An Evaluation of the Wet Oxidation Technique for Use in Determining the Energy Content of Seston Samples

Abstract

Many of the techniques available to determine energy content have problems inherent in their use on samples with a high proportion of inorganic minerals. One technique which may readily be used on such samples is wet oxidation, in which the sample is quantitatively chemically oxidized. However, this technique is infrequently used because of a potentially significant underestimation of energy content, due to incomplete oxidation of nitrogenous compounds. For a number of plant and animal tissues, wet oxidation with potassium dichromate gave values for energy content within ±3.0% of the value determined by bomb calorimetry.Seston samples on glass fiber filters may also be quickly and accurately analyzed using this procedure. The conversion from either weight loss on ignition or carbon and nitrogen content to energy content, using literature-derived conversion factors, is extremely inaccurate. Conversion of the wet oxidation values to carbon content gave inconsistent results, if the carbon content of the samples is required this should be determined directly by C:N analysis, or by quantifying the CO₂ liberated by wet oxidation.Key words: wet oxidation, seston analysis, energy budgets, calorimetry, weight loss on ignition, CHN analysis