Project: Automated Instrumentation for Chemical Oceanography Based on Sequential Injection Lab-On-valve Technology

NSF Abstract:

The ability of oceanographers to investigate and understand chemical processes in the ocean is only as good as the accuracy and precision of the techniques available for making chemical measurements. This project seeks to upgrade an existing analytical method (the micro-Sequential Injection Lab on Valve; uSI-LOV methodology) for measurement of dissolved aluminum (Al) and phosphate (P) in seawater. Aluminum is an abundant element used for tracking dust input to the ocean from the atmosphere and the movement of water masses. Phosphate is an essential nutrient for biological growth in the ocean, showing spatial and temporal variability that affects the growth of phytoplankton. The novel uSI-LOV methods would allow unattended and accurate measurement of Al and P together, with direct benefit for oceanographic research on biogeochemical cycles and ecosystem dynamics. Additionally, the uSI-LOV methodology includes an ingenious "single standard" technique that greatly simplifies calibration of the system, can be developed for analysis of many other elements beyond Al and P, and would provide a procedure for improved inter-comparison between different studies. The refined, modular uSI-LOV system produced by this proposal will be widely applicable for use by the oceanographic community. The project will also fund an excellent interdisciplinary PhD student thesis opportunity that incorporates aspects of engineering, analytical chemistry, and oceanography.

The PIs on this project intend to adapt the micro-Sequential Injection Lab on Valve (uSI-LOV) system to the measurement of seawater Al and P using fluorescent and spectrophotometric detection with flow injection analysis. They will develop and evaluate a novel "single standard" calibration process that uses the precisely reproduced timing of the rising and falling edge of a single standard injection peak as a pseudo-standard addition curve, potentially providing better calibration of other seawater analytical systems designed for trace element and nutrient concentrations in the ocean. The improved uSI-LOV methodology has advantages of physical robustness, as well as lowered power, sample, and reagent requirements. The project will field test the uSI-LOV system during an at-sea intercalibration against established shipboard analytical methods for P and Al, and deploy a small battery operated version in shallow water to test autonomous operation. The work is directed at eventual use of the uSI-LOV technology on existing and future remote platforms and autonomous vehicles. Successful adaptation, integration into the chemical oceanography community, and future deployments would provide greatly improved chemical data sets that would inform biogeochemical models and promote significant advancements in our understanding of marine biogeochemical cycles.