Enrichment Patterns and Geochemical Behavior of Rare Earth Elements in the Sediments of the Linggi River, Malaysia

Sediment samples from seven sites along the
Linggi River (Malaysia) were collected in the dry season to
study their spatial distribution, enrichment patterns, and
geochemical behavior of REEs and Fe. Surface sediments
were analyzed by neutron activation analysis, adhering to
strict quality control procedures that included standard
reference materials IAEA-Soil-7, SL-1, and MIX
PTS-16/17. The results obtained show that total REE
concentrations range from 166.6 to 206.1 ppm, with a
dominance of LREEs over HREEs (LREE/HREE = 7.4
10.5). The concentrations of La (47.7–60.4 mg/kg), Ce
(93–116 mg/kg), and Sm (8.2–10.4 mg/kg) are constantly
greater than their UCC values, whereas Dy (7.6–14 mg/kg),
Tb (1.4–1.8 mg/kg), and Yb (5.3–8.7 mg/kg) are enriched
up to fourfold. Spatial patterns include the following:
upstream Dy and Yb enrichment, midstream variability
related to industrial inputs, and downstream increases of La
and Ce due to estuarine trapping. Ce/Ce* ratios of between
0.95 and 1.11 indicate stable oxic depositional conditions,
while a negative Eu anomaly (Eu/Sm = 0.09–0.14) reflects
felsic lithological sources. Enrichment factors (EF):
Moderate to strong enrichment of Dy, Tb, and Yb is
suggested by EF values up to 6.8, whereas the values of
Igeo (-0.99 to 1.42) suggest the sediment to be
non-polluted to slightly polluted, having hotspots at S1 and
S5. Taken together, the results imply that the present REE
concentration patterns in the sediment of the Linggi River
are mainly controlled by felsic weathering materials,
overlain by industrial influences.