Ion-exchange chromatography as a tool for investigating vanadium speciation in sediments: preliminary studies
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SEDIMENTS AS A DYNAMIC NATURAL RESOURCE – FROM CATCHMENT TO OPEN SEA
Ion-exchange chromatography as a tool for investigating vanadium speciation in sediments: preliminary studies Lucija Knežević 1 & Nuša Cukrov 1 & Elvira Bura-Nakić 1 Received: 1 June 2019 / Accepted: 1 October 2019 # Springer-Verlag GmbH Germany, part of Springer Nature 2019
Abstract Purpose We conducted this investigation in order to develop a simple method for the determination of bioavailable vanadium and its speciation within sediments. Materials and methods The developed method is based on the determination of acid-extractable vanadium, as this fraction is presumably bioavailable, and its subsequent speciation using IC–UV/Vis (ionic chromatography with an ultraviolet-visible detector). A published procedure for vanadium speciation in pore water was further optimized in order to separate V(IV) and V(V) species using column EDTA derivatization on sediment samples. The analytical approach was applied in order to assess acid-extractable vanadium and its speciation within estuary sediments of the Krka River at the Dalmatian coast of Croatia. Results and discussion The results imply that the majority of vanadium within estuary sediments is in the form of less soluble fraction while the acid-extractable fraction comprises approximately 40% of the total vanadium present. In contrast, open sea sediment (station K4) was completely dominated by the acid-extractable vanadium. The extracted vanadium is in the form of V (IV). Conclusions Ion-exchange chromatography with an UV/Vis detector is a promising analytical method for vanadium speciation, however, further optimization of the conditions (improvement of the sequential extraction procedure) is needed in order to assess speciation also within other vanadium sedimentary fractions. Keywords Extractable sediment fraction . Ion chromatography . Krka River estuary . Speciation . Trace metals . Vanadium chemistry
1 Introduction Vanadium, V, is a transition metal and is one of the most abundant elements in Earth’s crust (among the 20) with the average content in the upper part of Earth’s crust of 60 μg g−1, reaching concentrations over 200 μg g−1 within bulk and lower continental crust (Taylor and McLennan 1995). It is the second most abundant transition metal in seawater with its concentration only being exceeded by molybdenum (~ 35 nmol dm−3 and 110 nmol dm−3, respectively— e.g., Emerson and Husted 1991 and references therein). The prevailing vanadium valence states in nature are vanadium(III),
Responsible editor: Elena Romano * Elvira Bura-Nakić [email protected] 1
Department for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička 54, 10 000 Zagreb, Croatia
vanadium(IV), and vanadium(V) of which the latter two are the most soluble (Wanty and Goldhaber 1992) making the determination of vanadium speciation a challenging task. Under acidic conditions most V species display cationic character, such as the vanadyl (VO2+) and vanadate (VO2+) ions, while under less acidic to mildly alkaline c
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