摘要 : This study estimates product-level in-use stocks of aluminum in the United States for the period 1960-2009 (or longer in some cases) and explores patterns of the historical evolution of in-use aluminum stocks at both product and s... 展开 This study estimates product-level in-use stocks of aluminum in the United States for the period 1960-2009 (or longer in some cases) and explores patterns of the historical evolution of in-use aluminum stocks at both product and sector levels. The principal findings are the following: (1) results estimated by the product-level methods in this study match reasonably well with those estimated by the sector-level method for five sectors (except the Machinery and Equipment sector), meaning that the methods verify the robustness and reliability of each other; (2) after early period(s) of increase since aluminum-containing products were introduced into the market, in-use aluminum stocks at the product level, based on either absolute, per capita, or per household terms, follow one of four different patterns (Increase, Decrease, Saturation, and Fluctuation), determined by the historical evolution of product stocks and flows and aluminum contents in products; and (3) when aggregated, in-use aluminum stocks at the product level can be used to compare with and explain the historical evolution of the in-use aluminum stocks at the sector level that are estimated by the top-down method, with only a few products dominating or significantly influencing the historical evolution pattern for a whole sector. These results may enable manufacturers, metal suppliers, recyclers, and governments to plan their material-related policies and actions with increased precision compared to previous top-down results that are only available at the sector level. 收起