Distribution And Radioactive Disequilibrium Of ²¹⁰Po And ²¹⁰Pb In Changjiang Estuary And The Yellow Sea

The monthly various of activities of 210Po and 210Pb in riverine water(Xuliujing), surface sediment of Chongming of Changjiang estuary and the Yellow Sea water were characterized by Gamma spectrometry and alpha spectrometry. More, the atmospheric deposition fluxes of these 2 nuclides were also determined. The details of the present thesis were showed below:(1)Methods were established for extraction, purification, and determination of natural 210Po and 210Pb in rainwater, river water, seawater, suspended particulate matter, and tidal flat sediments. Both of the Gamma and alpha spectrometry were used for 210Po and 210Pb measurement.(2) The atmospheric deposition fluxes for both 210Po and 210Pb in Changjiang estuary is higher than those in Xiamen and Qingdao coast area, China. The depositional fluxes of 210Po and 210Pb have been found to be seasonal change with similar trend. The value of flux measured in spring and winter are a little higher than those in summer and autumn. In spring and summer, the deposition fluxes for the two nuclides didn't behave any significant correlation with rain precipitation, which might be caused by the monsoon climate in shanghai.(3) The activities of 210Po and 210Pb in the dissolved phase at Xuliujing range from 0.02 to 1.81 and 0.17 to 2.33 Bq/m3, respectively.210Po and 210Pb in riverine water waters were mainly carried by particulates, indicating that 210Po and 210Pb was easily absorbed and removed from the solution by the riverine particles.(4) From the high flat, middle to the low flat, the mean activities of 210Po and 210Pb in the surface sediment of east tidal flat of Chongming were:194,122,93.2 Bq/kg for 210Po and 72.8,58.61,41.9 Bq/kg for 210Pb, respectively.(5) The dissolved 210Pb in surface water of the Yellow sea generally displays higher activities (around 0.38-2.97 Bq/m3) relative to deep seawater, reflecting atmospheric input dominantly. It was seen that, the activities of 210Po in the water column and in the particlesare strongly deficient relative to its parent nuclide-210Pb.Using a box-model, the 210Pb residence time was less than 0.08a in the turbid western shallow water domain and about 0.17a in the clear water domain as observed...