Distribution and potential contamination assessment of rare earth elements (REE) in Indonesian volcanic soil

Abstract

Rare earth elements (REE) are essential elements used in various products. Meanwhile, in several countries, REE is feared will pollute the ecosystem. The occurrences of REE in soil depend on the natural influence of the parent material. However, anthropogenic activities could also be responsible for REE enrichment in soil. To understand the effect of volcanic soil parent material (as a natural influence) and anthropogenic activities, we analyzed the enrichment and geoaccumulation factor of REE. The ecological risk index is used to obtain the potential REE contamination into ecosystem. The samples were taken from three Andisols soil profiles (Pangalengan, Lembang, and Wayangwindu) from the same quaternary volcanic rocks in West Java, Indonesia. REE content in Pangalengan soil varied from 0.25mgkg−1 (Tm) to 73.50mgkg−1 (Ce), Lembang soil ranged from 0.57mgkg−1 (Tm) to 77.30mgkg−1 (Ce), and Wayangwindu ranged from 0.17mgkg−1 (Tm) to 77.30mgkg−1 (Ce). The enrichment of REE in all Andisols soils from three different sites (Pangalengan, Lembang, Wayangwindu) was classified as a deficiency to minimal enrichment. The geoaccumulation of REE is classified as moderately contaminated that occurs only in A horizon in Pangalengan soil. The REE enrichment seems closely related to anthropogenic factors, especially in A horizon at Pangalengan. Parent materials weathering is the most dominant factor in REE enrichment in the subsurface horizon for all sites but in the surface horizon in Pangalengan related to agricultural activities. The ecological risk index of REE was smaller than 40 (low risk), except for Lu in Pangalengan soil at moderate risk.