Measurements of Salinity in the Coastal Ocean: A Review of Requirements and Technologies

Woody, Catherine; Shih, Eddie; Miller, Jerry L.; Royer, Thomas C.; Atkinson, Larry P.; Moody, Richard S.

doi:10.4031/mtsj.34.2.4

Cited by 21 publications

(7 citation statements)

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“…25–42 with acceptable accuracy, its use in low salinity waters is however limited , and consequently the desalination unit may provide an alternative for in situ salinity measurements in most types of natural water. Optical sensors − are currently emerging for this same purpose, but they have not yet been implemented for in situ measurements and field data continue to be extracted from EC measurements using CTD multiparameter probes.…”

Section: Resultsmentioning

confidence: 99%

In Situ Detection of Macronutrients and Chloride in Seawater by Submersible Electrochemical Sensors

et al. 2018

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A new submersible probe for the in situ detection of nitrate, nitrite, and chloride in seawater is presented. Inline coupling of a desalination unit, an acidification unit, and a sensing flow cell containing all-solid-state membrane electrodes allows for the potentiometric detection of nitrate and nitrite after removal of the key interfering ions in seawater, chloride and hydroxide. Thus, the electrodes exhibited attractive analytical performances for the potentiometric detection of nitrate and nitrite in desalinated and acidified seawater: fast response time ( t < 12 s), excellent stability (long-term drifts of <0.5 mV h), good reproducibility (calibration parameter deviation of <3%), and satisfactory accuracy (uncertainties <8%Diff compared to reference technique). The desalination cell, which can be repetitively used for about 30 times, may additionally be used as an exhaustive, and therefore calibration-free, electrochemical sensor for chloride and indirect salinity detection. The detection of these two parameters together with nitrate and nitrite may be useful for the correlation of relative changes in macronutrient levels with salinity cycles, which is of special interest in recessed coastal water bodies. The system is capable of autonomous operation during deployment, with routines for repetitive measurements (every 2 h), data storage and management, and computer visualization of the data in real time. In situ temporal profiles observed in the Arcachon Bay (France) showed valuable environmental information concerning tide-dependent cycles of nitrate and chloride levels in the lagoon, which are here observed for the first time using direct in situ measurements. The submersible probe based on membrane electrodes presented herein may facilitate the study of biogeochemical processes occurring in marine ecosystems by the direct monitoring of nitrate and nitrite levels, which are key chemical targets in coastal waters.

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Section: Resultsmentioning

confidence: 99%

In Situ Detection of Macronutrients and Chloride in Seawater by Submersible Electrochemical Sensors

et al. 2018

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“…We now demonstrate the utility of the compensation methods described above to the salinity measurement. Salinity measurements are important in many areas of environmental and marine science such as global warming, − ecological variations, − and biotic activities. − The refractive index of seawater changes by Δ n ≈ 2 × 10 –3 /% salinity, so the demonstrated sensitivity of a GMR sensor in the low 10 –5 range allows the determination of salinity with high accuracy. Salinity measurements are typically conducted in the field and involve mechanical vibrations and temperature fluctuations; hence, salinity measurements are ideally suited to showcasing the benefit of the compensation methods introduced here.…”

Section: Resultsmentioning

confidence: 99%

“…We now demonstrate the utility of the compensation methods described above to the salinity measurement. Salinity measurements are important in many areas of environmental and marine science such as global warming, 34 − 36 ecological variations, 37 − 39 and biotic activities. 40 − 42 The refractive index of seawater changes by Δ n ≈ 2 × 10 –3 /% salinity, 43 so the demonstrated sensitivity of a GMR sensor in the low 10 –5 range 4 allows the determination of salinity with high accuracy.…”

Section: Resultsmentioning

confidence: 99%

Noise Tolerant Photonic Bowtie Grating Environmental Sensor

Li,

Suliali,

Sahoo

et al. 2024

ACS Sens.

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Resonant photonic refractive index sensors have made major advances based on their high sensitivity and contact-less readout capability, which is advantageous in many areas of science and technology. A major issue for the technological implementation of such sensors is their response to external influences, such as vibrations and temperature variations; the more sensitive a sensor, the more susceptible it also becomes to external influences. Here, we introduce a novel bowtieshaped sensor that is highly responsive to refractive index variations while compensating for temperature changes and mechanical (linear and angular) vibrations. We exemplify its capability by demonstrating the detection of salinity to a precision of 0.1%, corresponding to 2.3 × 10 −4 refractive index units in the presence of temperature fluctuations and mechanical vibrations. As a second exemplar, we detected bacteria growth in a pilot industrial environment. Our results demonstrate that it is possible to translate high sensitivity resonant photonic refractive index sensors into real-world environments.

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“…Three years later, to fix the fouling problem when used in seawater, an inductive cell was added to STD [ 77 ]. In the following decades, digitalization and microprocessor were added into the development of sensing instruments gradually, which solved salinity ’spiking’ issues caused by a mismatch of sensor response time between temperature and conductivity [ 78 ]. After that, the practical salinity scale was proposed, which leads to the generalization and standardization of the measurement [ 79 , 80 ].…”

Section: Essential Ocean Variablesmentioning

confidence: 99%

Review of Underwater Sensing Technologies and Applications

Sun

Cui

Chen

2021

Sensors

119

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As the ocean development process speeds up, the technical means of ocean exploration are being upgraded. Due to the characteristics of seawater and the complex underwater environment, conventional measurement and sensing methods used for land are difficult to apply in the underwater environment directly. Especially for the seabed topography, it is impossible to carry out long-distance and accurate detection via electromagnetic waves. Therefore, various types of acoustic and even optical sensing devices for underwater applications have come into use. Equipped by submersibles, those underwater sensors can sense underwater wide-range and accurately. Moreover, the development of sensor technology will be modified and optimized according to the needs of ocean exploitation. This paper has made a summary of the ocean sensing technologies applied in some critical underwater scenarios, including geological surveys, navigation and communication, marine environmental parameters, and underwater inspections. In order to contain as many submersible-based sensors as possible, we have to make a trade-off on breadth and depth. In the end, the authors predict the development trend of underwater sensor technology based on the future ocean exploration requirements.

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Measurements of Salinity in the Coastal Ocean: A Review of Requirements and Technologies

Cited by 21 publications

References 0 publications

In Situ Detection of Macronutrients and Chloride in Seawater by Submersible Electrochemical Sensors

In Situ Detection of Macronutrients and Chloride in Seawater by Submersible Electrochemical Sensors

Noise Tolerant Photonic Bowtie Grating Environmental Sensor

Review of Underwater Sensing Technologies and Applications

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