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City of Boulder/USGS Water Quality Monitoring
General Information on Total Organic Carbon
Larry B. Barber II, PhD, US Geological Survey

Total Organic Carbon (TOC): Organic matter plays a major role in aquatic systems. It affects biogeochemical processes, nutrient cycling, biological availability, chemical transport and interactions. It also has direct implications in the planning of wastewater treatment and drinking water treatment. Organic matter content is typically measured as total organic carbon and dissolved organic carbon, which are essential components of the carbon cycle.

Organic matter in water consists of thousands of components, including macroscopic particles, colloids, dissolved macromolecules, and specific compounds.

Measurement of TOC

The TOC in Boulder Creek samples is analyzed at the U.S. Geological Survey on a Sievers Model 800 Carbon Analyzer. TOC concentration is not directly measured; the Analyzer measures total carbon (TC) and total inorganic carbon (TIC) and subtracts TIC from TC to obtain TOC. An oxidizer and an acid are added to the sample. The acid reacts with bicarbonate and carbonate ions present in the sample to release carbon dioxide (CO2). The CO2 released from bicarbonate and carbonate ions represents the TIC in the sample. The sample is then subjected to ultra-violet (UV) radiation, which reacts with the oxidant and breaks down all remaining carbon bonds in the sample to release CO2. The CO2 released from both the acid reaction and the UV radiation represents all the carbon (TC) released from the sample. TOC is then obtained by subtracting TIC from TC.

The TOC of a water body is affected by several factors, including:



Treated Sewage

Water Quality Standards and Other Criteria Regarding TOC will be available soon

Other Information about TOC will be available in the near future.

Select here for a list references used in the preparation of this information
Select here for general information about other water quality parameters.
Select here for interpretation of Total Organic Carbon data in the Boulder Creek Watershed

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Last Page Update - Monday April 23, 2007