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Wu Xiaodan,Song Jinming,Wu Bin,Li Tiegang,Li Xuegang. 2014. Geochemical processes controlling dissolved selenium in the Changjiang (Yangtze) Estuary and its adjacent waters. Acta Oceanologica Sinica, 33(10):19-29
Geochemical processes controlling dissolved selenium in the Changjiang (Yangtze) Estuary and its adjacent waters
长江口及其邻近海域溶解硒的地球化学控制过程研究
Received:April 18, 2013  Revised:December 13, 2013
DOI:10.1007/s13131-014-0537-z
Key words:dissolved selenium  distribution  geochemical behavior  Changjiang (Yangtze) Estuary
中文关键词:  溶解硒  分布特征  地球化学行为  长江口
基金项目:The National Natural Science Foundation of China for Creative Research Groups under contract No. 41121064; the Strategic Priority Research Program of the Chinese Academy of Sciences under contract No. XDA05030402; the National Basic Research Program of China (973 Program) under contract No. 2011CB403602; the National Natural Science Foundation of China under contract No. 41306055.
Author NameAffiliationE-mail
Wu Xiaodan Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China  
Song Jinming Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China jmsong@qdio.ac.cn 
Wu Bin Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
University of Chinese Academy of Sciences, Beijing 100049, China 
 
Li Tiegang Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China  
Li Xuegang Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China  
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Abstract:
      Dissolved selenium in the Changjiang (Yangtze) Estuary and its adjacent waters was determined by hydride generation atomic fluorescence spectrometry to elucidate the source, behavior in estuary, adsorption-desorption process and biological role. In surface water, Se(IV) concentration ranged 0.05-1.14 nmol/L and Se(VI) concentration varied 0.01-1.20 nmol/L, with the means of 0.76 and 0.49 nmol/L, respectively. In bottom water, Se(IV) content varied 0.03-0.27 nmol/L and Se(VI) content ranged 0.04-0.85 nmol/L, with the averages of 0.10 and 0.40 nmol/L, respectively. High level of Se(IV) was observed near the shore with a significant decrease towards the open sea, suggesting the continental input from the adjacent rivers. Large value of Se(VI) was found in bottom water, reflecting the release from suspended sediment. Besides, high value appeared in the same latitude of the Changjiang Estuary and Hangzhou Bay illustrated the effect of lateral mixing and the long-distance transport of selenium. Se(VI), more soluble, occupied higher percentage in aqueous environment. The presence of Se(IV) resulted from the degradation of residue and the reduction of Se(VI) under anaerobic condition. The positive relationship to suspended particulate material (SPM) and negative correlation to depth indicated that Se(IV) tended to be released from the high density particulate matter. Instead, Se(VI) content did not significantly relate to SPM since it generally formed inner-sphere complex to iron hydroxide. Se(IV) content negatively varied to salinity and largely depended on the freshwater dilution and physical mixing. While, Se(VI) level deviated from the dilution line due to the in situ biogeochemical process such as removal via phytoplankton uptake and inputs via organic matter regeneration. As the essential element, Se(IV) was confirmed more bioavailable to phytoplankton growth than Se(VI), and moreover, seemed to be more related to phosphorus than to nitrogen.
中文摘要:
      利用氢化物原子荧光光谱法测定了长江口及邻近海域海水中溶解硒的含量水平,阐明其物质来源、河口行为、吸附-解吸过程和生物利用性。表层水体,Se(IV)和Se(VI)浓度范围分别为0.05-1.14 nmol/L和0.01-1.20 nmol/L,平均值分别为0.76 nmol/L和0.49 nmol/L。底层水体,Se(IV) 含量分布在0.03-0.27 nmol/L之间,Se(VI)分布在0.04-0.85 nmol/L之间,平均值分别为0.10 nmol/L和0.40 nmol/L。Se(IV)高值出现在河口区,随离岸距离增加浓度显著减小,说明陆源Se(IV)通过邻近河流进入外海。Se(VI)高值出现在底层水体,说明再悬浮沉积物的释放是其主要来源。另外,长江口和杭州湾的同纬度地区亦是Se(VI)高值区,说明横向平流也是影响河口地区元素重新分配的重要因素,硒是可远距离输送的元素。高溶解性Se(VI)是海水中无机硒的主要存在形态,Se(IV)的存在则是厌氧条件下生物残渣降解和高价Se(VI)还原的结果。Se(IV)与悬浮颗粒物(suspended particulate matter,SPM)的正相关关系及与海水深度的负相关关系均证实Se(IV)易于从高密度颗粒相释放。相反,Se(VI)含量尚未呈现与SPM的显著关系,这是因为其通常与铁氢氧化物形成内层配合物。受物理混合与稀释作用影响,Se(IV)含量负相关于盐度,在河口区行为保守。Se(VI)含量却因如浮游植物吸收和有机物再生等地球化学过程影响而偏离稀释线。作为生命必需元素,Se(IV)确实较Se(VI)更利于浮游植物生长。并且,与氮相比,其生物利用性与磷更相似。
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