The REE concentration in the water of the Tinto river decreases from the fluvial sector (1098.63 μg·l-1) to
the zone of greater marine influence (0.33 μg·l-1) showing a strong longitudinal gradient in the estuarine
mixing zone, where conductivity goes from 10 to 50 mS·cm-1 and pH from 3 to 6. The fluvial sector shows
a typical fractionation pattern of acid environments, with a convex morphology centered in the Gd. In
agreement we approached the marine sector of the estuary, with conductivities greater than 50 mS·cm-1
and pH bigger than 6, this model evolves towards a fractionation pattern with a clear depletion in LREE
that preferably are adsorbed on the particle surfaces