Estimating gaseous mercury emissions from contaminated floodplain soils to the atmosphere with simple field measurement techniques

The atmospheric emission of mercury (Hg) from a contaminated wetlands system was studied in the floodplains along the river Elbe (Northern Germany). Results suggest that wetlands can be important transformation and phase transfer regions, linking the terrestrial, aquatic and atmospheric compartments of regional biogeochemical Hg cycles. Fluxes determined by flux chamber measurements averaged 43 +/- 5 ng m(-)2 h(-)1. Additionally, soil gas probe sampling was introduced to determine mercury concentrations in soil air. This technique shows some promise for detecting and confining mercury contamination in soils. We also propose that measurements of total gaseous mercury (TGM) in soil air and the near-surface atmosphere, in combination with simple soil physical parameters, may be suitable for calculating semiquantitative estimates of Hg evaporation from contaminated soils, based on laminar diffusion considerations. The results are compared to other Hg flux measurements, and the advantages and disadvantages of different approaches to quantify Hg emissions from soils are discussed, especially with regard to possible systematic bias.