toxic risk for sorrounding biota. In addition, stability of V(+IV)/V(+V) species was investigated in the presence of structurally simple organic ligand (succinic acid) and sulphurised organic ligands (3 mercaptopropionic acid, L-cysteine, thioacetic and ethanthiol) under modelled conditions. Stability constants for V(+IV) and V(+V) complexes with succinic acid in acidic aqueous solution are determined, where higher affinity of V(+IV) species, compared to V(+V), towards complexation was observed. In addition, stability of V(+V) species in the presence of sulpfurized organic ligands was monitored by novel combined approach based on the usage of spectrophotometric and chromatographic instrumentation. Results show that V(+V) reduction is a pH dependant and proton catalysed process which can play a significant role in decreasing V(+V) toxicity in natural systems.

Abstract (croatian)

Doktorski rad temelji se na razvijenim i prilagođenim postojećim specifičnim analitičkim metodama za određivanje koncentracije redoks vrsta vanadija u uzorcima vode i biodostupne faze površinskih sedimenata estuarija rijeke Krke. Rezultati pokazuju da je V pretežno prisutan u obliku V(+V) vrsta u oksičnom vodenom stupcu estuarija rijeke Krke, dok je utvrđena prisutnost V(+IV) povezana s niskom koncentracijom kisika u vodenom sloju na gornjem dijelu estuarija, te stabilizacijom s organskim ligandima na antropogeno opterećenom mjestu uzorkovanja. Utvrđeno blago obogaćenje V u sedimentu uglavnom je popraćeno zadržavanjem V u manje pokretnim fazama sedimenta, vjerojatno zbog niske pokretljivosti reduciranih vrsta i njihovog vezanja na organsku tvar. Redoks specijacija u biodostupnoj frakciji površinskih sedimenata estuarija rijeke Krke pokazala je da je V prisutan u obliku V(+IV), stoga ne predstavlja toksičan rizik za okolnu biotu. Nadalje, istražena je stabilnost V(+IV)/V(+V) vrsta u prisutnosti strukturno jednostavnog organskog liganda (sukcinske kiseline) i sumpornih organskih liganda (3 merkaptopropionske kiseline, L-cisteina, tioctene kiseline i etantiola) u modeliranim uvjetima. Određene su konstante stabilnosti za V(+IV) i V(+V) komplekse sa sukcinskom kiselinom u kiseloj vodenoj otopini, gdje je utvrđena viša stabilnost V(+IV) komplekasa, u usporedbi s V(+V). Dodatno, stabilnost V(+V) vrsta u prisutnosti sumpornih organskih liganda praćena je novim pristupom koji se temelji na usporednom korištenju spektrofotometrijske i kromatografske instrumentacije. Rezultati pokazuju da je redukcija V(+V) protonski kataliziran proces ovisan o pH, te može igrati važnu ulogu u smanjenju toksičnosti V(+V) u prirodnim sustavima.

• Keywords: Vanadium redox speciation; ion chromatography; mobility; toxicity; succinic acid; sulphurized organic ligands
• Keywords (croatian): Redoks specijacija vanadija; ionska kromatografija; mobilnost; toksičnost; sukcinska kiselina; sulfurizirani organski ligandi
• Language: english
• URN:NBN: urn:nbn:hr:217:986213
• Study programme: Title: Interdisciplinary doctoral study in Oceanology; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje interdisciplinarne prirodne znanosti (znanost o moru) (doktor/doktorica znanosti, područje prirodnih znanosti, polje interdisciplinarne prirodne znanosti (znanost o moru))
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-06-20 09:28:37