Talk 1:

The ability of the ocean to sequester CO­₂ is determined by its carbonate chemistry, which can be altered by calcifying organisms. One such group are the coccolithophores, which are phytoplankton that surround themselves with microscopic calcite scales known as coccoliths. These coccoliths are often shed by the cell and when high rates of shedding occur, the ocean turns milky, which can be visible from space. To understand the physiology of coccolithophore blooms and its impact on ocean alkalinity, a bloom was sampled in the Icelandic Basin in 2024. This allowed us to analyse changes in coccolithophore growth rates, turnover of particulate inorganic carbon, species composition and nutrient depletion across the bloom. Using this data we hope to investigate the impact of coccolithophores on total alkalinity and the fate of this alkalinity.

Talk 2:

Continental shelf sediments are vast areas, some regions of which accumulate and store organic carbon. However, these regions are increasingly impacted by anthropogenic pressures, particularly from infrastructure related to energy extraction. Estimating carbon accumulation potential of sediments can be confounded by this anthropogenic activity, particularly around oil and gas extraction activities. This study describes carbon stocks, sediment type and carbon accumulation rates (CARs) in sediment surrounding the North West Hutton decommissioned platform in the northern North Sea.
By accounting for heavy metals derived from ICP-MS to create correction factors, previous estimates of CARs from gamma spectrometry have been corrected and CARs close to North West Hutton, which were previously undetermined, have been calculated. Results show that CARs determined by gamma spectrometry alone are consistently lower than those corrected by heavy metal attenuation factors and also using polonium-210 measurements from alpha spectrometry analysis. This work indicated that CARs could be underestimated in regions directly impacted by heavy metals associated with the extraction activity. This study highlights the potential underestimation in the offshore environment, but if this approach is applied to coastal sites where accumulation rates are generally considerably higher, and impacted by industry, this could have widespread implications for service assessments and blue carbon accounting.