The authors are grateful to PICDT/CAPES for the doctoral fellowship and to ANEEL for the support provided for field and laboratory work. We also thank Msc. Augusto R. P. Pires for his assistance during field work and Simone Gioia for the analytical support in the mass spectrometry activities. We would also like to thank Marcio Pimentel, Roberto Weinberg and Reinhardt A. Fuck for their reviews and editorial work.