T02_P02

Preliminary studies on tracing the source of carbon in organic matter and carbonate in coral and aquatic snail by ¹⁴C

Cheng P¹,  Du H¹, Lu X¹

¹Institute of Earth Environment,CAS, Xi'an, China

The variation of ¹⁴C concentrations in organic matter and inorganic carbonates in coral and aquatic snail shells may reflect how carbon is used by these organisms. However, there are few studies on the source of organic matter in coral and snail shells. The main reasons are as follows:1) there is less organic matter in shells and coral; 2) there are few reliable methods for extracting organic matter. In order to verify the reliability of our extracted method, four water-soluble substances with known ¹⁴C ages (50,000 to modern) were oxidized by sodium persulfate oxidation method. The results show there is no obvious old or young carbon contamination during the oxidation process. Further analysis of the samples showed that the ¹⁴C age of the organic matter of the coral was older than the ¹⁴C age of the carbonate, to a maximum of 670 years and to a minimum of 80 years, the organic matter of the snails in the lake had a ¹⁴C age 90 years older than the carbonates. The differences of ¹⁴C ages of organic matter and carbonate indicate that corals and aquatic snail have different carbon utilization and carbon source during growth. The change of carbon source is reasonable to trace the changes of water environment.