Cyanate distribution and uptake above and within the Eastern Tropical South Pacific oxygen deficient zone. (20th November 2017)

• Record Type: Journal Article
• Authors: Widner, Brittany; Mordy, Calvin W.; Mulholland, Margaret R.
• Is Part Of: Limnology and oceanography. Volume 63(2018)Supplement 1
• Page Start: S177
• Page End: S192
• Publication Date: 2017-11-20
• Subjects: Limnology -- Periodicals; Oceanography -- Periodicals; Océanographie; Limnologie; Limnology; Oceanography; Computer network resources; Périodique électronique (Descripteur de forme); Ressource Internet (Descripteur de forme); Periodicals; 551.4805
• DOI: 10.1002/lno.10730
• Languages: English
• ISSNs: 0024-3590

Abstract

Abstract: Cyanate is a simple reduced nitrogen (N) compound that can be a source of N and carbon (C) for marine organisms and may also be a substrate for dissimilatory N processes such as nitrification and anammox. We measured cyanate distributions and cyanate and urea uptake in the Eastern Tropical South Pacific, a region defined by coastal upwelling, high primary productivity, a shallow oxic layer, and rapid N loss from a large oxygen deficient zone (ODZ). Cyanate concentrations ranged from below the limit of detection (0.4 nM) to 45 nM in the oxic upper water column. Below the oxycline, cyanate concentrations were largely below detection except for small cyanate peaks (2–8.3 nM) within the core of the ODZ at some stations. The majority of N taken up in the shallow oxic layer was from ammonium and urea (78% ± 8%); cyanate uptake was < 2% of these. Uptake of cyanate fluctuated diurnally with the highest rates of cyanate N uptake in the early afternoon. In the ODZ, rates of cyanate, urea, and ammonium uptake were similar to each other (0.1–14 nmol N L −1 d −1 ) and to previously reported rates of 29 N2 production supported by cyanate and ammonium (3–14 nmol N2 L −1 d −1 ). This suggests a role for cyanate in the metabolism of anaerobic microbes and a potential role for cyanate in the anammox reaction (cyanammox). To our knowledge, these represent the first rates of N uptake in a marine anoxic water column.