Modeling Transition Metals in East Asia and Japan and Its Emission Sources.

Emission inventories of anthropogenic transition metals, which contribute to aerosol oxidative potential (OP), in Asia (Δx = 0.25°, monthly, 2000–2008) and Japan (Δx = 2 km, hourly, mainly 2012) were developed, based on bottom‐up inventories of particulate matters and metal profiles in a speciation database for particulate matters. The new inventories are named Transition Metal Inventory (TMI)‐Asia v1.0 and TMI‐Japan v1.0, respectively. It includes 10 transition metals in PM2.5 and PM10, which contributed to OP based on reagent experiments, namely, Cu, Mn, Co, V, Ni, Pb, Fe, Zn, Cd, and Cr. The contributions of sectors in the transition metals emission in Japan were also investigated. Road brakes and iron‐steel industry are primary sources, followed by other metal industry, navigation, incineration, power plants, and railway. In order to validate the emission inventory, eight elements such as Cu, Mn, V, Ni, Pb, Fe, Zn, and Cr in anthropogenic dust and those in mineral dust were simulated over East Asia and Japan with Δx = 30 km and Δx = 5 km domains, respectively, and compared against the nation‐wide seasonal observations of PM2.5 elements in Japan and the long‐term continuous observations of total suspended particles (TSPs) at Yonago, Japan in 2013. Most of the simulated elements generally agreed with the observations, while Cu and Pb were significantly overestimated. This is the first comprehensive study on the development and evaluation of emission inventory of OP active elements, but further improvement is needed. Plain Language Summary: Aerosol oxidative potential (OP) has been focused on as a better health hazard of aerosols than PM2.5. OP is quantified by in vitro assays to mimic the in vivo generation of superoxide radicals to cause oxidative stress on human cells. OP has been reported to be more strongly associated with cardiorespiratory outcomes than PM2.5. Transition metals ions, organics, and elementary carbon, together with their interactions, have been reported as important compounds, but the relative magnitudes of contributions to total OP have not yet been fully understood. In this study, as a first step, we developed emission inventories and a numerical model to predict OP active transition metals in Asia and Japan and compared them with observations. We also quantitatively derived the major emission sources for the important metals such as Cu, Mn, Fe, V, and Ni in Japan. The current study is the first step toward better predicting the health hazard of aerosols. As the next step in the future, water solubility of metals and OP active organics, together with their interactions, should be considered. Key Points: Emission inventories of transition metals, which contribute to aerosol oxidative potential (OP), in Asia and Japan were developedMost of simulated elements (Mn, V, Ni, Fe, Zn, and Cr) agreed with observation, while Cu and Pb were significantly overestimatedRoad brakes and iron‐steel industry are primary sources, followed by metal industry, navigation, incineration, power plants, and railway [ABSTRACT FROM AUTHOR]