Rare-earth elements and yttrium distributions in mangrove coastal water systems: The western Gulf of Thailand
Rare-earth elements and yttrium distributions in mangrove coastal water systems: The western Gulf of Thailand
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DOI：
10.1080/02757540500213216
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发表时间：
2005-08
影响因子：
2.5
通讯作者：
P. Censi;S. Spoto;G. Nardone;F. Saiano;R. Punturo;S. D. Di Geronimo;S. Mazzola;A. Bonanno;B. Patti;M. Sprovieri;D. Ottonello
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文献类型：
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作者：
P. Censi;S. Spoto;G. Nardone;F. Saiano;R. Punturo;S. D. Di Geronimo;S. Mazzola;A. Bonanno;B. Patti;M. Sprovieri;D. Ottonello
研究了泰国湾西海岸溶解相、悬浮颗粒物和海底沉积物中稀土元素和Y(Y)的含量。样品在页岩归一化REY模式中显示出Eu和Gd正异常，特别是在悬浮颗粒物中。另一方面，近岸海域的稀土元素含量很高，这可能是由于梅克龙河水域对研究区地形和矿床产生的富稀土元素副矿物的风化作用所致。溶解相Y和REE的页岩归一化模式表明，中稀土元素(MREE)富集，具有广泛的水-岩相互作用和大陆环境中的风化特征。悬浮物的稀土元素浓度与从潮滩采集的每个沉积物中的稀土元素浓度进行了归一化，在pH值约为5.5-6.2的范围内，表现出与实验测定的表观稀土总体分配系数1相同的行为。由于水团的REY浓度受研究区的海洋特征、河流输入和离子直的控制，我们认为该水团的溶解相代表了真正的溶解和胶体池(<；0.2μm)的混合体，在大陆环境的岩水相互作用中，REY在其中得到了富集。在河口体系中，由于岩石-水的相互作用，发生了盐诱导胶体池的凝聚，形成了自生的悬浮物部分，呈现出典型的稀土元素行为。
The concentration of rare-earth elements and yttrium (REY) was investigated in dissolved phase, suspended particulate matter, and seafloor sediments of the western coastal area of the Gulf of Thailand. The samples show Eu and Gd positive anomalies in the shale-normalized REY patterns, especially in the suspended particulate matter. On the other hand, a very high REE content was detected in the coastal waters, probably due to the weathering produced by the Mae Klong river waters on rare-earth element (REE)-rich accessory minerals coming from terrains and mineral deposits cropping out in the studied area. The shale-normalized patterns of yttrium and REE estimated for the dissolved phase show an enrichment of medium rare-earth elements (MREE), characteristic of extensive water–rock interactions and weathering occurring in the continental environment. The REE concentrations of suspended particulate, normalized to the REE concentrations in each sediment sampled from the tidal flat, show the same behaviour of the experimentally determined apparent REE bulk distribution coefficients 1 for pH values ranging from about 5.5 to 6.2. Since the REY concentration of the water masses is controlled by the oceanographic features of the studied area, riverine inputs, and ionic straight, we suppose that the dissolved phase represents a mix of truly dissolved and colloidal pool (<0.2 μm) in which REY were enriched during the rock–water interactions of continental environment. In the estuarine system, the salt-induced coagulation of colloidal pool takes place and an authigenic fraction of suspended matter is formed, assuming the typical REE behaviour due to rock–water interactions.