Program and Agenda

Abstract

AMMONIUM DISTRIBUTION AT STATION ALOHA IN THE NORTH PACIFIC SUBTROPICAL GYRE

Primary production in oligotrophic systems, like the North Pacific Subtropical Gyre (NPSG), is partly driven by remineralized nutrients, including ammonium which is also a substrate for nitrification. Despite its importance, ammonium has not been routinely measured as part of the Hawaii Ocean Time-series (HOT) because its concentration is generally below the detection limits of commonly used methods. Automated methods for the colorimetric analysis of ammonium, urea and nitrite were developed using a Liquid Waveguide Capillary Cell, which allowed its detection above 4 nM (1 nM for nitrite). The distribution of ammonium was studied during two cruises at St. ALOHA, obtaining a total of 63 profiles. These profiles allow the study of short-term changes in the ammonium distribution, as well as its occasional accumulation at specific regions of the water column (e.g. deep chlorophyll maximum-DCM). We found that the accumulation of ammonium around the DCM was inversely correlated with chlorophyll concentration, dissolved oxygen and light, suggesting net production by heterotrophs and net uptake by growing phytoplankton. We also measured relatively high ammonium concentrations (60-70 nM) below the euphotic zone, in well oxygenated waters.

ePoster: https://sites.google.com/site/cmoresegura/

Authors

Segura-Noguera, M., CMORE, University of Hawai'i, USA, mariona.segura@gmail.com

Curless, S. E., CMORE, University of Hawai'i, USA, curless@hawaii.edu

Church, M. J., CMORE, University of Hawai'i, USA, mjchurch@hawaii.edu

Karl, D. M., CMORE, University of Hawai'i, USA, dkarl@hawaii.edu

Details

Poster presentation

Session #:049
Date: 2/27/2014
Time: 16:00 - 18:00
Location: Poster/Exhibit Hall

Presentation is given by student: No

PosterID: 2441