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Abstract: We describe the first long-term implementation of the radiocarbon (14C) method to study the share of biogenic (%Bio C) and fossil (%Fos C) carbon in combustion CO2. At five Swiss incinerators, a total of 24 three-week measurement campaigns were performed over 1year. Temporally averaged bag samples were analyzed for 14CO2 by accelerator mass spectrometry. Significant differences between the plants in the share of fossil CO2 were observed, with annual mean values from 43.4±3.9% to 54.5±3.1%. Variations can be explained by the waste composition of the respective plant. Based on our dataset, an average value of 48±4%Fos C was determined for waste incineration in Switzerland. No clear annual trend in %Fos C was observed for four of the monitored incinerators, while one incinerator showed considerable variations, which are likely due to the separation and temporary storage of bulky goods. [Copyright &y& Elsevier]

A field application of the radiocarbon (14C) method was developed to determine the ratio of biogenic vs. fossil CO2 emissions from waste-to-energy plants (WTE). This methodology can be used to assign the Kyoto relevant share of fossil CO2 emissions, which is highly relevant for emission budgets and emission trading. Furthermore, heat and electricity produced by waste incinerators might be labelled depending on the fossil or biogenic nature of the primary energy source. The method development includes representative on-site CO2 absorption and subsequent release in the laboratory. Furthermore, a reference value for the 14C content of pure biogenic waste (f M,bio) was determined as 1.130±0.038. Gas samples for 14CO2 analysis were taken at three WTEs during one month each. Results were compared to an alternative approach based on mass and energy balances. Both methods were in excellent agreement and indicated a fraction of biogenic CO2 slightly above 50%. [Copyright &y& Elsevier]

Abstract: The 13C/12C ratio of atmospheric CO2 (δ13C–CO2) is a powerful tool to quantify CO2 flux strength of different ecosystem compartments, which is especially important in understanding the global carbon cycle and in predictions of the future uptake or release of CO2 in the global environment. To date, the majority of CO2 isotope studies have required air sample collection at remote locations, followed by laboratory analysis, which limits the number and frequency of measurements. In our study, we have developed a novel calibration strategy for the precise measurement of δ13C–CO2 in ambient air using a field-deployable Fourier transform infrared (FTIR) spectrometer. Quantification relies on a robust partial least squares (PLS) algorithm in combination with a set of multi-component standard spectra to determine δ13C–CO2 values from −8.7‰ to −19.0‰. Furthermore, the instrumental setup has significantly been improved to stabilize gas temperature and pressure. Thus we achieved an average accuracy for δ13C–CO2 of 0.4‰ and a precision of 0.15‰. [Copyright &y& Elsevier]