Hidrogeochemical study in South Amazon region using Photoacoustic Spectroscopy N. K. Leite, J. G. Santos, R. F. Souza, G. M. Cabianchi, F. O. Xavier, B. M. Gomes, L. B. Silveira, A. C. Oliveira, A. F.R. Rodriguez and P. C. Morais Eur. Phys. J. Special Topics, 153 (2008) 45-48 Published online: 12 March 2008 DOI: 10.1140/epjst/e2008-00390-y