Marine Chemical Technology and Sensors for Marine Waters: Potentials and Limits

Abstract

A significant need exists for in situ sensors that can measure chemical species involved in the major processes of primary production (photosynthesis and chemosynthesis) and respiration. Some key chemical species are O2, nutrients (N and P), micronutrients (metals), pCO2, dissolved inorganic carbon (DIC), pH, and sulfide. Sensors need to have excellent detection limits, precision, selectivity, response time, a large dynamic concentration range, low power consumption, robustness, and less variation of instrument response with temperature and pressure, as well as be free from fouling problems (biological, physical, and chemical). Here we review the principles of operation of most sensors used in marine waters. We also show that some sensors can be used in several different oceanic environments to detect the target chemical species, whereas others are useful in only one environment because of various limitations. Several sensors can be used truly in situ, whereas many others involve water brought into a flow cell via tubing to the analyzer in the environment or aboard ship. Multi-element sensors that measure many chemical species in the same water mass should be targeted for further development.

Development and Deployment of a Microfluidic Platform for Water Quality Monitoring

“…Diamond and co-workers [29,30] evaluated the yellow vanadomolybdophosphoric acid method as an analytical method for the determination of phosphate in water within a microfluidic device with the aim of producing an automated device with a field-deployable lifetime of one year. In this method ammonium molybdate, (NH 4 ) 6 3 . The resulting solution has a distinct yellow colour arising from the strong absorbance of this complex below 400 nm.…”

“…While this approach yields high quality and reliable data (assuming that the appropriate protocols are followed during collection, transport, storage and analysis of the sample) the cost per sample is significant due to the manpower requirement for sample collection as well as the cost of analysis. This approach is therefore incapable of meeting the demand for monitoring at the much higher temporal frequencies and geographical densities which are envisaged [6].…”

Development of an In-situ Analyzer for Nutrient Monitoring in Seawater

“…With the use of in situ analyzers, high precision and accuracy of measurements can be achieved, and the spatial and temporal resolution of the acquired data can be increased [2,3].…”

“…Using wet chemical techniques with the addition of chemical regents and based on laboratory methods, there has been a rapid development of in-situ analyzers for the determination of nutrient in seawater during the past decades [2][3][4]. Nutrients react with the added chemical regents, form new chemical compounds with chromogenic groups, thus can be detected using spectrometric method.…”

Environmental monitoring using autonomous vehicles: a survey of recent searching techniques

“…However, sensing methods and platforms are a very broad field that is out of the scope of this paper. The interested reader is referred to the review articles [5,6] for sensing systems in air or water.…”