Long-term trends at the Boknis Eck time series station (Baltic Sea), 1957–2013: does climate change counteract the decline in eutrophication?

Autor: S. T. Lennartz, A. Lehmann, J. Herrford, F. Malien, H.-P. Hansen, H. Biester, H. W. Bange
Jazyk: angličtina
Rok vydání: 2014
Předmět:
Zdroj: Biogeosciences, Vol 11, Iss 22, Pp 6323-6339 (2014)
Druh dokumentu: article
ISSN: 1726-4170
1726-4189
6323-2014
DOI: 10.5194/bg-11-6323-2014
Popis: The Boknis Eck (BE) time series station, initiated in 1957, is one of the longest-operated time series stations worldwide. We present the first statistical evaluation of a data set of nine physical, chemical and biological parameters in the period of 1957–2013. In the past three to five decades, all of the measured parameters underwent significant long-term changes. Most striking is an ongoing decline in bottom water oxygen concentration, despite a significant decrease of nutrient and chlorophyll a concentrations. Temperature-enhanced oxygen consumption in the bottom water and a prolongation of the stratification period are discussed as possible reasons for the ongoing oxygen decline despite declining eutrophication. Observations at the BE station were compared with model output of the Kiel Baltic Sea Ice Ocean Model (BSIOM). Reproduced trends were in good agreement with observed trends for temperature and oxygen, but generally the oxygen concentration at the bottom has been overestimated.
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