Total carbon and total organic carbon in sediments and soils are measured independently using a LECO CR-412 Carbon Determinator. The percent Total Carbon (TC) is determined by analyzing an oven-dried sediment sample. Percent Total Organic Carbon (TOC) is determined by analyzing a dried sediment sample after all inorganic carbon has been removed by acidification. The percent Total Inorganic Carbon (TIC) is determined by subtracting the TOC result from the TC result for a given sediment sample.

During analysis, dried sediment goes through a combustion process that causes carbon-bearing compounds to break down and free the carbon for detection. The carbon is combusted at 1,350°C under an oxygen atmosphere and is oxidized to form CO2 gas. This sample gas flows through scrubber tubes to remove any water and other interfering species, then flows through a linearized non-dispersive infrared (NDIR) detection cell. The NDIR cell measures the mass of carbon dioxide gas present relative to set of 6 calibration standards, and this mass is converted to a percentage value taking into account the sample weight.