Hg, Se and Cd belong to the group of metals that Topotecan HCl sublime below 800 °C; thus, their concentrations in samples collected after the thermal decomposition processes are lower than those in the starting samples. Arsenic, despite its similar properties, shows no such tendencies and may occur in UCG post-process ashes, as confirmed by Liu et al. .
In terms of volatility, the metals in the hard coals studied were distributed differently than in brown coal, which has a much higher moisture content and contains substances that are readily released upon heating. Following heating, coal bed cracks and loose structures were formed with an increased surface area due to the reaction, as a result of which a considerably higher amount of substances could be released from brown coal than from hard coal. Thus, the properties of the metals showed a tendency to shift toward anaerobic of metals in group III (Fig. 2).
3.2. The reference values for eluates
Excessive concentrations of parameters obtained in eluates relative to the adopted upper limits of the hydro-geochemical background for groundwater are written in italics and the values above the worst class limits for groundwater are written in bold (Table 3).