The development of the digital economy is conducive to the innovative development of foreign trade and the formation of a “dual circulation” development pattern in China. Based on the panel data of 285 prefecture-level cities in China from 2005 to 2019, this paper examines the influence of the digital economy on urban export trade and its heterogeneity. And we use a mediating effect model to explore the possible mediating role of technological progress in the above influences. The results find that: (1) The improvement of the digital economy can promote cities export; (2) The promotion of the digital economy to the growth of city export scale is heterogeneous, which is more significant in the western and northeastern cities with relatively remote geographical locations, and the third-tier and lower cities with relatively backward economic development. (3) Technological progress has played a significant role in promoting the growth of export for the digital economy. Thus, it’s of great importance for China to increase investment in digital economy infrastructure and pay more attention to the differences in diverse city development processes. It should also support basic research and development in information technology to promote high-quality development of China’s foreign trade through the digital economy.

As increasing demand for green energy and high‐tech devices grows, so does the rising prospecting of rare earth metals required for their production. Protecting the environment and public health from rare earth element (REE) mining as well as emerging pollutants is urgently required to achieve sustainable development. This study mapped Earth's hidden REE deposits to identify potential contamination hotspots with the aim of preventing its deleterious effects on the environment. We worry that there would be widespread tailing facilities concomitant with serious pollutions, such as the Bayan Obo tailings site, and argue that a tradeoff between the underground REE exploration and environment conservation should be reached as soon as possible.