Temporal variability in the fluxes of various elements and radionuclides in San Pedro Basin have been estimated using week-long sediment trap samples collected continuously from January to July 1988. Deposition in this marginal basin is controlled by seasonal changes in both upper ocean hydrography (i.e., upwelling) and local climate (i.e., precipitation, runoff). The fluxes of elements derived primarily from continental sources (Al, Ti, Na, and V) were highest during the winter (late January to early February) in association with the highest rainfall recorded during the study period. The flux patterns for the biologically active elements (Br, Ca, and I) are highest during the spring upwelling period (April--May) and correlate well with organic carbon fluxes. Due to significant input of continentally derived Ba, the flux of this element in San Pedro Basin is dominated by terrestrial input and not biological processes. The ultimate removal of 234Th and 210Pb from the water column appears to be controlled primarily by organic carbon flux. However, the sources of organic carbon vary seasonally, with significant terrestrial organic carbon input during the winter and predominantly marine organic carbon during the spring and summer. This suggests that the removal of these two radionuclides is independent of the source of the organic carbon. In contrast, the flux of 228Th is controlled by seasonal changes in terrigenous input. ¿ American Geophysical Union 1994