[Changes in Land Use Carbon Emissions and Coordinated Zoning in China].

Carbon emissions from land use changes have become one of the main sources of regional carbon emissions. In order to explore its changes, based on the MCD12Q-LUCC data of MODIS from 2001 to 2019 using the carbon emission coefficient method, clustering, and outlier analysis method, the spatial characteristics of land use carbon emissions in various provinces in China in the past 19 years were discussed from the perspectives of carbon emission economy contributive coefficient, carbon ecological support coefficient, and their coupling and coordination relationship. The results showed that:① from 2000 to 2019, the national land use carbon emissions increased significantly; however, after 2011, the growth rate of carbon emissions became flat, whereas the growth of carbon sinks was relatively slow, and the gap between the two was still large. ② Clustering and outlier analysis showed that during the study period, the high-value agglomeration centers of land use carbon emissions in various provinces and cities across the country shifted from Guangdong, Jiangsu, and other provinces to Hebei, Shanxi, Inner Mongolia, and other provinces, and the agglomeration status became increasingly obvious. ③ The economy contributive coefficient of carbon emissions in all provinces and cities across the country had the spatial characteristics of being high in the south and low in the north, and the ecological support coefficient gradually developed from high in the west to low in the east, followed by that in the north, and the coupling coordination between the two showed a downward trend. ④ Based on the economy contributive of carbon emissions and carbon ecological support, this study divided the provinces into four categories:low-carbon maintenance area, economic development area, carbon sink development area, and comprehensive optimization area. We also put forward our own development suggestions, striving to achieve carbon neutrality and low-carbon sustainable development.

[Spatialization and Spatio-temporal Dynamics of Energy Consumption Carbon Emissions in China].

The adverse effects of global climate change on human production and life are becoming increasingly prominent. Responding to climate change has become a severe challenge faced by human society, and the reduction in greenhouse gas emissions has gradually become a common action by all countries. Therefore, analyzing carbon emissions through scientific methods has become an important foundation for responding to the national "dual carbon" strategy. This study used provincial-level carbon emission statistics, combined with nighttime light data and population data, and assigned carbon emissions to the grid scale. It also analyzed the temporal and spatial characteristics and evolution characteristics of carbon emissions in China in 2000, 2005, 2010, 2015, and 2018, as well as the correlation between carbon emissions and the economy. The results showed that:① from 2000 to 2018, the total CO2 emissions in China continued to grow, but the growth rate slowed over time. The average annual growth rate of carbon emissions dropped from 9.9% in 2000-2010 to 7.4% in 2010-2018. From the perspective of spatial distribution, carbon-free areas were mainly distributed in the northwest uninhabited area and northeast forest and mountainous areas, low-carbon emissions were mainly distributed in the vast small and medium-sized cities and towns, and high-carbon emissions were concentrated in northern, central, eastern coastal, and western provincial capitals and urban agglomerations. ② Carbon emissions had high-value or low-value agglomerations at prefecture-level cities; this agglomeration tended to stabilize as a whole and had strengthened after 2005. Low-low agglomeration areas were mainly distributed in the western contiguous areas and Hainan Island. With economic and social development, low-low agglomeration areas began to fragment and reduce in size; high-high agglomeration areas were mainly distributed in the Beijing-Tianjin-Hebei urban agglomeration, Taiyuan urban agglomeration, Yangtze River Delta urban agglomerations, and Pearl River Delta urban agglomerations, and the scale was gradually strengthened and consolidated; high-low and low-high agglomeration areas mainly appeared in neighboring cities with large differences in economic development levels. ③ Carbon emissions in most parts of China were relatively stable. The areas where carbon emissions had changed were mainly distributed in the peripheral areas of provincial capitals and key cities, and there was a circle structure with no changes in the central urban area and changes in carbon emissions in the peripheral areas. ④ The overall process of urban development in China from 2000 to 2018 followed a shift from "low emission-low income" to "high emission-low income" to "high emission-high income" and finally to "low emission-high income." The growth rate of carbon emissions in China is slowing down. Under the background of the "dual carbon" strategy, different regions face different carbon emission reduction tasks and pressures due to different carbon emission situations. Therefore, the differentiated carbon emissions policy should be implemented by regions and industries.

[Organic carbon mineralization in various size aggregates of paddy soil under aerobic and submerged conditions].

With incubation tests in laboratory, the mineralization of organic carbon in various size aggregates of paddy soil was investigated under aerobic and submerged conditions. The results showed that the organic carbon mineralization in various size aggregates decreased quickly at the beginning of the incubation, but remained stable during the late period of incubation. The mineralization rate varied significantly with the size of the aggregates. Through the incubation time, the organic carbon in 1-2 mm aggregates had the highest mineralization rate, while that in < 0.053 mm aggregates had the lowest one. Statistic analyses indicated that the mineralization rate of organic carbon in various size aggregates was significantly and linearly correlated with the contents of organic carbon and microbial biomass carbon in the aggregates. 0.25-1 mm aggregates had the highest contribution to the cumulative mineralization of soil organic carbon, accounting for 41.77% under aerobic condition and 34.11% under submerged condition, while < 0.053 mm and 1-2 mm aggregates had the lowest contribution under aerobic and submerged conditions, accounting for 7.8% and 6.6%, respectively.