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Abstract:
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The distribution and accumulation of the rare earth elements (REE) in the sediments of the Cochin
Estuary and adjacent continental shelf were investigated. The rare earth elements like La, Ce, Pr, Nd,
Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and the heavy metals like Mg, V, Cr, Mn, Fe, Cu, Zn, U, Th
were analysed by using standard analytical methods. The Post-Archean Australian Shale composition
was used to normalise the rare earth elements. It was found that the sediments were more enriched with
the lighter rare earth elements than the heavier ones. The positive correlation between the concentrations
of REE, Fe and Mn could explain the precipitation of oxyhydroxides in the study area. The factor
analysis and correlation analysis suggest common sources of origin for the REEs. From the Ce-anomalies
calculated, it was found that an oxic environment predominates in all stations except the station No. 2.
The Eu-anomaly gave an idea that the origin of REEs may be from the feldspar. The parameters like
total organic carbon, U/Th ratio, authigenic U, Cu/Zn, V/Cr ratios revealed the oxic environment and
thus the depositional behaviour of REEs in the region |