Elemental mercury in the atmosphere of a tropical Amazonian forest (FrenchGuiana)

Gaseous atmospheric mercury was investigated at two sites of a tropical Ama zonian forest (French Guiana) in the Petit Inini River basin and the Petit Saut Lake in June, 1998. Gaseous atmospheric mercury was identified as elem ental mercury (Hg-0). Diurnal variation of atmospheric Hg-0 in both studied aquatic environments were significantly correlated with air temperature an d anticorrelated with relative humidity. Average Hg-0 concentrations were h igher above the Petit Inini River (75 pmol m(-3)/15.0 ng m(-3)) than the Pe tit Saut Lake (14 pmol m(-3)/2.8 ng m(-3)). Background Hg-0 concentrations in the Petit Inini River basin were higher (27 pmol m(-3)/5.4 ng m(-3)) tha n those observed in remote environments. These data suggest that gold minin g activity (i.e., Petit Inini River basin) may influence mercury mobilizati on in tropical forest ecosystems and that atmospheric transfer is a major p athway for mercury cycling in these environments.