Sources and conservative mixing of uranium in the Taiwan Strait
- PDF / 1,095,542 Bytes
- 10 Pages / 595 x 842 pts (A4) Page_size
- 4 Downloads / 183 Views
Sources and conservative mixing of uranium in the Taiwan Strait CEN Rongrong1, 2, LIU Yanna1, XING Na1, CHEN Min1, CHENG Hua3, CAI Yihua1, 2* 1 State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Science, Xiamen University,
Xiamen 361005, China 2 Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, Xiamen University, Xiamen
361005, China 3 Department of Physics, Xiamen University, Xiamen 361005, China
Received 27 October 2016; accepted 2 December 2016 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2017
Abstract
Seawater samples are collected in the spring of 2013 from the Taiwan Strait for the analysis of uranium (U) concentrations and isotopic compositions using MC-ICP-MS, and the geochemical behavior patterns of U in the Taiwan Strait are then investigated. Average concentrations of individual U isotopes are (3.23±0.14) μg/kg for 238U, (2.34±0.09)×10–2 μg/kg for 235U and (2.05±0.07)×10–4 μg/kg for 234U. Correspondingly, the U isotopic compositions are 155±18 for δ234U and 138±2 for 238U:235U. The U concentrations and isotopic ratios in the Taiwan Strait are similar to those of open ocean seawater, suggesting the dominance of the open ocean input to the strait’s U pool. However, river input, as suggested by the slightly lower salinity than that of the open ocean, also affected the U concentrations and isotopic compositions in the strait. From a compilation of U concentrations in the Taiwan Strait and adjacent areas, including the Jiulong Estuary and Zhujiang Estuary, the Xiamen Bay and the northern South China Sea, a strong and significant relationship between U concentration and salinity [U:S; U=(0.093 4±0.002 4)S+ (0.092 0±0.061 5)] is revealed, suggesting conservative mixing of U in the Taiwan Strait. To better understand the U geochemistry in the Taiwan Strait, a multiple endmembers mixing model is applied to estimate the contributions of potential sources. The open ocean seawater contributed 69%–95% of U in the Taiwan Strait, with river water approximately 2%, and dust deposition only around 0.13%. Therefore, the model results supported the open ocean input source and the conservative mixing behavior of U derived from the observation of U concentrations and isotopic ratios and U:S ratios. The sediment interstitial water may be an important source of U to the Taiwan Strait with a possible contribution of 3%–29%, consistent with previous investigations based on radium isotopes. However, further investigations are warranted to examine the U concentration in the sediment interstitial water and its input to the overlying seawater in the Taiwan Strait. Key words: conservative mixing, uranium, seawater, Taiwan Strait Citation: Cen Rongrong, Liu Yanna, Xing Na, Chen Min, Cheng Hua, Cai Yihua. 2017. Sources and conservative mixing of uranium in the Taiwan Strait. Acta Oceanologica Sinica, 36(3): 72–81, doi: 10.1007/s13131-017-0985-3
1 Introduction Uranium (U) in the ocean is derived mostly from terrestrial sources through river tr
Data Loading...
