Non-optical in-situ Measurement of Phosphorous in Marine Environments

Protecting the quality of water in the nation’s streams, rivers, lakes, and estuaries is of critical importance for human and ecosystem health. Current measurement tools to quantify nutrients in the terrestrial-aquatic- interface (TAI), and specifically phosphorus, are subject to a number of challenges. Biological fouling is a major concern to any technique requiring an optical path, chemical methods require exhaustible reagents, and ion-selective electrodes have poor accuracy and precision and are plagued by interferences. TDA Research Inc. (TDA) proposes a non-optical based approach immune to bio-fouling and capable of high accuracy and precision with excellent sensitivity. The technique does not require reagent cartridges or rely on chemical binding of only specific types of phosphate. The technique will be able to present measurement of orthophosphate and other phosphorus compounds clearly and without the need for extraction/concentration. The method is fast and low power. Since the technique does not require an optical path, it is nearly immune to biofouling and is intended for measurement in remote locations over long duration. The goal of this project is to show a novel, non-optical, non-chemometric measurement method can measure orthophosphate at 0.25 mg/L along with other phosphorus compounds. We will establish how many different phosphorus species can be measured simultaneously since laboratory experiments with this technique have already shown that phosphonates, phosphates, pyrophosphates, and polyphosphates are easily distinguished by their spectroscopic characteristics. Our goal in the Phase I is to demonstrate portable measurement solution can deliver both sensitivity and selectivity and benchmark its performance against elemental analysis using MP-AES. In the Phase I we will build a protype sonde with our technology and demonstrate its monitoring capability in Evergreen Lake in the Bear Creek watershed. Our sensor will provide near-real time measurements (time scale of minutes) necessary to understand phosphorus nutrient cycles under normal conditions and also after transient events like floods or hurricanes. Data from our sensor will improve predictive models for marine ecosystem health. The sensor can be deployed for ecosystem study, or also for monitoring for high influxes of phosphorus to mitigate eutrophication events. Remote monitoring in marine environments is well established for nitrates, but very few options exist for phosphorus measurements. Our sensor will add a new capability where a great need currently exists.