Chiang Po Neng, Wang Ming Kuang, Huang Pan Ming, Wang Jeng Jong
Department of Agricultural Chemistry, National Taiwan University, Taipei 106, Taiwan.
J Environ Radioact. 2008 Jan;99(1):159-66. doi: 10.1016/j.jenvrad.2007.07.009. Epub 2007 Aug 31.
(137)Cs is one of the major artificial radionuclides found in environments; but the mechanisms behind fertilizer-induced (137)Cs desorption from soil remain unknown. This study aimed to investigate the kinetics and mechanisms underlying the various cations and anions that cause Cs release from soil under acidic conditions. NH(4)H(2)PO(4) (1M), 0.5M (NH(4))(2)SO(4), 1M NH(4)Cl, 1M KCl or 1M NaCl solutions were added to (137)Cs-contaminated soil. The power function model well described the short term (137)Cs desorption with the solutions. The rate coefficients for (137)Cs release from soil in NH(4)H(2)PO(4), (NH(4))(2)SO(4), NH(4)Cl, and KCl solutions were 7.7, 7.3, 6.8, and 6.1 times higher than the rate observed in a NaCl solution, respectively. The NH(4)H(2)PO(4) and (NH(4))(2)SO(4) solutions induced significantly greater (137)Cs release from the contaminated soil than the NH(4)Cl, KCl and NaCl solutions. After four times repeated extractions with the fertilizer solutions, the total amount of (137)Cs extracted by (NH(4))(2)SO(4) and NH(4)Cl solutions reached equilibrium, while that extracted using an NH(4)H(2)PO(4) solution continued to increase. The combined effect of phosphate and protons was the major mechanism behind (137)Cs release from contaminated soils, when an NH(4)H(2)PO(4) solution was used.
铯-137是环境中发现的主要人工放射性核素之一；但肥料诱导土壤中铯-137解吸的机制仍不清楚。本研究旨在探究在酸性条件下导致土壤中铯释放的各种阳离子和阴离子的动力学及机制。将磷酸二氢铵（1M）、0.5M硫酸铵、1M氯化铵、1M氯化钾或1M氯化钠溶液添加到受铯-137污染的土壤中。幂函数模型很好地描述了溶液短期解吸铯-137的情况。在磷酸二氢铵、硫酸铵、氯化铵和氯化钾溶液中，铯-137从土壤中释放的速率系数分别比在氯化钠溶液中观察到的速率高7.7、7.3、6.8和6.1倍。磷酸二氢铵和硫酸铵溶液比氯化铵、氯化钾和氯化钠溶液从污染土壤中诱导释放出显著更多的铯-137。用肥料溶液重复萃取四次后，硫酸铵和氯化铵溶液萃取的铯-137总量达到平衡，而用磷酸二氢铵溶液萃取的铯-137总量持续增加。当使用磷酸二氢铵溶液时，磷酸盐和质子的联合作用是污染土壤中铯-137释放的主要机制。
