[Impact of Environmental Protection Tax on Green Economic Efficiency in Guanzhong Plain Urban Agglomeration within the Framework of Sustainable Development Goals].

The environmental protection tax （EPT） is beneficial to improving the green economy efficiency （GEE）， but due to the difference of the total amount， structure， and intensity of pollutants in cities， the role of EPT in the local green development transformation is not consistent. In the sustainable development goals （SDGs） proposed by the United Nations， core indicators for the coordinated development of "economic-social-environmental" dimensions have been identified. The super-efficiency slacks-based measure （super-SBM） model， which encompasses expected outputs from both production and consumption activities， was employed to assess the GEE of the Guanzhong Plain urban agglomeration from 2010 to 2022. The aim was to explore the impact of EPT on GEE and the transmission role of the advanced industrial structure （AIS） and technological innovation level， including technological innovation （TI） and investment of research and development （R＆D） in the Guanzhong Plain urban agglomeration， by developing a bidirectional fixed effects model and two-step intermediary effect model. To further discuss the role of EPT in affecting the GEE， heterogeneity tests were conducted by grouping regional policies， marketization levels， and population density， and on this basis， the differentiated impact of EPT on the GEE was analyzed. The results show that： ① The impact of EPT on the GEE in the Guanzhong Plain urban agglomeration presented a "U"-shaped relationship from 2010 to 2022. It showed the nonlinear characteristic of "inhibition first and then promotion，" and the result was robust and significant at the 1% level. The positive effect of EPT on the GEE will be manifested in the long term. ② In the process of the impact of EPT on the GEE of urban agglomerations， there was a "U"-shaped intermediary effect on TI and R＆D in the level of technological innovation， and the results were robust and significant at the level of 1%， respectively， while the intermediary effect of AIS was not robust. ③ The heterogeneity tests showed that within urban agglomerations， the "U"-shaped impact of EPT within Shaanxi Province and technological innovation levels in cities with a high level of marketization on the GEE was more significant， at the levels of 1% and 5%， respectively. However， the EPT in cities with a lower population density will have a negative impact on the GEE.