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Colored Dissolved Organic Matter (CDOM/fDOM)

Chromophoric Dissolved Organic Matter or Colored Dissolved Organic Matter (CDOM): Both refer to organic matter in water that absorbs strongly in the ultraviolet (UV) spectrum. Fluorescent Dissolved Organic Matter (fDOM) refers to the fraction of CDOM that fluoresces. fDOM is a surrogate for CDOM, and a fast and easy means of tracking DOM in natural waters.

DOM and sediment in North Sea. Photo by NASA Earth Observatory
DOM and sediment in North Sea. Photo by NASA Earth ObservatoryDOM and sediment in North Sea. Photo by NASA Earth Observatory DOM in wastewater settling tank. Photo by John Rostron, wikimedia commonsDOM in wastewater settling tank. Photo by John Rostron, wikimedia commons EXO fDOM sensorEXO fDOM sensor


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YSI has Authorized Distributors all over the globe. View a map and find your closest contact for YSI Colored Dissolved Organic Matter (CDOM/fDOM) products and accessories.

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Have a question about your YSI Colored Dissolved Organic Matter (CDOM/fDOM) product? Check out the support page with resources compiled just for you.

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Want to return a product for service? Here you’ll find authorized service centers and instructions on how to send in your YSI Colored Dissolved Organic Matter (CDOM/fDOM) product.

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Measuring CDOM/fDOM is important because concentrations of CDOM affect submerged aquatic vegetation, coral reefs and other benthic communities.

Other fDOM applications include:

  • Continuous monitoring of wastewater discharge. fDOM fluorescence corresponds to total organic carbon (TOC), which is an indicator of discharge water quality.
  • fDOM concentration can indicate the dispersion, transport and mixing of a water mass.
  • Hydrology studies demonstrate connection between flow/discharge and fDOM concentrations in rivers and floodplains

EXO1 water quality sonde from YSI

EXO1 Water Quality Sonde

The EXO1 multiparameter water quality sonde collects data with up to four user-replaceable smart sensors and an integral pressure transducer for depth.


 EXO2 water quality sonde from YSI

EXO2 Water Quality Sonde

Collect data to 250 m with the advanced EXO2 sonde – six replaceable smart sensors and a central wiper to clean biofouling.


EXO sonde with fDOM sensor in forested watershed

A Closer Look at fDOM Measurement

Archived Webinar:
A Closer Look at fDOM Measurement

Original Broadcast: February 26, 2013 —1:00 PM - 1:45 PM EST

Listen to an informative webinar about measuring dissolved organic matter in surface water using YSI's newest smart sensor, fDOM.

We discuss topics including:

• What is fDOM?
• How does field fDOM measurement work?
      - Details on YSI's EXO fDOM sensor
• Applications for fDOM measurement with EXO, including:
     - Augmented sensor suite for enhanced ecosystem monitoring
     - Proxy for DOM/DOC/TOC, land-derived nutrients and contaminants
     - Light attenuation and primary productivity studies 
• Interpreting fDOM data and interferences
• Benefits of combining fDOM with other water quality sensors




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