Also check please the following good link: https://aambpublicoceanservice.blob.core.windows.net/oceanserviceprod/education/earthscientists/pdf/measuring-carbon-sequestration.pdf
The following link is also very useful: https://www.canterbury.ac.nz/media/documents/oexp-science/geography/community-engagement/geog-309/2019/GEOG309-19-Estimation-of-Carbon-Sequestration-Levels.pdf