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DatoValore
TitleRecords of environmental and climatic changes during the late Holocene from Svalbard: Palaeolimnology of Kongressvatnet
AbstractA multi-core, multidisciplinary palaeolimnological study of the partially varved sediment of a deep, meromictic, arctic lake, Kongressvatnet (Svalbard, Western Spitsbergen), provides a record of environmental and climatic changes during last ca. 1800 years. The chronology of sedimentation was established using several dating techniques (Cs-137, Pb-210, varve counts, palaeomagnetic correlation). A multiproxy record of palaeolimnological variability was compiled based on sedimentation rates, magnetic properties, varve thickness, organic matter, geochemistry, pigments from algal and photosynthetic bacteria, mineralogy and biological assemblages (diatoms, Cladocera). The major features recognised in our master core K99-3 include a shift in sediment source and supply (magnetic measurements, geochemistry) probably caused by glaciological changes in the catchment around 38-32 cm core depth (AD 700-820). Additional environmental changes are inferred at 20-18, 8-4.5 and 3-2 cm (AD ca. 1160-1255; 1715-1880; 1940-1963, respectively). During the past ca. 120 years a prominent sedimentological change from brownish-grey, partly laminated silt-clay (varves) to black organic-rich deposits was observed. From AD 1350 to AD1880 the sediment is comprised of a continuous sequence of varves, whereas the earlier sediments are mostly homogeneous with only a few short intercalated laminated sections between AD 860 and 1350. Sedimentation and accumulation rates increased during the last 30 years (modern warming). Pigment concentrations are very low in the lower ca. 32 cm of the core (AD 820) probably because of the high turbidity high energy environment. The high sulphur content in the uppermost 32 cm of sediment has given rise to two horizontally stratified populations of sulphur anaerobic photosynthetic bacteria, as inferred from their specific carotenoids. These bacteria populations are much more abundant during the Little Ice Age (LIA) than during warmer periods (e.g., during the Medieval Warm Period and 20th century). Diatoms are lacking from the core base up to 18 cm (ca. AD 1255); at this level, species indicative of mesotrophic water are present, whereas from 17 cm to the top of the core, oligotrophic taxa such as Staurosira construens/S. pinnata complex dominate, indicating extended ice coverage and more oligotrophic waters during the LIA. The concentration of Cladocera subfossil remains (dominated by Chydorus) are relatively high in the deepest sections (54-32 cm), whereas the upper 32 cm are characterized by a very low concentration of remains, possibly because of the strongly anoxic conditions, and in this upper sediment section rotifer resting eggs become prevalent. We interpret these changes as responses to climate forcing through its impact on glacial melt water, lake ice cover duration and mainly redox conditions in deep water. The observed changes suggest that at least some of our recorded changes may parallel the Greenland Ice core, although our study added more details about the inferred climatic changes. Further aspects are discussed, such as catchment processes, glacial activity, duration of the Medieval Warm Period, the Little Ice Age, local human activity, and limnology.
SourceJournal of paleolimnology 36(4), pp. 325–351
KeywordsDiatomsPigmentsCladoceraSedimentGeochemistry
JournalJournal of paleolimnology
EditorKluwer Academic, Boston, Paesi Bassi
Year2006
TypeArticolo in rivista
DOI10.1007/s10933-006-9002-0
AuthorsGuilizzoni P., Marchetto A., Lami A., Brauer A. (1), Vigliotti L. (2), Musazzi S., Langone L. (2), Manca M., Lucchini F. (3), Calanchi N. (3), Dinelli E. (3), Mordenti A. (3)
Text171934 2006 10.1007/s10933 006 9002 0 ISI Web of Science WOS 000241355700001 Diatoms Pigments Cladocera Sediment Geochemistry Records of environmental and climatic changes during the late Holocene from Svalbard Palaeolimnology of Kongressvatnet Guilizzoni P., Marchetto A., Lami A., Brauer A. 1 , Vigliotti L. 2 , Musazzi S., Langone L. 2 , Manca M., Lucchini F. 3 , Calanchi N. 3 , Dinelli E. 3 , Mordenti A. 3 1 CNR—Istituto per lo Studio degli Ecosistemi ex Istituto Italiano di Idrobiologia , Largo V. Tonolli 50, 28922 Verbania Pallanza, Italy 2 CNR ISMAR, Istituto Scienza del Mare, Via P. Gobetti 101, 40129 Bologna, Italy 3 GeoForschungsZentrum, D 14473 Potsdam, Germany 4 Dipartimento Scienze della Terra, Universita di Bologna, Piazza Porta S. Donato, 40126 Bologna, Italy 1 GeoForschungsZentrum, Postdam, Germania; 2 CNR ISMAR, Bologna, Italia; 3 Dipartimento di Scienze della Terra, Universita di Bologna A multi core, multidisciplinary palaeolimnological study of the partially varved sediment of a deep, meromictic, arctic lake, Kongressvatnet Svalbard, Western Spitsbergen , provides a record of environmental and climatic changes during last ca. 1800 years. The chronology of sedimentation was established using several dating techniques Cs 137, Pb 210, varve counts, palaeomagnetic correlation . A multiproxy record of palaeolimnological variability was compiled based on sedimentation rates, magnetic properties, varve thickness, organic matter, geochemistry, pigments from algal and photosynthetic bacteria, mineralogy and biological assemblages diatoms, Cladocera . The major features recognised in our master core K99 3 include a shift in sediment source and supply magnetic measurements, geochemistry probably caused by glaciological changes in the catchment around 38 32 cm core depth AD 700 820 . Additional environmental changes are inferred at 20 18, 8 4.5 and 3 2 cm AD ca. 1160 1255; 1715 1880; 1940 1963, respectively . During the past ca. 120 years a prominent sedimentological change from brownish grey, partly laminated silt clay varves to black organic rich deposits was observed. From AD 1350 to AD1880 the sediment is comprised of a continuous sequence of varves, whereas the earlier sediments are mostly homogeneous with only a few short intercalated laminated sections between AD 860 and 1350. Sedimentation and accumulation rates increased during the last 30 years modern warming . Pigment concentrations are very low in the lower ca. 32 cm of the core AD 820 probably because of the high turbidity high energy environment. The high sulphur content in the uppermost 32 cm of sediment has given rise to two horizontally stratified populations of sulphur anaerobic photosynthetic bacteria, as inferred from their specific carotenoids. These bacteria populations are much more abundant during the Little Ice Age LIA than during warmer periods e.g., during the Medieval Warm Period and 20th century . Diatoms are lacking from the core base up to 18 cm ca. AD 1255 ; at this level, species indicative of mesotrophic water are present, whereas from 17 cm to the top of the core, oligotrophic taxa such as Staurosira construens/S. pinnata complex dominate, indicating extended ice coverage and more oligotrophic waters during the LIA. The concentration of Cladocera subfossil remains dominated by Chydorus are relatively high in the deepest sections 54 32 cm , whereas the upper 32 cm are characterized by a very low concentration of remains, possibly because of the strongly anoxic conditions, and in this upper sediment section rotifer resting eggs become prevalent. We interpret these changes as responses to climate forcing through its impact on glacial melt water, lake ice cover duration and mainly redox conditions in deep water. The observed changes suggest that at least some of our recorded changes may parallel the Greenland Ice core, although our study added more details about the inferred climatic changes. Further aspects are discussed, such as catchment processes, glacial activity, duration of the Medieval Warm Period, the Little Ice Age, local human activity, and limnology. 36 4 articolo pubblicato 04_JOPL_2006.pdf Articolo in rivista Kluwer Academic 0921 2728 Journal of paleolimnology Journal of paleolimnology J. paleolimnol. aldo.marchetto MARCHETTO ALDO piero.guilizzoni GUILIZZONI PIERO andrea.lami LAMI ANDREA leonardo.langone LANGONE LEONARDO luigi.vigliotti VIGLIOTTI LUIGI marinamarcella.manca MANCA MARINA MARCELLA TA.P02.005.002 Uso della paleolimnologia come strumento per lo studio del paleoclima e dell evoluzione climatica TA.P02.028.002 Struttura dei margini continentali, emissione dei fluidi attraverso di essi, e impatto sugli ecosistemi