In this report the state of knowledge of sediment transport by rivers of the Amazon drainage basin is reviewed. On an annual basis the Amazon river transports about 1200×106 tons of sediment from the South American continent to the ocean, which puts it among the world's largest rivers in this respect. The main source of sediment is erosion in the Andes mountains and this material is progressively diluted with sediment poor runoff from lowland draining tributaries. Almost half of the Amazon river transport is attributable to one tributary, the Rio Madeira (488×106 t/y). The Rio Negro, which drains the N crystalline shield, has a comparable water discharge to the Rio Madeira, but only contributes 7×106 t/y. In general the sediments in transport are about 1% organic carbon by weight and this results in an annual particulate carbon to the oceans of 13×106 t/y. Total carbon transport, particulate plus dissolved, is about twice this amount. © 1989 Kluwer Academic Publishers.
|
