Distribution of rare earth elements, thorium and uranium in Gulf of Thailand’s sediments

Abstract

Distribution of rare earth elements (REEs), thorium and uranium in 54 marine sediments collected from five selected areas along the Gulf of Thailand is discussed in this paper. These areas have been selected as potential sites to set up thermal and nuclear power plants. Concentration of elements was determined using inductively coupled plasma mass spectrometry (ICP-MS). Absolute concentrations of REEs, Th and U show a sample-to-sample variation and may be due to different geological characteristic of area as well as grain size effect. Total REE concentrations (not including Y) range between 9.4 and 206 μg/g. The chondrite-normalized REE patterns of all samples are similar to Post-Archean Australian Shale (PAAS) and average Upper Continental Crust, with LREEs’ enrichment relative to HREEs (LaN/YbN = 6.5–29), fairly flat HREEs’ patterns (GdN/YbN = 1.0–3.8) and ubiquitous negative Eu anomaly (Eu/Eu* = 0.3–0.7). Th concentrations (0.9–28 μg/g) are relatively higher than those of uranium (0.4–4.0 μg/g). Th/U ratios (1.5–9.9) are higher than the average upper crust. These results are consistent with terrigenous sediments that formed from the weathering and erosion of felsic rocks.