Deposition, Degradation and Preservation of Organic Carbon in the Pulicat Lake, Tamil Nadu, East Coast of India: Preliminary Results

The sequential extraction of core sediment samples of Pulicat lake for the determination of exchangeable, carbonate-bound. Fe-Mn oxides-bound, and organic-bound fractions of Fe and Mn were carried out to study the remineralization of organic matter in the sediments. Iron and manganese oxides are highly depleted in the upper portion (0-18 cm) of the core due to their reduction during organic matter oxidation. The model calculations based on the solid phase organic carbon depth profile indicate an average accumulation rate for organic carbon in the Pulicat lake sediments to be 13.5 gC/m².yr. The average remineralization rate is 12gC/m².yr. This is around 89% of the organic carbon deposited in thc sediments. The remineralization of organic carbon in this lake sediment could release 16 x 10³ tonnes of CO₂ /yr.