Improved determination of gaseous divalent mercury in ambient air using KCl coated denuders

An improved method for the determination of gaseous divalent mercury (GDM) in ambient air using KCl coated denuders has been developed and tested. GDM collected in the KCl coated denuders can be quantitatively desorbed at 450 degrees C in 10 min. After being complete thermally reduced to Hg-0 at 900 degrees C, all mercury released from the denuder is pre-concentrated on the analytical Au trap, and detected by cold vapor atomic fluorescence spectrometry (CVAFS). The absolute detection limit of the method is less than 3 pg. Preliminary data of GDM concentration in ambient air from different sampling stations show that GDM concentrations in the urban air of Goteborg are much higher than in rural air (Rorvik and Sasetta), which indicates the anthropogenic origin of GDM.