Speciation of mercury in soils and sediments by thermal evaporation and cold vapor atomic absorption

Evaporation studies of mercury in several chemical compounds, soils, and sediments with a high content of organic matter indicate that a quantitative release is possible at temperatures as low as 400°C. The desorption behaviour from a gold column is not influenced. Only from samples with a thermal prehistory, such as brown coal ash, did mercury evaporate at higher temperatures. Qualitative conclusions can be derived about the content of metallic mercury as well as mercury associated with organic matter or sulfide. A comparison of the analytical results obtained by using the evaporation technique or by dissolving using a mixture of conc. HCl and HNO₃ shows good agreement; the advantages of the evaporation technique are obvious at very low mercury concentrations.