Transport of organic carbon to the oceans by rivers of North America: a synthesis of existing data

Transport of organic carbon in rivers of North America to the oceans was assessed by compiling and analyzing data from 82 North American rivers draining 60% of Canada and the United States. These data were collected by the U.S. Geological Survey and the Water Resources Branch of Canada's Inland Waters Directorate. Mean annual concentrations of total organic carbon showed considerably less variation than did annual specific export (gC m^-2 yr-1). Regional variation in annual specific export of total organic carbon was attributed primarily to differences in annual runoff. Transport of total organic carbon to coastal regions by North American rivers totalled about 35 × 10¹² ± 5 × 10¹² gC yr^-1 in 1977 and 1978. The total organic carbon flux to the oceans associated with the long-term average annual flow in North American rivers was computed to be about 40 × 1012 gC yr^-1, slightly larger than that in 1977 and 1978 because of the lower-than-average runoff in some regions those years.