Résumé
This chapter considers the organic carbon species distributions in the few mainstreams and their tributaries, to compare levels and yields between the few basins and to present quantitative estimates of organic fluxes from Congo-Zaire and Amazon rivers entering the Atlantic Ocean. The Congo-Zaire basin lies at the center of equatorial Africa and is the second largest basin in the world. Its watershed is mostly constituted by a large peneplain surrounded by highlands to the north and the south and by the mountainous chain of the East African valley to the east. The Ngoko-Sangha River constitutes the upper part of the Sangha River, a right bank tributary of the Congo-Zaire River. The entire Amazon basin is covered by tropical rainforest and savannas. Native vegetation in the forested basins is classified as moist open tropical forest and consists of perennially evergreen broadleaf trees with a high number of Palms.