Transport and hydraulically-induced recycling of phosphorus in the North Sea-Baltic Sea transition zone

Autor: Christian Christiansen, Anke Struve, Rikke R. Kepp, Lars Chresten Lund-Hansen, Morten Holtegaard Nielsen, Torben Vang
Jazyk: angličtina
Rok vydání: 2006
Předmět:
Zdroj: Oceanologia, Vol 48, Iss 2, Pp 175-191 (2006)
Druh dokumentu: article
ISSN: 0078-3234
Popis: Bottom-mounted acoustic Doppler current profiler measurementsindicate that the net transport of water (844 m3 s-1) in theLittle Belt makes up only 6% of the total transport betweenthe Baltic Sea and the North Sea. This is a smaller percentagethan the 9% commonly found in the literature. Owing to barotropicand tidal currents the gross transport is 5 times larger. Thenet transport is directed towards the North Sea mainly in thetop 32 m of the water column but towards the Baltic Sea it occursin the lower 5 m of the water column. The resulting transportof phosphorus is strongly affected by vertical mixing in an areaof hydraulic control in the narrow part of the Little Belt. Comparisonsof phosphorus profiles in stratified waters and in the mixingarea indicate a yearly entrainment of 15 tonnes P from the bottomwater to the surface layer. This vertical transport of P formspart of an internal loop in the general transport between theBaltic Sea and the North Sea. Compared to the transport observed15-16 years ago, the present net phosphorus transport of 163tonnes yr-1 from the Baltic Sea through the Little Belt is substantiallylower.
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