Akhtar Shaheen, Equeenuddin Sk Md, Roy Priyadarsi D
Department of Earth and Atmospheric Sciences, National Institute of Technology, Rourkela, 769008, Odisha, India.
Department of Earth and Atmospheric Sciences, National Institute of Technology, Rourkela, 769008, Odisha, India.
Chemosphere. 2022 Jun;297:134195. doi: 10.1016/j.chemosphere.2022.134195. Epub 2022 Mar 3.
Multi-element composition including rare earth elements (REE) of surface sediment from the Devi river estuary, eastern coast of India, have been analysed in order to study the weathering characteristics and provenance of sediment along with their behaviour under different physicochemical conditions. These sediments with dominantly felsic provenance have undergone low to moderate chemical alterations. Bulk chemical composition is mainly represented by SiO, AlO, FeO and KO. Concentrations of Ba, Nb, Pb, Rb, Th and Zr are above their respective upper crustal abundances. High LREE/HREE ratio, negative Eu anomalies, and (La/Yb) and (Tb/Yb) values confirm that sediments are dominantly derived from the Eastern Ghat Group of rocks. Upper estuary sediments show negative Eu anomalies which is similar to that of the source. However, positive Eu anomaly is mostly observed in lower estuary. Contrasting Eu anomalies between upper- and lower-estuarine sediments are uncharacteristic of previously studied major global estuaries. Strong negative correlation between Mn and Eu suggests control of redox conditions over distribution of Eu. Concentration of REEs, Sc, Fe, Mo, V, Zn, Zr, Nb, U, Ti, Na and P increases up to 20 ppt salinity, and followed by declining trend towards mouth. This is mostly due to removal through flocculation of colloidal particles from water column during fresh- and saline-water interaction. This could be the first report about coagulation-based behaviour of Mo in estuarine environment. There is gradual decline in concentration of Cr, Co, Ni, Cu, Rb, Sr, Sb, Cs, Ba, Pb, Al, Mn, Mg, Ca and K with increase in salinity which is attributed to saline induced desorption of elements from sediments. The SiO content shows increasing trend towards mouth. Findings of this study highlight the importance of intrinsic physicochemical parameters, mainly salinity and redox condition, on governing geochemical behaviour of different elements including REE in mangrove dominated estuarine sediment.
为了研究印度东海岸德维河河口表层沉积物的风化特征、物源及其在不同物理化学条件下的行为，对包括稀土元素（REE）在内的多元素组成进行了分析。这些以长英质物源为主的沉积物经历了低到中等程度的化学变化。总体化学成分主要由SiO、AlO、FeO和KO表示。Ba、Nb、Pb、Rb、Th和Zr的浓度高于各自的上地壳丰度。高LREE/HREE比值、负Eu异常以及(La/Yb)和(Tb/Yb)值证实沉积物主要源自东高止山脉岩石群。河口上游沉积物显示出与源岩相似的负Eu异常。然而，在河口下游大多观察到正Eu异常。河口上下游沉积物之间相反的Eu异常是先前研究的主要全球河口所没有的特征。Mn和Eu之间的强负相关表明氧化还原条件对Eu分布的控制。REEs、Sc、Fe、Mo、V、Zn、Zr、Nb、U、Ti、Na和P的浓度在盐度达到20ppt之前增加，然后向河口方向呈下降趋势。这主要是由于在淡水与盐水相互作用期间，胶体颗粒通过絮凝作用从水柱中去除。这可能是关于河口环境中Mo基于凝聚行为的首次报道。随着盐度增加，Cr、Co、Ni、Cu、Rb、Sr、Sb、Cs、Ba、Pb、Al、Mn、Mg、Ca和K的浓度逐渐下降，这归因于盐诱导沉积物中元素的解吸。SiO含量向河口方向呈增加趋势。本研究结果突出了内在物理化学参数，主要是盐度和氧化还原条件，对控制红树林主导的河口沉积物中包括REE在内的不同元素地球化学行为的重要性。
