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The time scale of transport and reaction processes in the ocean can be evaluated using natural radionuclides of different half-lives.In the present study,we evaluated the residence times of particulate reactive radionuclides 7 Be,210 Pb xs and 234 Th in the Changjiang (Yangtze River) estuary,which is a high turbidity estuary,in June,2006.The residence times of particulate 7 Be,234 Th xs and 210 Pb xs in the Changjiang estuary were calculated to be 0.7-20.4,0.18-4.1 and 0.6-89.8 d,respectively.The obtained residence times of those nuclides are comparable with those of other estuaries and bays.For 234 Th xs and 7 Be,the residence times decreased with increasing concentrations of suspended particulate matter (SPM);however,those of 210 Pb xs increased.Moreover,scavenging residence times of 234 Th and 7 Be increased from coast to offshore,while those of 210 Pb xs decreased.
The time scale of transport and reaction processes in the ocean can be evaluated using natural radionuclides of different half-lives. In the present study, we evaluate the residence times of particulate inactivation radionuclides 7 Be, 210 Pb xs and 234 Th in the Changjiang Yangtze River) estuary, which is a high turbidity estuary, in June, 2006. The residence times of particulate 7 Be, 234 Th xs and 210 Pb xs in the Changjiang estuary were calculated to be 0.7-20.4, 0.18-4.1 and 0.6- 89.8 d, respectively. The obtained residence times of those nuclides are comparable with those of other estuaries and bays. For 234 Th xs and 7 Be, the residence times decreased with increasing concentrations of suspended particulate matter (SPM); however, those of 210 Pb xs increased. Moreover, scavenging residence times of 234 Th and 7 Be increased from coast to offshore, while those of 210 Pb xs decreased.