RT Journal Article T1 Temporal trends of pollution in an estuary affected by phosphogypsum leachates and acid mine drainage: Waste management implications T2 Evolución temporal de la contaminación en un estuario afectado por lixiviados de fosfoyeso y drenaje ácido de minas: implicaciones para la gestión de residuos A1 Caño Marmol, María A1 Barba Lobo, Alejandro A1 Gutiérrez de San Miguel Herrera, Enrique A1 Guerrero, José Luis A1 Bolívar Raya, Juan Pedro AB The Huelva estuary has been historically impacted by multiple pollution sources, including acid mine drainage (AMD), industrial emissions, and discharges from phosphogypsum (PG) piles. This study analyses the concentrations of heavy metals, major and trace elements, and radionuclides from the 238U series in two sediment cores collected from the Tinto River estuary: one adjacent to the PG piles (Core 1) and the other on the opposite riverbank (Core 2). A reference core from the Piedras River was used to establish natural background levels. Core 1 provides a clear stratigraphic record of industrial activity, showing three contamination phases. The open-discharge period (60–30 cm) is characterized by extremely high values of P (∼4 %), 238U (∼1200 Bq·kg−1), 226Ra (∼800 Bq·kg−1), and metals such as As (∼4700 μg·g−1) and Pb (∼3000 μg·g−1). Contamination indices (EF, Igeo, PERI) peak in this interval, confirming severe ecological risk. A decline from 30 to 10 cm reflects the shift to closed-circuit waste management, although U and P persist due to PG leaching. The surface layer (0–10 cm) records a marked reduction, but concentrations remain above background, evidencing long-term legacy pollution. The sedimentation rate (sr = 1.2 cm/yr) provides high temporal resolution. In contrast, Core 2 shows attenuated contamination restricted to the upper 20 cm, with lower radionuclide activities (226Ra ∼ 80 Bq·kg−1, 210Pb ∼ 90 Bq·kg−1) and metals, and a reduced sr = 0.4 cm/yr. Profiles suggest diffuse AMD influence rather than direct PG input. PCA differentiates contamination sources, confirming PG-dominated inputs in Core 1 and AMD-related contributions in Core 2. PB Elsevier SN 0025-326X SN 1879-3363 (electrónico) YR 2026 FD 2026 LK https://hdl.handle.net/10272/27447 UL https://hdl.handle.net/10272/27447 LA eng NO Caño-Mármol, M., Barba-Lobo, A., San Miguel, E. G., Guerrero, J. L., & Bolívar, J. P. (2026). Temporal trends of pollution in an estuary affected by phosphogypsum leachates and acid mine drainage: Waste management implications. Marine Pollution Bulletin, 223, 118996. https://doi.org/10.1016/j.marpolbul.2025.118996 DS Repositorio Institucional de la Universidad de Huelva RD 31 may 2026