ABSTRACT
This chapter compares changes on the composition of riverine organic matter in watersheds with diverse land uses. The main land cover change in the Amazon watershed has been the replacement of the original forest by pasture. The south border of this watershed has been severely affected by the conversion of forests into pastures. The Mogi-Guacu watershed is also located in the state of Sao Paulo and its land cover is similar to that of the Piracicaba River watershed. The main channel of the Amazon watershed, the Solimoes/Amazon river, was sampled by Hedges et al. few times during 1982 and 1983. The Particulate organic matter (POM) was separated into coarse and fine fractions based on the fact that both fractions have different compositions and different sources. Seasonal differences between watersheds can be assessed by correlating the suspended solids concentration with compositional attributes. The riverine coarse and fine POM was already altered by human intervention on the soil cover.
