| 1. |
- Fältmarsch, Rasmus, et al.
(author)
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Metal concentrations in oats (Avena sativa L.) grown on acid sulphate soils
- 2009
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In: Agricultural and Food Science. - 1459-6067 .- 1795-1895. ; 18:1, s. 45-56
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Journal article (peer-reviewed)abstract
- The aim of the study was to investigate the impact of soil chemistry on the concentrations of Co, Ni, Zn, Mn, Cu and Fe in oats (Avena saliva L. cv. Fiia) grown on Finnish acid sulphate (AS) soils with varying geochemical characteristics. Twenty two soil profiles, which were sampled to a depth of 1 m (five 20 cm section splits), and 26 composite oat grain samples were collected on a total of five fields. The concentrations of Co, Ni, Zn and Mn in the grains were correlated with the NH(4)Ac-EDTA-extractable concentrations in the soils. However, as these four chalcophilic metals are in general easily lost to drains and not retained as a large pool in the soil in easily-extractable form, also the concentrations in the oats were not in general elevated as compared with average values on other soils. On one of the fields, however, the Co and Ni concentrations in the soil, and thus also in the oats, were clearly elevated. Copper and Fe displayed no correlation between the soil and oat concentrations, indicating that the plant-uptake mechanisms are much more important than variations in geochemistry. It was suggested that the NH(4)Ac-EDTA solution was not efficient in extracting Fe and Cu, which shows that these metals are bound in relatively immobile oxyhydroxides.
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| 2. |
- Lavergren, Ulf, et al.
(author)
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Metal dispersion in groundwater in an area with natural and processed black shale - Nationwide prespective and comparison with acid sulfate soils
- 2009
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In: Applied Geochemistry. - : Elsevier BV. - 0883-2927 .- 1872-9134. ; 24:3, s. 359-369
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Journal article (peer-reviewed)abstract
- Black shale is often rich in sulfides and trace elements, and is thus a potential environmental threat in a manner similar to acid sulfate soils and active or abandoned sulfide mines. This study aims at characterising how exposed and processed (mined and burnt) black shale (alum shale) in Degerhamn, SE Sweden, affects the chemistry (Al, As, Ba, Cd, Ca, Cr, Co, Cu, Fe, Pb, Mg, Mn, Mo, Ni, K, Si, Na, Sr, S, U, V and Zn) of the groundwater. There were large variations in groundwater chemistry between nearby sampling points, while the temporal variations generally were small. Acidic groundwater (around pH 4), found in deposits of burnt and carbonate-poor shale where the conditions for sulfide oxidation were favourable, was strongly elevated in Al, U and several chalcophilic metals (Cd, Co, Cu, Ni and Zn). Cadmium and U were also, together with Mo, abundant in many of the near-neutral waters, both in the non-mined black shale bedrock and in the deposits of burnt shale. An extrapolation to a national level suggests that the dispersion of Ni from naturally occurring black shale is similar to that from anthropogenic point sources, while for Cd and As it is assessed to be approximately one tenth of that from point sources. The processed shale was, however, a much larger source of metals than the black shale bedrock itself, showing this material's potential as a massive supplier of metals to the aquatic environment. A comparison of waters in contact with the processed Cambrian-Ordovician black shale in Degerhamn and acid sulfate soils of the region shows that these two sulfide-bearing materials, in many respects very different, delivers basically the same suite of trace elements to the aquatic environment. This has implications for environmental planning and protection in areas where these types of materials exist.
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| 3. |
- Lavergren, Ulf, et al.
(author)
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Mobility of trace elements in black shale assessed by leaching tests and sequential chemical extraction
- 2009
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In: Geochemistry. - : Geological Society of London. - 1467-7873 .- 2041-4943. ; 9, s. 71-79
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Journal article (peer-reviewed)abstract
- This study focuses on the abundance and mobility of Ca, Fe, S and trace elements (As, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, U, V and Zn) in black shale (alum shale) in SE, Sweden. Samples of non-weathered, weathered and burnt black shale were chemically characterized and the potential element release from them was assessed by standard water-based leaching tests and pH/redox-regulated availability tests. Sequential chemical extractions provided further information on the phases in which the elements are bound. Results show that the shale is very rich in As (88-122 ppm), Cd (0.4-4.6 ppm), Mo (61-176 ppm), U (27-71 ppm) and V (496-1560 ppm). Cadmium and Mo, bound mainly in sulphides or organic matter, are very mobile in the non-burnt shale, with mobilization rates of up to 19% (190 mu g/kg) and 25% (16 mg/kg), respectively, using only water as extraction medium. The non-weathered shale is also relatively rich in Cu (113 ppm), Ni (100 ppm) and Zn (304 ppm), the latter two in particular showing behaviour similar to that of Cd, but with lower mobilization rates. In all samples U and V arc found mainly in weathering-resistant mineral phases and thus have a lower mobility, but due to the high abundance in the material, significant amounts of U can be released on longer time scales (up to 6 mg/kg, as indicated by the pH/redox-regulated test). Less than 1% of the As is released in all the leaching tests, indicating that upon oxidation it is retained in the solid phase. The overall conclusion is that this material has a high potential for releasing Cd, Mo, Ni, U and Zn (luring weathering.
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| 4. |
- Åström, Mats E., et al.
(author)
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Uranium in surface and ground waters in Boreal Europe
- 2009
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In: Geochemistry. - : Geological Society of London. - 1467-7873 .- 2041-4943. ; 9, s. 51-62
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Journal article (peer-reviewed)abstract
- This study focuses on uranium (U) in surface and groundwaters in Boreal Europe (Sweden, Finland, Russia). Data from recently completed regional hydrogeochemical surveys and from site-specific studies were combined, in order to enhance the current understanding of U behaviour in the catchments and water bodies of these northerly latitudes. Over Precambrian areas (dominated by igneous and metamorphic rocks) the aqueous U concentrations in general increased in a downward direction, i.e. from stream waters to overburden groundwaters to bedrock groundwaters, and they were correlated with the U abundance in the surrounding overburden (mainly glacial till). Over Phanerozoic areas (dominated by terrigene deposits containing or composed of limestone) the aqueous U concentrations were, in contrast, unrelated to overburden U concentrations and strongly correlated with dissolved Ca and HCO(3) concentrations. There is thus an overall geochemical and hydrochemical control, respectively, related to the underlying lithology. At geologically specific and local sites there is a range of correlations and control mechanisms of aqueous U. From acid sulphate soils, occurring abundantly on coastal plains, runoff below pH 4.0 is enriched in U (up to 55 mu g/l) most likely due to oxidation of U(IV) minerals followed by subsequent limited sorption of U(VI) in the acidic environment. In a studied black shale setting, characterized by high U concentrations (LIP to > 200 ppm), U levels increased in groundwater (up to 200 mu g/l) and surface water (up to 80 mu g/l) as the conditions changed from reducing to oxidizing. In an unmineralized granitic setting, proposed as a repository for spent nuclear fuel, elevated U concentrations in surface waters (up to 25 mu g/l) reflect a regional stream-hydrochemical anomaly and in bedrock groundwaters (up to > 100 mu g/l), most likely mobilization of uranyl from U-rich fracture coatings. In the Baltic Sea, which has unique brackish water, the ratio of U to Cl is similar to that in the oceans but contrasting near-coastal U trends exist, characterized by all inverse relationship between IT and Cl concentrations. These coastal-water anomalies are most likely caused by high U levels in inflowing streams, and possibly to some extent submarine discharge of U-enriched waters.
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