Kinetics of radiocesium released from contaminated soil by fertilizer solutions.
(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.
Chiang
Po Neng
PN
Department of Agricultural Chemistry, National Taiwan University, Taipei 106, Taiwan.
Wang
Ming Kuang
MK
Huang
Pan Ming
PM
Wang
Jeng Jong
JJ
D002588:Cesium Radioisotopes / Q000737:chemistry*; D005308:Fertilizers; D008670:Metals / Q000737:chemistry; D012990:Soil Pollutants, Radioactive / Q000737:chemistry*
D002588:Cesium Radioisotopes; D005308:Fertilizers; D008670:Metals; D012990:Soil Pollutants, Radioactive