Universität zu Köln

Moros, Matthias, Andersen, Thorbjorn J., Schulz-Bull, Detlef, Haeusler, Katharina, Bunke, Dennis ORCID: 0000-0001-5462-6306, Snowball, Ian ORCID: 0000-0002-6257-3088, Kotilainen, Aarno, Zillen, Lovisa, Jensen, Jorn B., Kabel, Karoline, Hand, Ines, Leipe, Thomas, Lougheed, Bryan C., Wagner, Bernd ORCID: 0000-0002-1369-7893 and Arz, Helge W. (2017). Towards an event stratigraphy for Baltic Sea sediments deposited since AD 1900: approaches and challenges. Boreas, 46 (1). S. 129 - 143. HOBOKEN: WILEY. ISSN 1502-3885

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Abstract

Reconstructions of environmental changes at sub-decadal to decadal resolution based on central Baltic Sea sediments rely on accurate and precise high-resolution sediment depth/age relationships. A model chronology for Baltic Sea sediments is presented here based on established historical records of anthropogenic radionuclides (Cs-137/Am-241/bomb(14)C), polychlorinated biphenyls (PCBs), lead (Pb) and stable lead isotope (Pb-206/207 ratios), and radionuclide Pb-210 and C-14 decay dating methods. Marker horizons consisting of chemical precipitates formed by documented Major Baltic Inflow (MBIs) events and an extended diatom bloom period were also integrated into the model. The main time markers in Baltic Sea sediments that formed during the last 120years were the following: (i) the deepest observation of Pb-210(unsupp.) (marking the Pb-210 dating horizon) and departure of Hg from natural background levels at c.AD 1900; (ii) first detectable presence of PCBs at AD 1935; (iii) radionuclide production (i.e. Am-241) due to nuclear weapons testing between AD 1954 and AD 1975, with a peak in AD 1963; (iv) maximum heavy metal and PCB concentrations in the AD 1960s/1970s; (v) the Chernobyl nuclear accident in AD 1986 as a sharp Cs-137 increase; (vi) exceptionally strong diatom blooms with a massive diatom layer found in the Eastern Gotland Basin in AD 1988-1990; and (vii) characteristic manganese-carbonate layers in the deeper central basins formed by MBIs in AD 1993 and AD 2003. A precise and accurate sediment depth/age relationship can only be achieved in restricted areas of the Baltic Sea where continuous sedimentation has prevailed and there has been limited postdepositional disturbance. We demonstrate that parallel Hg and Cs-137 measurements can be used to assess the quality of sediment sequences for high-resolution environmental reconstructions. We show examples of sediment profiles that conform to the historical record, and examples from Western Baltic Sea areas where it appears to be impossible to establish accurate geochronologies.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Moros, Matthias UNSPECIFIED UNSPECIFIED UNSPECIFIED Andersen, Thorbjorn J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schulz-Bull, Detlef UNSPECIFIED UNSPECIFIED UNSPECIFIED Haeusler, Katharina UNSPECIFIED UNSPECIFIED UNSPECIFIED Bunke, Dennis UNSPECIFIED orcid.org/0000-0001-5462-6306 UNSPECIFIED Snowball, Ian UNSPECIFIED orcid.org/0000-0002-6257-3088 UNSPECIFIED Kotilainen, Aarno UNSPECIFIED UNSPECIFIED UNSPECIFIED Zillen, Lovisa UNSPECIFIED UNSPECIFIED UNSPECIFIED Jensen, Jorn B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kabel, Karoline UNSPECIFIED UNSPECIFIED UNSPECIFIED Hand, Ines UNSPECIFIED UNSPECIFIED UNSPECIFIED Leipe, Thomas UNSPECIFIED UNSPECIFIED UNSPECIFIED Lougheed, Bryan C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wagner, Bernd UNSPECIFIED orcid.org/0000-0002-1369-7893 UNSPECIFIED Arz, Helge W. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-247676
DOI:	10.1111/bor.12193
Journal or Publication Title:	Boreas
Volume:	46
Number:	1
Page Range:	S. 129 - 143
Date:	2017
Publisher:	WILEY
Place of Publication:	HOBOKEN
ISSN:	1502-3885
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language HISTORICAL EMISSION INVENTORY; PCB CONGENERS; GEOCHEMICAL RECORDS; LAMINATED SEDIMENTS; 3 DECADES; CS-137; ACCUMULATION; WATER; RADIONUCLIDES; SCANDINAVIA Multiple languages Geography, Physical; Geosciences, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/24767