Abstract:

The study on soil carbon storage is of great significance in carbon cycle and global change research. However, past calculation accuracy of carbon storage was restricted by the data sources. Thanks to the double layer gridded sampling method and analysis, which was applied on the multi-target regional geochemical survey in Shandong Province, we gathered a bulk of large density, high precision soil organic carbon (SOC) data, which was a good foundation for the accurate quantification of soil carbon pool. These data were used for the calculation of SOC density and storage in the surface (0-20 cm), middle-top (0-100 cm) and full-thickness (0-160 cm) layers of the soil in the Blue Economic Zone of Shandong Peninsula, and the spatial distributions of SOC storage and the potential for soil carbon sequestration were also studied. The results showed that, in the Blue Economic Zone, the soil carbon pool compositions of the above 3 soil layers were different. The SOC storage in the surface soil accounted for 71.67% of total organic carbon (TC) storage, and decreased with the depth increases, whereas the proportion of SIC storage increased with the depth increases, both storage proportions of the full-thickness soil were close. Total SOC storage and average SOC density for the surface soil were 132.64 Mt and 2.06 kg/m², respectively. For the middle-up soil, they were 458.27 Mt and 7.11 kg/m², and for the fullthickness soil, they were 619.96 Mt and 9.61 kg/m². The above SOC density numbers were all lower than the national average. In addition, SOC density was different with soil types, landforms and land uses. SOC density of the cinnamon soil surface was the largest (2.48 kg/m²), and that of the aeolian sandy soil was the smallest (0.91 kg/m²). SOC density of the irrigation paddy field soil surface was the largest (3.45 kg/m²), and that of the vegetable field was the smallest (1.61 kg/m²). The spatial distribution of the surface soil SOC density showed a pattern of low values in coastal areas, middle values in the North Shandong Plain and the Jiaolai basin, and high values in the hills and low mountains. According to the regression equations established using the second soil survey data and the multi-target regional geochemical survey data, and it shows that the surface soil in the Blue Economic Zone of Shandong Peninsula will act as a carbon sink in the future period. There will be a net increase of 60.94 Mt more TOC, of which, a decrease of 5.07 Mt will originate from carbon emissions and an increase of 65.97 Mt will originates from carbon sequestrations.

Key words: soil organic carbon, organic carbon density, organic carbon storage, spatial distribution, potentials of carbon sequestration, Blue Economic Zone of Shandong Peninsula