Anomalous concentrations and environmental implications of rare earth elements in the rock-soil-moss system in the black shale area

Yiyuan Xu; Chaokun Luo; Lei Gao; Jie Long; Hai Xu; Ruidong Yang

doi:10.1016/j.chemosphere.2022.135770

Anomalous concentrations and environmental implications of rare earth elements in the rock-soil-moss system in the black shale area

Chemosphere. 2022 Nov;307(Pt 1):135770. doi: 10.1016/j.chemosphere.2022.135770. Epub 2022 Jul 20.

Authors

Yiyuan Xu¹, Chaokun Luo¹, Lei Gao¹, Jie Long², Hai Xu³, Ruidong Yang⁴

Affiliations

¹ College of Resources and Environment Engineering, Guizhou University, Guiyang, 550025, China; Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China.
² State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
³ College of Resources and Environment Engineering, Guizhou University, Guiyang, 550025, China; Department of Tourism and Geography, Tongren University, Tongren, 554300, China.
⁴ College of Resources and Environment Engineering, Guizhou University, Guiyang, 550025, China; Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China. Electronic address: rdyang@gzu.edu.cn.

PMID: 35870610
DOI: 10.1016/j.chemosphere.2022.135770

Abstract

Nowadays, rare earth elements (REEs) pollution caused by anthropogenic activities has aroused great attention, but the contribution of natural geological sources remains unclear. In this study, parent rocks, corresponding soil, and overlying moss (Pohlia flexuosa Harv. In Hook) were collected to identify the release, transportation, and environmental exposure of REEs in the black shale areas. The results showed that black shales had elevated REEs levels (245 ± 124 mg kg^-1) and served as a geogenic source of REEs. The released REEs were temporarily enriched in the acidized soil (327 ± 91.8 mg kg^-1, pH 4.87 ± 0.810) and were still highly bioavailable, thereby resulting in REEs accumulated up to a high level in moss P. flexuosa (86.2 ± 64.3 mg kg^-1). Hence, the ecological risks of REEs in black shale areas were assuredly enhanced. The shale-normalized results of REEs concentrations in the parent rock - soil - moss system followed a remarkably identical pattern and were characterized by strong enrichment in HREEs (La_N/Yb_N 0.520 ± 0.274), indicating that geogenic input was responsible for the concentration and composition of REEs in mosses. Moreover, REEs were readily preserved and not easily fractionated in moss P. flexuosa due to its special morphological features, indicating the lithological signatures of REEs in black shales were readily inherited by moss P. flexuosa, and underwent only minor losses. Overall, moss P. flexuosa could be used as a powerful tool to reflect the content and composition of REEs in black shale areas.

Keywords: Biogeochemistry; Emerging pollutants; Geogenic pollution; Pohlia flexuosa; REEs patterns.

MeSH terms

Bryophyta*
Environmental Monitoring / methods
Environmental Pollution / analysis
Metals, Rare Earth* / analysis
Minerals
Soil
Soil Pollutants* / analysis

Substances

Metals, Rare Earth
Minerals
Soil
Soil Pollutants