Articles | Volume 11, issue 6
Ocean Sci., 11, 937–946, 2015
Ocean Sci., 11, 937–946, 2015

Research article 27 Nov 2015

Research article | 27 Nov 2015

An improved method for the determination of dissolved nitric oxide (NO) in seawater samples

H. E. Lutterbeck and H. W. Bange H. E. Lutterbeck and H. W. Bange
  • Chemical Oceanography, Division of Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany

Abstract. Nitric oxide (NO) is a short-lived intermediate of the oceanic nitrogen cycle; however, due to its high reactivity, measurements of dissolved NO in seawater are rare. Here we present an improved method to determine NO concentrations in discrete seawater samples. The set-up of our system consisted of a chemiluminescence NO analyser connected to a stripping unit. The limit of detection for our method is 5 pmol NO in aqueous solution, which translates into 0.25 nmol L−1 when using a 20 mL seawater sample volume. Our method was applied to measure high-resolution depth profiles of dissolved NO during a cruise to the eastern tropical South Pacific Ocean. It is fast and comparably easy to handle; thus it opens the door for investigating the distribution of NO in the ocean, and it facilitates laboratory studies on NO pathways.