Contamination time effect on lead and cadmium fractionation in a tropical coastal clay

被引:75
作者
Lim, TT
Tay, JH
Teh, CI
机构
[1] Nanyang Technol Univ, Sch Civil & Environm Engn, Div Enviorn & Water Resources Eng, Singapore 639798, Singapore
[2] Nanyang Technol Univ, Sch Civil & Environm Engn, Div Geotech & Transp Eng, Singapore 639798, Singapore
关键词
D O I
10.2134/jeq2002.0806
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
The capability of a tropical coastal clay to immobilize lead (Pb) and cadmium (Cd) was investigated in laboratory batch sorption tests conducted under acidic, neutral, and slightly alkaline conditions. The contact time was extended to 65 d. The distribution of Pb and Cd among various sorbed phases was examined using a sequential extraction technique. The sorbed phases were fractionated into the exchangeable, carbonate, reducible, organic, and residual fractions. There were only small changes in the total Pb and Cd sorption beyond a 1-d sorption period. The metal fractionation results show that the amount of Pb and Cd in various fractions changed with sorption time, and the changes were pH-dependent. These changes could be attributed to mineral dissolution and transformation or redistribution of the sorbed phases. Transformation of the sorbed phases resulted in increasing Pb and Cd retention in the more persistent fractions with time, at the expense of reductions in the loosely bound fractions. Nevertheless, Pb and Cd fractionation in the solid phase appeared to reach equilibrium within the 65-d sorption period. These Pb and Cd fractionation results reflect the effect of contamination time on the heavy metal lability and bioavailability in the subsurface environment.
引用
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页码:806 / 812
页数:7
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