Legacy PCB and hydrocarbon reservoirs in estuarine sediments: from historical contamination to hidden mass hotspots
Abstract
Infrastructure-induced sediment deposits are common features in engineered river systems, yet their role as longterm reservoirs of persistent organic pollutants remains poorly quantified. The upper Seine Estuary (France), historically affected by intense industrial contamination and extensive river engineering, provides a relevant example of this issue. Here, we combined near-infrared hyperspectral imaging, 3D stratigraphic modelling and sediment-thickness-based extrapolation to quantify depth-integrated and spatially explicit stocks of polychlorinated biphenyls (PCBs) and total hydrocarbons (THC) across three infrastructure-induced sediment deposits. Sediment records revealed high historical contamination, with PCBs reaching 2.59 mg kg -1 during the 1970s, followed by a marked decline, while THC exhibited a similar temporal trend. Total stocks were estimated at 128 ± 67.9 kg for PCBs and 55.5 .10 3 ± 20.8 .10 3 kg for THC over only 0.1 km² of sediment deposits. Accordingly, surface-normalized PCB storage averaged 1310 mg m -2 , several orders of magnitude higher than values reported for other estuarine environments worldwide (0.01 -4.4 mg m -2 ). These exceptionally high stocks result from sustained historical contaminant inputs from nearby industrial sources and enhanced sediment accumulation promoted by river engineering works. Importantly, the uppermost 5 cm, commonly considered in stock assessments, contained only 0.4 % of the total PCB stock, showing that such contaminant mass hotspots may remain largely hidden. Because the estimated PCB stock was of the same order of magnitude as annual upstream PCB inputs previously measured to the estuary, these deposits may constitute a substantial secondary source of contamination if remobilized.
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BibTeX
@article{barrois2026legacy,
title = {{Legacy PCB and hydrocarbon reservoirs in estuarine sediments: from historical contamination to hidden mass hotspots}},
author = {Jean-Marie Barrois and Maxime Debret and Kévin Jacq and Alexandra Coynel and Olivier Evrard and Pierre-Alexis Chaboche and Julie Cosme and Ines Crochet and Florence Portet-Koltalo},
journal = {Journal of Hazardous Materials Advances},
year = {2026},
month = sep,
doi = {10.1016/j.hazadv.2026.101556},
url = {https://cea.hal.science/cea-05751829v1},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - Legacy PCB and hydrocarbon reservoirs in estuarine sediments: from historical contamination to hidden mass hotspots
AU - Jean-Marie Barrois
AU - Maxime Debret
AU - Kévin Jacq
AU - Alexandra Coynel
AU - Olivier Evrard
AU - Pierre-Alexis Chaboche
AU - Julie Cosme
AU - Ines Crochet
AU - Florence Portet-Koltalo
PY - 2026
DA - 2026/09/16
JO - Journal of Hazardous Materials Advances
DO - 10.1016/j.hazadv.2026.101556
UR - https://cea.hal.science/cea-05751829v1
AB - Infrastructure-induced sediment deposits are common features in engineered river systems, yet their role as longterm reservoirs of persistent organic pollutants remains poorly quantified. The upper Seine Estuary (France), historically affected by intense industrial contamination and extensive river engineering, provides a relevant example of this issue. Here, we combined near-infrared hyperspectral imaging, 3D stratigraphic modelling and sediment-thickness-based extrapolation to quantify depth-integrated and spatially explicit stocks of polychlorinated biphenyls (PCBs) and total hydrocarbons (THC) across three infrastructure-induced sediment deposits. Sediment records revealed high historical contamination, with PCBs reaching 2.59 mg kg -1 during the 1970s, followed by a marked decline, while THC exhibited a similar temporal trend. Total stocks were estimated at 128 ± 67.9 kg for PCBs and 55.5 .10 3 ± 20.8 .10 3 kg for THC over only 0.1 km² of sediment deposits. Accordingly, surface-normalized PCB storage averaged 1310 mg m -2 , several orders of magnitude higher than values reported for other estuarine environments worldwide (0.01 -4.4 mg m -2 ). These exceptionally high stocks result from sustained historical contaminant inputs from nearby industrial sources and enhanced sediment accumulation promoted by river engineering works. Importantly, the uppermost 5 cm, commonly considered in stock assessments, contained only 0.4 % of the total PCB stock, showing that such contaminant mass hotspots may remain largely hidden. Because the estimated PCB stock was of the same order of magnitude as annual upstream PCB inputs previously measured to the estuary, these deposits may constitute a substantial secondary source of contamination if remobilized.
SN - 2772-4166
ER -