Geochemical baselines of major, minor and trace elements in the tropical sediments of the Terengganu River basin, Malaysia

The geochemical baselines and distribution of 31 elements (Al, Fe, K, Na, Mg, Ca, Mn, Ba, Cr, Zr, Ni, Sr, Zn, Y, Li, Cu, Mo, Nb, Th, Co, Ga, W, Ta, Be, Ti, Ge, Se, Bi, Te, Sc and Re) and physico-chemical parameters of the tropical surface sediments of the Terengganu River basin, Malaysia, are reported. Sediments are sandy loam to sand in texture consisting of mostly quartz, low organic matter content (average–2.68%), low CEC (average–2.02 cmol₍₊₎/kg) and mildly acidic pH_1:5 (average–5.91). Concentrations of Mn, Fe, Ba, Cr, Ni, Cu, Mo and Se were measured to be above the environmental sediment quality criteria at various locations. Lake sediments registered significantly higher Al, Fe, Ti, Mg, Ca, Mn, Te and Sc concentrations as compared to the river sediments. Most of the elements investigated showed an association with silt size fraction (2–63 μm). Among the investigated metals, Mo and Fe concentrations showed an increasing (>5-fold) and decreasing (>3-fold) trend, respectively, along the river path from the upstream to the downstream depending on the stream pH-redox conditions. The enrichment factor values (EF >5) of Cr, Ni, Mo and Se indicated enrichment from anthropogenic activities. Alkali and alkali earth metals registered a significant depletion (EF values <0.7) as compared to the Earth's crust. Principal component analysis of the two main components (PC1, 87.4% and PC2, 8.7%) revealed a well-defined group of estuary sediments. Lake and river sediment sampling locations did not form defined groups revealing heterogeneity in the origin of geologic material and the in-stream geochemical processes. However, Cr, Ni, Mo and Se formed a separate group with elevated concentrations (e.g. Cr>1,000 mg/kg) indicating contamination of sediments. This work presents the geochemical baselines of the tropical sediments as industrial development and urbanization along the north east coast of Peninsular Malaysia are advancing rapidly.