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 org anic-bound fractions of Fe and Mn were carried out to study the remineraliz ation of organic matter in the sediments. iron and manganese oxides are hig hly depleted in the upper portion (0-18 cm) of the core due to their reduct ion during organic matter oxidation. The model calculations based on the so lid phase organic carbon depth profile indicate an average accumulation rat e for organic carbon in the Pulicat lake sediments to be 13.5 gC/m(2).yr. T he avenge remineralization rate is 12gC/m(2).yr. This is around 89% of the organic carbon deposited in the sediments. The remineralization of organic carbon in this lake sediment could release 16 x 10(3) tonnes of CO2/yr.