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Top1. Introduction
China’s scale-driven economic growth mode has made significant successes in recent decades. This rapid economic development was highly dependent on the exploitation and utilization of natural resources. According to International Resource Panel, United Nations Environment Program (UNEP-IRP, 2019), the global resource extraction has increased from 27 billion tons in 1970 to 92 billion tons in 2017, and more than a third of all resources in 2017 were generated in China, followed by 7.6% in India and 7.1% in the United States. The massive natural resource consumption has resulted in a series of environmental problems, such as air and water pollution, soil contamination and greenhouse effect (Wang et al., 2022a). Under such a circumstance, China has committed to achieve a win-win situation for economic prosperity and environmental protection by establishing a resource-saving and environment-friendly society. Considering that national sustainable development policies are usually implemented by provincial administrative units in China, it is necessary to conduct in-depth research on regional material metabolism, which can help to identify the causes of environmental problem and design effective resource management schemes.
Material Flow Analysis (MFA) is an efficient method for quantifying the flows and stocks of resources within a defined space and time (Graedel, 2019; Wang et al., 2022b). It provides a comprehensive and systematic description of extraction, consumption, trade and recycling of different materials, and further establishes a physical linkage among social-economic activities, nature resources and environmental problems. According to the law of conservation of matter, the obtained results of MFA can be controlled by material balances, making all inputs, stocks, and outputs of process comparable (Islam & Huda, 2019). MFA is first introduced by Ayres & Kneese (1969), who apply this method to evaluate the material flows in the United States from 1963 to 1965. Since then, an increasing number of scholars have made significant contributions to modify the framework of MFA (Schandl & West, 2012; Voskamp et al., 2017; Eurostat, 2013; Eurostat, 2018; Shah et al., 2020). At the same time, MFA has also been widely used to deal with resource metabolism in mineral and metal fields, such as dysprosium (Wang et al., 2022b), aluminum (Zhao et al., 2022), and copper (Wang et al., 2018). Other applications of MFA include plastic waste management (Lee et al., 2021) and E-waste management (Islam & Huda, 2019).
MFA was initially developed to describe material flows at the global and national levels. Krausmann et al. (2016) demonstrate a brief overview of the global patterns and trends of material use, followed by a decoupling analysis between material use and economic development. Schandl & West (2012) make a comparison among China, Australia and Japan from the perspective of material flows and material productivity during 1970-2005. Sastre et al. (2015), Shammugam et al. (2019), Alonso-Fernandez & Regueiro-Ferreira (2022) focus on illustrating the material flows in Spanish, Germany and South America, respectively. However, few studies have investigated the characteristics and trends of material metabolism at the regional level, this is primarily due to the unavailability of reliable data (Sastre et al., 2015; Xu et al., 2021).