[4] Wang Ye, Zhang Xing, Jie Yucheng, et al. Agricultural Science & Technology, 2012, 13(2): 375.
[8] Verner J F, Ramsey M H, Helios-Rybicka E, et al. Applied Geochemistry, 1996, 11(12): 11.
[9] Cappuyns V, Swennen R, Vandamme A. Journal of Geochemical Exploration, 2006, 88(1-3): 6.
[14] Anderson T A, Kruger E L, Coat J R, et al. Chemosphere, 1994, 28: 1551.