Validating an Evaporative Calibrator for Gaseous Oxidized Mercury.

摘要: Understanding atmospheric mercury chemistry is the key for explaining biogeochemical cycle of and improving predictive capability computational models. Increased efforts are being made to ensure comparable Hg speciation measurements in air through establishing metrological traceability. While traceability elemental has been recently set, this by no means case gaseous oxidized (GOM). Since a calibration unit suitable traceable GOM calibrations based on evaporation HgCl2 solution was developed, purpose our work extensively evaluate its performance. A highly specific sensitive 197Hg radiotracer used validation over wide range concentrations. By comparing experimental calculated values, we obtained recoveries unit. The average ranged from 88.5% 1178 ng m−3 gas concentration 39.4% 5.90 concentration. losses were due adsorption inner walls calibrator tubing. An isotherm applied estimate enthalpy (ΔHads); ΔHads value −12.33 kJ mol−1 obtained, suggesting exothermal adsorption. results performance evaluation suggest that newly developed only concentrations higher than 1 µg m−3. dependence prevents system instruments ambient measurements. Moreover, previously assessed uncertainty at level (2.0%, k = 2) re-evaluated including related recovery found be 4.1%, 2. Calibrator also evaluated HgBr2 calibration; much lower even high (>1 m−3). As often as proxy various HgBr species, suitability such must further developed.