Rare earth elements concentrations and speciation in rainwater from Guiyang, an acid rain impacted zone of Southwest China

Abstract

Rare earth elements (REEs) and major ions were determined in rainwater samples collected from Guiyang in the acid rain impacted zone of Southwest China. The concentrations of total dissolved and acid-soluble REEs in rainwater are higher than those of most of the world's cities as well as the local surface water. The dissolved REE concentrations are negatively correlated to pH in rainwater. This is consistent with acidification of rainwater resulting in increasing REE concentrations. Speciation calculations using the PHREEQC-Model predict that the free REE metal ion (i.e., Ln 3+), sulfate (LnSO 4 +), oxalate (LnOx + and LnOx 2-) and fluoride (LnF 2+) complexes were relatively important forms of dissolved REE. Although the contribution to rainwater acidity of oxalic acid is much lower than that of sulfuric acid, the proportion of REE-oxalate complexes is not lower than that of REE-sulfate complexes in rain waters. The rainwater is enriched in the middle REEs (MREE) compared to both the light REEs (LREE) and heavy REEs (HREE). REE-phosphate complexes, phosphatic minerals and a Fe-Mn-oxyhydroxide coating are more likely controls on the development of MREE enrichment in the rainwater. Complexation of sulfate and REE played little role in the development of MREE enrichment, even though sulfate is the most important anion in acidic rainwater. In the shale-normalized REE pattern plot, La showed a clear positive anomaly. La might have two main anthropogenic sources in rainwater. One of the important sources could be automobile emission; another main source of excess La in rainwater could be the REE fertilizer that has been widely used in the agriculture of China for approximately 30 years.

Effect of rare earth elements on rice plant growth

“…At a pH of 5.7, the pH of the rice growth medium, LnSO 4 + should be present as the main form of the REE interacting with the rice root. This is consistent with the results of Zhu et al (2016), who showed that LnSO 4 + is the dominant species within the pH range of 3.4 and 6.0 under similar solution conditions. The results of speciation calculations in Fig.…”

Geochemical signatures of rare earth elements and yttrium in the vicinity of an ion-adsorption type deposit: roles of source sediment control

“…Considering the extremely low concentrations of REE+Y in rainwater (Zhang and Liu, 2004;Zhu et al, 2016), REE+Y are ultimately sourced from rocks which fluids move through. Studies have proposed a preferential leaching of REE-bearing solid phases to be a cause for the enrichment patterns (Sun et al, 2012a;Wallrich et al, 2020 and references therein).…”

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

“…Areas with potential environmental problems include cities with large populations, extensive infrastructure, manufacturing industries, and sources of industrial waste (Dai et al 2016;Valdes et al 2013;Zhu et al 2016). Large cities are also influenced by factors related to the variety of geological materials and sedimentary deposits on which they are situated (Duplaya et al 2014;Radomskaya et al 2018).…”

“…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).…”