DETERMINATION OF TOTAL AND BIOAVAIABLE RARE EARTH ELEMENTS IN ALLUVIAL SOIL SAMPLES FOR RICE CULTIVATION USING ICP-OES

Abstract

This study determined the total and bioavailable rare earth element (REE) concentrations in alluvial soil
samples from the Mekong Delta and Red River Delta using ICP-OES. The method detection limits ranged
from 0,27 to 0,85 mg/kg, and the quantitation limits ranged from 0,85 to 2,7 mg/kg. Recoveries for spiked
samples were between 81,2% and 109,4%, and relative errors for a certified reference material were
between 1,1% and -14,4%. Samples were acid-digested with aqua regia and HClO4 to analyze total REEs,
while bioavailable REEs were assessed using 0,1 M HCl. Soils treated with REEs-containing fertilizers
exhibited significantly higher total and bioavailable REE concentrations than untreated soils and the
regional averages. These findings highlight the potential impact of REEs-containing fertilizers on REE
levels in agricultural soils.