variability of organic carbon matter and nitrogen deposits in a carbonate platform of mangroves

mangroves are usually characterized by their high potential for longterm sequestration of organic carbon. sediment accretion by these valuable habitats increased their capability of organic carbon sequestration. in this study, we aimed to examine the organic carbon sequestration of mangrove expansion (avicennia germinans) in southern iran. different variables have been investigated in the sampled sediments, including δ^13c, δ^ 15n, toc, tn, and c/n ratio. our findings indicated the significant variation of measured variables in several top intervals, reflecting the existence of autochthonous and allochthonous organic substances. our data showed that the minority of δ^13c values are lower than 23% in the s3 site, suggesting that mangrove litter is a critical input oc (δ^13c, 28 to 30%). on the other hand, the significantly higher value of δ^13c (14 to 23%) indicates that phytoplankton and possibly local microphytobenthos are the primary sources of organic materials inputs. moreover, site s4 presents the highest mean value of c/n, tn, and δ^15n, which can be justified because of its proximity to the estuary and supply of organic matters imported from algal sources. the substantial role of mangrove forests depositing organic carbon should be investigated in the global carbon cycle.