Aquatic Sciences Meeting, Albuquerque 2001

CS20 Microbial Dynamics

Date: Friday, February 16, 2001, Time: 11:45:00 AM

Location: Ruidoso/Pecos

Sanderson, M, P, College of William and Mary/VIMS, Gloucester Point, USA, mps@vims.edu

Wheeler, B, R, University of Delaware, Lewes, USA, jaywh@udel.edu

Bronk, D, A, College of William and Mary/VIMS, Gloucester Point, USA, bronk@vims.edu

INORGANIC AND ORGANIC NITROGEN UPTAKE IN THE SOUTH ATLANTIC BIGHT

Inorganic (ammonium, nitrate) and organic (urea, DPA) nitrogen uptake rates were measured in two regions of the South Atlantic Bight (SAB) using N15 techniques. Experiments were conducted in the southern SAB in June 1997 and in the northern SAB (Charleston Bump region) in March 1999. In both regions greater than 90% of the total dissolved nitrogen was dissolved organic nitrogen (DON), however near the Charleston Bump, urea comprised approximately 40% of the DON compared to 6% in the south. In the southern SAB, upwards of 70% of total nitrogen uptake was as ammonium, followed by 16% as urea with nitrate and DPA accounting for 10 and 4% respectively. The Charleston Bump region was dominated by urea uptake (52% total nitrogen) followed by ammonium (44%), then nitrate and DPA (3 and 1% respectively). Uptake of humic nitrogen was also measured and appeared to be significant. However, abiotic absorption of N15-labeled humic nitrogen was observed in controls suggesting that the bulk of incorporation of humic nitrogen into particles was not biologically mediated.

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Aquatic Sciences Meeting, Albuquerque 2001

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