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Water Sample Collection
Water samples for both NO2 and NH4 analyses were collected using a 24 x 10-liter Niskin bottle rosette sampler equipped with a conductivity, temperature, and pressure instrument package (SBE9, Sea-Bird Electronics, Bellevue, Washington, U.S.A.). The sampler was also equipped with sensors for dissolved oxygen (SBE43, Sea-Bird) and chlorophyll fluorescence (FluoroSeatechWetlabsFLF Sensor). NH4 and NO2 were measured on board immediately after sample collection.
NO2 Analysis
Nitrite concentration was measured manually colorimetrically using standard methods (Hansen and Koroleff, 1999).
NH4 Analysis
Duplicate samples for ammonium concentration were measured immediately upon retrieval and were not filtered prior to analysis. Ammonium concentration was measured manually fluorometrically using standard methods (Holmes et al. 1999).
Measurements were compiled in Excel with CTD collection metadata.
Water samples were collected using a 24 x 10-liter Niskin bottle rosette sampler equipped with a conductivity, temperature, and pressure instrument package (SBE9, Sea-Bird Electronics, Bellevue, Washington, U.S.A.), a sensor for dissolved oxygen (SBE43, Sea-Bird), and a sensor for chlorophyll fluorescence (FluoroSeatechWetlabsFLF_Sensor).
The Sea-Bird SBE 911 plus is a type of CTD instrument package for continuous measurement of conductivity, temperature and pressure. The SBE 911 plus includes the SBE 9plus Underwater Unit and the SBE 11plus Deck Unit (for real-time readout using conductive wire) for deployment from a vessel. The combination of the SBE 9 plus and SBE 11 plus is called a SBE 911 plus. The SBE 9 plus uses Sea-Bird's standard modular temperature and conductivity sensors (SBE 3 plus and SBE 4). The SBE 9 plus CTD can be configured with up to eight auxiliary sensors to measure other parameters including dissolved oxygen, pH, turbidity, fluorescence, light (PAR), light transmission, etc.). more information from Sea-Bird Electronics
A CTD-fluorometer is an instrument package designed to measure hydrographic information (pressure, temperature and conductivity) and chlorophyll fluorescence.
10-liter Niskin bottle
A Niskin bottle (a next generation water sampler based on the Nansen bottle) is a cylindrical, non-metallic water collection device with stoppers at both ends. The bottles can be attached individually on a hydrowire or deployed in 12, 24, or 36 bottle Rosette systems mounted on a frame and combined with a CTD. Niskin bottles are used to collect discrete water samples for a range of measurements including pigments, nutrients, plankton, etc.
The Sea-Bird SBE 43 dissolved oxygen sensor is a redesign of the Clark polarographic membrane type of dissolved oxygen sensors. more information from Sea-Bird Electronics
An instrument used to measure the relative absorption of electromagnetic radiation of different wavelengths in the near infra-red, visible and ultraviolet wavebands by samples.
Fluorescence was measured on a Turner Designs fluorometer Model: 7200-000 using a 1 cm cell.
The Trilogy Laboratory Fluorometer is a compact laboratory instrument for making fluorescence, absorbance, and turbidity measurements using the appropriate snap-in application module. Fluorescence modules are available for discrete sample measurements of various fluorescent materials including chlorophyll (in vivo and extracted), rhodamine, fluorescein, cyanobacteria pigments, ammonium, CDOM, optical brighteners, and other fluorescent compounds.
Date and time (UTC) of the cast/event in ISO 8601 format (source: CTD)
Local date of cast/event in UTC-3
Latitude, N is positive (source: Ship)
Latitude degrees, N is positive
Latitude minutes
Longitude, E is positive (source: Ship)
Longitude degrees, E is positive
Longitude minutes
Station identifier, project-specific, PS = Process stations, T = Transect station
CTD cast number
Niskin bottle number
Depth (source: CTD)
Target depth of sample collection
Nitrite (NO2) concentration in µM
Ammonium (NH4) concentration in µM
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