Spatiotemporal Dynamics Of In-Use Copper Stocks In The Jing-Jin-Ji Urban Agglomeration, China

Copper is ubiquitously used in buildings, infrastructure, transportation, machinery, and other products because of its high conductivity. Massive amounts of copper have accumulated in cities with rapid urbanization. However, the lack of detailed spatiotemporal information on copper stocks presents a challenge for waste management and resource recycling. Here, we took the Jing-Jin-Ji urban agglomeration in China, which has experienced rapid urbanization over the past few decades, as a case study to characterize the spatiotemporal patterns of in-use copper stock. The results showed that in-use copper stocks per capita had reached 61 kg in 2016, about 3.8 times the level it was in 1990. Buildings, electric power transmission and distribution systems, small passenger cars, industrial machinery, and air conditioners dominated the in-use stocks and thus, they were the main reservoirs of secondary resources. Significant economic and population growth stimulated a rapid increase in copper stocks, especially in the megacities (e.g., Beijing, Tianjin, Shijiazhuang, Tangshan, and Handan). Based on the scenarios of urbanization, we estimated that in-use stocks of copper per capita would continue to grow in the Jing-Jin-Ji urban agglomeration until saturation, and that the saturation level might be lower than that of developed countries. High population density was key to promoting copper resource utilization efficiency, particularly in the infrastructure sector. This critical information highlights the urgent need for developing compact cities to reduce the pressure caused by copper resource consumption in China.