This project will examine the relation between clay-sized particles and the organic matter that is sorbed to them as they are transported through a river system (Eel River, California) and deposited on the continental shelf. Preliminary work indicates that during episodic floods, particles discharged by this river carry a smaller load of terrigenous organics to the marine environment than during nonflood periods. Analyses of the organic material (stable isotopes, C/N, molecular composition) and of clay particles (mineralogy, surface area) will be used to determine whether the amount of organic material associated with the clays is controlled by residence time of particles in the river, preferential erosion of deep soil horizons or rocks during periods of intense rainfall, or breakup of soil aggregates during turbulent transport. The results of this investigation will improve understanding of the controls on the amount of terrigenous carbon buried on continental margins, which play a primary role in the global carbon budget.
