| 1. |
- Allard, Bert, 1945-, et al.
(författare)
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Metal Exchangeability in the REE-Enriched Biogenic Mn Oxide Birnessite from Ytterby, Sweden
- 2023
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Ingår i: Minerals. - : MDPI. - 2075-163X. ; 13:8
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Tidskriftsartikel (refereegranskat)abstract
- A black substance exuding from fractures was observed in 2012 in Ytterby mine, Sweden, and identified in 2017 as birnessite with the composition Mx[Mn(III,IV)](2)O-4 center dot(H2O)n. M is usually calcium and sodium, with x around 0.5. The Ytterby birnessite is unique, with M being calcium, magnesium, and also rare earth elements (REEs) constituting up to 2% of the total metal content. The biogenic origin of the birnessite was established in 2018. Analysis of the microbial processes leading to the birnessite formation and the REE enrichment has continued since then. The process is fast and dynamic, as indicated by the depletion of manganese and of REE and other metals in the fracture water during the passage over the precipitation zone in the mine tunnel. Studies of the exchangeability of metals in the structure are the main objective of the present program. Exposure to solutions of sodium, calcium, lanthanum, and iron led to exchanges and altered distribution of the metals in the birnessite, however, generating phases with almost identical structures after the exchanges, and no new mineral phases were detected. Exchangeability was more efficient for trivalent elements (REE) over divalent (calcium) and monovalent (sodium) elements of a similar size (ionic radii 90-100 pm).
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| 2. |
- Sjöberg, Susanne, et al.
(författare)
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Rare Earth element enriched birnessite in water-bearing fractures, the Ytterby mine, Sweden
- 2017
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Ingår i: Applied Geochemistry. - Amsterdam : Elsevier. - 0883-2927 .- 1872-9134. ; 78, s. 158-171
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Tidskriftsartikel (refereegranskat)abstract
- Characterization of a black substance exuding from fractured bedrock in a subterranean tunnel revealed a secondary manganese oxide mineralisation exceptionally enriched in rare earth elements (REE). Concentrations are among the highest observed in secondary ferromanganese precipitates in nature. The tunnel is located in the unsaturated zone at shallow depth in the former Ytterby mine, known for the discovery of yttrium, scandium, tantalum and five rare earth elements.Elemental analysis and X-ray diffraction of the black substance establish that the main component is a manganese oxide of the birnessite type. Minor fractions of calcite, other manganese oxides, feldspars, quartz and about 1% organic matter were also found, but no iron oxides were identified. The Ytterby birnessite contains REE, as well as calcium, magnesium and traces of other metals. The REE, which constitute 1% of the dry mass and 2% of the metal content, are firmly included in the mineral structure and are not released by leaching at pH 1.5 or higher. A strong preference for the trivalent REE over divalent and monovalent metals is indicated by concentration ratios of the substance to fracture water. The REE-enriched birnessite has the general formula Mx(Mn3+,Mn4+)2O4·(H2O)n with M = (0.37–0.41) Ca + 0.02 (REE + Y), 0.04 Mg and (0.02–0.03) other metals, and with [Mn3+]/[Mn4+] = 0.86–1.00.The influence of microorganisms on the accumulation of this REE enriched substance is demonstrated by electron paramagnetic resonance spectroscopy. Results show that it is composed of two or more manganese phases, one of which has a biogenic signature. In addition, the occurrence of C31 to C35 extended side chain hopanoids among the identified lipid biomarkers combined with the absence of ergosterol, a fungal lipid biomarker, indicate that the in-situ microbial community is bacterial rather than fungal.
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| 3. |
- Temnerud, Johan, et al.
(författare)
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Spatial patterns of some trace elements in four Swedish stream networks
- 2013
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 10, s. 1407-1423
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Tidskriftsartikel (refereegranskat)abstract
- Four river basins in southern Sweden, with catchment sizes from 0.3 to 127 km(2) (median 1.9), were sampled in October 2007. The 243 samples were analysed for 26 trace elements (Ag, As, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Ga, Ge, In, La, Li, Mo, Ni, Pb, Sb, Se, Sn, Tl, Ti, U, V and Zn) to identify spatial patterns within drainage networks. The range and median of each element were defined for different stream orders, and relationships to catchment characteristics, including deposition history, were explored. The sampling design made it possible to compare the differences along 40 stream reaches, above and below 53 stream junctions with 107 tributaries and between the 77 inlets and outlets of 36 lakes. The largest concentration differences (at reaches, junctions and lakes) were observed for lakes, with outlets usually having lower concentration compared to the inlets for As, Ba, Be, Bi, Cd, Co, Cr, Ga, Ge, Ni, Pb, Sn, Ti, Tl, U, V and Zn. Significantly lower concentrations were observed for Cd and Co when comparing headwaters with downstream sites in each catchment. Common factor analysis (FA) revealed that As, Bi, Cr, Ga, Ge, Tl and V co-vary positively with Al, Fe and total organic carbon (TOC) and negatively with La, Li and pH. The strong removal of a large number of trace elements when passing through lakes is evident though in the FA, where lake surface coverage plots opposite to many of those elements. Forest volume does not respond in a similar systematic fashion and, surprisingly, the amount of wetland does not relate strongly to either Fe or TOC at any of the rivers. A better understanding of the quantitative removal of organic carbon and iron will aid in understanding trace element fluxes from landscapes rich in organic matter and iron.
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| 4. |
- Bäckström, Mattias, 1974-, et al.
(författare)
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Effects of a fulvic acid on the adsorption of mercury and cadmium on goethite
- 2003
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Ingår i: Science of the Total Environment. - Amsterdam, Netherlands : Elsevier. - 0048-9697 .- 1879-1026. ; 304:1-3, s. 257-268
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Tidskriftsartikel (refereegranskat)abstract
- The effects of an aquatic fulvic acid on the pH-dependent adsorption of Hg(II) and Cd(II) to particulate goethite (a-FeOOH) were studied in batch systems. The ionic medium consisted of 0.01 M HClO and the total concentrations 4 of mercury and cadmium were maintained at 10y8 M with 203Hg and 109Cd as tracers. pH In the systems was varied in the range 3–10 by addition of HClO and NaOH.All commercial chemicals were of analytical grade or better. An 4 aquatic fulvic acid (20 ppm), previously isolated and characterised in detail, was used as a model for humic substances and its adsorption to goethite is included in this study. The adsorption of the fulvic acid (20 ppm) onto goethite decreased slowly from 90% at pH 3–7.5 to 10% at pH 10. In systems without fulvic acid the adsorption of mercury increased in a linear fashion from 10% at pH 3 to 70% at pH 10.In the presence of fulvic acid (20 ppm), the adsorption was almost quantitative in the intermediate pH range (pH 5–7), and exceeded 92% over the entire pH range. Thus, association between mercury and the fulvic acid enhanced adsorption in general although the largest impact was found at low pH.Adsorption of cadmium increased from nearly 0 to almost 100% at approximately pH 6. In the presence of fulvic acid, the adsorption increased below pH 7 and decreased above pH 7. The adsorption isotherm for mercury when the concentration was increased from 10y8 to 1.8=10y4 M showed a corresponding increase of K (lyg) up to a total concentration at 10y6 M.At higher mercury concentrations K was lowered. In the presence of fulvic acid the corresponding relationship of K was bi-modal, i.e. high values at low and intermediate concentrations of mercury. This behaviour suggests that in the absence of fulvic acid the adsorption follow the expected behaviour, i.e. adsorption sites with similar affinity for mercury. In the presence of fulvic acid, additional adsorption sites are available by the organic molecule (possibly sulfur groups) when it is associated to the goethite. The adsorption isotherm for cadmium indicates a lowering of K at 10y4 M. Cadmium had no competitive effect on mercury and vice versa. Zinc, however, affected the adsorption of cadmium but not the adsorption of mercury.
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| 5. |
- Greis, Christina, 1975-, et al.
(författare)
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Determination of plutonium in environmental samples with quadrupole ICP-MS
- 2008
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Ingår i: Journal of Radioanalytical and Nuclear Chemistry. - Berlin : Springer. - 0236-5731 .- 1588-2780. ; 275:1, s. 55-70
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Tidskriftsartikel (refereegranskat)abstract
- A method for rapid determination of plutonium isotopes in environmental samples with ultrasonic nebulisation and quadrupole ICP-MS detection was established. Techniques for sample dissolution, pre-concentration and chemical separation were evaluated and the optimal scheme outlined. Comparisons with α-spectrometry and high resolution ICP-MS confirmed the suitability of the method when applied to different environmental matrices within the global fallout concentration range in the northern hemisphere as well as more contaminated sites. Operational detection limits were 0.5–1.5 fg/l for fresh waters and 0.03–0.1 ng/kg for lake sediments and saline marsh sediments.
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| 6. |
- Liem-Nguyen, Van, et al.
(författare)
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Removal mechanism of arsenic (V) by stainless steel slags obtained from scrap metal recycling
- 2020
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Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier. - 2213-3437. ; 8:4
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Tidskriftsartikel (refereegranskat)abstract
- With this study, the removal mechanisms of arsenate by steel slag and its potential for treatment of contaminated water were elucidated. While original slag showed a poor fit to the Langmuir equation (R2 = 0.960), washed slag (the original slag is washed by low pH water solutions to remove readily soluble oxides) conformed better (R2 = 0.995). An initial pH of 2.0 give optimal adsorption, with a strong impact from the chemical speciation observed with highest efficiency for the fully protonated (OH)3AsO form. Adsorption capacity of the slag is 4.0 mg g−1, while together with precipitation the retention capacity reaches 13.7 mg g−1. However, removal by precipitation is a non-steady process due to re-dissolution of Ca3(AsO4)2(s). The washed slag shows a similar adsorption capacity to the original one but has not as strong alkaline properties. Batch experiment shows fast adsorption kinetics and column loading tests indicate an instant adsorption kinetics with 80 % As(V) removal for a 10 mg L−1 As(V) solution by 1.0 g of washed slag using a solution flowrate of 1 mL min−1. Common ions like sulfate, carbonate, chloride, iron(III), humic acid and fulvic acid do not significantly interfere with the removal efficiency. In combination with limited hazardous metals leaching, the slag is thus appropriate for use as a filter material for treatment of contaminated water and it has been successfully applied as filter material for treatment of arsenate spiked natural water sample with average removal efficiency of 84 % (solid to liquid ratio of 200).
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| 7. |
- Temnerud, Johan, 1969-, et al.
(författare)
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Landscape scale patterns in the character of natural organic matter in a Swedish boreal stream network
- 2009
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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 13:9, s. 1567-1582
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Tidskriftsartikel (refereegranskat)abstract
- This paper defines landscape-scale patterns in the character of natural organic matter (NOM) and tests for relationships to catchment soil, vegetation and topography. The drainage network of a boreal catchment, subcatchment size 0.12-78 km(2), in Northern Sweden was sampled in August 2002 during a period of stable low water flow. The NOM was characterized with UV/Vis spectroscopy, fluorescence, XAD-8 fractionation (%humic substances), gel permeation chromatography (apparent molecular weight), and elemental composition (C:N). The largest spatial variation was found for C: N, absorbance ratio, and specific visible absorptivity. The lowest variation was in fluorescence index, %humic substances and molecular retention time. The variation in total organic carbon (TOC), iron and aluminium concentration was more than twice that of C: N. Between headwater and downstream sites no significant changes were distinguished in the NOM character. At stream reaches, junctions and lakes little change (<10%) in NOM character was observed. Common factor analysis and partial least squares regression (PLS) revealed that the spatial variation in surface coverage of lakes and mires could explain some of the variation of TOC and NOM character. Our suggestion is that the mosaic of landscape elements (different amounts of water from lakes, forest soil and mires) delivers NOM with varying characteristics to a channel network that mixes conservatively downstream, with possible small changes at some stream reaches, junctions and lakes.
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| 8. |
- Allard, Bert, 1945-, et al.
(författare)
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Black shale : a biogeochemical archive
- 2014
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Ingår i: Sedimentary Pore Space Cementation: Role of Microbes. ; , s. 6-
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Konferensbidrag (refereegranskat)
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| 10. |
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