Yttrium in the Vigo Ria (NW Iberian Peninsula): Sources, distribution, and background levels

Certain heavy minerals enriched in yttrium, such as monazite and xenotime, have previously been indexed in the Vigo area. The levels and spatial distribution of this element were studied in 50 surface sediment samples from the Vigo Ria. The highest levels were found along the southern margin in the middle of the ria, coinciding with the geological source of the Galiñeiro Complex. From this zone, a dilution of yttrium in the sediments was observed seaward due to the presence of calcium carbonate (outer ria) and upstream due to the input of migmatites, anatexites, and two-mica granites (inner ria). The estimated background concentration in the Vigo Ria was 14.6 ± 2.6 mg kg^-1 (Sc normalized), which is close to the average concentration found in surface sediments (13.4 ± 5.4 mg kg^-1). This suggests that yttrium in the Vigo Ria sediments is mainly of lithogenic origin.