Sustained, autonomous coastal nutrient observations aboard moorings and vertical profilers

Egli, Peter J.; Veitch, Scott P.; Hanson, Alfred K.

doi:10.23919/oceans.2009.5422420

Cited by 3 publications

(5 citation statements)

References 11 publications

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“…Table 1 indicates the figures of merit of the analyzer following our analytical improvements and compares the performance with other portable on-site analyzers reported in the literature and/or commercially available (WIZ [25], APNA [52], Hydrocycle PO4 [53], NAS3X [54], ANAIS [26], ALCHEMIST [23], NuLAB [55], and Lab on Chip (LOC) [56][57][58], as well as other UV spectral sensors for NO 3 − such as SUNA [59], OPUS [13,60], and SUV-6 [61]). The WIZ, APNA, NAS3X, ANAIS, and NuLAB devices are the only multi-nutrient analyzers reported to date.…”

Section: Analytical Performancementioning

confidence: 99%

Improvement of On-Site Sensor for Simultaneous Determination of Phosphate, Silicic Acid, Nitrate plus Nitrite in Seawater

Altahan

Espósito

Achterberg

2022

Sensors

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Accurate, on-site determinations of macronutrients (phosphate (PO43−), nitrate (NO3−), and silicic acid (H4SiO4)) in seawater in real time are essential to obtain information on their distribution, flux, and role in marine biogeochemical cycles. The development of robust sensors for long-term on-site analysis of macronutrients in seawater is a great challenge. Here, we present improvements of a commercial automated sensor for nutrients (including PO43−, H4SiO4, and NO2− plus NO3−), suitable for a variety of aquatic environments. The sensor uses the phosphomolybdate blue method for PO43−, the silicomolybdate blue method for H4SiO4 and the Griess reagent method for NO2−, modified with vanadium chloride as reducing agent for the determination of NO3−. Here, we report the optimization of analytical conditions, including reaction time for PO43− analysis, complexation time for H4SiO4 analysis, and analyte to reagent ratio for NO3− analysis. The instrument showed wide linear ranges, from 0.2 to 100 μM PO43−, between 0.2 and 100 μM H4SiO4, from 0.5 to 100 μM NO3−, and between 0.4 and 100 μM NO2−, with detection limits of 0.18 μM, 0.15 μM, 0.45 μM, and 0.35 μM for PO43−, H4SiO4, NO3−, and NO2−, respectively. The analyzer showed good precision with a relative standard deviation of 8.9% for PO43−, 4.8% for H4SiO4, and 7.4% for NO2− plus NO3− during routine analysis of certified reference materials (KANSO, Japan). The analyzer performed well in the field during a 46-day deployment on a pontoon in the Kiel Fjord (located in the southwestern Baltic Sea), with a water supply from a depth of 1 m. The system successfully collected 443, 440, and 409 on-site data points for PO43−, Σ(NO3− + NO2−), and H4SiO4, respectively. Time series data agreed well with data obtained from the analysis of discretely collected samples using standard reference laboratory procedures and showed clear correlations with key hydrographic parameters throughout the deployment period.

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Section: Analytical Performancementioning

confidence: 99%

Improvement of On-Site Sensor for Simultaneous Determination of Phosphate, Silicic Acid, Nitrate plus Nitrite in Seawater

Altahan

Espósito

Achterberg

2022

Sensors

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“…Wet chemistry analyzers have addressed sample introduction and pretreatment requirements using 10 μm screen filters, at times paired with copper wire for biofouling mitigation, which have proven to be effective with minimal maintenance in real-world deployments. 110,115 Instrument service to components, including cleaning of external films and particulate matter, and replacement of reagents, standards, wash solution, and filters have been reported to take place on a weekly or biweekly basis, especially in turbid and highly eutrophic environments. 100,110 Challenges for extending deployments of wet chemistry FDS include accounting for inevitable optical issues in turbid and complex sample matrices, where colloidal and suspended particulate matter can cause light scattering and refraction.…”

Section: And Limitationsmentioning

confidence: 99%

“…110,115 Instrument service to components, including cleaning of external films and particulate matter, and replacement of reagents, standards, wash solution, and filters have been reported to take place on a weekly or biweekly basis, especially in turbid and highly eutrophic environments. 100,110 Challenges for extending deployments of wet chemistry FDS include accounting for inevitable optical issues in turbid and complex sample matrices, where colloidal and suspended particulate matter can cause light scattering and refraction. Biofouling, another inexorable process in the natural environment, can significantly affect optical measurements in under 1 week's time and still requires a sustainable and effective solution.…”

Section: And Limitationsmentioning

confidence: 99%

“…One of SubChemSystems’ (USA) current FDS, the Autonomous Profiling Nutrient Analyzer (APNA), is designed to measure submeter scale nutrient gradients in either autonomous interval or continuous data collection mode . SubChemSystems’ instrumentation has been reported to track nitrite and other nutrients in chemical plumes, investigate thin plankton layers and the influence of stratification and turbulence, identify fine-scale structures of nitrite profiles, and investigate biogeochemical cycling at ecologically critical scales for model validation and support. , Using the APNA in estuarine environments, Egli et al captured changes in nitrite concentrations caused by tidal oscillations and advective fluxes, turbulence from coastal storms, upwelling, and freshwater runoff. Gilbert et al sampled a salt-water estuary at an hourly time scale and used the enhanced spatial and temporal coverage to assess mixing behavior associated with ebb and flood tides and demonstrated nutrient transformations and water body mixing across the tidal and seasonal cycles.…”

Section: In Situ Examples and Current State Of The Artmentioning

confidence: 99%

“…For real-world applications, wet chemistry with the Griess assay remains the most popular detection strategy with the most prolific examples of deployment documentation (Table ). Wet chemistry analyzers have addressed sample introduction and pretreatment requirements using 10 μm screen filters, at times paired with copper wire for biofouling mitigation, which have proven to be effective with minimal maintenance in real-world deployments. , Instrument service to components, including cleaning of external films and particulate matter, and replacement of reagents, standards, wash solution, and filters have been reported to take place on a weekly or biweekly basis, especially in turbid and highly eutrophic environments. , …”

Section: Fds Outlook: Technical Advancements and Limitationsmentioning

confidence: 99%

See 2 more Smart Citations

Path to Impact for Autonomous Field Deployable Chemical Sensors: A Case Study of in Situ Nitrite Sensors

Schierenbeck

Smith

2017

Environ. Sci. Technol.

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Natural freshwater systems have been severely affected by excess loading of macronutrients (e.g., nitrogen and phosphorus) from fertilizers, fossil fuels, and human and livestock waste. In the USA, impacts to drinking water quality, biogeochemical cycles, and aquatic ecosystems are estimated to cost US$210 billion annually. Field-deployable nutrient sensors (FDS) offer potential to support research and resource management efforts by acquiring higher resolution data than are currently supported by expensive conventional sampling methods. Following nearly 40 years of research and development, FDS instruments are now starting to penetrate commercial markets. However, instrument uncertainty factors (high cost, reliability, accuracy, and precision) are key drivers impeding the uptake of FDS by the majority of users. Using nitrite sensors as a case study, we review the trends, opportunities, and challenges in producing and implementing FDS from a perspective of innovation and impact. We characterize the user community and consumer needs, identify trends in research approaches, tabulate state-of-the-art examples and specifications, and discuss data life cycle considerations. With further development of FDS through prototyping and testing in real-world applications, these tools can deliver information for protecting and restoring natural waters, enhancing process control for industrial operations and water treatment, and providing novel research insights.

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Toward a Harmonization for Using in situ Nutrient Sensors in the Marine Environment

et al. 2020

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Sustained, autonomous coastal nutrient observations aboard moorings and vertical profilers

Cited by 3 publications

References 11 publications

Improvement of On-Site Sensor for Simultaneous Determination of Phosphate, Silicic Acid, Nitrate plus Nitrite in Seawater

Improvement of On-Site Sensor for Simultaneous Determination of Phosphate, Silicic Acid, Nitrate plus Nitrite in Seawater

Path to Impact for Autonomous Field Deployable Chemical Sensors: A Case Study of in Situ Nitrite Sensors

Toward a Harmonization for Using in situ Nutrient Sensors in the Marine Environment

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