Urbanization Promotes Topsoil Black Carbon Accumulation: A Meta‐Analysis

Accelerated urbanization underscores the importance of black carbon (BC) in urban soils, a key component of soil organic carbon with implications for ecosystem function and human health. This meta‐analysis systematically integrated data from 54 studies comprising 4548 sampling sites across 40 Chinese cities, supplemented by targeted field sampling, to examine the distribution, sources, and influencing factors of soil BC in urban environments. After rigorous screening, standardization, and outlier removal, correlation analysis, and multivariate statistics were applied. Results showed an average urban topsoil BC content of 6.70 ± 5.34 g/kg, with marked spatial heterogeneity: higher concentrations were observed in eastern compared to western regions, and in northern relative to southern cities. Fossil fuel combustion—primarily vehicular emissions and industrial coal burning—was identified as the dominant source of BC, while biomass burning served as a secondary contributor, with additional local inputs from urban expansion and straw burning. Among natural factors, higher precipitation in southern regions enhanced BC migration, leading to reduced concentrations. Anthropogenic factors, however, exerted a stronger influence: cities with higher urbanization levels and greater energy consumption exhibited significantly elevated BC inputs. This study provides a comprehensive understanding of BC distribution patterns and source apportionment in China's urban soils, offering scientific support for urban environmental management and soil quality improvement amid ongoing urbanization, thereby contributing to sustainable urban development.