STEPWISE THERMAL-ANALYSIS TECHNIQUE FOR ESTIMATING MERCURY PHASES IN SOILS AND SEDIMENTS

Traces of Hg phases in soils, sediments and mineral standards were determined by thermal analysis at successively higher temperature steps. Mercury was liberated at each step, concentrated on Au, then determined by flameless atomic absorption. Some Hg determinations were made by liberating the element by continuous heating at the rate of 20 and 100-degrees-C min-1. Soil samples were collected from the vicinity of a Hg mine, a Cu deposit and fault zones. Sediment samples were collected near a Hg roasting plant, a chlor-alkali plant and a Cu smelter. The results show that, for all the samples, most of the Hg is liberated during the 200-degrees-C temperature step. Some samples show thermal release characteristics similar to those of a cinnabar-quartz mixture. Other samples show characteristics possibly related to sorbed elemental Hg. The results show that stepwise compared to continuous heating gives more resolution and thus may prove to be easier in estimating traces of Hg phases in soils and sediments.