Spatial Variation of Rare Earth Elements in Agricultural Soils Collected from Different Geographical Regions in Vietnam

Abstract

Rare earth elements (REEs) exist commonly in minerals, such as carbonates, silicates, fluorides, and phosphates. REEs are also found in coals, animals, algae, and plants which were proven to increase the growth, development, yield, and quality of crops. In the present study, a preliminary assessment of REEs contents in soils collected from different areas in Vietnam was performed using the methods of Fe(OH)₃ and Mg(OH)₂ co-precipitation to exclude interferences from the sample matrix before analyzing REEs on ICP-MS system. The contents of REEs (mg kg^-1) were in descending of Ce > Nd > La > Pr > Sm > Gd > Dy > Tb > Er > Yb > Lu. The light REEs contents were always higher than the heavy REEs, accounting for more than 70% of the total contents. In addition, the REEs also differed in total contents between areas. The contents of REEs were as
follows Northwest > Northeast > Central Highland > Southeast. These differences could be related to influences during the natural weathering processes for soil formation and human activities such as mining and cultivation via fertilizers