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Past occurrences of...
Past occurrences of hypoxia in the Baltic Sea and the role of climate variability, environmental change and human impact
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- Zillén, Lovisa (författare)
- Lund University,Lunds universitet,Kvartärgeologi,Geologiska institutionen,Naturvetenskapliga fakulteten,Quaternary Sciences,Department of Geology,Faculty of Science
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- Conley, Daniel (författare)
- Lund University,Lunds universitet,Kvartärgeologi,Geologiska institutionen,Naturvetenskapliga fakulteten,Quaternary Sciences,Department of Geology,Faculty of Science
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- Andrén, Thomas (författare)
- Södertörns högskola,Institutionen för livsvetenskaper
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- Andrén, Elinor (författare)
- Södertörns högskola,Institutionen för livsvetenskaper
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- Björck, Svante (författare)
- Lund University,Lunds universitet,Kvartärgeologi,Geologiska institutionen,Naturvetenskapliga fakulteten,Quaternary Sciences,Department of Geology,Faculty of Science
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(creator_code:org_t)
- Elsevier BV, 2008
- 2008
- Engelska.
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Ingår i: Earth-Science Reviews. - : Elsevier BV. - 0012-8252 .- 1872-6828. ; 91, s. 77-92
- Relaterad länk:
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http://dx.doi.org/10...
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https://urn.kb.se/re...
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https://doi.org/10.1...
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https://lup.lub.lu.s...
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Abstract
Ämnesord
Stäng
- The hypoxic zone in the Baltic Sea has increased in area about four times since 1960 and widespread oxygen deficiency has severely reduced macro benthic communities below the halocline in the Baltic Proper and the Gulf of Finland, which in turn has affected food chain dynamics, fish habitats and fisheries in the entire Baltic Sea. The cause of increased hypoxia is believed to be enhanced eutrophication through increased anthropogenic input of nutrients, such as nitrogen and phosphorus. However, the spatial variability of hypoxia on long time-scales is poorly known: and so are the driving mechanisms. We review the occurrence of hypoxia in modern time (last c. 50ᅵyears), modern historical time (AD 1950-1800) and during the more distant past (the last c. 10ᅵ000ᅵyears) and explore the role of climate variability, environmental change and human impact. We present a compilation of proxy records of hypoxia (laminated sediments) based on long sediment cores from the Baltic Sea. The cumulated results show that the deeper depressions of the Baltic Sea have experienced intermittent hypoxia during most of the Holocene and that regular laminations started to form c. 8500-7800ᅵcal. yr BP ago, in association with the formation of a permanent halocline at the transition between the Early Littorina Sea and the Littorina Sea s. str. Laminated sediments were deposited during three main periods (i.e. between c. 8000-4000, 2000-800ᅵcal. yr BP and subsequent to AD 1800) which overlap the Holocene Thermal Maximum (c. 9000-5000ᅵcal. yr BP), the Medieval Warm Period (c. AD 750-1200) and the modern historical period (AD 1800 to present) and coincide with intervals of high surface salinity (at least during the Littorina s. str.) and high total organic carbon content. This study implies that there may be a correlation between climate variability in the past and the state of the marine environment, where milder and dryer periods with less freshwater run-off correspond to increased salinities and higher accumulation of organic carbon resulting in amplified hypoxia and enlarged distribution of laminated sediments. We suggest that hydrology changes in the drainage area on long time-scales have, as well as the inflow of saltier North Sea waters, controlled the deep oxic conditions in the Baltic Sea and that such changes have followed the general Holocene climate development in Northwest Europe. Increased hypoxia during the Medieval Warm Period also correlates with large-scale changes in land use that occurred in much of the Baltic Sea watershed during the early-medieval expansion. We suggest that hypoxia during this period in the Baltic Sea was not only caused by climate, but increased human impact was most likely an additional trigger. Large areas of the Baltic Sea have experienced intermittent hypoxic from at least AD 1900 with laminated sediments present in the Gotland Basin in the Baltic Proper since then and up to present time. This period coincides with the industrial revolution in Northwestern Europe which started around AD 1850, when population grew, cutting of drainage ditches intensified, and agricultural and forest industry expanded extensively.
Ämnesord
- NATURVETENSKAP -- Geovetenskap och miljövetenskap (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences (hsv//eng)
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Geologi (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Geology (hsv//eng)
Nyckelord
- Baltic Sea
- Littorina Sea
- hypoxia
- Holocene
- Medieval Warm Period
- modern historical period
- climate change and human impact
- Earth sciences
- Geovetenskap
- climate change and human impact
- modern historical period
- Medieval Warm Period
- Holocene
- hypoxia
- Baltic Sea
- Littorina Sea
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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