Phosphate in rivers
A case study
Too much of anything is bad
The challenge of continuous monitoring
Low-resolution data may miss important pulses, such as rain runoff, and hence make it difficult to understand the sources and variability in phosphate pollution.
Phosphate is often measured using colourimetric methods, where the water sample is mixed with colour-forming reagents. The intensity of the colour produced is proportional to the phosphate concentration in the sample.
Some in-field phosphate analysers exist (using automated colourimetric methods), but these are either large/bulky, require mains power, or consume large quantities of fluid per sample. High fluid consumption results in large quantities of chemical waste left over from the analysis, and we think it is important that this is not released into the environment.
The ClearWater Sensors phosphate sensor uses microfluidics and lab-on-chip technology: colourimetric phosphate analysis is conducted on a miniaturised, low-power device that uses very low sample volumes (e.g. 0.5 mL per sample).
It can produce laboratory-quality data without the drawback of high power consumption, so can operate on batteries in remote locations.
Liquid waste from the chemical anlaysis is produced in such low volumes that it is stored onboard the sensor in a user-swappable reagent canister.
The sensor can conduct over 2000 measurements per deployment and operates without mains power. It can be submerged for discrete, in-stream deployment and is readily moved to new locations to map variations. It can operate in either freshwater, estuaries, or the ocean.
River monitoring application
The sensor was submerged 1 m below the surface, hung from a bracket extending out from the riverbank. No mains power was available in this remote location, so the sensor was powered by a 12 V battery and solar panel located on the riverbank. Data was telemetered using 3G so that it was accessible in real-time via a web portal. A multi-parameter sonde was deployed alongside the phosphate sensor to collect ancillary data on water temperature, conductivity and dissolved oxygen.
The sensor was deployed for 9 weeks, with occasional visits by the scientists to collect grab samples for comparison purposes.
Data for new insights
Please contact us at firstname.lastname@example.org for more information about how the ClearWater phosphate sensor can be used for your application.
Want to know more about how to use the sensors?
 Walter K. Dodds, Wes W. Bouska, Jeffrey L. Eitzmann, Tyler J. Pilger, Kristen L. Pitts, Alyssa J. Riley, Joshua T. Schloesser, and Darren J. Thornbrugh, Eutrophication of U.S. Freshwaters: Analysis of Potential Economic Damages, Environmental Science & Technology 2009 43 (1), 12-19
 Geraldine S. Clinton-Bailey, Maxime M. Grand, Alexander D. Beaton, Adrian M. Nightingale, David R. Owsianka, Gregory J. Slavik, Douglas P. Connelly, Christopher L. Cardwell, and Matthew C. Mowlem, A Lab-on-Chip Analyzer for in Situ Measurement of Soluble Reactive Phosphate: Improved Phosphate Blue Assay and Application to Fluvial Monitoring, Environmental Science & Technology 2017 51 (17), 9989-9995