Geothermal environmental assessment behaviour of selected geothermal brine contaminants in plants and soils

Abstract

The behaviour of selected elements found in geothermal fluids of the Roosevelt Hot Springs known geothermal resource area (KGRA) was investigated in plant and soil systems. The kinetics of these potential environmental contaminants were studied by using soil columns and selected cultivated and native plant species. The data collected indicate that, of the 26 elements examined, lithium is the best indicator of geothermal contamination. This element, which occurs in the fluids at concentrations exceeding 25.0 parts per million (ppm), was readily detected in and through a variety of different test soils. The plant species, which were exposed via a number of rooting media including soils, vermiculite, and hydroponic solution, absorbed and translocated lithium to all aerial plant parts. The greatest lithium concentration occurred in hydroponically grown tomatoes where the leaves, stems, and fruit contain 914.5±35.8 ppm, 106.5±3.2 ppm, and 35.7±4.8 ppm of this element, respectively. Two native species — four-winged saltbush, A triplex canescens, and bitterbush, Purshia tridentata — appear to be good biological indicators since they accumulated nearly twice as much lithium, 309.8±29.9 ppm and 226.0±5.8 ppm, respectively, as did other native species tested.