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With ever-increasing urbanization and industrialization in developing countries, the challenge posed by carbon dioxide emissions (CDEs) has become a hot topic of concern in the realm of sustainable development from a socioeconomic perspective. However, previous studies have only been conducted at macro and meso scales, including at the global, country, and urban levels, and few researchers have delved into the territorial space of urban areas due to a lack of high-precision data. To address this deficiency, we established a theoretical framework to explore the spatial zoning of CDEs based on the newly emerging China high-resolution emission gridded data (CHRED). This study's innovativeness lies in its provision of a step-by-step process for spatial matching of CDEs based on CHRED in the framework and the construction of square layers to reveal spatial heterogeneity of CDEs at the intra-city level. Taking Nanjing City as the case study area, our findings indicated that CDEs intensity (CDEI) shows an inverted "U-shaped" trend that first increased and then decreased, and finally stabilized from the center to the periphery of the city. With further urbanization and industrialization, the energy consumption sector was found to be the largest contributor to CDEs in Nanjing, and the expanding carbon source zonings will therefore shrink the existing carbon sink zonings. Collectively, these results can provide a scientific reference point to realize China's "dual carbon" target from the perspective of spatial layout optimization.

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Drylands, which account for 41% of Earth's land surface and are home to more than two billion people, play an important role in the global carbon balance. This study analyzes the spatio-temporal patterns of vegetation carbon sinks and sources in the arid region of northwest China (NWC), using the net ecosystem production (NEP) through the Carnegie-Ames-Stanford approach (CASA). It quantitatively evaluates regional ecological security over a 20-year period (2000-2020) via a remote sensing ecological index (RSEI) and other ecological indexes, such as the Normalized Difference Vegetation Index (NDVI), fraction of vegetation cover (FVC), net primary productivity (NPP), and land use. The results show that the annual average carbon capacity of vegetation in NWC changed from carbon sources to carbon sinks, and the vegetation NEP increased at a rate of 1.98 gC m-2 yr-1 from 2000 to 2020. Spatially, the annual NEP in northern Xinjiang (NXJ), southern Xinjiang (SXJ) and Hexi Corridor (HX) increased at even faster rates of 2.11, 2.22, and 1.98 gC m-2 yr-1, respectively. Obvious geographically heterogeneous distributions and changes occurred in vegetation carbon sinks and carbon sources. Some 65.78% of the vegetation areas in NWC were carbon sources during 2000-2020, which were concentrated in the plains, and SXJ, the majority carbon sink areas are located in the mountains. The vegetation NEP in the plains exhibited a positive trend (1.21 gC m-2 yr-1) during 2000-2020, but this speed has slowed since 2010. The vegetation NEP in the mountain exhibited only intermittent changes (2.55 gC m-2 yr-1) during 2000-2020; it exhibited a negative trend during 2000-2010, but this trend has reversed strongly since 2010. The entire ecological security of NWC was enhanced during the study period. Specifically, the RSEI increased from 0.34 to 0.49, the NDVI increased by 0.03 (17.65%), the FVC expanded by 19.56%, and the NPP increased by 27.44%. Recent positive trends in NDVI, FVC and NPP have enhanced the capacity of vegetation carbon sinks, and improved the eco-environment of NWC. The scientific outcomes of this study are of great importance for maintaining ecological stability and sustainable economic development along China's Silk Road Economic Belt.

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