Rare earth element and radionuclide distribution in surface sediments along an estuarine system affected by fertilizer industry contamination

Site-specific contamination related to fertilizer industry activity was demonstrated by light rare earth element (REE) anomalies (sum of La, Ce, Pr, Nd, Sm, and Eu concentrations up to 4.141 mg kg⁻¹) and radionuclides (²¹⁰Pb and ²²⁶Ra activities up to 994 and 498 Bq kg⁻¹, respectively) from industrial contamination, within a subtropical estuary (SE Brazil). Anthropogenic influence was also supported by the site-specific ²¹⁰Pb and ²²⁶Ra distribution down the estuarine system. The distribution of REE and radionuclide contamination varied along the estuary, which reflected differing sedimentation patterns of phosphogypsum and/or phosphate ore pollutants as identified downstream from the source, likely influenced by sediment–hydrodynamic processes within the estuarine system. Redox- and ion exchange-sensitive pollutants are mobile at the fresh–sea water interface causing an uneven distribution of the pollutants, indicating that the phosphgypsum and/or phosphate ore pollutant deposition can be also influenced by physical and/or geochemical processes associated to estuarine systems.