Biogeochemical Behavior of Rare Earth Elements in Environmental Systems

Rare earth elements (REEs) encompass the fifteen lanthanides plus yttrium and scandium, each exhibiting distinctive ionic radii, oxidation states and complexation tendencies. In natural settings, REEs undergo weathering of primary minerals, transport in solution and deposition within soils, sediments and waters. Their partitioning among solid and dissolved phases is controlled by redox conditions, pH, organic ligands and competing cations, leading to characteristic fractionation patterns between light and heavy REEs. Anthropogenic activities such as mining, ore processing, the use of phosphate fertilisers and discharge of contrast agents have markedly altered REE distributions, generating localised hotspots and diffuse contamination. Understanding the speciation, mobility and bioavailability of REEs is essential for assessing ecosystem impacts, informing reclamation strategies and guiding sustainable resource management.

Research from Nature Portfolio

Investigation of soils adjacent to a major rare earth mine tailing revealed exceptionally high REE concentrations well above crustal averages, with light and heavy REEs displaying distinct enrichment ratios. Normalised patterns indicated subtle cerium anomalies and variable europium depletion, reflecting oxidation–reduction transformations during weathering and aeolian dispersion. Prevailing winds were shown to influence lateral migration, enhancing REE enrichment in downwind soils.

An assessment of cereal crops grown near a rare earth mining district quantified fourteen REEs in wheat, maize and rice, uncovering enrichment of light REEs consistent with local bedrock signatures. Median dietary intake estimates for adults remained below established safety thresholds, yet elevated REE uptake in children prompted recommendations for age‐specific exposure monitoring and long‐term health surveillance in mining regions.

Biogeochemical Behavior of Rare Earth Elements in Environmental Systems publication trend

The graph below shows the total number of articles in biogeochemical behavior of rare earth elements in environmental systems across all publications each year (not limited to Nature Index journals).

Technical terms

Fractionation: Differential partitioning of rare earth elements into solid, adsorbed or dissolved phases during geochemical processes.

Light and heavy rare earth elements (LREEs/HREEs): Subclasses of REEs distinguished by atomic number, with LREEs (La–Sm) generally more mobile under low-pH conditions and HREEs (Gd–Lu, Y) exhibiting stronger complexation with organic ligands.

Speciation: The distribution of an element among different chemical forms, oxidation states or complexes, which dictates its solubility, reactivity and bioavailability.

Normalisation: A technique that compares measured REE concentrations against a reference shale composition (e.g. North American Shale Composite) to reveal anomalies and fractionation trends.

Bioaccumulation: The progressive concentration of substances such as REEs within an organism over time, often leading to higher internal levels than those in the surrounding environment.

References

1. The Environmental Impact of Medical Imaging Agents and the Roadmap to Sustainable Medical Imaging. Advanced Science (2025).
2. Cryptic footprints of rare earth elements on natural resources and living organisms. Environment International (2019).
3. An Updated Review of Toxicity Effect of the Rare Earth Elements (REEs) on Aquatic Organisms. Animals (2020).
4. Geochemical fractions of rare earth elements in soil around a mine tailing in Baotou, China. Scientific Reports (2015).
5. Review of Rare Earth Elements as Fertilizers and Feed Additives: A Knowledge Gap Analysis. Archives of Environmental Contamination and Toxicology (2020).
6. Toxicity of rare earth elements: An overview on human health impact. Frontiers in Environmental Science (2022).
7. Health risk assessment of rare earth elements in cereals from mining area in Shandong, China. Scientific Reports (2017).