Application of a laboratory gas exchange chamber for assessment of in situ mercury emissions

The potential for the use of a laboratory gas exchange system to estimate of mercury emissions from naturally and anthropogenically mercury-enriched areas was assessed by comparison of mercury fluxes measured from the same substrate in situ and in the laboratory. In general, mercury emissions measured with the laboratory chamber for daytime conditions were of the same magnitude as mean mercury emissions measured in situ with field chambers. Mercury emissions measured with both the field chamber and laboratory chamber were lower than those measured with micrometeorological methods. Within the controlled experimental regime of the laboratory chamber, data were developed that demonstrated that substrate mercury concentrations and light are important parameters in controlling mercury emissions. However, with light and other parameters interacting with the soil, the correlation between mercury fluxes and substrate mercury concentrations declined. Mercury emissions from a variety of substrates in the dark were similar to 25% of those emissions measured in the light at the same soil surface temperature.