Different Function Area Of Organic Carbon And Inorganic Carbon Spatial Distribution In The Urban Soil Of Kaifeng City

With the deepening research on the global climate change, the carbon cycle, as the impact on global climate change, has attracted increasing attention from all walks of life. Soil carbon is an important component of terrestrial carbon pool, including soil organic carbon and inorganic carbon. The understanding of soil carbon cycle is the important premise of terrestrial ecosystem carbon cycle research. As a new soil type, urban soil gains wide attention. The deepening of the urbanization is strongly affected in a larger scope and to a wider degree. Physical and chemical properties of urban soil changes greatly with the change of soil utilization types and other characteristics of the soil changes subsequently. For a long time, organic carbon, as the indicator of soil fertility, has been studied in many aspects. Organic carbon in urban soil is representative, and it is more disturbed by human factors in the change process, which is certainly different from carbon cycle process in natural soil or farmland. At the same time, the study of the inorganic carbon which is in the form of carbonate is also very important. The change of inorganic carbon content has an influence on soil properties and the urbanization exerts an impact on the content and distribution of inorganic carbon in the soil. Besides, whether there is a connection between inorganic and organic carbon remains uncertain. Therefore, analyzing the content and the distribution of inorganic and organic carbon in the urban soil respectively is very important. Kaifeng has a long history, and its development history causes the particularity of its urban soil. The case study of Kaifeng analyzes the increase and decrease of the organic and inorganic carbon in vertical direction and spatial distribution, the carbon density change trend and the influence on carbon content. Sixty-two section points are selected in the study, and foundation soil physical and chemical properties, the inorganic carbon content, water-soluble inorganic carbon composition and activated carbon content of 301 soil layers are examined.Through this study, the conclusions are as follows:1 Inorganic and organic carbon content in the soil of Kaifeng presents diversity in the vertical direction without a unified law. Inorganic carbon content of natural soil increases first and then decreases with depth in the vertical direction, while organic carbon content shows a trend of decline. On the spatial distribution, order of inorganic carbon density of each function zone according to size is : cultural and educational area > administrative/residential area > industrial area > leisure area > transport area; organic carbon density order is: administrative/residential area> leisure area >cultural and educational area> industrial area > transport area. The inorganic carbon density is 1/3 of the total carbon density.2 The proportion of difficult soluble inorganic carbon in the soil of Kaifeng is big. Soluble inorganic carbon is dominated by C in the form of HCO3-. Form differs in vertical direction, while its content order in the spatial distribution is: leisure area > transport area >administrative/residential area > cultural and educational area > industrial area. Activated carbon content varies in the vertical direction, and in space, its order is: leisure area > cultural and educational area > industrial area > transport area > administrative/residential areas.3 The sampling point can be divided into two categories: green space and non-green space. Inorganic carbon content in green space is relatively uniform in vertical direction, while change in non-green space shows diversity. The inorganic carbon content conforms to carbon density change on the spatial distribution. Green space order is: industrial area >administrative/residential area > cultural and educational area >transport area > leisure area. Non-green space order is: cultural and education area> transport area >administrative/residential area > industrial area > leisure area. The inorganic carbon content and carbon density of non-green space is higher than that of green space.(4)The change on organic carbon content and activated carbon content of green space and non-green space is irregular in the vertical direction; organic carbon content, activated carbon content and carbon density of non-green space is all above that of the green space; organic carbon content and carbon density on the spatial distribution is different from activated carbon content and carbon density in order.