Trace Metal Chemistry and Silicification of Micro-Organisms in Geothermal Sinter, Taupo Volcanic Zone, New Zealand

Abstract

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, By TI, and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92-94?C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthemophiles can be correlated with the dissolved silica content of the fluid. There was little evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature ends of the terrestrial thermal spring ecosystems studied.