Evidence of microbial control of Hg0emissions from uncontaminated terrestrial soils

Weinheim

2008

S. 200-209

6 Abb., 1 Tab., 38 Lit. Ang.

Artikel aus einer ZeitschriftUnselbständiges Werk

200146603

It is known that in wetland soils and soils contaminated with mercury (Hg), direct biotic reduction of Hg2+ to Hg0 leads to Hg0 emissions to the atmosphere. In terrestrial soils, numerous factors have been reported that control Hg0 emissions, but it is still unclear if biotic processes are also important. In this study, microbiological activity of Cambisol monoliths from a subalpine grassland with Hg concentrations of approx. 100 ng g-1 were manipulated in laboratory incubation experiments. Elemental Hg emissions were recorded together with CO2 emission rates as proxy for microbiological respiration. Emissions of Hg0 increased from approx. 5 ng m-2 h-1 up to 130 ng m-2 h-1 with stimulated biological activity (glucose addition, increase in temperature) and decreased with inhibited activity (chloroform fumigation, autoclaving, drying). Similar patterns with evasion rates of >90 ng m-2 h-1 were observed after dried soils were remoistened again. Our results indicated that processes leading to Hg0 emissions from uncontaminated terrestrial soils are at least partly controlled by biotic processes. However, it is still uncertain if Hg0 emission is caused directly by biotic reduction of Hg2+ or indirectly by abiotic reduction, induced by products of microbiological degradation, e.g., humic acids.