1. 1) Nippon Slag Association, Amounts of Steel Slag Produced and Used in FY 2016, http://www.slg.jp/e/index.htm, (accessed 2017-08-17).
2. 2) Japan Oil, Gas and Metals National Corporation, Material flow of mineral resources in 2016, http://mric.jogmec.go.jp/public/report/2017-01/31_201701_P.pdf, (accessed 2017-08-17), (in Japanese).
3. 3) K. Matsubae, J. Kajiyama, T. Hiraki and T. Nagasaka: Chemosphere, 84(2011), 767.
4. 4) H. Ohtake and K. Okano: Glob. Environ. Res., 19(2015), 49.
5. 5) H. Kubo, K. Matsubae-Yokoyama and T. Nagasaka: ISIJ Int., 50(2010), 59.