Chapter 7: Determination of Blue Carbon sequestration rates in the UK North Sea using lead-210 and complementary fingerprinting tools

The fallout of lead-210 (²¹⁰Pb), present naturally in the atmosphere from the decay of radon gas, is a source of information that is commonly utilised to estimate time-trends of relatively recent environmental changes, variations and pressures recorded in aquatic sediment cores. Over the last four decades, this geochronological tool has been utilised in diverse environmental research applications. Currently in the United Kingdom (UK), there is a particular growing demand from marine scientists interested in further understanding the sequestration rates of natural sources of organic carbon, also known as Blue Carbon (BC), that help mitigate the effect of climate change. Between 2021 and 2022, several surveys were undertaken in different coastal and offshore regions of the UK North Sea. These presented an opportunity to test different sample preparative and analytical approaches for measuring ²¹⁰Pb and radium-226 (²²⁶Ra) in marine sediments, review the most important challenges and limitations when applying this geochronological tool in this marine region and investigate the best fingerprinting options available that could help validate results obtained from ²¹⁰Pb-based modelling.