Sedimentation dynamics in the East China Sea elucidated from 210Pb, 137Cs and 239,240Pu

Sedimentation dynamics in the East China Sea was investigated based on profiles and inventories of Pb-210(ex), Cs-137 and Pu-239,Pu-240 in sediment cores collected from various settings in this marginal sea. The derived sedimentation rates vary by two orders of magnitude, from similar to 2 to 0.02 cm yr(-1), and generally decrease southward along the inner shelf and eastward offshore. This pattern is consistent with the dispersal of Yangtze River-derived sediments by the current and tidal systems. The weighted mean sedimentation rate over the shelf (ca. 0.3 g cm(-2) yr(-1)) appears to be higher than fluvial inputs from the Yangtze River and Taiwan (0.14 g cm(-2) yr(-1)). The discrepancy can be reduced by considering the effect of sediment mixing (which renders sedimentation rates overestimated) and the possibility of additional sediment input from the Yellow River's dispersal system. Spatial variations of the observed nuclide inventories in sediments suggest extensive sediment redistribution, boundary scavenging of Pb-210, and large inputs of Cs-137 and Pu-239,Pu-240 from Yangtze River's drainage basin. (C) 1999 Elsevier Science B.V. All rights reserved.