Fluxes of dissolved aluminum and manganese to the Weddell Sea and indications for manganese co-limitation
Middag, R.; de Baar, H.J.W.; Klunder, M.B.; Laan, P. (2013). Fluxes of dissolved aluminum and manganese to the Weddell Sea and indications for manganese co-limitation. Limnol. Oceanogr. 58(1): 287-300. dx.doi.org/10.4319/lo.2013.58.1.0287
In: Limnology and Oceanography. American Society of Limnology and Oceanography: Waco, Tex., etc. ISSN 0024-3590; e-ISSN 1939-5590, more
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| Abstract |
The trace metals aluminum (Al) and manganese (Mn) were studied in the Weddell Sea in March 2008. Concentrations of dissolved Al ([Al]) were slightly elevated (0.23-0.35 nmol L-1) in the surface layer compared to the subsurface minimum (0.07-0.21 nmol L-1) observed in the winter water. Atmospheric deposition is the main source of Al to the central Weddell Sea (22 mu mol m(-2) yr(-1)), and the residence time of dissolved Al in the upper mixed layer is similar to 0.8 yr. The flux from the shelf and slope regions equals about 50% of the atmospheric input of Al to the western Weddell Sea. The highest [Al] in the Weddell Sea bottom water (WSBW) is related to the formation of deep water, and the associated downward flux is in the range of 3-10 mu mol Al m(-2) yr(-1). The concentrations of dissolved Mn ([Mn]) were depleted in the surface layer, likely as a result of biological uptake, as indicated by the correlation among Mn, major nutrients, and fluorescence. The significant negative relation between the Delta Mn:Delta P ratio and the ambient concentration of dissolved iron indicates iron-Mn co-limitation. The flux of Mn from the continental margin is about 2.2 times greater than atmospheric input (1.1 mu mol m(-2) yr(-1)). The flux of both Al and Mn from the continental margin indicates melting of continental ice (icebergs) or direct continental runoff. The slightly elevated [Mn] in the WSBW is due to a relatively small flux of 1 mu mol Mn m(-2) yr(-1) associated with WSBW formation. |
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