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Vapour-phase fumigation with HCl is routinely used to remove inorganic carbon in preparation for the measurement of the concentration and δ13C value of organic carbon in a sample using elemental analysis coupled to an isotope ratio mass spectrometer. Acidification of the sample to be analyzed can lead to the loss of low molecular weight conjugate bases as volatile organic acids during the acidification and/or the drying steps following fumigation, through protonation of the conjugate base and volatilization. Such loss could lead to a severe bias in incubation experiments where 13C-enriched compounds such as acetate are used to trace reaction pathways or metabolites in a cultivation medium or a mesocosm for example. In this work, we enriched a carbonate-free freshwater sediment with 1-13C sodium acetate by 5, 10 and 20 ‰ relative to the δ13C value of the natural organic carbon of the sediment, and then tested the effects of HCl fumigation, drying at 50 °C and drying at room temperature, alone or in combination, on the measured δ13C values. We found that fumigation and drying at 50 °C, alone or in combination, both lead to the loss of the majority of the 13C-enriched acetate spike. [ABSTRACT FROM AUTHOR]

The mapping of the damage caused by natural disasters is a crucial step in deciding on the actions to take at the international, national, and local levels. The large variety of representations that we have observed leads to problems of transfer and variations in analysis. In this article, we propose a representation, Regular Dot map (RD), and we compare it to 4 others routinely used to visualise post-disaster damage. Our comparison is based on a user study in which a set of participants carried out various tasks on multiple datasets using the various visualisations. We then analysed the behaviour during the experiment using three approaches: (1) quantitative analysis of user answers according to the reality on the ground, (2) quantitative analysis of user preferences in terms of perceived effectiveness and appearance, and (3) qualitative analysis of the data collected using an eye tracker. The results of this study lead us to believe that RD is the best compromise in terms of effectiveness among the various representations studied. [ABSTRACT FROM AUTHOR]