Simultaneous determination of particulate organic carbon, nitrogen and phosphorus collected on filters, using a semiautomatic wet-oxidation method

Abstract

A wet-oxidation method is presented for determining simultaneously particulate organic carbon (POC), particulate organic nitrogen (PON) and particulate organic phosphorus (POP) collected on filters. Conversion of POC, PON and POP to inorganic products, carbon dioxide, nitrate+nitrite and soluble reactive phosphate respectively, is performed by a persulfate wet-oxidation in slight alkaline condition. After oxidation, inorganic products are dissolved in the digestion mixture and concentrations are measured automatically by colorimetry using a 3 channel Technicon AutoAnalyzer®. Concurrent comparisons were made with dry combustion at 950°C for POC and PON (CHN analysis) and with former wet-oxidation procedure for POP. Results indicated high efficiency to oxidize natural suspended particulate matter from sea- and freshwater as well as phytoplankton cultures and sinking particles collected by sediment traps. This method also exhibits good reliability and precision in comparison with former procedures and is highly suitable for routine analysis and especially appropriate for shipboard work.