Distributions of dissolved rare earth elements during estuarine mixing at the Changjiang River mouth

The first data on the concentrations of dissolved REE in surface waters col lected from the north passage of the Changjiang Estuary where the salinity ranges from 0.15 to 19 mg/g were determined by ICP-MS after preconcentratio n with solvent extraction and back-extraction techniques. Relative to other estuaries, the river-water end-member concentrations of dissolved REE are very low, ranging from 11.963 (Y) to 0.098 ng/kg (Lu). Dissolved REE remove d markedly from water in the Changjiang Estuary where salinity lies within the range of 0.15-1 mg/g, but the percent removal is low, ranging only from 47%(La) to 25%(Lu). Strong water-sediment interaction due to shallow water depth in the Changjiang Estuary leads to remarkable concentration peaks of dissolved REE in the location where the salinity varies from 1 to 8 mg/g. In the moderate and high salinity regions from 8 to 19 mg/g, the concentrat ions of dissolved REE gradually increase as a result of desorption or parti al dissolution of particles.