This paper builds a complex network of weighted and directed coal trade based on the international coal trade data in the United Nations trade database from 1999 to 2018, specifically analyzes the trade scale, trade relations, and trade distribution and other characteristics of international coal trade, and determines the main trade core countries and trade hub countries. The results show that the scale of international coal trade has grown steadily, but the transformation of trade relations is complicated. Especially in the context of increasing trade frictions, trade links between countries have decreased significantly, trade balance has declined, and trade agglomeration has increased. Australia, the United States, Japan and other countries are big coal trading countries, while the United States, South Africa, India and other countries are important trading hubs. Based on the theory of competitive advantage, this paper proposes corresponding countermeasures for different countries to enhance their competitive advantages.
Cross-regional air pollutant spillovers aggravate air pollution in China. To mitigate air pollution, identifying and monitoring air pollution spreaders (APS) is a vital strategy that helps locate the source of air pollution and guides the Joint Prevention and Control of Air Pollution. In this paper, we define an APS as a city with a high spillover impact (CHSI) of air pollution and propose a transfer entropy network to investigate the APS from a multi-timescale analysis perspective. Taking the time series of PM2.5 concentration of 358 Chinese cities from 1 January 2015 to 31 December 2020 as the sample, they are decomposed into short, medium, and long timescales, corresponding to an average period of 12, 111, and 530 days, respectively. Then, we use transfer entropy networks to analyze APS’s spatial distribution and temporal variation patterns on each timescale. The results demonstrate that air pollution spillover widely exists in Chinese cities, and the short-term air pollution spillover dominates all spillovers. The CHSIs form large agglomeration areas in Central and East China on short and medium timescales, while the results of the undecomposed data show a more discrete distribution. In addition, the cities’ air pollution spillover impact is usually high in winter and spring and low in summer. Moreover, the spillover impacts of half of the cities have a lead-lag relationship between short and medium timescales. All results suggest that combining short-term controls and longer-term strategies helps China mitigate air pollution and develop sustainably.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.