Rapid Phosphate Monitoring in Irish Freshwater Systems Using a Novel Microfluidic Colorimetric System
Authors: Bracker Rachel , Cronin Lisa , Grubliauskas Aironas , Free Louis , O’Grady Joyce , Power Sean , Daly Karen , Kent Nigel , Regan Fiona , White Blánaid 
Published: February 2023

The discharge of phosphorus associated with wastewater has decreased significantly in Europe over the past 25 years1, however the problem of diffuse pollution persists2.&#160; Studies have shown that regulatory monitoring can miss elevated spikes in phosphorus concentrations3 and high frequency monitoring is required4. Such programmes are resource intensive, requiring effective tools which enable appropriate water quality data collection and quality assurance5.A low cost, portable, and rapid phosphate detection system is needed to enable the quick detection of phosphate in areas affected by high phosphate levels6. A new system is being developed by evolving a colorimetric detection system using microfluidic lab-on-a-disc technology which has previously been demonstrated7. It utilizes a micro-spectrometer and the molybdenum blue method, and has been built with the intent of requiring limited training.The range of the system is 5-400 &#181;g/L, which encompasses the threshold value of 35 &#181;g/L P for Irish rivers and groundwaters8. The system is extremely portable due to its compact size and weighing less than 2 kg. With a run time of 15 minutes per ten samples, it enables the in-situ detection of phosphate for rapid on-site monitoring.To test the system, rivers in the northwest of Ireland were identified. Three of these rivers have historical orthophosphate readings in the range of 5 - 47 &#181;g/L and two others were reported considerably higher at 84 &#181;g/L.&#160;&#160;With this microfluidic phosphate detection system, rapid in-situ detection and reliable, real-time monitoring of phosphorus in freshwater systems can be achieved.&#160;References:1)European waters -- Assessment of status and pressures 2018 &#8212; European Environment Agency. https://www.eea.europa.eu/publications/state-of-water (accessed 2022-06-13).2)Biddulph, M.; Collins, A. l.; Foster, I. d. l.; Holmes, N. The Scale Problem in Tackling Diffuse Water Pollution from Agriculture: Insights from the Avon Demonstration Test Catchment Programme in England. River Research and Applications 2017, 33 (10), 1527&#8211;1538. https://doi.org/10.1002/rra.3222.3)Fones, G. R.; Bakir, A.; Gray, J.; Mattingley, L.; Measham, N.; Knight, P.; Bowes, M. J.; Greenwood, R.; Mills, G. A. Using High-Frequency Phosphorus Monitoring for Water Quality Management: A Case Study of the Upper River Itchen, UK. Environ Monit Assess 2020, 192 (3), 184. https://doi.org/10.1007/s10661-020-8138-0.4)Bowes, M. J.; Palmer-Felgate, E. J.; Jarvie, H. P.; Loewenthal, M.; Wickham, H. D.; Harman, S. A.; Carr, E. High-Frequency Phosphorus Monitoring of the River Kennet, UK: Are Ecological Problems Due to Intermittent Sewage Treatment Works Failures? Environ. Monit. 2012, 14 (12), 3137&#8211;3145. https://doi.org/10.1039/C2EM30705G.5)Quinn, N. W. T.; Dinar, A.; Sridharan, V. Decision Support Tools for Water Quality Management. Water 2022, 14 (22), 3644. https://doi.org/10.3390/w14223644.6)Park J.; Kim, K. T.; Lee; W. H. Recent advances in information and communications technology (ICT) and sensor technology for monitoring water quality. 2020, Water, 12 (2)7)O&#8217;Grady, J., Kent N., Regan, F. (2021). Design, build and demonstration of a fast, reliable&#160; portable phosphate field analyser. Case Stud. Chem. Environ. Eng., 2020, 4, 1001688)Tierney, D.; O&#8217;Boyle, S. Water Quality in 2016: An Indicators Report; Environmental Protection Agency, Ireland: Wexford, 2018; p 48.