利用多目标区域地球化学调查数据，估算了重庆西部地区表层土壤有机碳密度和储量。结果表明，重庆西部地区表层（0～20 cm）土壤有机碳储量为41038589 t，平均密度为2929 t·km－2。从地貌类型看，低山（2984 t· km－2）和中山（2986 t·km－2）区土壤有机碳密度较高，丘陵区（2628 t·km－2）最低，山地土壤有机碳储量最丰富。不同类型土壤中，石灰土有机碳平均密度最高（5043 t·km－2），其次为黄壤（3756 t·km－2），紫色土最低（2329 t· km－2），紫色土有机碳储量最大。就土地利用方式而言，林地土壤有机碳平均密度最高（4071 t·km－2），耕地土壤处于中等水平（2752 t·km－2），居民及建筑用地有机碳密度最低（2416 t·km－2），耕地土壤有机碳储量最大。与第二次土壤普查数据对比发现，该区土壤有机碳储量和密度呈降低趋势，表层土壤作为碳源向大气释放碳，尤其是江津、潼南地区土壤有机碳密度分别降低了56．7％、45．1％。%Based on the soil data obtained by multi⁃purpose regional geochemical survey, the authors estimated the surface soil organic carbon storage and organic carbon density in western Chongqing. The results show that the surface soil organic carbon storage is 41 038 589 t, with organic carbon average density of 2 929 t·km-2. As for geomorphological types, the soils of low maintains (2 984 t· km-2 ) and middle maintains ( 2 986 t·km-2 ) have higher organic carbon density, the density of hills soil is the lowest, and the main⁃tainous soil has most abundant organic carbon storage. In different soil types, the organic carbon density of limestone soil is the highest ( 5 043 t·km-2 ) , followed by yellow soil ( 3 756 t·km-2 ) , the organic carbon density of purple soil is the lowest ( 2 329 t·km-2 ) , and the organic carbon storage of purple soil is the highest. Regarding the land use, the organic carbon density of forest land is the highest ( 4 071 t·km-2 ) , the cultivated land is at the middle level ( 2 752 t·km-2 ) , the resident and building soil is the lowest ( 2 416 t·km-2 ) , and the organic carbon storage of the cultivated land is the highest. A comparison with the data of the Second Soil Gen⁃eral Survey shows that the surface soil organic carbon storage and organic carbon density have been reduced and, as‘carbon source’ , the surface soil has released organic carbon to the air. Especially the soil in Nanchuan and Jiangjin has decreased by 56.7% and 45.1%respectively.
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