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Microbial uptake of dissolved organic and inorganic nitrogen in Randers Fjord

Veuger, B. and Middelburg, J.J. and Boschker, H.T.S. and Nieuwenhuize, J. and Rijswijk van, P. and Rochelle-Newall, E.J. and Navarro, N. (2004) Microbial uptake of dissolved organic and inorganic nitrogen in Randers Fjord. Estuarine Coastal and Shelf Science, 61, 507-515. ISSN 0272-7714.

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Uptake of 15N labeled NH4+, NO3-, urea and dissolved free amino acids (DFAA) was measured in April and August 2001 at 6 stations along the salinity gradient of Randers Fjord (Denmark) in order to clarify the relative importance of dissolved organic and inorganic nitrogen (DON and DIN) as N sources for the estuarine planktonic microbial community. Although microbial N uptake was generally dominated by DIN (especially NH4+), DON (both urea and DFAA) also served as an important N source and occasionally dominated uptake. Uptake of 15N labeled algal derived DON was measured in an attempt to mimic uptake of the complex ambient DON pool. Uptake rates for the algal derived DON in April were similar to those for NH4+ and even higher than the summed uptake of NH4+, NO3-, urea and DFAA in August, suggesting that DON other than urea and DFAA, likely dissolved combined amino acids (DCAA), also served as an important N source. In addition, the relative contributions of heterotrophic bacteria and phytoplankton to total microbial N uptake was estimated from bacterial productivity and measured by inhibiting bacterial N uptake with antibiotics. [KEYWORDS: nitrogen uptake; DON; DIN; amino acids; urea; phytoplankton; heterotrophic bacteria; Randers Fjord; estuary]

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:11614
Deposited On:23 Nov 2011 01:00
Last Modified:31 Mar 2014 11:06

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