Emission inventories of anthropogenic transition metals, which contribute to aerosol oxidative potential (OP), in Asia (Δx ¼ 0.25°, monthly, 2000-2008) and Japan (Δx ¼ 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 PM 2.5 and PM 10 , 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 ¼ 30 km and Δx ¼ 5 km domains, respectively, and compared against the nationwide seasonal observations of PM 2.5 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 PM 2.5. 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 PM 2.5. 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.

Light-absorbing particles (LAPs), such as black carbon (BC) and mineral dust (hereafter referred to as dust), within the snow cover modulate the snow-atmosphere energy exchanges by reducing the snow albedo. This modulation is particularly important at visible wavelengths . When the absorption of shortwave radiant flux at the snow surface is enhanced by the reduction in the visible snow albedo and surface air temperature is sufficiently high, surface snow melting can be induced. The presence of meltwater accelerates snow grain growth via wet snow metamorphism (Brun, 1989), resulting in the reduction of the near-infrared snow albedo . This implies that the presence of LAPs in snow cover plays a unique role in positive feedback that induces snow ablation and increase in surface air temperature, that is, the snow-albedo feedback (e.g., Budyko, 1969;Qu & Hall, 2007). The first detailed quantification of the impacts of LAPs within snow and ice on the terrestrial climate system was carried out by Hansen and Nazarenko (2004).During the past two decades, efforts to consider the effects of LAPs on snow albedo explicitly in snow models have been made to provide more reliable quantitative estimates. Flanner and Zender (2005) developed the snow, ice, and aerosol radiative (SNICAR) model, which calculates radiative transfer in the