Abstract: Aquaculture ponds are important sources of greenhouse gas (CO₂) emissions in subtropical estuaries. However, the kinetic characteristics of organic carbon mineralization of the sediments in these aquaculture ponds have not been clarified yet. Here, we investigated the CO₂ accumulation yields of the sediments collected from six Litopenaeus vannamei  aquaculture ponds in subtropical estuaries (Min River, Mulan River and Jiulong River) in southeast China, after anaerobically incubated for 60 days. The results showed that CO₂ production in the sediments mainly occurred in the first two days of incubation, and then decreased rapidly. The cumulative carbon mineralization amounts (C₀) ranged between 190.12-480.94 μg·g^-1, while the mineralization constants (k) ranged between 0.17-0.42 d^-1. There were significant differences in organic carbon mineralization of the sediments among aquaculture ponds with different salinities, with low-salinity aquaculture ponds showing higher value of C₀ and lower value of k. Porewater Cl^-, SO₄^2-, DOC and NH₄⁺ were the most important environmental factors affecting organic carbon mineralization in the sediments. Ponds with high salinity had higher concentrations of Cl^- and SO₄^2- and lower concentrations of DOC and NH₄⁺ in porewater than low-salinity ponds. Hence, the aquaculture of L. vannameiin highsalinity ponds can effectively inhibit the mineralization of organic carbon in sediments.

Key words: organic carbon mineralization, the first-order kinetic model, Litopenaeus vannamei aquaculture pond.