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| Remediation of Multi-metals Contaminated Acidic Soil by Mixed Inorganic Amendments |
| Received:November 17, 2014 |
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| KeyWord:limestone;hydroxyapatite;zeolite;multi-metals contaminated acidic soil;metal bioavailability |
| Author Name | Affiliation | E-mail | | GUO Rong-rong | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | HUANG Fan | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | YI Xiao-mei | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | LONG Xin-xian | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | longxx@scau.edu.cn |
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| Abstract: |
| The main objective of the present study was to determine the capacity of mixtures of some inorganic amendments to reduce the bioavailability of heavy metals in multiple-metals-contaminated acidic soil. Incubation experiment with orthogonal experimental design was conducted to study the efficiency of mixed inorganic amendments in increasing soil pH and decreasing the mobility of Cd, Pb, Cu and Zn in a multi-metals-contaminated acid soil collected from the Dabaoshan area of Shaoguan City, Guangdong Province. Then a pot experiment was carried out to examine the effects of six different combinations of three inorganic amendments on heavy metal bioavailability and growth and heavy metal accumulation of red leaf lettuce(Lactuca sativa L.). All combinations of three inorganic amendments significantly increased soil pH and reduced the mobility and bioavailability of Cd, Pb, Cu and Zn in soil. The ability of immobilizing soil Pb, Cd, and Zn decreased in order of limestone > hydroxyapatite > zeolite, but for soil Cu it was limestone> zeolite> hydroxyapatite. There were significant negative correlations between soil pH and bioavailable Cd, Zn, and Cu. When soil pH was raised to 6~7 by supplying inorganic amendments, red leaf lettuce grew healthy and the highest shoot biomass was obtained in soil treated with 4 g·kg-1 zeolite+2 g·kg-1 limestone+6 g·kg-1 hydroxyapatite. However, over-doses of inorganic amendments inhibited the growth of red leaf lettuce. Though all these mixed amendments significantly reduced the bioavailability of Pb and Cd in soil, the shoot Cd concentrations were still greater than 0.2 mg·kg-1(the limit for food health standard), while shoot Pb concentrations were close to the limit value(0.3 mg·kg-1). In summary, mixed amendments of limestone, zeolite and hydroxyapatite can improve the growth of red leaf lettuce in multi-metals contaminated acid soil, but the safety of red leaf lettuce is still a concern. |
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