Development and evaluation of a sampling system to determine gaseous Mercury fluxes using an aerodynamic micrometeorological gradient method

An aerodynamic gradient micrometeorological approach to the measurement of total gaseous mercury (TGM) flux has been developed. This method has been applied in many field studies for the characterization of TGM flux from various mercuriferous substrates. The resolution of the gradient method depends on the sampling systems characteristics and has been demonstrated to be on the order of 0.01 ± 0.01 ng Hg m^-3 or better. The method is best suited to measuring high-emitting sites such as studied here. The TGM flux resolution is based on the gradient resolution and depends on the site characteristics and the atmospheric condition. For a typical friction velocity u_* of 0.1 m s^-1 and gradient intake heights of 0.15 and 0.4 m the method can resolve a TGM flux on the order of 1.5 ng m^-2 h^-1. The system can be configured for two-level or multilevel sampling, as needed. The method compares well with other micrometeorological methods as demonstrated during the Nevada storms intercomparison study. The micrometeorological method is shown to compare well with chamber techniques under comparable conditions.