| 1. |
- Kotilainen, Aarno T., et al.
(författare)
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Echoes from the Past : A Healthy Baltic Sea Requires More Effort
- 2014
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 43:1, s. 60-68
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Tidskriftsartikel (refereegranskat)abstract
- Integrated sediment multiproxy studies and modeling were used to reconstruct past changes in the Baltic Sea ecosystem. Results of natural changes over the past 6000 years in the Baltic Sea ecosystem suggest that forecasted climate warming might enhance environmental problems of the Baltic Sea. Integrated modeling and sediment proxy studies reveal increased sea surface temperatures and expanded seafloor anoxia (in deep basins) during earlier natural warm climate phases, such as the Medieval Climate Anomaly. Under future IPCC scenarios of global warming, there is likely no improvement of bottom water conditions in the Baltic Sea. Thus, the measures already designed to produce a healthier Baltic Sea are insufficient in the long term. The interactions between climate change and anthropogenic impacts on the Baltic Sea should be considered in management, implementation of policy strategies in the Baltic Sea environmental issues, and adaptation to future climate change.
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| 2. |
- Virtasalo, Joonas J., et al.
(författare)
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Enrichment of trace metals from acid sulfate soils in sediments of the Kvarken Archipelago, eastern Gulf of Bothnia, Baltic Sea
- 2020
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Ingår i: Biogeosciences. - : Copernicus Gesellshaft MBH. - 1726-4170 .- 1726-4189. ; 17:23, s. 6097-6113
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Tidskriftsartikel (refereegranskat)abstract
- Rivers draining the acid sulfate soils of western Finland are known to deliver large amounts of trace metals with detrimental environmental consequences to the recipient estuaries in the eastern Gulf of Bothnia, northern Baltic Sea. However, the distribution of these metals in the coastal sea area and the relevant metal transport mechanisms have been less studied. This study investigates the spatial and temporal distribution of metals in sediments at nine sites in the Kvarken Archipelago, which is the recipient system of Laihianjoki and Sulvanjoki rivers that are impacted by acid sulfate soils. The contents of Cd, Co, Cu, La, Mn, Ni, and Zn increased in the cores during the 1960s and 1970s as a consequence of intensive artificial drainage of the acid sulfate soil landscape. Metal deposition has remained at high levels since the 1980s. The metal enrichment in sea floor sediments is currently visible at least 25 km seaward from the river mouths. Comparison with sediment quality guidelines shows that the metal contents are very likely to cause detrimental effects on marine biota more than 12 km out from the river mouths. The dynamic sedimentary environment of the shallow archipelago makes these sediments potential future sources of metals to the ecosystem. Finally, the strong association of metals and nutrients in the same sediment grain size class of 2-6 pm suggests that the transformation of dissolved organic matter and metals to metal-organic aggregates at the river mouths is the key mechanism of seaward trace metal transport, in addition to co-precipitation with Mn oxyhydroxides identified in previous studies. The large share of terrestrial organic carbon in the total organic C in these sediments (interquartile range - 39 %-48 %) highlights the importance of riverine organic matter supply. These findings are important for the estimation of environmental risks and the management of biologically sensitive coastal sea ecosystems.
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| 3. |
- Virtasalo, Joonas J., et al.
(författare)
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Pyritic and baritic burrows and microbial filaments in postglacial lacustrine clays in the northern Baltic Sea
- 2010
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Ingår i: Journal of the Geological Society. - : Geological Society of London. - 0016-7649 .- 2041-479X. ; 167:6, s. 1185-1198
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Tidskriftsartikel (refereegranskat)abstract
- Holocene postglacial lacustrine clays in the northern Baltic Sea were studied for ichnofossils,petrography, and microscale elemental and 34S/32S composition to understand the impact of benthos-producedorganic matrices on the early diagenesis of sediments. X-radiographs of these clays display intense burrowmottling with discrete Palaeophycus, ‘Mycellia’ and rare Arenicolites. Small burrow-like and irregularlyshaped concretions were separated from these clays. The burrow-like concretions are composed of framboidalpyrite and poorly crystalline FeS2 cement. They formed within worm-produced burrows by the decompositionof mucous coatings on the burrow walls by sulphate reduction. 34SCDT composition of the framboidsindicates saline inflows from the North Sea as the sulphate source. The irregular concretions are microcrystallinepyritic masses that formed in pore spaces with less reactive organic compounds. Their 34SCDT valuesreflect precipitation from the ambient porewater sulphate by sulphate reduction. The burrow-like and irregularconcretions are microcrystalline barite in the lower parts of the clays. ‘Mycellia’ are mineral-replacedfilaments produced by large sulphur-oxidizing bacteria or mycelial fungi. They concentrate in monosulphidebands in the lower substrate levels, but are associated with organic patches upward. This study demonstratesthat substantial amounts of pyrite formed within organic matrices close to the sediment–water interface. Thisdiffers from previous studies that proposed a deeper-burial origin and allochthonous sulphur source.
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