Researches on carbon absorption in marine ecosystems continue increasing worldwide, and marine ecosystems are able to absorb 26% of the world’s carbon emissions every year. Seaweeds use carbon dioxide as substrate for photosynthesis to generates oxygen into the air and carbohydrates accumulated in their tissue which supports for their growth. Therefore, their capacity of collecting (or sequestrating) carbon dioxide can be counted in an annual carbon absorption amount. Blue carbon stores more carbon in sediments than green carbon in vegetation. C arbon stored in sediments is known to decompose very slowly and last for hundreds or even thousands of years. However, there have been no studies on carbon sequestration capacity of sediments around seaweed ecosystems . We estimated the carbon sequestration potential of seaweed aquaculture and blooms, and nearby sediments. We measured the tissue carbon content and organic carbon in different depths of sediments at six tidal flat (BR, SA, GN, SY, WJ) and seaweed aquaculture (JD) and marine forests (PH) in South Korea. Seaweed samples were collected from each site, dried, and ground for carbon analysis. Sediments were collected using a corer , separated into 5 cm intervals and homogenized at each depth. Total carbon and organic carbon contents, and sediment size were analyzed for the sediments. The amount of carbon dioxide removal by tidal flats seaweed was 0.025-0.51 tCO2 /ha, and the sediment removed 82-2,110 tCO2/ha. The potential carbon dioxide sequestration by sediment in seaweed aquaculture area was 243-351 tCO2/ha
. As the paradigm of climate change policy shifts from land-based to marine sector due to acceleration and expansion of climate change effects, it is critical to evaluate carbon reduction potential of algae clusters and surrounding sediments.