The metallurgy, nonmetal products and chemical industry sectors (MN&C) are the three major industrial sources of air pollutants in China. Previous studies have focused on calculating emissions from MN&C via production-based accounting and identifying the drivers of MN&C using consumption-based accounting. However, these previous studies did not discuss how the total outputs from MN&C upstream and downstream industries influence air pollutant emissions. In this study, we use a pure backward linkage (PBL) method to quantify emissions from industries upstream of MN&C and to evaluate how the downstream industries drive the outputs of MN&C in China. We find that the emissions from industries upstream of MN&C are generally higher than the production-based emissions of MN&C. In particular, the chemical industry largely increased its contribution to air pollution according to the PBL method. Furthermore, much of upstream emissions of MN&C are embodied in the interregional trade, transferring substantial emissions from the eastern region to inland provinces. Regarding the drivers of MN&C, our results reveal that consumption-based accounting underestimates the importance of many sectors. The outputs of these previously underestimated sectors could maximally cover 80% of metallurgy, 85% of nonmetal products and 25% of chemical industry outputs. We suggest that improving the structure of MN&C would considerably help decrease the environmental burden on the entire supply chain. Additionally, improving the productivities of MN&C downstream industries could also address the air pollution caused by MN&C.
The unbalanced use of phosphorus fertilizers at the global scale has resulted in phosphorus fertilizer scarcity in less developed areas as well as eutrophication problems in developed and large emerging countries. Historically, the uneven distribution of phosphate rock has been regarded as the major reason for this unbalanced use. However, the international trade of commodities may also play an important role in the unbalanced use of phosphorus fertilizers. By tracing the trade flows of commodities, we found that nearly 5.2 Tg of phosphorus fertilizer was embodied in traded commodities, which were mainly exported from large emerging countries (with low phosphorus use efficiencies) to developed countries (e.g., the US, Western Europe and Japan, commonly with high phosphorus use efficiencies). Furthermore, among the 5.2 Tg of phosphorus fertilizer embodied in traded commodities, 2.5 Tg was embodied in the trade of commodities from industry, construction, and services. Our results indicate that this trade pattern could create substantial mutual benefits if improvements are made to the phosphorus supply chain. With technology transfer and financial support from developed countries, large emerging countries could use phosphorus fertilizers more efficiently, thereby reducing the risk of eutrophication and lowering the cost of agricultural production. The phosphorus fertilizers saved by large emerging countries could be partially used to enhance food production in Sub‐Saharan African countries. This optimized supply chain could reduce eutrophication, conserve phosphate rock resources, and enhance global agricultural production.
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