Autonomous Monitoring of Low Phosphate Concentrations at TAIs

C53-25a-271365Although phosphate is a critical nutrient involved in estuarine productivity, it is also a well-known contaminant of surface and ground water. This contamination can have significant effects in sensitive areas such as terrestrial aquatic interfaces (TAIs) where the flux of nutrients can change over a relatively short period of time leading to hypoxia and the formation of harmful algal blooms. Researchers and other stakeholders have not been able to adequately monitor these potentially dangerous nutrient fluctuations because of limitations in the monitoring equipment currently available. This knowledge gap will be addressed with the development of a phosphate monitoring system that is robust, accurate and capable of making frequent measurements. Our approach is to adapt and integrate our cutting-edge technologies into a robust, modular micro-fluidic platform. With a micro-fluidic based system, the resulting instrument will be extremely portable and require minimal resources for long-term autonomous operation. In Phase I of this project, an automated instrument was designed, built, and used to detect orthophosphate over a wide dynamic range (0.03 mg/L to 18 mg/L). More significantly, this instrument was able to operate in a variety of challenging situations where other portable instruments do not function accurately. These challenging environments include: 1) water with high sediment concentration and high total suspended solids; 2) locations where biofouling is a problem; 3) water with a high concentration of chemicals that interfere with the phosphate assay chemistry; and 4) locations with shallow boreholes or streams. All three of these challenging scenarios have been addressed in the Phase I work toward an autonomous, robust and field-deployable orthophosphate analyzer. In Phase II of this project, a modular instrument based on our work in Phase I will be developed, manufactured, and deployed in the field. The main module will consist of the optofluidic and sample- handling systems. Another module will contain reagents and waste necessary for the phosphate assay and instrument maintenance. The final module will contain the power and communication systems that will allow researchers to stream data from the instrument in real time. This modular system allows the user to customize the instrument depending on their specific needs. With these features the instrument will be deployable for months at a time without maintenance. Parties from the private sector that would be interested in the development of the proposed instrument include environmental researchers in both academia and industries that conduct continuous water/process monitoring. Ultimately, we believe that the proposed product is both highly marketable and has a high likelihood of attracting further funding from large instrument companies already involved in water monitoring.