COMPOSITIONS AND VARIATION RULE OF SOIL CARBON POOL IN THE COASTAL AREA OF WESTERN LIAONING PROVINCE

Based on the surface and deep soil carbon content data obtained from multi-objective geochemical survey in the coastal area of western Liaoning Province, the paper calculates the soil carbon density and storage in surface (0-20 cm), middle (0-100 cm) and deep (0-180 cm) layers of the study area, and discusses the compositions of soil carbon pool (SCP) and carbon sequestration potential(CSP) in terms of classification, as well as the variation rule of soil organic carbon (SOC) in the last 40 years. The results show that the SCP is dominated by organic carbon, while the inorganic carbon storage increases with depth, with the soil organic carbon density(SOCD) of 2.14, 7.59 and 11.27 kg/m² for surface, middle and deep layers respectively, lower than the average of national multi-objective survey areas and circum-Bohai Sea area. The compositions of SCP vary in different classifications as follows: The carbon density of Proterozoic and Mesozoic units is high in surface layer, while that of Paleozoic unit is high in middle and deep layers; The soil carbon density of mountain is higher than that of hills and plain by landforms, the highest in cinnamon soil and the lowest in moisture soil by soil types, the highest in forest and grass lands and lower in cultivated land and garden by land use types. The CSPs of surface, middle and deep soils are 33.91, 103.32 and 129.37 Mt, respectively, with CSP of organic carbon higher than that of inorganic carbon. The SOC was increasing generally in the last 40 years, among which the surface soil of cultivated land and garden showed carbon source effect, releasing 0.29 Mt of SOC. The distribution of brown soil and forest land contributes the most to the input of SOC.