Rare Earth Elements in Soils from Selected Areas on the Island of Hawaii

Abstract

Fifty soil samples from the wet, windward (east) side and dry, leeward (west) side of the Island of Hawaii were analyzed for La, Ce, Sm, Eu, Yb, and Lu by neutron activation/gamma-ray spectroscopic analysis. Data on concentrations in each sample are listed and analyzed statistically for soil samples collected from the western slope of Kohala Mountain, the western coastal plain of Mauna Kea , and the northeastern coastal plain of Mauna Loa . Rare earth element (REE) concentrations are two to six times greater in soils from the western , dry side of the island ; arid good statistical correlation is exhibited among the samples for pairs of individual REEs. In the organic-rich soils of the east side, correlations are poor but are markedly improved when sample weights are adjusted for weight due to organic matter and water in soil colloids. If the mean compositions of selected rock samples from the Hawaii Reference Suite are representative of the compositions of the parent materials, REEs in the soils are moderately enriched (up to two times, based on oven-dry weights). Rare earth element concentrations in the island 's western soils are as much as two times greater than the mean REE values of common sedimentary rock s worldwide; however , they are well within the concentration ranges of soils of continental origin . The eastern soils tend to have less La and Ce, but similar amounts of the middle and heavy REEs.