| 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 |
| Sources and conservative mixing of uranium in the Taiwan Strait |
| 台湾海峡铀的来源及保守性混合 |
| Received:October 27, 2016 Revised:December 02, 2016 |
| DOI：10.1007/s13131-017-0985-3 |
| Key words:conservative mixing uranium seawater Taiwan Strait |
| 中文关键词: 保守性混合 铀 海水 台湾海峡 |
| 基金项目:The National Basic Research Program (973 Program) of China under contract Nos 2014CB953700 and 2014CB953702; the National Natural Science Foundation of China under contract Nos 40906040 and 41276063; the Natural Science Foundation of Fujian Province under contract No. 2015Y0040; the Public Science and Technology Research Fund of the State Oceanic Administration of China under contract No. 201505034; the Fundamental Research Funds for the Central Universities of China and the Scientific Research Foundation for Returned Overseas Chinese Scholars of the Ministry of Education of China. |
| Author Name | Affiliation | E-mail | | CEN Rongrong | State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Science, Xiamen University, Xiamen 361005, China
Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, Xiamen University, Xiamen 361005, China | | | LIU Yanna | State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Science, Xiamen University, Xiamen 361005, China | | | XING Na | State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Science, Xiamen University, Xiamen 361005, China | | | CHEN Min | State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Science, Xiamen University, Xiamen 361005, China | | | CHENG Hua | Department of Physics, Xiamen University, Xiamen 361005, China | | | CAI Yihua | State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Science, Xiamen University, Xiamen 361005, China
Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, Xiamen University, Xiamen 361005, China | yihua_cai@xmu.edu.cn |
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| 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. |
| 中文摘要: |
| 本研究通过MC-ICP-MS对在台湾海峡南部采集的2013年春季海水样品进行了U含量及同位素组成的测定分析，探究了U在台湾海峡的地球化学行为。U的各个同位素的平均浓度如下：238U为3.23±0.14 μg/kg，235U为（2.34±0.09）×10-2 μg/kg，234U为（2.05±0.07）×10-4 μg/kg。而U同位素比值分别是：δ234U为155±18，238U：235U为138±2。台湾海峡的U含量和同位素比值与开阔大洋基本一致，由此可见，该海峡的U主要由开阔大洋所贡献。将本研究结果与研究海域附近海区的相关结果一同比较，包括九龙江和珠江河口区，厦门湾及南海南部，可以看到台湾海峡U浓度与盐度具有显著的正相关关系（U：S；U=（0.0934±0.0024）×S+（0.0920±0.0615）），表明U在台湾海峡呈现保守性混合。为更好地了解U在台湾海峡的地球化学行为，本文运用了多端元混合模型来比较各个潜在来源的贡献大小。开阔大洋对本研究中U的贡献比例为69-95%，河流为~2%，而大气沉降仅约为0.13%。因此，该模型结果与U浓度和同位素比值分析所得出的结论是一致的，即台湾海峡的U主要由开阔大洋所贡献，并具有保守性的地球化学行为。另外，沉积物间隙水有可能是台湾海峡U的一个重要来源，其可能的贡献比例为3-29%，这与前人基于镭同位素得到的观测结果一致。但后续还需要对台湾海峡沉积物间隙水及其向上覆水体的扩散进行更深入的调查研究。 |
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