To explore the impacts of green technology innovation and environmental policies on regional carbon emissions as well as their scale effects, this study employs a panel data sample of 306 county-level units in the Yangtze River Delta region from 2007 to 2017. A fixed-effects model is applied to analyze the effects of green technology innovation and environmental policies on regional carbon emissions, while quantile regression is used to examine the differential impacts of green technologies at different scales and environmental policies at varying levels. The findings indicate that: (1) The carbon emission intensity in the Yangtze River Delta region shows a development trend of first increasing and then decreasing, and the regional gap has significantly reduced. (2) The carbon emissions of counties in the Yangtze River Delta region have a clear “core-periphery” structure, with regions with high carbon emissions concentrated in the Z-shaped urban belt of Hefei, Nanjing, Shanghai, Hangzhou, and Ningbo. (3) The scale of green technology in the Yangtze River Delta region continues to rise, with local technology occupying an absolute position, and the proportion of cross-region co-patents steadily increasing. The rules of hierarchical diffusion, geographical proximity, and strong ties play an important role in the cross-region green technology cooperation networks. (4) The improvement of local green technology has led to more carbon emissions, and cross-region cooperation in green technology has reduced regional carbon emission intensity. Provincial and urban-level environmental policies have almost no impact on regional carbon emissions, while county-level policies have a significant limiting effect; the larger the scale, the weaker the policy effectiveness. The Yangtze River Delta regions should continue to strengthen green technology transfer and cross-region cooperation, continuously amplify the spillover effects of technology and the attributes of public goods, and promote green technology innovation to empower carbon reduction. At the same time, focusing on county-level units, formulating environmental policies that are more in line with regional realities to better leverage the hard constraints of policies.

To reveal the spatial pattern and coordination mechanisms of urban multi-element flow networks, this paper constructs urban transportation, enterprise, and information flow networks in the urban agglomeration of the middle reaches of the Yangtze River based on train schedules, branch offices of listed companies, and Baidu index data. The study employs social network analysis, entropy method, coupling coordination degree model, and QAP analysis to explore the evolution characteristics of the urban network structure in the middle reaches of the Yangtze River from 2014 to 2024. The results indicate that: (1) In terms of network topology, the transportation network tends toward balanced optimization, the enterprise network shows fluctuation diffusion and secondary agglomeration, and the efficiency and agglomeration of the information network are enhanced. The overall node centrality increases, while the differentiation of betweenness centrality intensifies. (2) In terms of spatial structure, the transportation network forms a “Z”-shaped backbone structure with Wuhan, Changsha, and Nanchang as the core of the “Iron Triangle”. The enterprise network shifts from a dual-core drive to gradient penetration, and the information network forms a structure of long-distance connections and multi-polar coordination. (3) In terms of network relationships, the coupling coordination degree of centrality among the three networks is in a mild state of imbalance. The core-periphery structure is prominent, link coordination continues to improve, and the overall correlation among the three flows continues to strengthen, with significant synergy and radiation effects in the information flow. In conclusion, the current network is overall closely connected, but coordination of element flows is insufficient, and spatial heterogeneity is prominent. Accordingly, it is suggested that network coordination and resilience be enhanced by focusing on the construction of hub systems, restructuring regional development axes, and promoting digital integration.