An Approach to Problems of a Geothermal Mercury Survey, Puna, Hawaii

Abstract

Concentrations of soil mercury of 15 to 1250 ppb were determined in the Puna geothermal area on the lower east rift zone of Kilauea volcano. As the area is young and volcanically active a wide range of soils exist. Hg concentrations are partly controlled by such factors as soils development and organic content, which tend to complicate interpretation of the absolute concentrations measured. The pH of both ground gas and soil may also influence transport and fixation of the Hg, and some low pH solids may be due to SO2 and CO2 in ground gas. By relating the Hg concentration of different soil types these influences can be significantly reduced, producing results that better reflect the geothermal component of Hg to the soil. The major difficulty in using this approach in an area with marked variations in soil type is in determining the background concentrations and in the classification of the soil types.