Carbon Burial Inferred from Minerals and Lake Water Properties:A Case Study of Guozha Co in Xizang

Lacustrine sediments not only record the evolutionary processes of lakes but also contain rich carbon reserves.Taking the 407 cm-long lake sediments of Guozha Co in western Qinghai-Xizang Plateau as an example,this paper discusses the changes and factors influencing the organic carbon and inorganic carbon flux,as well as the amount of carbon buried since 8.7 ka BP,during which the lake has evolved from freshwater to saline.The results show that,since 8.7 ka BP,the flux of inorganic carbon in Guozha Co has ranged from 4.6 to35.1 g·m^-2·a^-1,with an average of 17 g·m^-2·a^-1,while the buried amount ranged from 2.5×10~6 to 19.1 ×10~6 t/a,with an average of 9.2×10~6 t/a.Approximately 18.5×10~9 t of inorganic carbon has been buried.The flux of organic carbon ranged from 1.6 to 7.3 g·m^-2·a^-1,with an average of 4.0 g·m^-1·a^-1,while the amount of organic carbon buried ranged from 1.5×10~6 to 3.3×10~6 t/a,with an average of 2.2×10~6 t/a.Approximately 1.63×10~9 t of organic carbon has been buried.Guozha Co has evolved from a freshwater lake in a warm climate setting during8.7-4.0 ka BP to a freshwater lake in cold climate setting during 4.0-1.5 ka BP,and finally to a saline lake from1.5 ka BP to present.The deposition flux and reserves of both inorganic carbon and organic carbon were lower during the period of 4.0-1.5 ka BP than in the other two periods.According to the characteristics of carbon deposition flux and reserves,inorganic carbon burial is related to carbonate minerals,while organic carbon burial is related to clay minerals,with both types of burial related to the environment and properties of the lake.Temperature had the most significant effect on both the flux and burial of inorganic carbon;however,salinity had a greater effect on organic carbo n burial.