- 1Centre for Environment, Fisheries and Aquaculture Science, Lowestoft, United Kingdom of Great Britain – England, Scotland, Wales (franck.dal-molin@cefas.gov.uk)
- 2University of Essex, Colchester, United Kingdom of Great Britain - England, Scotland, Wales (h.woodwardrowe@essex.ac.uk)
In recent years, the lead-210 (210Pb) geochronological tool has been extensively utilised to determine the burial rate of Blue Carbon in various marine environments. Numerous physical disturbances, originating from both anthropogenic and natural sources, can influence its applications. Additionally, many non-nuclear industries discharge waste containing elevated levels of naturally occurring radioactive materials, known as NORM industries, which presents another challenge if sediment cores are collected near such industrial activities.
The presence of anthropogenically derived 210Pb and radium-226 (226Ra) is often associated with high concentrations of heavy elements such as aluminium, barium, iron, manganese, strontium, zinc, and lead. These elements can significantly impact the direct measurement of 210Pb via gamma spectrometry and, subsequently, the application of various 210Pb-based dating techniques, making estimates of accumulation rates particularly challenging.
In this study, several sediment cores were collected in proximity to a decommissioned oil and gas platform located offshore in the UK North Sea (North West Hutton (NWH), 61.11N, 1.31E). Elemental and radioelemental signatures from legacy NORM discharges were observed in the sediment cores collected within 200 metres north and south of the former NWH platform and were thoroughly characterised using ICP-MS and gamma spectrometry, respectively. This enabled the forensic differentiation of the NORM-derived 226Ra fraction from the natural background and the generation of relative factors based on bulk elemental composition analysis to correct 210Pb results obtained from initial gamma spectrometric analysis. This corrective approach was validated by measuring polonium-210, a decay product of 210Pb, via alpha spectrometry, and allowed the estimation for the first time of carbon accumulation rates in sediment cores using different modelling approaches (CIC, CFCS, CRS, and RPLUM).
How to cite: Dal Molin, F., Woodward-Rowe, H., Davis, T., Jervis, J., Parker, R., and Hicks, N.: Corrected Pb-210 based estimations of accumulation rates in marine sediments contaminated by legacy NORM discharges, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11525, https://doi.org/10.5194/egusphere-egu25-11525, 2025.
