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Crmarić D, Bura-Nakić E. Interaction between Cu and Thiols of Biological and Environmental Importance: Case Study Using Combined Spectrophotometric/Bathocuproine Sulfonate Disodium Salt Hydrate (BCS) Assay. Molecules 2023; 28:5065. [PMID: 37446731 DOI: 10.3390/molecules28135065] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 06/15/2023] [Accepted: 06/20/2023] [Indexed: 07/15/2023] Open
Abstract
Considering the biological and ecological importance of Cu-thiol interactions and the discrepancies in previous research, this study focuses on Cu interactions with biologically and ecologically relevant thiols: glutathione (GSH), L-cysteine (L-cys), 3-mercaptopropionic acid (MPA), and thioacetic acid (TAA) in aqueous solution. The addition of Cu(II) to a thiol-containing solution led to a rapid reduction of Cu(II) and the formation of a Cu(I)-thiol complex. The mechanism of Cu(II) reduction and Cu(I) complex formation as well as the kinetics of Cu(I) oxidation strongly depend on the structural properties of the individual thiols investigated. The reducing power of the investigated thiols can be summarized as follows: L-cys ≅ GSH > MPA > TAA. The reaction order, with respect to Cu(I) oxidation, also changes over the time of the reaction course. The deviation of the reaction kinetics from the first order with respect to Cu(I) in the later stages of the reaction course can be attributed to a Fenton-like reaction occurring under low thiol concentration conditions. At high Cu:thiol ratios, in the case of GSH, L-cys, and MPA, the early stage of the reaction course is characterized by high Cu(I) stability, most likely as a result of Cu(I) complexation by the thiols present in excess in the reaction mixture.
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Affiliation(s)
- Dora Crmarić
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička Cesta 54, 10 000 Zagreb, Croatia
| | - Elvira Bura-Nakić
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička Cesta 54, 10 000 Zagreb, Croatia
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Knežević L, Bura-Nakić E. Investigation of thiol compounds (L-cysteine, thioacetic acid and ethanethiol) with V(V) and V(IV) using combined spectroscopy and chromatography. J Inorg Biochem 2023; 242:112158. [PMID: 36773444 DOI: 10.1016/j.jinorgbio.2023.112158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 01/30/2023] [Accepted: 02/02/2023] [Indexed: 02/07/2023]
Abstract
The interactions of V(V) and L-cysteine, thioacetic acid and ethanethiol were studied in aqueous solution using chromatographic and spectral analysis. The chromatographic determination of V(V) and V(IV) species in the presence of thiols was enabled by inducing the ligand exchange reaction with EDTA as the competing ligand. Analytical setup allowed investigation of the possible redox and structural transformations of V(V) in the presence of thiols used over a wide pH range. Obtained data strongly suggest that the reduction of V(V) is proton catalyzed in case of L-cysteine and thioacetic acid. In the case of ethanethiol, the reduction did not seem to be proton dependent, as no reduction was observed above pH = 2. Thus, reduction was inhibited by the deprotonation of L-cysteine and thioacetic acid, with L-cysteine being the strongest reducing agent of V(V), followed by thioacetic acid and finally ethanethiol. Apart from structural thiol properties, the reduction reaction seems to be influenced by the aqueous V(V) speciation due to the observed nonlinear kinetics. In the case of all investigated thiols, the formation of V(V)-thioester intermediate species was an essential step for V(V) reduction. The structural properties of the V(IV)-thiol complexes were also found to be pH-dependent.
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Affiliation(s)
- Lucija Knežević
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Elvira Bura-Nakić
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
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Knežević L, Zanda E, Bura-Nakić E, Filella M, Sladkov V. Vanadium(IV) and vanadium(V) complexation by succinic acid studied by affinity capillary electrophoresis. Simultaneous injection of two analytes in equilibrium studies. J Chromatogr A 2023; 1695:463941. [PMID: 37019062 DOI: 10.1016/j.chroma.2023.463941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 03/21/2023] [Accepted: 03/22/2023] [Indexed: 04/05/2023]
Abstract
The interaction of V(IV) and V(V) with succinic acid was investigated by affinity capillary electrophoresis (ACE) in aqueous acid solutions at pH values 1.5, 2.0 and 2.4, and different ligand concentrations. V(IV) and V(V) form protonated complexes with succinic acid ligand at this pH range. The logarithms of the stability constants, measured at 0.1 mol L-1 (NaClO4/HClO4) ionic strength and 25 °C, are logβ111=7.4 ± 0.2 and logβ122=14.1 ± 0.5 for V(IV), and logβ111=7.3 ± 0.1 for V(V), respectively. The stability constant values, extrapolated to zero ionic strength with the Davies equation, are logβ°111=8.3 ± 0.2 and logβ°122=15.6 ± 0.5 for V(IV) and logβ°111=7.9 ± 0.1 for V(V). The application of ACE to the simultaneous equilibria of V(IV) and V(V) (injection of two analytes) was also attempted. When the results were compared with those obtained when introducing only one analyte in the capillary, using the traditional version of the method, similar stability constants and precision are obtained. The possibility of studying two analytes simultaneously decreases the time needed for the determination of the constants; this feature is especially valuable when working with hazardous materials or when only small quantities of ligand are available.
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Rovan L, Zuliani T, Horvat B, Kanduč T, Vreča P, Jamil Q, Čermelj B, Bura-Nakić E, Cukrov N, Štrok M, Lojen S. Uranium isotopes as a possible tracer of terrestrial authigenic carbonate. Sci Total Environ 2021; 797:149103. [PMID: 34303980 DOI: 10.1016/j.scitotenv.2021.149103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/13/2021] [Accepted: 07/13/2021] [Indexed: 06/13/2023]
Abstract
The concentration and isotopic composition of uranium (δ238U, 234U/238U activity ratio) in combination with traditional isotopes (δ18O, δ13C) were examined as potential tracers of authigenic carbonate formation in a karst aquifer. The U concentration and 234U/238U activity ratios in the tufa-precipitating sections of two connected karst rivers (Krka and Zrmanja, Croatia) decreased downstream in water and in precipitated carbonate due to active self-purification processes, i.e. adsorption of isotopically lighter U(VI) on mineral particles, sedimentation and co-precipitation with carbonate. The isotopic composition of carbonate in tufa mostly resembled the 234U/238U activity ratio and the δ238U values of dissolved U in water but was also affected by the presence of detrital carbonate flushed into the river from soil and weathered bedrock. This interpretation was supported by the δ18O and δ13C values of tufa, which were shifted out of equilibrium with river water and dissolved in organic carbon and in their isotopic signature, which showed the presence of lithic carbonate. Large fluctuations of the δ238U values of water, leachable U (eluted in acetic acid buffered with Na-acetate) and residual U fraction could not be fully explained by available data due to the overlapping U isotopic signatures of leachable (mainly carbonate) and residual fractions of soil, bedrock and tufa. Therefore, a long-term, systematic, seasonal and event-based observation of the isotopic composition of dissolved and suspended particulate U in water is necessary. Nevertheless, the U isotopes were found to have the potential to be used as identifiers of authigenic carbonate and the storage of CO2 in terrestrial river sediments, to improve knowledge on fluxes within local and global biogeochemical carbon cycle.
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Affiliation(s)
- Leja Rovan
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000 Ljubljana, Slovenia
| | - Tea Zuliani
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000 Ljubljana, Slovenia
| | - Barbara Horvat
- Slovenian National Building and Civil Engineering Institute, Dimičeva ulica 12, 1000 Ljubljana, Slovenia
| | - Tjaša Kanduč
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia
| | - Polona Vreča
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia
| | - Qasim Jamil
- Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000 Ljubljana, Slovenia
| | - Branko Čermelj
- Marine Biology Station, National Institute of Biology, Fornače 40, 6330 Piran, Slovenia
| | - Elvira Bura-Nakić
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Neven Cukrov
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Marko Štrok
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000 Ljubljana, Slovenia.
| | - Sonja Lojen
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia; School of Environmental Sciences, University of Nova Gorica, Glavni trg 8, 5271 Vipava, Slovenia
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Bura-Nakić E, Knežević L, Mandić J, Cindrić AM, Omanović D. Rhenium Distribution and Behavior in the Salinity Gradient of a Highly Stratified Estuary and Pristine Riverine Waters (The Krka River, Croatia). Arch Environ Contam Toxicol 2021; 81:564-573. [PMID: 34357425 DOI: 10.1007/s00244-021-00876-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 07/14/2021] [Indexed: 06/13/2023]
Abstract
The abundance and distribution of dissolved Re (DRe) were determined in the freshwater part of the Krka River (Croatia), which drains a karst landscape, and in the salinity gradient of its highly stratified estuary. Due to the low DRe concentration, a batch procedure consisting of a pre-concentration step using an anion exchange resin (Dowex) and analysis of DRe in 8 M HNO3 eluate using high-resolution inductively coupled plasma mass spectrometry (HR ICP-MS) was applied. Due to potentially inconsistent recoveries, which ranged from 60 to 87%, quantification was performed using the isotope dilution technique (ID). DRe concentrations in the Krka River increased downstream, from 6.2 pM at the spring site to 11.9 pM upstream of the estuary region. Weathering of the surrounding carbonate lithology is assumed to be the source of the natural Re. Two specific anomalies were registered: a strong increase in DRe concentration due to anthropogenic input near the town of Knin (27.5 pM) and a decrease at a downstream site caused by subsurface input of freshwater from the Zrmanja River, resulting in a relatively low DRe concentration (8.5 pM). In the estuarine region, a near-conservative behavior of DRe was found in the salinity gradient of the upper surface layer, with DRe concentrations ranging from 18 to 38 pM. Anthropogenic input was suspected within the estuarine segment near the urban area, causing a small positive deviation from the conservative line. In the bottom seawater layer, a minor decrease in DRe concentration in the most upstream estuarine regions was apparent, implying weak scavenging of Re.
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Affiliation(s)
- Elvira Bura-Nakić
- Department for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb, Croatia.
| | - Lucija Knežević
- Department for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb, Croatia
| | - Jelena Mandić
- Laboratory of Chemical Oceanography and Sedimentology of the Sea, Institute of Oceanography and Fisheries, Split, Croatia
| | - Ana-Marija Cindrić
- Department for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb, Croatia
| | - Dario Omanović
- Department for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb, Croatia
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Strmečki S, Ciglenečki I, Gligora Udovič M, Marguš M, Bura-Nakić E, Dautović J, Plavšić M. Voltammetric Study of Organic Matter Components in the Upper Reach of the Krka River, Croatia. CROAT CHEM ACTA 2018. [DOI: 10.5562/cca3443] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Kerl CF, Lohmayer R, Bura-Nakić E, Vance D, Planer-Friedrich B. Experimental Confirmation of Isotope Fractionation in Thiomolybdates Using Ion Chromatographic Separation and Detection by Multicollector ICPMS. Anal Chem 2017; 89:3123-3129. [PMID: 28192962 DOI: 10.1021/acs.analchem.6b04898] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Molybdenum 98Mo/95Mo isotope ratios are a sediment paleo proxy for the redox state of the ancient ocean. Under sulfidic conditions, no fractionation between seawater and sediment should be observed if molybdate (MoO42-) is quantitatively transformed to tetrathiomolybdate (MoS42-) and precipitated. However, quantum mechanical calculations previously suggested that incomplete sulfidation could be associated with substantial fractionation. To experimentally confirm isotope fractionation in thiomolybdates, a new approach for determination of isotope ratios of individual thiomolybdate species was developed that uses chromatography (HPLC-UV) to separate individual thiomolybdates, collecting each peak and analyzing isotope ratios with multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). Using commercially available MoO42- and MoS42- standards, the method was evaluated and excellent reproducibility and accuracy were obtained. For species with longer retention times, complete chromatographic peaks had to be collected to avoid isotope fractionation within peaks. Isotope fractionation during formation of thiomolybdates could be experimentally proven for the first time in the reaction of MoO42- with 20-fold or 50-fold excess of sulfide. The previously calculated isotope fractionation for MoS42- was confirmed, and the result for MoO2S22- was in the predicted range. Isotopic fractionation during MoS42- transformation with pressurized air was dominated by kinetic fractionation. Further optimization and online-coupling of the HPLC-MC-ICPMS approach for determination of low concentrations in natural samples will greatly help to obtain more accurate species-selective isotope information.
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Affiliation(s)
- Carolin F Kerl
- Department of Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth , Universitaetsstrasse 30, 95440 Bayreuth, Germany
| | - Regina Lohmayer
- Department of Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth , Universitaetsstrasse 30, 95440 Bayreuth, Germany
| | - Elvira Bura-Nakić
- Institute of Geochemistry and Petrology, Department of Earth Sciences, ETH Zürich , Clausiusstrasse 25, 8092 Zürich, Switzerland
| | - Derek Vance
- Institute of Geochemistry and Petrology, Department of Earth Sciences, ETH Zürich , Clausiusstrasse 25, 8092 Zürich, Switzerland
| | - Britta Planer-Friedrich
- Department of Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth , Universitaetsstrasse 30, 95440 Bayreuth, Germany
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Lohmayer R, Reithmaier GMS, Bura-Nakić E, Planer-Friedrich B. Ion-pair chromatography coupled to inductively coupled plasma-mass spectrometry (IPC-ICP-MS) as a method for thiomolybdate speciation in natural waters. Anal Chem 2015; 87:3388-95. [PMID: 25707674 DOI: 10.1021/ac5046406] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Molybdenum precipitates preferentially under reducing conditions; therefore, its occurrence in sediment records is used as an indicator of paleoredox conditions. Although thiomolybdates (MoO4-xSx(2-) with x = 1-4) supposedly are necessary intermediates in the process of molybdenum precipitation under anoxic conditions, there is no information about their abundance in natural environments, because of a lack of element-specific methods with sufficiently low detection limits. Here, we optimized ion-pair chromatographic separation for coupling to an inductively coupled plasma-mass spectrometry detector (IPC-ICP-MS). 2-Propanol (10%-25% gradient) replaced the previously used acetonitrile (25%-75%) as the solvent, to reduce the carbon load into the plasma. In synthetic solutions, formation of thiomolybdates was found to occur spontaneously in the presence of excess sulfide and the degree of thiolation was highest at pH 7. Excess hydroxyl led to a transformation of thiomolybdates to molybdate. Under acidic to neutral conditions, precipitation of molybdenum and hydrolysis of tetrathiomolybdate were observed. Flash-freezing was found to be suitable to stabilize tetrathiomolybdate, with <4% transformation over more than two months. High ionic strengths matrices (>2 mM) negatively affected the detection of molybdate, which eluted mainly in the dead volume, but had no negative effect on higher thiolated molybdates. Detection limits were ∼10 nM. With the newly developed IPC-ICP-MS method, thiomolybdates were found to form spontaneously in euxinic marine waters after adding a molybdate spike and occur naturally in sulfidic geothermal waters.
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Affiliation(s)
- Regina Lohmayer
- †Department of Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth, Universitaetsstrasse 30, 95440 Bayreuth, Germany
| | - Gloria Maria Susanne Reithmaier
- †Department of Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth, Universitaetsstrasse 30, 95440 Bayreuth, Germany
| | - Elvira Bura-Nakić
- ‡Center for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Britta Planer-Friedrich
- †Department of Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth, Universitaetsstrasse 30, 95440 Bayreuth, Germany
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Bura-Nakić E, Marguš M, Jurašin D, Milanović I, Ciglenečki-Jušić I. Chronoamperometric study of elemental sulphur (S) nanoparticles (NPs) in NaCl water solution: new methodology for S NPs sizing and detection. Geochem Trans 2015; 16:1. [PMID: 25722648 PMCID: PMC4339783 DOI: 10.1186/s12932-015-0016-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 01/24/2015] [Indexed: 06/04/2023]
Abstract
BACKGROUND Elemental sulfur (S) persists in natural aquatic environment in a variety of forms with different size distributions from dissolved to particulate. Determination of S speciation mainly consists of the application of chromatographic and electrochemical techniques while its size determination is limited only to the application of microscopic and light scattering techniques. S biological and geochemical importance together with recent increases of S industrial applications requires the development of different analytical tools for S sizing and quantification. In recent years the use of electrochemical measurements as a direct, fast, and inexpensive technique for the different nanoparticles (NPs) characterization (Ag, Au, Pt) is increasing. In this work, electrochemical i.e. chronoamperometric measurements at the Hg electrode are performed for determination of the size distribution of the S NPs. RESULTS S NPs were synthesized in aqueous medium by sodium polysulphide acidic hydrolysis. Chronoamperometric measurements reveal the polydisperse nature of the formed suspension of S NPs. The electrochemical results were compared with dynamic light scattering measurements parallel run in the same S NPs suspensions. The two methods show fairly good agreement, both suggesting a log-normal size distribution of the S NPs sizes characterized by similar parameters. CONCLUSIONS The preliminary results highlight the amperometric measurements as a promising tool for the size determination of the S NPs in the water environment.
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Affiliation(s)
- Elvira Bura-Nakić
- />Center for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička 54, 10 000 Zagreb, Croatia
| | - Marija Marguš
- />Center for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička 54, 10 000 Zagreb, Croatia
| | - Darija Jurašin
- />Division of Physical Chemistry, Ruđer Bošković Institute, Bijenička 54, 10 000 Zagreb, Croatia
| | - Ivana Milanović
- />Center for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička 54, 10 000 Zagreb, Croatia
| | - Irena Ciglenečki-Jušić
- />Center for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička 54, 10 000 Zagreb, Croatia
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Ciglenečki I, Marguš M, Bura-Nakić E, Milanović I. Electroanalytical methods in characterization of sulfur species in aqueous environment. J Electrochem Sci Eng 2014. [DOI: 10.5599/jese.2014.0053] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Kružić P, Vojvodić V, Bura-Nakić E. Inshore capture-based tuna aquaculture impact on Posidonia oceanica meadows in the eastern part of the Adriatic Sea. Mar Pollut Bull 2014; 86:174-185. [PMID: 25110046 DOI: 10.1016/j.marpolbul.2014.07.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 07/10/2014] [Accepted: 07/19/2014] [Indexed: 06/03/2023]
Abstract
Mapping and monitoring of the seagrass Posidonia oceanica in the eastern (Croatian) part of the Adriatic Sea since 2004 indicates a significant decline in meadow density in an area impacted by inshore capture-based tuna aquaculture. The density and overall condition of P. oceanica meadows impacted by tuna farms near Fulija Islet was compared to two reference sites (Iž Island and Mrtovnjak Islet). The factors with the most significant influence on P. oceanica meadows were found to be the input of organic matter originating from the cages, as well as high epiphyte biomass caused by nutrient enrichment. Significant differences in nutrient concentrations were found between the sites impacted by tuna farms (Fulija Islet) and the control stations. Shoot density of the P. oceanica meadows decreased at the stations in close vicinity to the tuna farm, which suggests that the tuna farm activity strongly affected the surrounding meadows.
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Affiliation(s)
- Petar Kružić
- Department of Biology, Faculty of Science, Zagreb University, Rooseveltov trg 6, 10000 Zagreb, Croatia.
| | - Vjeročka Vojvodić
- Department for Research of Sea and Environment, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia; Martinska Laboratory, 22000 Šibenik, Croatia
| | - Elvira Bura-Nakić
- Department for Research of Sea and Environment, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia; Martinska Laboratory, 22000 Šibenik, Croatia
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Bura-Nakić E, Viollier E, Ciglenečki I. Electrochemical and colorimetric measurements show the dominant role of FeS in a permanently anoxic lake. Environ Sci Technol 2013; 47:741-749. [PMID: 23240551 DOI: 10.1021/es303603j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Recent publications have shown that the anodic reaction between FeS and Hg can be used for electrochemical detection of colloidal and particulate FeS in natural waters. Anodic waves that were recorded around -0.45 V (vs Ag/AgCl) in model solutions correspond to the electrochemical transformation of nanoparticulate FeS to HgS. Here, as a further step, the proposed approach is tested on anoxic, sulfidic, and iron-rich samples of a meromictic freshwater lake (Lake Pavin, France). Based on new and more comprehensive work on FeS electrochemistry in model and anoxic Lake Pavin samples, a new interpretation is given for previously recorded voltammetric signals in sulfide and iron rich environment, usually designated FeS(aq), and its role in controlling solubility of different FeS phases. A comparison of the depth profiles of S(-II) measured by voltammetry and the methylene blue method showed that the majority of S(-II) is in the form of FeS. In the monimolimnion layer, thermodynamic calculations based on total Fe(II) and S(-II) concentration, measured by ferrozine and the methylene blue method, predict precipitation of FeS with log K(s) values between -3.6 and -3.8, very close to mackinawite's K(s) value. In the upper part of the same layer, precipitation of greigite is predicted. It is shown that modification of a Hg electrode by surface-formed FeS has a significant influence on voltammetric Fe(II) determination, since reduction of Fe(II) under such conditions occurs both on bare (-1.4 V) and on FeS modified Hg surfaces (-1.1 V); Fe(II) may be underdetermined when only the -1.4 V peak is measured.
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Affiliation(s)
- Elvira Bura-Nakić
- Center for Marine and Environmental Research, Rudjer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
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Affiliation(s)
- G. R. Helz
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
- Center for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička 54, 1000 Zagreb, Croatia
| | - I. Ciglenečki
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
- Center for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička 54, 1000 Zagreb, Croatia
| | - D. Krznarić
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
- Center for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička 54, 1000 Zagreb, Croatia
| | - E. Bura-Nakić
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
- Center for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička 54, 1000 Zagreb, Croatia
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Bura-Nakić E, Krznarić D, Helz GR, Ciglenečki I. Characterization of Iron Sulfide Species in Model Solutions by Cyclic Voltammetry. Revisiting an Old Problem. ELECTROANAL 2011. [DOI: 10.1002/elan.201000675] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Krznarić D, Helz GR, Bura-Nakić E, Jurasin D. Accumulation mechanism for metal chalcogenide nanoparticles at Hg0 electrodes: copper sulfide example. Anal Chem 2008; 80:742-9. [PMID: 18183961 DOI: 10.1021/ac071180z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mercury electrodes preconcentrate metal chalcogenide nanoparticles effectively, enabling their detection at submicromolar concentrations (as Sigma chalcogenide) by adsorptive cathodic stripping voltammetry. Understanding the unique behavior of nanoparticle analytes during preconcentration is critical for lowering detection limits and for quantification. A multistep mechanism is proposed on the basis of accumulation experiments with polydisperse copper sulfide (CuxS) nanoparticles. Particles first diffuse and adsorb at the Hg0 surface. When both the electrode and particles have negative surface potentials, this process resembles charge-impeded coagulation, obeying the Schulze-Hardy rule at various electrolyte strengths. Consequently, accumulation rates are surprisingly sensitive to electrolyte concentration. Choosing accumulation potentials where the electrode and particles have opposite surface potentials greatly improves collection efficiency, especially for the smallest particles. After adsorption, particles undergo transformations. One product is a more stable (harder to reduce) form of CuxS, interpreted to consist of adclusters or adlayers. A very significant (approximately 0.3 V) negative shift in reduction potential results from this transformation. Loss of analyte to at least one nonelectroactive product is also observed. Loss is greatest for the smallest particles and is sensitive to choice of accumulation potential. To improve accumulation efficiency, accumulation potentials more positive that the potential of zero charge of Hg electrodes are advantageous but care must be taken to remove dissolved chalcogenides under these conditions in order to avoid artifacts.
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Affiliation(s)
- Damir Krznarić
- Center for Marine and Environmental Research, Institute Ruer Bosković, Bijenicka 54, 10000 Zagreb, Croatia
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Bura-Nakić E, Krznarić D, Jurašin D, Helz GR, Ciglenečki I. Erratum to “Voltammetric characterization of metal sulfide particles and nanoparticles in model solutions and natural waters” [Anal. Chim. Acta 594 (2007) 44–51]. Anal Chim Acta 2007. [DOI: 10.1016/j.aca.2007.08.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bura-Nakić E, Krznarić D, Jurasin D, Helz GR, Ciglenecki I. Voltammetric characterization of metal sulfide particles and nanoparticles in model solutions and natural waters. Anal Chim Acta 2007; 594:44-51. [PMID: 17560384 DOI: 10.1016/j.aca.2007.04.065] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 04/27/2007] [Accepted: 04/30/2007] [Indexed: 11/24/2022]
Abstract
Voltammetric scans in sulfidic natural waters often reveal reduction peaks in the range -0.9 to -1.35 V versus Ag/AgCl. These peaks have been attributed to iron sulfide complexes or clusters. However, sols containing CuS nanoparticles now also are known to produce reduction peaks in this range. Here we investigate the voltammetric behavior of two additional metal sulfides at the Hg electrode in 0.55 M NaCl + 0.03 M NaHCO3 electrolyte, pH=8.5. We show that Pb and Hg sulfides, either as suspended powders or as precipitated nanoparticles, also yield cathodic peaks between -0.9 and -1.35 V, similar to peaks obtained with CuS and FeS. For precipitated nanoparticles, the position and shape of these reduction peaks change with ageing. Freshly formed nanoparticles produce less negative reduction peaks than aged nanoparticles. Peaks from aged nanoparticles often consist of two or more superimposed reduction peaks. When all other experimental parameters are held constant, the amount of nanoparticle analyte accumulated on the electrode increases with the amount of ageing (< or = 1 h). Addition of EDTA or acidification followed by purging can be used to distinguish PbS nanoparticles and Fe sulfide clusters from CuS and HgS nanoparticles or from colloidal S. This test was applied to interpret -0.9 to -1.35 V reduction peaks observed in two meromictic lakes. In conjunction with other evidence, this test suggests that FeS clusters are present in one case whereas colloidal S is present in the other. Interpreting -0.9 to -1.35 V voltammetric peaks observed in sulfidic natural waters requires caution, but these peaks are potentially rich sources of information about trace metal speciation.
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Affiliation(s)
- Elvira Bura-Nakić
- Center for Marine and Environmental Research, Rudjer Bosković Institute, Bijenicka 54, 10 000 Zagreb, Croatia.
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