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A portable sensing platform for the detection of nutrients (PO4 3−, NO2 −, NO3 −) in natural waters has been realized through the use of rapid prototyping techniques, colorimetric chemistries, electronics, and LED-based optical detection. The sensing platform is modular in design incorporating interchangeable optical detection units, with a component cost per unit of ca. €300, and small form factor (20 cm × 6 cm x 3.5 cm). Laboratory testing and validation of the platform was performed prior to deployment at the CNR Dirigibile Italia Arctic Research Station, Ny-Aselund (79°N, 12°E). Results obtained showed excellent linear response, with a limit of detection of 0.05 μM (NO2 −, NO3 −), and 0.03 μM (PO4 3−). On the June 22, 2016 a field campaign took place within Kongsfjorden, Ny-Aselund (78.5–79°N, 11.6–12.6°E), during which 55 water samples were acquired using 10 L Niskin bottles on board the MS Teisten research vessel. 23 hydrological casts were also performed using a Seabird 19plus V2 SeaCAT Profiler CTD probe with turbidity and dissolved oxygen sensors. Water samples were subsequently analyzed for PO4 3−, NO2 −, NO3 − at the CNR Dirigibile Italia Arctic Research Station Laboratory using the adaptive sensing platform. Nutrient concentrations were compared to hydrological data to assess the processes that influence the nutrient concentrations within the Fjord. This research highlights the potential use of the adaptive sensing platform in remote locations as a stand-alone platform and/or for the validation of deployable environmental sensor networks.
Nutrients such as phosphate (PO4
3−), nitrite (NO2
−), and nitrate (NO3
−) are central in many environmental processes within the marine environment (
The measurement of nutrients in the marine environment is more complicated than tracking physical parameters (e.g., temperature, salinity, pH), but despite this, they have been amongst the major observational variables in several international global ocean expeditions since the 1970s (
Herein, we present a cost-effective, reliable bench top sensing platform for the measurements of key nutrients within the marine and freshwater environments which was developed through the COMMONSENSE project. The sensing platform was developed through the use of rapid prototyping such as FDM (Fused deposition modelling) and laser ablation, colorimetric reagent chemistries, LED (Light Emitting Diode) based optical detection. Samples were acquired in June 2016 in the Kongsfjorden, an inlet on the west coast of the Norwegian Spitsbergen Island, part of the Svalbard archipelago in the Arctic Ocean and measured on the benchtop platform at the Dirigibile Italia Arctic Research Station in Ny-Alesund.
Kongsfjorden (78.5–79°N, 11.6–12.6°E) is a fjord located in the north western part of the of the Norwegian Svalbard archipelago (
Detail of the north western part of the of the Norwegian Svalbard archipelago (inset) showing the locations of Kongsfjorden (78.5–79°N, 11.6–12.6°E) fjord, and the Kongsbreen, Kronebreen and Kongsvegen glaciers.
In summer it is mixed with Arctic water masses on the West Spitsbergen shelf and then advected inside the fjord as Transformed Atlantic Water (TAW), with characteristics and volume that significantly vary from year-to-year (TAW, Θ = 1.0–3.0°C, SA > 34.65 g/kg and σθ < 27.92 kg/m3; (Stefano
Map of Kongsfjorden showing each sampling point, depths (m) and glacier locations within the fjord generated using Ocean Data View Software.
Images of
Electronic Control was achieved
The alignment of the LED and photodiode was achieved through a 3D printed (Stratasys Objet260 Connex1) custom designed holder, through which the LED photodiode was easily removed and replaced while maintaining alignment (
The analytical performance of the sensing platform was evaluated using test solutions of known concentrations of NO2
−, NO3
− and PO4
3− (0–20 μM). All reagents and test solutions were prepared using ultra high purity (UHP) water (MilliQ, Millipore, Burlington, MA, United States) and analytical grade chemicals (Sigma Aldrich, St. Louis, MO, United States). For NO2
− analysis, 900 μL of sample and test solutions were transferred to 1.5 ml Eppendorf vials. 50 μL of Griess reagent was then added to the vials and the sample was mixed and the resulting solution was left at room temperature (approx. 20°C) for 20 min. For the determination of NO3
−, 100 μL of VCl3 (
Linear calibration curves for the detection of PO43− (0-20 μM) on the benchtop sensing platform in chamber one and chamber two and for the detection of NO2−, NO3− (0-10 μM) in chamber three and chamber.
During a cruise in Kongsfjorden on the June 22, 2016 a total of 55 water samples (10 ml aliquots) were acquired for nutrient analysis using 10 L Niskin bottles. Water samples were acquired from the surface <1 m, middle and bottom depths depending on the sample station. A total of 23 hydrological casts were performed using a Seabird 19plus V2 SeaCAT Profiler CTD probe with turbidity and dissolved oxygen sensors
Concentrations of NO2 −, NO3 − and PO4 3- at (<0.5 m) in Kongsfjorden on the June 22, 2016.
At the southern-most part of the fjord, nearest the Kronebreen-Kongsvegen glacial fronts at station 009b (see
Nutrient profiles
In the outer region of the fjord at the station 001, samples also show an increase in NO2
−, NO3
− and PO4
3− concentrations with increasing depth from <0.5 m (4.14 μM NO2 –, 0.17 NO3
− μM, 1.37 μM PO4
3−) to 150.83 m (4.14 μM NO2
−, 5.10 NO3
− μM, 22.63 μM PO4
3−) and 290 m (6.43 μM NO2
−, 8.48 NO3
− μM, 25.83 μM PO4
3−) (
Maps showing nutrient and hydrological data obtained at different depths along a transect from the sampling station 001 to 008.
Characterising the distribution of nutrients is essential for understanding and protecting marine habitats. Nutrient availability is one of the most direct mechanisms by which glacial discharge affects marine primary productivity in polar environments (
The original contributions presented in the study are included in the article/Supplementary Material; further inquiries can be directed to the corresponding author.
MM: Project management, platform development, data analysis, fieldwork, manuscript preparation. AR: Field Scientific Co-ordinator,
This work was carried out with substantial contributions of the EU-funded FP7 project COMMON SENSE (Grant agreement No 614155), the availability of the CNR Dirigibile Italia Arctic Station and its laboratory managed by the Italian National Research Council (CNR) and the facilities of the international scientific base in Ny-Ålesund (Svalbard, Norway). 3D printing was carried out at the Nano Research Facility in Dublin City University, which was funded under the Programme for Research in Third Level Institutions (PRTLI) Cycle 5. Insight (INSIGHT Centre, Grant number SFI/12/RC/2289).
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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