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SUNA V2 UV Nitrate Sensor

The SUNA V2 UV nitrate sensor is the ultimate chemical-free solution for autonomous monitoring of nitrogen-based nutrient concentrations in ocean, estuarine, and high turbidity freshwater environments to 500 m.
For Descriptions,
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USGS real-time interactive multi-parameter map of water quality in the US. IOOS automated nutrient monitoring observatory in the coastal and estuarine waters of the Northeast, with the goal of obtaining and delivering high-frequency nutrient data.
The Indian River Lagoon Observatory Network of Environmental Sensors is conducting long-term ecosystem-based research to provide data to managers and decision-makers about this nationally significant estuary. “Super” or sentry, water gages provide real-time, continuous measurements of water quality characteristics and nutrients multiple times a day over the course of a year.
Super-gage sites in Illinois with HydroCycle-PO4. NOAA GLERL helps CILER forecast HAB blooms in the Western Lake Erie. Buoy P data.
HAB Bulletin  

[Latest firmware available here]

The SUNA V2 is the ultimate solution for real-time nutrient monitoring. This sensor measures nitrate with industry leading accuracy and stability over a wide range of environmental conditions (including extremely turbid and high CDOM conditions), from blue-ocean nitraclines to storm runoff in rivers and streams. The SUNA V2 incorporates the proven MBARI-ISUS nitrate measurement technology, which is based on the absorption characteristics of nitrate in the UV light spectrum. 

Features

  • Accuracy and stability over a wide range of environmental conditions*
  • Adaptive sampling intelligence
  • Universal real-time nitrate processing algorithm
  • 10 optical pathlength
  • Serial data output
  • Titanium housing with a 500 meter depth rating**
  • User-friendly UCI software (Windows and Mac OS X compatible)

*Class based freshwater calibration stock. Specific calibration must be added (freshwater, seawater, high range freshwater).
** Images on this site may show older housing materials. All SUNA V2's now have titanium housings.

A Versatile UV Nitrate Sensor for Operation in Diverse Environments
The SUNA V2 (Submersible Ultraviolet Nitrate Analyzer) is a chemical-free UV nitrate sensor based on the ISUS (In Situ Ultraviolet Spectroscopy) UV nitrate measurement technology developed at MBARI. Sea-Bird Scientific adapted the technology to develop the SUNA V2 to measure nitrate in increasingly more challenging environments including extremely turbid and high CDOM conditions. With improved optics and built-in logic, the SUNA V2 measures nitrate with industry leading accuracy and stability over a wide range of environmental conditions, from blue-ocean nitraclines to storm runoff in rivers and streams.

The SUNA V2 is the ultimate solution for real-time nutrient monitoring. Every SUNA V2 now comes with our proven universal real-time nitrate processing algorithm, which has been upgraded to include adaptive sampling intelligence that automatically adjusts for signal strength. Also included in every SUNA V2 is a 10 mm pathlength, a class based nitrate calibration, serial data output and a 500 meter depth rating.In addition to these standard features, a wide range of optional features provide the ability to customize the instrument to meet your specific research and deployment needs.

Optional Features

  • Reduced 5 mm pathlength for high turbidity environments
  • Active fouling control with built in wiper
  • Freshwater and seawater calibrations
  • Internal data logging and scheduling with 2 GB memory
  • SDI-12 interface
  • USB communications

 

Performance    

  10 mm Pathlength 5 mm Pathlength
Accuracy 2 µM (0.028 mgN/L) 4 µM (0.056 mgN/L)
  Fresh water or Seawater with T-S Correction Seawater withour T-S Correction
Precision (at 3σ) 0.3 µM 2.4 µM
Limit of Detection 0.3 µM 2.4 µM
Drift (per hour of lamp time) <0.3 µM <1.0 µM


See User’s Manual for detailed performance specifications.

Optics

Path Length 10 mm & 5 mm (high turbidity option)
Wavelength Range 190-370 nm
Lamp Type Continuous Wave, Deuterium Lamp
Lamp Lifetime 900 h

 

Electrical

Input Voltage 8-18 VDC
Power Consumption 7.5 W (0.625 A at 12 V) nominal

 

Resolution

Material  Titanium
Depth Rating 500 m
Weight (Acetal/ Titanium) 5.1 kg
Displacement 1749 cm3

 

Calibration

Methods
  • Seawater
  • Freshwater
  • Class-based Freshwater
Correction

Real-Time temperature-salinity correction available*  (0-35 oC, 0-40 PSU)

* Requires external T/S data.

 

Dimensions in mm [inches]

The list below includes (as applicable) the current product brochure, manual, and quick guide; software manual(s); and application notes.

Title Type Publication Date PDF File
SUNA V2 Datasheet Product Datasheet Wednesday, September 13, 2017 datasheet_SUNAV2.pdf
In Situ Nutrient Sensors Product Brochure Friday, October 13, 2017 web-seabird_nutrients-October-2017-4pager.pdf
REMINDER: SUNA V2 Humidity Bulletin: A complete solution for ingress Field Service Bulletins Thursday, June 22, 2017 SUNA V2 Humidity Bulletin - A complete solution for ingress.pdf
SUNA Update: SUNA Standard service description and V2 warranty quality upgrade Field Service Bulletins Thursday, June 22, 2017 SUNA Standard service description and V2 warranty quality upgrade.pdf
AN118 Nutrient Units Primer Application Notes Friday, June 23, 2017 Nutrient-Units-Primer.pdf
AN119 CDOM Interference on Nitrate Measurements Application Notes Friday, June 23, 2017 SUNA-CDOM Interference on Nitrate Measurements.pdf
In Situ Nutrient Monitoring in the Murderkill Estuary Application Article Thursday, June 22, 2017 In Situ Nutrient Monitoring in the Murderkill Estuary.pdf
Real Time Nitrate and Phosphate Monitoring for Ecosystem Modelling Application Article Thursday, June 22, 2017 Real Time Nitrate and Phosphate Monitoring for Ecosystem Modeling .pdf
Nutrient Monitoring in Foreman Branch in Support of the Chester River Watershed Observatory Application Article Thursday, June 22, 2017 Nutrient Monitoring in Foreman Branch in Support of the Chester River Watershed Observatory.pdf
ISUS/SUNA Nitrate Measurements in Networked Ocean Observing Systems Application Article Thursday, June 22, 2017 ISUS SUNA Nitrate Measurements in Networked Ocean Observing Systems.pdf
In Situ Nutrient Sensors Product Brochure Wednesday, October 11, 2017 web-seabird_nutrients-October-2017-4pager.pdf
SUNA V2 user manual Product Manual Tuesday, September 26, 2017 SUNAe.pdf
SUNA V2 (Deep) user manual Product Manual Tuesday, September 26, 2017 SUNADeepe.pdf
Measuring Nitrate in Puget Sound using Optical Sensors White Paper Wednesday, November 1, 2017 Measuring Nitrate in Puget Sound using Optical Sensors.pdf
In-Situ Esturine Observatory To Evaluate Interannual Varibility In Nutrient Dynamics In Yaquina Bay Scientific Poster Thursday, June 22, 2017 In-Situ Esturine Observatory To Evaluate Interannual Varibility In Nutrient Dynamics In Yaquina Bay.pdf
UCI Manual Software Manual Wednesday, September 6, 2017 UCI-1.2-User-Manual.pdf

UCI

UCI is a graphical software application that makes setup, operation, and in-field reference checks easy and robust. UCI is the recommended software for interacting with HydroCAT, HydroCAT-EP, SUNA, and Deep SUNA.
Version 1.2.4 released November 3, 2017
UCI-1.2.4-b210-x86.exe for Windows 7/8/10
UCI-1.2.4-195-macos-x86_64.pkg for Mac OS X / macOS
Version 2.5.1 released February 10, 2015
SUNA-LC_Release_2.5.1.zip for Windows 7/8/10


How does absorption from CDOM affect the SUNA V2 nitrate measurement?

The SUNA V2 determines nitrate concentrations from the shape of the UV absorption curve. The least squares curve fitting algorithm uses calibrated extinction coefficients for nitrate and bromide (strong absorbing species in salt water) to calculate the concentration of nitrate from the UV absorption curve. The algorithm also employs a linear baseline correction that accounts for absorption that is not associated with either nitrate or bromide. The linear baseline correction successfully compensates for CDOM absorption in cases where the CDOM absorption is close to linear in the low UV. The composition of CDOM is dependent on the type of drainage area around a particular watershed and is therefore highly variable. As a result, the shape of CDOM absorption curve can vary from region to region. For this reason, the baseline correction does not always successfully compensate for CDOM absorption. In cases where the CDOM absorption curve mimics the shape of the nitrate absorption curve, a positive bias can occur.

The most common approach for correcting a positive bias caused by CDOM absorption is to correlate the continuous in situ nitrate data provided by the SUNA V2 with nitrate concentrations from discrete water quality samples measured in a laboratory. The bias may then be calculated either as an absolute offset or as a factor. In order to provide the most robust correction possible, the discrete sample size should be sufficiently large to allow for comparisons and the relationship between the in situ and discrete concentrations should be highly correlated. 

What is "adaptive sampling" and how does it work?

The SUNA V2 contains a 256 channel spectrometer that is programmed to integrate for a specific length of time (usually 300 - 500 ms) while sampling to maximize signal. That is, when the SUNA V2 takes a sample, the spectrograph collects UV light for the length of the integration period. In optically dense waters (e.g. high turbidity or CDOM), very little UV light is transmitted through the water and therefore the spectrometer "sees" a much lower signal. The new SUNA V2 is programmed to automatically increase the integration period to compensate for the low light levels. This enables the instrument to collect a strong signal in extreme environmental conditions.

Is an instrument with the class based calibration still within the published specification for accuracy? If not, what is the accuracy?

Instrument specific calibrations are more accurate and correspond to the published accuracy specifications. 

The accuracy of the class based calibration is estimated to be 2.2 uM +/- 20%.

When running my SUNA V2 on the bench, the data shows that the lamp is turning on and off. Why is this happening?

This is a safety feature of the instrument, whereby the lamp is turned off when its temperature reaches 35°C (95°F) to prevent damage from overheating. The SUNA continues to output dark frames while monitoring the temperature, and will restart the lamp once it has dropped back below 35°C. If extended in-lab use is required, immersing the SUNA in a cool bath can  prevent this behavior.

 

My SUNA V2 fails the self-test function when it tries to report the internal voltage measurements.

Although most functions of the SUNA V2 can be accomplished though the USB connection, parts of the self-test require that external power be applied. In this case, connect external power and repeat the test. If the problem persists, please contact Customer Support.

Can I use SUNA V2 that is calibrated for freshwater, in salt water applications and vice versa?

To remove baseline water absorbance spectra, SUNAs are calibrated with nitrate-spiked water, as well as nitrate-free water. The default class-based calibration uses coefficients generated from a library of historical calibrations. For greater accuracy, SUNA sensors are individually calibrated at Sea-Bird Scientific for use in fresh or seawater. Due to difference in absorptivity characteristics of seawater and freshwater, the calibration data for each of these applications is distinct.

Calibrations for instruments to be used in freshwater are determined from aqueous nitrate standards of deionized water with 40 and 4000 µmolar nitrate concentrations and pure deionized water. The second calibration at 4000 µmolar is performed for accuracy in terrestrial applications where nitrate concentrations are large. It is important to note that SUNA units configured for use in freshwater do not give reliable nitrate readings in seawater, as the interference from bromide will not be accounted for without seawater absorption data.

Instruments calibrated for use in seawater use nitrate standards of seawater with 40 µmolar nitrate concentrations and nitrate-free seawater to determine the baseline seawater absorbance spectrum. The use of seawater enables the correction for the UV absorption of bromide and other sea salt components. Instruments calibrated for use in seawater can be used in freshwater applications, but the accuracy will be decreased in regions of high nitrate concentration because the instrument is calibrated for the smaller range of nitrate concentrations typically found in seawater.

Should I provide my ISUS or SUNA with a warmup time before recording data?

We recommend updating the ISUS or SUNA's reference spectrum portion of the calibration with the instrument in the same state it will be used in the field. To update the reference spectrum, you will have to run the calibration feature in ISUSCom or UCI using a pure water sample.

For best results, we recommend the following:

1. For profiling situations, when the instrument will be run for extended times, the reference spectrum should be updated after the sensor has been run for several minutes. This will allow the Nitrate reading to stabilize.

2. For moored applications, we recommend that the instrument only be run for a short duration to collect the pure water data during the calibration. Data collection in the field should only have the instrument run for 20 seconds per acquisition.

SUNA V2 Hydro-Wiper

The Hydro-Wiper is an external anti-fouling system fully integrated with SUNA V2 nitrate sensor. The Hydro-Wiper keeps the SUNA V2 sample windows clean for several months and is specifically intended for use in freshwater and coastal systems.

Do not attempt removal of the wiper yourself. It requires a return to our service department for this task.

 

SUNA V2 Anti-fouling guard

The SUNA V2 anti-fouling guard is a semi-circular piece of perforated copper attached to a plastic armature that fits into the sample chamber. The anti-fouling guard provides passive fouling prevention through the release of copper ions that inhibit biological growth in the area. The anti-fouling guard provides a reliable and affordable approach to increase deployment time, decrease operating costs, and collect high quality data for mooring applications. The anti-fouling guard is intended for use in blue-ocean applications with low suspended sedimentation and/or low turbidity.

 

SUNA V2 Flow cell

 

The SUNA V2 flow cell is designed to adapt the SUNA V2 for flow through operations on moorings with pumped flow, ship-board underway systems or for laboratory testing and calibration. The flow cell attaches to the SUNA V2 sample chamber and tightly seals against the optical chamber windows. Nylon barbed fittings are provided to connect the flow cell to available pumped flow.

 

SBE 5P Pump

The pump module is a compact unit consisting of a centrifugal pump head and a long-life, brushless, DC, ball-bearing motor. The pump impeller and electric drive motor are coupled magnetically through the housing, providing high reliability by eliminating moving seals. The 5P has a 600-meter (1960 ft.) plastic housing.

 

Alkaline Battery Pack

Reliable and user-friendly Alkaline Battery Packs are available in 102 Ah and 51 Ah capacities. The design of the internal battery compartment allows the user to easily change the D-Cell batteries with off-the-shelf replacements. The battery packs consist of an anodized aluminum pressure case, a D-cell battery compartment and a removable end-cap.

 

Compare  Moored / Time Series Recording Instruments

SBE Measures
(C, T, P)
Auxiliary Sensors Memory Power Communication Real-Time
Data
Comments
Internal External
SBE 16plus V2 SeaCAT C-T (P) Recorder C, T, P* 6 A/D; 1 RS-232 64 Mb RS-232 Optional pump
SBE 16plus SeaCAT C-T (P) Recorder
C, T, P* 4 A/D; optional RS-232 or PAR 8 Mb RS-232 or -485 Replaced by SBE 16plus V2 in 2008
SBE 16 SeaCAT C-T (P) Recorder
C, T, P* 4 A/D 1 Mb RS-232 Replaced by SBE 16plus in 2001
SBE 16plus-IM V2 SeaCAT C-T (P) Recorder C, T, P* 6 A/D; 1 RS-232 64 Mb   Inductive Modem Optional pump
SBE 16plus-IM SeaCAT C-T (P) Recorder
C, T, P* 4 A/D; optional RS-232 or PAR 8 Mb   Inductive Modem Replaced by SBE 16plus-IM V2 in 2008
SBE 19plus V2 SeaCAT Profiler CTD C, T, P 6 A/D; 
1 RS-232
64 Mb RS-232 Programmable mode — profiling or moored
SBE 19plus SeaCAT Profiler CTD
C, T, P 4 A/D; optional PAR 8 Mb RS-232 Replaced by SBE 19plus V2 in 2008
SBE 19 SeaCAT Profiler CTD
C, T, P 4 A/D 1 - 8 Mb RS-232 Replaced by SBE 19plus in 2001
SBE 37-SM MicroCAT C-T (P) Recorder C, T, P*   8 Mb RS-232 or -485  
SBE 37-SMP MicroCAT C-T (P) Recorder C, T, P*   8 Mb RS-232, RS-485, or SDI-12 Integral pump
SBE 37-SMP-IDO MicroCAT C-T-DO (P) Recorder C, T, P* Integrated DO 8 Mb RS-232 or -485 Integral pump; Replaced by SBE 37-SMP-ODO in 2014
SBE 37-SMP-ODO MicroCAT C-T-DO (P) Recorder C, T, P* Integrated Optical DO 8 Mb RS-232, RS-485, or SDI-12 Integral pump
HydroCAT C-T-(DO)-(P) Recorder C, T, P* Integrated Optical DO* 8 Mb RS-232 & SDI-12 Integral pump; for Coastal applications to 350 m
HydroCAT-EP
C-T-pH-(DO)-(P)-(Chl)-(NTU) Recorder
C, T, P* Integrated pH, Optical DO*, Chlorophyll*, Turbidity* 16 Mb RS-232 & SDI-12 Integral pump; for Coastal applications to 350 m
SeapHOx Ocean C-T-DO-pH (P) Recorder C, T, P* Integrated Optical DO, pH 8 Mb RS-232 37-SMP-ODO with SeaFET pH sensor; to 50 m
Deep SeapHOx Ocean C-T-DO-pH (P) Recorder C, T, P* Integrated Optical DO, pH 8 Mb RS-232 37-SMP-ODO with Deep SeaFET pH sensor; to 2000 m
SBE 37-IM MicroCAT C-T (P) Recorder C, T, P*   8 Mb   Inductive modem  
SBE 37-IMP MicroCAT C-T (P) Recorder C, T, P*   8 Mb   Inductive modem Integral pump
SBE 37-IMP-IDO MicroCAT C-T-DO (P) Recorder C, T, P* Integrated DO 8 Mb   Inductive modem Integral pump; Replaced by SBE 37-IMP-ODO in 2014
SBE 37-IMP-ODO MicroCAT C-T-DO (P) Recorder C, T, P* Integrated Optical DO 8 Mb   Inductive modem Integral pump
SBE 37-SI MicroCAT C-T (P) Recorder C, T, P*   8 Mb   RS-232 or -485  
SBE 37-SIP MicroCAT C-T (P) Recorder C, T, P*   8 Mb   RS-232 or -485 Integral pump

SBE 37-SIP-IDO MicroCAT C-T-DO (P) Sensor

C, T, P* Integrated DO 8 Mb   RS-232 or -485 Integral pump
SBE 39plus Temperature (P) Recorder T, P*   64 Mb Optional USB & RS-232 Optional  
SBE 39 Temperature (P) Recorder
T, P*   32 Mb Optional RS-232 Optional Replaced by SBE 39plus in 2014
SBE 39plus-IM Temperature (P) Recorder T, P*   64 Mb   Inductive Modem & USB  
SBE 39-IM Temperature (P) Recorder T, P*   32 Mb   Inductive modem Replaced by SBE 39plus-IM in 2016
SBE 56 Temperature Logger T   64 Mb   USB    
SBE 26plus Seagauge Wave & Tide Recorder T, P C optional 32 Mb RS-232
(tides, waves, & wave statistics)
Wave & tide recorder
SBE 26 Seagauge Wave & Tide Recorder
T, P C optional 8 Mb RS-232   Replaced by SBE 26plus in 2004
SBE 53 BPR Bottom Pressure Recorder T, P C optional 32 Mb RS-232 Bottom pressure recorder
SBE 54 Tsunameter Tsunami Pressure Sensor T, P   128 Mb Optional RS-232 Tsunami pressure sensor

C = conductivity, T = temperature, P = pressure, DO = dissolved oxygen
* = optional
products are no longer in production. Follow the links above to the product page to retrieve manuals and application notes for these older products.