Ash content was determined by combusting samples in a furnace at 600°C for 8 hours.
Beta-counting was performed on samples combusted in a sample oxidiser, i.e. a process where the radioactivity is transferred into CO2 and trapped before counting in order to avoid any quenching.
Once the compound is nebulized onto the torch, the high temperature plasma combusts the sample to the atomic state.
The ash-free dry weight (AFDW) of the sediment was determined after combusting the sample at 450°C in a muffle furnace for 24 hours.
The tritium activity was corrected for the proportion of the bubbler trapping solution taken and for the weight of sample combusted to yield the specific activity in the sample.
C and N isotopic analyses were performed by combusting samples (triplicates) using a Flash EA 1112 series elemental analyzer (Thermo Finnigan, Milano, Italy) coupled to a Delta Plus XP IRMS (Thermo Electron, Karlsruhe, Germany), at the University of Cape Town.
(Fuel)I = Mass or volume of the fuel combusted during the sample period "i," (e.g., monthly, quarterly, semi-annually, or by lot) from company records (express mass in short tons for solid fuel, volume in standard cubic feet (e.g., for gaseous fuel, and volume in gallons for liquid fuel).
The carbon-14 activity was corrected for the proportion of the bubbler trapping solution taken and for the weight of sample combusted.
To quantify the non-extractable 14C-residues (NER), soil material after ASE was homogenized and three aliquots (250 300 mg) were combusted in a Sample Oxidizer (Packard, Dreieich, Germany).
Samples were combusted in a Roboprep CHN sample converter unit, operating in continuous flow mode interfaced with a Europa Scientific ANCA-MS system consisting of a 20-20 IR mass spectrometer allowing measurement of δ13C, %C and C∶N ratio.
