The evolution patterns and driving factors of urban domestic water pollution utilizing China's two national pollution source surveys

Characteristics of domestic water pollution are of significant practical importance for implementing targeted urban wastewater treatment strategies. The pollutant source census in China serves as a fundamental undertaking in the study of pollution sources, providing crucial data for the analysis of pollution from domestic sources. This study employs pollution coefficients derived from China's two national pollution source surveys, integrating spatial autocorrelation and center-of-gravity shift analysis methods to investigate the national-scale spatial evolution characteristics of major urban domestic water pollutants, including BOD, TN, TP, and Oils. Furthermore, the impact of urbanization processes in population, economic, social, and spatial dimensions on urban domestic water pollution sources is explored using the multi-scale geographically weighted regression (MGWR) method. The results show that: (1) Urban domestic water pollution exhibits an east-high and west-low distribution pattern, with EHL being the primary region of pollution generation. Compared to 2007, the western region experienced a faster increase in BOD (30% increase), while the eastern region showed a sharper decline in TN (45% decrease) by 2017. (2) The results of spatial autocorrelation show that high-value clusters of urban domestic water pollution are located in the eastern China and around Chongqing, while low-value clusters are extensively distributed in the western region, indicating significant spatial heterogeneity in water pollution. (2) Based on center-of-gravity analysis, pollution displays a discernible migration trend from the northeast to the southwest, with the center located near the border of Henan and Hubei provinces, within the latitudinal and longitudinal range of 32°N–32.79°N and 113.09°E−113.85°E. The migration distances, ranked in descending order, are as follows: Oils (72.23 km) > BOD (65.59 km) > TN (63.9 km) > TP (22.73 km). (3) Significant differences are observed in the effects and spatial regions influenced by urbanization factors across different dimensions. Population and social urbanization exhibit pollution-increasing effects, whereas economic and spatial urbanization demonstrate pollution-reducing effects. These results will deepen our understanding of the spatial differentiation patterns of urban domestic source pollution, providing theoretical guidance for alleviating the pressure of urban pollution management. In addition, this article is an in-depth