Continuous Phosphate Monitoring in Rivers and Streams and Its Correlation to Total P Loads.

Continuous monitoring of phosphorus loads in rivers and streams will be an important tool to assess whether or not state nutrient reduction plans are meeting their established goals. Continuous real time monitoring for phosphorus in rivers and streams is not practical because there is no sensor technology available. However, autonomous, microfluidics-based analyzers are one option for achieving continuous near real-time monitoring. One such analyzer, the Cycle-P, which is manufactured by Seabird Coastal, was placed in Lake Decatur in Central Illinois as part of the National Great River Research and Education Center’s (NGRREC) Great Rivers Ecological Observatory Network (GREON). The phosphate analyzer was accompanied by a spectroscopic nitrate sensor and a multiple parameter water quality sonde. Orthophosphate concentrations measured by the Cycle-P were compared to grab samples collected adjacent to the GREON unit where the Cycle-P was housed. The grab samples were analyzed for orthophosphate and total P. A correlation was developed between orthophosphate measured by the Cycle=P and total P measured in the grab samples. The goal is to use orthophosphate data from microfluidic analyzers to predict total P fluxes in rivers and streams.