Concentrations of Trace Elements in Waters, Soils, and Plants of the Olkaria Geothermal Field, Kenya

Abstract

Concentrations of lead, zinc, copper, cadmium, and boron have been measured in geothermal waters from wells and cooling tower discharges, as well as in soils and plants that are in contact with geothermal waters of the Olkaria field. Element concentrations were also determined in naturally discharging hot springs at Hell's Gate. Results show no differences between metal concentrations in natural discharges, compared to drilled geothermal fluids. Soils in contact with geothermal fluids concentrate elements by factors of between 13 and 6000 in comparison to the metal concentration in the overlying water column.; The concentration factors between soils and water increase in the order B,Cd,Pb,Cu,Zn. Plants in contact with geothermal waters also have high metal concentrations, comparable to the levels in the soils. Green algae show a very high capacity to concentrate metals in geothermal waters and may be good indicators of trace metal; pollution in geothermal areas.

Waste geothermal waters should therefore be reinjected, rather than being disposed of on surface ponds and lagoons, to ameliorate the problem of meal enrichment in soils and their uptake by plants and animals.