Project II.2.2a: Quantifying fluxes and gradients - River to ocean CDOM Fluorescence

Project Name:II.2.2a: Quantifying fluxes and gradients - River to ocean CDOM Fluorescence
Project Lead: Joseph Needoba

Project Description
Dissolved organic carbon (DOC) represents a significant carbon reservoir in all aquatic systems and is a dominant source of organic carbon in rivers and estuaries. Characterization of DOC concentration and composition is challenging and typically requires advanced chemical methodology. Colored dissolved organic matter (CDOM) is a component of DOC with chemical properties that absorb and re-emit energy as fluorescence. The wavelength-specific properties of absorption and fluorescence can be used to quantify and characterize CDOM with relative ease. Recent advances in spectrofluorometry now make it possible to analyze samples accurately and efficiently as a tool to quantify CDOM composition in aquatic systems.

This project will employ both a sensitive spectrofluorometer (Horiba Jobin yvon, Fluoromax-4) and a photodiode-array spectrophotometer (World Precision Instruments, TIDAS I) to characterize CDOM optical properties of the Columbia River, the Columbia River estuary, the coastal ocean, and offshore waters within the CMOP operational domain. Employing CMOP cruises to collect samples, we will strive to measure all representative environments over multiple seasons.

Fit in program
Provides an important river-to-ocean characterization of the organic carbon cycle. Utilizes cutting-edge instruments and techniques in aquatic biogeochemistry. Provides fundamental information for near-future advances in sensor technology. trongly aligned with goals of microbial team to understand drivers of biological production (by characterizing carbon compounds, potentially indicating substrates for growth and/or cycling of carbon and other organic materials. Aligned with goals of ‘microbial modulation of methane dynamics’ project.

Outcomes
Desired outcomes are: (a) PARAFAC, SUVA, and Fluorescence Index analysis of Pacific Northwest CDOM composition; (b) identification of suitable excitation/emission pairs for sensor development; (c) scientific publications