Distribution, pollution, and ecological risks of rare earth elements in soil of the northeastern Qinghai–Tibet Plateau

Abstract

Information on rare earth elements (REEs) in soils of the Qinghai-Tibet Plateau is very limited. Therefore, this study performed field sampling to explore the concentrations, contamination degree, and potential ecological risks of REEs in soil of the northeastern Qinghai-Tibet Plateau. Concentrations of total REEs (TREEs) ranged from 95.82 to 544.01 mg/kg with average value of 241.81 mg/kg. Light REEs accounted for 72.3%-84.2% of TREEs, whereas Ce was the dominant element. Four methods were employed to evaluate the pollution of soil REEs. About 45.7% of sampling sites exhibited uncontaminated to moderately contaminated levels based on geoaccumulation index values of TREEs. Over 95.7% of sampling sites exhibited deficiency to minimal enrichment based on enrichment factor values of TREEs. The pollution load index evaluation results illustrated that about 85.7% of sampling sites possessed moderate levels of pollution, more serious than those evaluated by modified degree of contamination method. The potential ecological risk indexes of soil REEs in study area ranged from 11.02 to 40.55, showing low risk levels. This study provided important information on REEs in soils of the northeastern Qinghai-Tibet Plateau for soil pollution prevention and control at the highelevation areas.

Distribution, pollution, bioaccumulation, and ecological risks of trace elements in soils of the northeastern Qinghai-Tibet Plateau

“…Soil samples were digested using a microwave dissolution system (SINEO Microwave Chemistry Technology Co., China). The digestion procedures referred to Wu et al (2018b). The digested soil samples were analyzed by an Agilent7900 inductively coupled plasma mass spectrometry (ICP-MS, Agilent Inc, USA) to determine the concentrations of 12 typical heavy metals including lead (Pb), cadmium (Cd), chromium (Cr), nickel (Ni), zinc (Zn), molybdenum (Mo), copper (Cu), tin (Sn), mercury (Hg), cobalt (Co), antimony (Sb), and vanadium (V) as well as 16 REEs consisting of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), Lutetium (Lu), scandium (Sc), and yttrium (Y).…”

“…Five methods including I geo , EF, PLI, mC d , and Nemerow pollution index (PN) were adopted to evaluate pollution of trace elements in topsoils of the northeastern Qinghai-Tibet Plateau. The detailed information on calculation of I geo , EF, PLI, and mC d referred to previously published articles (Wu et al, 2018a(Wu et al, , 2018b. The background concentrations of trace elements in soils used for calculating I geo , EF, PLI, mC d , and PN referred to MEPC (1990).…”

“…Therefore, this study also explored the ecological risks of soil trace elements using potential ecological risk index (RI). The calculation of RI referred to published articles (Wu et al, 2018a(Wu et al, , 2018b and was briefly listed as the following:…”

“…However, many studies have showed astonishing facts on environmental quality of this "pure land" in China (Wu et al, 2016(Wu et al, , 2018a. Trace elements are detected in diverse matrices such as water, sediments, soils, and biota with relatively high concentrations (Luo et al, 2014;Wu et al, 2018aWu et al, , 2018bXie et al, 2014). The northeastern Qinghai-Tibet Plateau is more populated and industrialized than the other parts.…”

Rare earth elements in poplar leaves as indicators of geological environment and technogenesis

“…Rare earth elements (REEs) are of increasing scientific interest (Kabata-Pendias 2011; Liang et al 2014;Zhang et al 2013;Ladonin 2017;Moreira et al 2018;Wu et al 2018;Fabijańczyk et al 2019;Rzymski et al 2019;Elias et al 2019), especially concerning the application of lanthanides in classifying geological materials (Haskin et al 1966), describing and modeling different geological (Taylor and McLennan 1985) and industrial processes (Du and Turner 2015;Zhu et al 2016), and identifying mineral sources (Celo et al 2012;Censi et al 2017).…”