Rare earth elements (REEs) are indispensable to the U.S. supply chain. Increasing global demand and China’s dominance in REE production underscore the urgency of developing sustainable domestic sources. Although REE deposits exist in the United States, mining them remains economically challenging due to low ore concentrations, inefficient extraction methods, and high environmental costs. Exploring alternative recovery strategies is therefore essential. Seaweeds, known for their capacity to bioaccumulate metals, present a potential natural pathway for REE recovery from the marine environment.

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Rare Earth Elements here include all 15 lanthanides plus scandium and Yttrium.

Not rare per se, but difficult to extract.

 

OBJECTIVE:

Investigate the feasibility of seaweed-based REE recovery by examining the spatial and temporal accumulation of REEs in seaweed tissue.

 

RARE EARTH ELEMENT USES:

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STUDY SITE AND METHODS:

• Sample collection of water (n= 124) at 2 and 10 m below surface, and kelp and fucoids (n= 1513) along four transects at Moira (22 locations) and Kendrick Bays (12 locations) in April, June, and September 2024 and April 2025.

• REE quantification via ICP-MS.

• Compositional analysis to determine correlations between REE concentration and carbohydrates.

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RESULTS:

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• Among the sampled sites, Moira Bay showed the highest REE concentrations in marine waters (2 m), reaching a maximum in June (8.65 × 10⁻² ppb in at least one location).•Fucus distichus showed the highest concentration of REEs in the tissue, with peak concentration measured in June.

• REE concentration in the tissue varied with the element.•Cerium (Ce), Neodymium (Nd), and Yttrium (Y) showed the highest concentrations.

• Location 6 is situated on the delta of Perkins Creek, the major contributor of REEs to Moira Bay.•REE adsorption was most strongly associated with fucose content, indicative of fucoidan.

• Although fucose and REE levels varied by nearly three-fold, fucoidan or alginic acid content alone did not consistently predict REE concentrations.

• REE concentrations in seaweed tissue (≤ ~1000 ppbw) are too low to be economically viable for REE recovery. At observed concentrations, seaweed biomass does not represent a feasible alternative source of REEs.