Environ Monit Assess. 2026 Apr 22;198(5):490. doi: 10.1007/s10661-026-15354-6.
ABSTRACT
China confronts dual environmental challenges: PM2.5-O3 synergistic pollution and mounting CO2 emissions, demanding a strategic shift from single-pollutant control to coordinated management. In response, this study develops a trivariate synergy index (TSI) based on the bivariate synergy index (BSI), integrating PM2.5, O3, and CO2 into a single metric to quantify differences in synergy levels across regions. Using high-resolution remote sensing and 2023 statistical data, we apply an XGBoost-SHAP modeling framework to analyze the seasonal spatio-temporal patterns and drivers of the TSI in 82 key Chinese cities. The results revealed that (1) the BSIPM2.5-O3 was positive only in summer (mean = 0.03), with better conditions along the eastern coast. BSIPM2.5-CO2 was most negative in summer (mean = -2.74), while BSIO3-CO2 shifted from negative in summer to positive in autumn, showing a latitudinal gradient with higher values in the north. (2) Summer TSI showed the weakest antagonism (mean = -1.37) among the four seasons, with values increasing northward and decreasing eastward. Spatially, coastal Bohai regions shifted from positive in spring to negative in summer, while the area surrounding Jiangsu exhibited persistent negative values. (3) The core factors driving TSI variation across all four seasons are temperature, precipitation, and elevation, with their effects exhibiting nonlinear threshold effects. Among socioeconomic factors, GDP exerted a positive influence only after surpassing a critical threshold, whereas increased population density had a negative regulatory effect. Based on the findings, this study offers a seasonal, spatially differentiated reference for synergistic pollution and carbon reduction.
PMID:42020634 | DOI:10.1007/s10661-026-15354-6
