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Underway monitoring of nanomolar nitrate plus nitrite and phosphate in oligotrophic seawater
Author(s) -
Li Qian P.,
Hansell Dennis A.,
Zhang JiaZhong
Publication year - 2008
Publication title -
limnology and oceanography: methods
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.898
H-Index - 72
ISSN - 1541-5856
DOI - 10.4319/lom.2008.6.319
Subject(s) - nitrate , nitrite , seawater , phosphate , nutrient , environmental chemistry , environmental science , oceanography , chemistry , geology , organic chemistry
To study nutrient dynamics and cycling in oligotrophic open ocean environments, continuous measurements of nanomolar nitrate, nitrite, and phosphate are valuable. However, such studies are usually impeded by the detection limits of conventional nutrient‐sensors and analyzers. Here, we developed a shipboard deployable underway system for simultaneously monitoring nitrate plus nitrite and phosphate at nanomolar concentrations by the coupling of an optimized flow injection analytical system with two long‐path liquid waveguide capillary cells (LWCC). The detection limits are ~2 nM for nitrate plus nitrite and ~1.5 nM for phosphate, respectively. Results from realtime surveys of waters over the west Florida continental shelf and the oligotrophic Sargasso Sea are presented. This system has also been successfully used to analyze more than 1000 discrete seawater samples manually during 2 cruises in the North Atlantic.