Denitrification rates and excess nitrogen gas concentrations in the Arabian Sea oxygen deficient zone

Show simple item record Devol, A.H. Uhlenhopp, A.G. Naqvi, S.W.A. Brandes, J.A. Jayakumar, D.A. Naik, H. Gaurin, S. Codispoti, L.A. Yoshinari, T. 2008-02-12T04:35:58Z 2008-02-12T04:35:58Z 2006
dc.identifier.citation Deep-Sea Research I, Vol.53; 1533-1547p.
dc.description.abstract Rates of canonical, i.e. heterotrophic, water-column denitrification were measured by sup(15)N incubation techniques at a number of coastal and open ocean stations in the Arabian Sea. Measurements of N2 :Ar gas ratios were also made to obtain independent estimates of N2 excess resulting from denitrification. Measured denitrification rates (sup(15)NO3 sup(-) - sup(15-14) N2 ) at open ocean stations averaged 9.1 plus or minus 1.0 nmol Nl sup(-1) d sup(-1) (n = 15), and coastal rates averaged 33.2 plus or minus 12.4 nmol Nl sup(-1) d sup(-1) (n = 18). When extrapolated to the entire Arabian Sea, deep measurements within the offshore perennial suboxic zone indicate an overall denitrification rate of 41 TgNa sup(-1) plus or minus 18 TgNa sup(-1), which is within the range (10-44 TgNa sup(-1)) of previous estimates for canonical denitrification in the region based on stoichiometric calculations and electron transport system activity. Nitrogen excess gas measurements predict a larger nitrogen anomaly than estimated by classical stoichiometric methods (maximum anomaly = 23 mu g at Nl sup(-1) vs. 13 mu g at Nl sup(-1), respectively). This mismatch may result from incorrect assumptions of Redfield stoichiometry inherent in the nitrate deficit calculation, inputs of new nitrogen through N-fixation, N2 contributions from sedimentary denitrification along continental margins, the anammox reaction, and metal catalyzed denitrification reactions. Nevertheless, if denitrification is defined as the conversion of combined nitrogen to a gaseous end product, then the data suggest that denitrification in the Arabian Sea may have been underestimated so far
dc.language.iso en
dc.publisher Elsevier
dc.rights Copyright [2006]. It is tried to respect the rights of the copyright holders to the best of the knowledge. If it is brought to our notice by copyright holder that the rights are voilated then the item would be withdrawn.
dc.subject denitrification
dc.subject nitrowater column
dc.subject water samples
dc.title Denitrification rates and excess nitrogen gas concentrations in the Arabian Sea oxygen deficient zone
dc.type Journal Article

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