Radium isotopes 226Ra and 228Ra in seawater of the western Yellow Sea were measured by using the Mn-fiber adsorption-HPGe γ spectrum method. The distribution features of the two isotopes have been studied. The activi...Radium isotopes 226Ra and 228Ra in seawater of the western Yellow Sea were measured by using the Mn-fiber adsorption-HPGe γ spectrum method. The distribution features of the two isotopes have been studied. The activities of 226Ra and 228Ra are 2.72-5.57 Bq m -3 and 7.51-34.3 Bq m -3, respectively. The activities of 226Ra and 228Ra from surface to bottom for each depth profile station are comparable within the experimental error, but the mean activities decrease with distance from the shore. From the distribution data of 228Ra, the horizontal eddy diffusion coefficient was estimated at 29×106 cm2 s -1.展开更多
Material fluxes （e.g., nutrients） from coastal waters to offshore areas play an important role in controlling the water quality of the adjacent sea areas not only by increasing nutrient concentration hut also by cha...Material fluxes （e.g., nutrients） from coastal waters to offshore areas play an important role in controlling the water quality of the adjacent sea areas not only by increasing nutrient concentration hut also by changing nutrient structures. In this study, naturally occurring isotopes, ^226Ra and ^228Ra, were measured with the alpha spectrometry in the Wenjiao-Wenchang and Wanquan estuaries and adjacent sea areas along the east coast of Hainan Island. The excess ^226Ra and ^228Ra activities were observed by comparison with the values derived from the conservative mixing of freshwater and seawater end-members in both estuaries. Using a one-dimensional diffusion model, the horizontal eddy diffusion coefficient of 3.1 6 × 10^5 cm^2/s, for nutrients diffusing from their sources, was derived from 228Ra activities. Consequently, the corresponding nutrient fluxes flowing into the coastal waters were assessed. The results can provide useful information for the study of the mixing and exchange processes of coastal waters as well as dissoluble pollutant transport in this sea area.展开更多
The 226 Ra and 228 Ra activities of Qinghai Lake surface water,groundwater,river water,suspended particles,and bottom sediments were measured in a gamma-ray spectrometer.The sources of 226 Ra and 228 Ra were discussed...The 226 Ra and 228 Ra activities of Qinghai Lake surface water,groundwater,river water,suspended particles,and bottom sediments were measured in a gamma-ray spectrometer.The sources of 226 Ra and 228 Ra were discussed according to their distribution characteristics.226 Ra and 228 Ra activities(dpm/(100 L)) ranged from 14.13±0.22 to 19.22±0.42 and 17.72±0.66 to 30.96±1.47 in the surface water of the North Bay,respectively,and from 7.88±0.24 to 33.80±0.47 and 15.73±0.74 to 57.31±1.44,respectively,in the South Bay.The surface water near the estuary had a lower salinity and had a higher concentration of radium isotopes than the samples collected further away.The farther offshore the sample,the higher the salinity was,and the lower the radium isotope activity.The distribution of radium activities in the western part of Qinghai Lake is controlled by several factors,including Buha River runoff,desorption from suspended particles derived from the river,groundwater discharge,and a small amount of diffusion from the sediment.展开更多
文摘Radium isotopes 226Ra and 228Ra in seawater of the western Yellow Sea were measured by using the Mn-fiber adsorption-HPGe γ spectrum method. The distribution features of the two isotopes have been studied. The activities of 226Ra and 228Ra are 2.72-5.57 Bq m -3 and 7.51-34.3 Bq m -3, respectively. The activities of 226Ra and 228Ra from surface to bottom for each depth profile station are comparable within the experimental error, but the mean activities decrease with distance from the shore. From the distribution data of 228Ra, the horizontal eddy diffusion coefficient was estimated at 29×106 cm2 s -1.
基金supported by the Natural Science Foundation of China (Grant No.41021064)the Sino-German Cooperation Project of Ministry of Science and Technology of China (Grant No.2007DFB20380)the Ph. D. Program Scholarship Fund of East China Normal University (Grant No.2010047)
文摘Material fluxes （e.g., nutrients） from coastal waters to offshore areas play an important role in controlling the water quality of the adjacent sea areas not only by increasing nutrient concentration hut also by changing nutrient structures. In this study, naturally occurring isotopes, ^226Ra and ^228Ra, were measured with the alpha spectrometry in the Wenjiao-Wenchang and Wanquan estuaries and adjacent sea areas along the east coast of Hainan Island. The excess ^226Ra and ^228Ra activities were observed by comparison with the values derived from the conservative mixing of freshwater and seawater end-members in both estuaries. Using a one-dimensional diffusion model, the horizontal eddy diffusion coefficient of 3.1 6 × 10^5 cm^2/s, for nutrients diffusing from their sources, was derived from 228Ra activities. Consequently, the corresponding nutrient fluxes flowing into the coastal waters were assessed. The results can provide useful information for the study of the mixing and exchange processes of coastal waters as well as dissoluble pollutant transport in this sea area.
基金Supported by the"One Hundred Plan"Project of Chinese Academy of Sciences:Groundwater Discharge and Geochemical Processes of Plateau Inland Lakes(No.Y210101028)the Tracer of Groundwater Discharge by Radioactive Isotope(No.Y360051010)
文摘The 226 Ra and 228 Ra activities of Qinghai Lake surface water,groundwater,river water,suspended particles,and bottom sediments were measured in a gamma-ray spectrometer.The sources of 226 Ra and 228 Ra were discussed according to their distribution characteristics.226 Ra and 228 Ra activities(dpm/(100 L)) ranged from 14.13±0.22 to 19.22±0.42 and 17.72±0.66 to 30.96±1.47 in the surface water of the North Bay,respectively,and from 7.88±0.24 to 33.80±0.47 and 15.73±0.74 to 57.31±1.44,respectively,in the South Bay.The surface water near the estuary had a lower salinity and had a higher concentration of radium isotopes than the samples collected further away.The farther offshore the sample,the higher the salinity was,and the lower the radium isotope activity.The distribution of radium activities in the western part of Qinghai Lake is controlled by several factors,including Buha River runoff,desorption from suspended particles derived from the river,groundwater discharge,and a small amount of diffusion from the sediment.
