RIVER1NE TRANSPORT OF ATMOSPHERIC CARBON : SOURCES, GLOBAL TYPOLOGY AND BUDGET Michel MEYBECK Laboratoire de G6ologie Appliqu6e, C.N.R.S. Place Jussieu, 75257 Paris Cedex 05 France Abstract. Atmospheric C (TAC) is continuously transported by rivers at the continents' surface as soil dissolved and particulate organic C (DOC, POC) and dissolved inorganic C (DIC) used in rock weathering reactions. Global typology of the C export rates (g.m-2.yr -1) for 14 river classes from tundra rivers to monsoon rivers is used to calculate global TAC flux to oceans estimated to 542 Tg.yr 1, of which 37 % is as DOC, 18 % as soil POC and 45 % as DIC. TAC originates mostly from humid tropics (46 %) and temperate forest and grassland (31%), compared to boreal forest (14 %), savannah and sub-arid regions (5 %), and tundra (4 %). Rivers also carry to oceans 80 Tg. yr 1of POC and 137 TG.yr-1 of DIC originating from rock erosion. Permanent TAC storage on land is estimated to 52 Tg.yr 1in lakes and 17 Tg.yr 1 in internal regions of the continents. 1. Introduction Delivery of inorganic C budget to the oceans by rivers was first estimated by Clarke (1924) but reliable budgets of total organic carbon (TOC) have become available only recently. There is little mention of TOC in Livingstone's master review on world's rivers (1963). The first budgets were published in 1981 by Schlesinger and Melack, and by Meybeck. Since then, our understanding of the C content in world's rivers has improved substantially largely by means of the SCOPE-CARBON Water, Air, and Soil Pollution 70: 443-463, 1993. 9 1993 Kluwer Academic Publishers. Printed in the Netherlands.