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| 3. |
- Boström, Kurt, et al.
(författare)
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Geochemistry, mineralogy and origin of the sediments in the Gulf of Bothnia
- 1978
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Ingår i: Proceedings of the Finnish-Swedish seminar on the Gulf of Bothnia. - : Merentutkimuslaito. - 9514636430 ; , s. 8-35
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Konferensbidrag (refereegranskat)abstract
- and DWD at larger depths, but DWD does also occur in some protected depressions where bottom depths may be 20-30 meters or less. DWD represents Postglacial deposits, whereas SWD represents more or less reworked tills. SWD largely consist of little altered rock detritus and are rich in silty, sandy or coarser fractions. DWD contains much clay sized material, but silts and sand may occur occasionally. In general SWD are rich in quartz and feldspars, whereas the DWD are poor in these minerals, but instead show higher contents of X-ray amorphus (background producing) matter, and clay-minerals. The relation Quartz-Feldspar also varies latitudinally, the feldspar-richest sediments occurring towards the North. DWD are enriched in Ti, Fe, Mn, Ba and probably some trace elements (e.g. Cu, Cr) whereas SWD are relatively rich in Si. Al, Ca, Na, and some traces occur in the same concentrations in both sediment types. DWD are identical to average shale in composition and SWD to average granite. This is probably due to a mechanical action, the panning of sediments by waves, bottom currents etc. preferentially moving clay and mica minerals into the deep basins, whereas coarse weathering residues, rich in quartz and feldspar, remain in shallow waters. Iron-manganese concretions occur extensively on the bottom areas that are protected from excessive abrasion and rapid accumulation. The nodules in the Bothnian Bay, are richer in Mn, Cu, Ni and Co than in other parts of Gulf of Bothnia. It is concluded that, in addition to organic matter, hydroxides and other fines may be important adsorbers of pollutants in sediments
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- Boström, Kurt, et al.
(författare)
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Origin of iron-manganese-rich suspended matter in the Landsort Deep, NW Baltic Sea
- 1988
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203 .- 1872-7581. ; 24:1, s. 93-98
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Tidskriftsartikel (refereegranskat)abstract
- Water sampling was undertaken in 1982 in the Landsort Deep, NW Baltic Sea, at eight depth levels. In the 0-150 m interval oxidizing conditions prevailed, with suspended phases being particularly rich in Fe (with a maximum at 150 m), Mn and Ba (with maxima at 100 m). The anoxic zone below 150 m showed high concentrations of dissolved Fe and particularly dissolved Mn which were much higher than in the Black Sea, for instance. This is probably due to the migratory behavior of the redoxcline in the Landsort Deep. The metal-rich suspended matter probably arises when dissolved Fe and Mn from the anoxic zone precipitate as hydroxyoxides at the redoxcline; lateral transport of such suspended matter may explain the large-scale selective loss of Mn and Ba from the Baltic basin.
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- Boström, Kurt, et al.
(författare)
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Selective removal of trace elements from the Baltic by suspended matter
- 1981
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Ingår i: Marine Chemistry. - 0304-4203 .- 1872-7581. ; 10:4, s. 335-354
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Tidskriftsartikel (refereegranskat)abstract
- Suspended matter was collected at 30 stations in the Baltic and Kattegatt, at the thermocline and at the bottom, and analysed for Na, Ca, Mg, Si, Ti, Al, Fe, Mn, Ba, Sr, Ni and V. The composition of the suspended matter varies considerably, but can be described as a mixture of: (1) 12-25% terrigenous detritus with much Si, Al, Ti and Fe; (2) 75-88% biological matter with much Ni, V and Ba; and (3) some Mn-oxyhydroxide.The annual efflux of water from the Baltic is about 460 km3, with a suspended load in the Baltic straits of 1.2-3.6 mg ash material l-1 These values imply that much Si, Ti, Al, Fe, Sr, Ni and V and particularly much Ba and Mn are lost from the Baltic in the suspended load.The average suspended matter is richer in Mn(5×), Ba(2.5×), Sr(4×) and V(1.8×) than permanently depositing Baltic sediments. These constituents are relatively enriched in pelagic deposits, i.e. it is likely that much Mn, Ba and V in deep-sea sediments derive from the continents via suspended transport. This conclusion is supported by the similarity between suspended matter and average Atlantic pelagic sediment.
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- Ingri, Johan, et al.
(författare)
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Environmental monitoring with river suspended matter : case study in the River Dalälven, central Sweden
- 1993
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Ingår i: Applied Geochemistry. - 0883-2927 .- 1872-9134. ; 8:Suppl. 2, s. 125-130
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Tidskriftsartikel (refereegranskat)abstract
- Heavy metal concentrations are presented for suspended sediment from the River Dalälven, central Sweden. The river is contaminated by acid mine drainage and data from the most polluted tributary, Garpenbergsån, are also presented. Element/Al ratios in the suspended phase showed that K, Mg and Ti were mainly hosted in detrital particles together with a large fraction of Si. Between 50 and 60% of the load of Fe, Ca and Na were in non-detrital form. Less than 10% of the total load of suspended Mn and P were in a detrital form. The sediment in the River Dalälven is polluted by As, Cr, Cu, Hg, Ni, Pb and Zn. These elements, except Pb, showed an even stronger enrichment in the suspended phase. This indicated that between one third and one half of the suspended load was recirculated to the water column during sedimentation. Arsenic, Cr, Cu, Hg, Ni, Pb and Zn showed linear correlations with non-detrital Fe, close to the inflow of the polluted stream Garpenbergsån. Deposition of non-detrital Fe, Na, Cr, Cu and Ni in the sedimentation basins close to the river mouth reduced the suspended discharge of these elements to the Baltic Sea. However, the basins acted as sources for non-detrital suspended As, Hg, Pb, and Zn during the studied period. The calculated net export, in a non-detrital form, for these elements was 141, 3.7, 1100 and 7000 kg, respectively as measured between May and October.
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- Ingri, Johan, et al.
(författare)
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Iron and manganese layering in recent sediments in the Gulf of Bothnia
- 1986
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Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 56:1-2, s. 105-116
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Tidskriftsartikel (refereegranskat)abstract
- The oxidized surface layer of recent soft sediments in the Gulf of Bothnia, northern part of the Baltic Sea, has been investigated. Distinct stratification of Fe and Mn is observed, with up to five different horizons in well-developed profiles. These layered top sediments, although not previously noticed, occur extensively in the Gulf of Bothnia. There is a close association of Mn and Ni, Ba, Zn and Cu, whereas P, Ca and Sr are associated with Fe. High dissolved Fe and Mn contents coupled with a strong redox gradient are recorded in the interstitial waters. Formation of these layers is linked to varying redox conditions. Fe and Mn tend to be dissolved under reducing conditions, to migrate upwards and to reprecipitate as oxyhydroxides along favourable redox horizons. Reaching oxidizing conditions Fe precipitates prior to Mn, and is always found below the Mnrich strata. The character of the oxidized zone is quite different in the two sub-basins of the Gulf of Bothnia. Mn-rich horizons together with spherical Mn-rich nodules are frequently found in the Bothnian Bay, while in the Bothnian Sea mostly Fe-rich layers are present together with abundant Fe-rich flat concretions. This difference is interpreted as being due to a lower redox level in the Bothnian Sea.
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| 9. |
- Ingri, Johan, et al.
(författare)
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Rare earth abundance patterns in ferromanganese concretions from the Gulf of Bothnia and the Barents Sea
- 1987
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 51:1, s. 155-161
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Tidskriftsartikel (refereegranskat)abstract
- Ferromanganese concretions from the Svalbard shelf in the Barents Sea show slightly convex shale-normalized REE patterns with no Eu anomalies. Concretions from the Gulf of Bothnia, northern part of the Baltic Sea, exhibit an enrichment of light REE and negative Eu anomalies. This difference is interpreted as a consequence of different conveyor mechanisms of the REE to the sediment. It is suggested that dissolving biogenic debris contributes to the convex pattern obtained in the Barents Sea, whereas an inorganic suspended fraction with scavenged REE is the main carrier in the Gulf of Bothnia. During oxic diagenesis in the sediment, the scavenged REE are set free into the porewater and contribute to the distribution pattern in concretions found in the Gulf of Bothnia. Small Mn-rich spheroidal concretions are enriched two to five times in REE compared to average shale, whereas Mn-poor flat concretions are low in REE. Specific surface area of the concretion and the depth of burial in the oxidized surface sediment are two factors that strongly affect the enrichment of the REE. Weak Ce anomalies are present in the analysed concretions and a redox level dependence is seen.
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