1. Departamento
de Química, Universidade Federal de Santa Maria, 97105-900 Santa Maria, Rio
Grande do Sul, Brazil
2. Department
of Geochemistry, Geological Survey of Denmark and Greenland, Ø.
Voldgade 10, 1350 Copenhagen, Denmark
3. Center
for Permafrost (CENPERM), Department of Geosciences and Natural Resource
Management, University of Copenhagen, 1350 Copenhagen, Denmark
4. Departamento
de Química Inorgânica, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, Rio
Grande do Sul, Brazil