Sediment Organic Carbon Stocks in Mangrove Ecosystems of Bidkhun, Persian Gulf

Mangroves play a vital role in climate change mitigation by storing a significant amount of blue carbon, particularly in their sediment layers. This study quantifies the sediment organic carbon (SOC) stored in the Bidkhun mangrove forests along the northern Persian Gulf coast. The area represents one of the world’s northernmost mangrove forests, preserved as Iran’s first National Marine Reserve since 2004. Sediment cores were collected to a depth of about one meter using a Russian peat corer. Sediment cores were sectioned into depth intervals of 0–15, 15–30, 30–50, and 50–100 cm. The midpoint of each sediment layer was sampled for subsample collection. Samples were stored at 4°C and, then dried at 60°C until constant weight was reached. Dry bulk density was calculated based on dry mass and sample volume. SOC density was calculated by multiplying dry bulk density by the percentage of organic carbon. Total carbon stocks were calculated by integrating carbon content over sediment depth. SOC density ranged from 0.0036 to 0.0069 g/cm3, corresponding to total carbon stocks between 190.6 and 293.1 mg C/ha. Carbon concentrations were higher in surface sediments and decreased with depth, likely due to mineralization and dilution by pore water. These findings underscore the significant carbon sequestration potential of the Bidkhun mangroves and highlight the importance of protecting and restoring these habitats.