Trans-boundary total suspended particulate matter (TSPM) in urban ecosystems

The highly-industrialized regions in China have been facing a serious problem of haze mainly consisted of total suspended particulate matter (TSPM), which has attracted great attention from the public since it clinically increases the risks of various respiratory and pulmonary diseases and directly impairs urban ecosystem health. In this paper, we set up a multi-regional input-output (MRIO) model to analyze the transferring routes of TSPM emissions between urban ecosystem and surrounding regions through trades. TSPM emission from particulate source regions and sectors are identified by analyzing the embodied TSPM flows through inter-regional trade. The track of TSPM from origin to end via consumption activities is also revealed by tracing the product supply chain associated with the TSPM emissions. Beijing-Tianjin-Hebei (Jing-Jin-Ji) as the most industrialized district of China is selected for a case study. The result shows that over 70% of TSPM emissions associated with goods consumed in Beijing and Tianjin occurred outside of their own administrative boundaries, implying that Beijing and Tianjin are net TSPM exporters. Meanwhile, 63% of the total TSPM emissions in Hebei province are resulted from the outside demand, indicating Hebei is a net importer. In addition, nearly half of TSPM emissions are the by-products related to electricity and heating supply and non-metal mineral production in Jing-Jin-Ji district. Based on the modeling results, we provided new insights into establishing systemic strategies and identifying mitigation priorities to stem TSPM emissions in urban ecosystem and its surrounding areas.