Distribution of Rare Earth Elements in the Pichavaram Mangrove Sediments of the Southeast Coast of India
Distribution of Rare Earth Elements in the Pichavaram Mangrove Sediments of the Southeast Coast of India
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DOI：
10.2112/05-0533.1
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
M. Prasad;A. Ramanathan
中科院分区：
文献类型：
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作者：
M. Prasad;A. Ramanathan
摘要 采用电感耦合等离子体质谱法测量了印度 Coleroon-Vellar 河口复合体 Pichavaram 红树林沉积物中的稀土元素 (REE)。轻稀土元素（LREE）比重稀土元素（HREE）更富集，Eu异常相对较弱。除了少数金属和极少数稀土元素外，红树林不同区域之间没有发现明显差异。地壳表面的强烈风化控制了它们的分布。页岩归一化值表明除了其分布模式有一些波动之外，具有相似的模式。 HREE 富集的变化受盐度梯度和河口区输入的控制。相关性和因子分析还解释了大陆风化以及盐度控制、人为来源输入等其他过程的贡献。富集因子证实了大多数稀土元素都有风化源，并在复杂的生物地球化学过程中发生了改变。很少有金属源自人类活动，但通常低于污染水平。 Ce、Gd 和 Eu 的比率证实了天然和人为来源。一般来说，内河河道和高盐度区域的重稀土元素比轻稀土元素更丰富（即，重稀土元素似乎更多地被困在这里）。红树林向邻近海域贡献了约70%~80%的轻稀土元素（包括中稀土元素）和20%~30%的重稀土元素。
Abstract The rare earth elements (REEs) in the sediments of the Pichavaram mangrove of the Coleroon-Vellar estuarine complex in India were measured by inductively coupled plasma mass spectrometry. The light rare earth elements (LREEs) were more enriched than the heavy rare earth elements (HREEs) and the Eu anomaly was relatively weak. No obvious differences were found among the different zones of the mangrove except for a few metals and very few REEs. Intense weathering of the surface crustal areas controls their distribution. The shale-normalized values indicate a similar pattern except for a few fluctuations in their distribution patterns. The variation in the enrichment of HREEs was controlled by the salinity gradient and inputs from estuarine zones. Correlation and factor analysis also explain the contribution from the continental weathering followed by other processes like salinity control, input from anthropogenic sources, etc. The enrichment factor substantiates that most of the REEs have weathering sources and are altered in the complex biogeochemical processes operating here. Few metals were derived from anthropogenic activities but were generally below the contamination levels. The Ce, Gd, and Eu ratios confirm the natural and anthropogenic source. In general, the interior channels and high-salinity zones were more enriched with HREEs than LREEs (i.e., HREEs seemed to be trapped more here). The mangroves contribute around 70%–80% of the LREEs (including middle rare earth elements) and 20%–30% of HREEs to the adjacent sea.