Embodied black carbon emission transfer within and across the Jing-Jin-Ji urban agglomeration

Black carbon (BC) is a vital air pollution particulate. Urban agglomeration has complex trade linkages internally and externally. Jing-Jin-Ji (JJJ) is the largest urban agglomeration in northern China and suffers from severe air pollution problems. Despite the importance of BC mitigation and the study area of JJJ, there is a lack of studies exploring the embodied BC emission transfers hidden behind trade within and across the JJJ urban agglomeration at the city scale, given the importance of interregional collaboration among cities for air pollution control. This paper applied the multiregional input-output (MRIO) analysis and structure path analysis (SPA) to investigate the impact of trade on the BC emissions in JJJ and identify the critical sectors and supply chains, using the latest available China's city-level MRIO table. The results show that the embodied BC emission intensity in JJJ is 143.17 g/10⁴ yuan, which exceeds the national average (121.89 g/10⁴ yuan). The Construction sector contributes 27.93 % of the total embodied BC emissions in JJJ. The cities of Handan, Tangshan, and Hengshui are the largest providers of emission-intensive products (3.51, 2.83, and 2.05 Gg, respectively) while Beijing is the largest receiver (5.78 Gg). From a supply chain perspective, Coal and Metal Mining are the main upstream industries, accounting for a considerable proportion of the BC emissions supply chain. To enhance the interregional collaborative governance of BC pollution control in JJJ, horizontal governance mechanisms, decentralized and polycentric urban planning, industrial clustering and technology upgrading, and effective policies for specific regions and industrial sectors are suggested.