Observations and analysis of mercury in the topsoil within a 100-m radius of a chlor-alkali plant in northern Kazakstan using EPA method 7473

摘要

This limited study has shown a comparison of mercury concentrations at different sample collection locations at the chlor-alkali plant in Northern Kazakhstan. Method 7473 uses a direct mercury analyzer for Hg in solid samples. A small amount of sample is dried and combusted. The elemental Hg is amalgamated with gold. The gold film is then heated to release the Hg, which is detected at 253.7 nm similar to CVAAS methodology. Soils were analyzed directly and eliminated the need for acid digestion, however it was not well-suited for samples with high total mercury (i.e. greater than 1 wt pencent). Methyl mercury in soil was prepared by acid bromide/methylene chloride extraction and analyzed by aqueous phase ethylation, isothermal GC separation, and CVAFS detection. Results show low production of methyl mercury in the topsoil near the chlor-alkali plant. Hg hot spots were identified in the middle of the plant at various locations. A variety of different cleanup measures have been identified.