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	Size-fractionated uranium isotopes in surface waters in the Jiulong Estuary in China
	Lue, E. ; Zhang, L. ; Chen, M. ; Qiu, Y. S. ; Xing, N. ; Yang, W. F. ; Li, Y. P. ; Huang, Y. P. ; Huang YP(黄奕普)
	2008
关键词	DISSOLVED URANIUM AMAZON SHELF BALTIC SEA BEHAVIOR RIVER GEOCHEMISTRY TRANSPORT SEDIMENTS TH-232
英文摘要	Surface water was collected form the Jiulong Estuary for determination of activity concentrations of uranium isotopes in different size fractions, namely, greater than 53, 10 similar to 53, 2 similar to 10, 0.4 similar to 2 mu m, 10 000 u similar to 0. 4 mu m and less than 10 000 u fractions by microfiltration and cross-flow ultrafiltration technologies. Results indicated that most of the dissolved uranium (< 0.4 mu m) existed in the low molecular mass fraction (< 10 000 u), and the colloidal uranium-238 (10 000 u similar to 0. 4 mu m) only contributed less than I 17o of the dissolved uranium-238. The fractions of colloidal uranium in the dissolved phases decreased with the increasing salinity. A positive linear relationship between uranium-238 activities and salinities was observed for the dissolved, colloidal and low molecular mass fractions, indicating a conservative behavior of uranium in the Jiulong Estuary. In the particulate phases (> 0.4 mu m), the partitioning of uranium isotopes among different size fractions was controlled by the partitioning of particle concentrations. In the regions with salinities below 20, the partitioning of uranium-238 among different size fractions was as follows: 10 similar to 53 mu m > 2 similar to 10 mu m > 0.4 similar to 2 mu m greater than above 53 mu m. However, the order at the offshore station with salinities above 30 changed as follows: 0.4 similar to 2 mu m > 10 similar to 53 mu m > 2 similar to 10 mu m greater than above 53 mu m. The fraction of the 0.4 similar to 2 mu m particles increased at the offshore station, suggesting the increased contribution of the authigenic uranium. The activity ratio of uranium-234 to uranium-238 in the dissolved phases, including the low molecular mass fraction and the colloidal fraction, was larger than unity, showing the occurrence of excess uranium-234. In contrast, the activity ratio of uranium-234 to uranium-238 in all size fractions of the particulate phase was close to the equilibrium value (1.0). The observed different values of the activity ratio of uranium-234 to uranium-238 in the dissolved phase and the particulate phase were ascribed to the preferential leaching of uranium-234 and the small amount of the leaching particulate uranium. The mass ratio of thorium-232 to uranium-238 also showed different values between the dissolved phase and the particulate phase. Mass ratio of thorium-232 to uranium-238 in the dissolved, colloidal and low molecular mass fractions was less than unity, while those in the different size fractions of particulate phases were larger than unity, reflecting a different behavior between uranium and thorium during their transport into the ocean.
语种	英语
内容类型	期刊论文
源URL	[http://dspace.xmu.edu.cn/handle/2288/60946]
专题	海洋环境－已发表论文
推荐引用方式 GB/T 7714	Lue, E.,Zhang, L.,Chen, M.,et al. Size-fractionated uranium isotopes in surface waters in the Jiulong Estuary in China[J],2008.
APA	Lue, E..,Zhang, L..,Chen, M..,Qiu, Y. S..,Xing, N..,...&黄奕普.(2008).Size-fractionated uranium isotopes in surface waters in the Jiulong Estuary in China..
MLA	Lue, E.,et al."Size-fractionated uranium isotopes in surface waters in the Jiulong Estuary in China".(2008).

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