SUMMARY
In order to improve the understanding of the water in the Amazon Basin, samples of rain and moisture were collected daily at Belém and Manaus from August 78 to January 80. All isotope data are presented. The most depleted values, sometimes lower than — 10‰ in δ18O at Belém or Manaus, were encountered during the rainy season (January-April).
Possible causes of the seasonal differences in tne isotope pattern are discussed.