Work

Temporal trends of pollution in an estuary affected by phosphogypsum leachates and acid mine drainage: Waste management implications

Year: 2025

Type: article

Abstract: 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 238 U 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 %), 238 U (∼1200 Bq·kg −1 ), 226 Ra (∼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 ( 226 Ra ∼ 80 Bq·kg −1 , 210 Pb ∼ 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. • This study analyzes the temporal evolution of pollution in the Tinto River Estuary. • Sediments near the phosphogypsum piles reveal three distinct contamination phases in the Tinto estuary. • Sediments near the phosphogypsum piles show extreme enrichment in U, 226 Ra, P, As, and Pb. • Opposite-bank sediments record attenuated contamination mainly from AMD influence. • Pollution indices and Principal Component Analysis disentangle sources and assess ecological risk levels.

Source: Marine Pollution Bulletin

DOI: 10.1016/j.marpolbul.2025.118996

Authors: M. del Caño-Mármol, A. Barba-Lobo, E.G. San Miguel, J.L. Guerrero, J.P. Bolívar

Institutions: Universidad de Huelva, Universidad Rey Juan Carlos

Language: English

Topic: Heavy metals in environment

Subfield: Pollution

Field: Environmental Science

Domain: Physical Sciences

SDGs: Clean water and sanitation, Responsible consumption and production

Open Access status: hybrid

Estimated APC paid: $3,740