How do environmental and technological expenditure intensities affect sustainable blue economy development in China’s coastal provinces?

Purpose This study aims to examine the determinants of sustainable blue economy development in China’s coastal provinces, focusing on how environmental expenditure intensity, technological expenditure intensity and industrial structure influence marine economic performance across different developmental stages. Design/methodology/approach This study develops a Sustainable Blue Economy Index using entropy-based weighting and panel data from China’s coastal provinces from 2008 to 2020, capturing multidimensional performance in innovation, structural optimization, environmental sustainability, openness and social welfare. This study uses the Method of Moments Quantile Regression to examine heterogeneous effects across different development stages. Findings Technological expenditure intensity is positively associated with sustainable blue economy development, with effects declining from 0.200 at the 25th to 0.170 at the 90th quantile. Interestingly, environmental expenditure intensity is negatively associated with sustainable blue economy development, with the negative effect increasing from −0.036 at the 25th to −0.130 at the 90th quantile, indicating inefficiencies in environmental governance. Moreover, industrial structure and foreign direct investment positively influence the sustainable blue economy. Originality/value This study introduces a multidimensional sustainable blue economy framework, revealing heterogeneous determinant effects across development levels through quantile regression. It examines the influence of technological and environmental expenditure intensities on sustainable blue economy development, providing empirically grounded policy recommendations to enhance sustainability in developing coastal economies.