Apatite and phillipsite as sequestering agents for metals and radionuclides
A S Knox1, D I Kaplan, D C Adriano
1Westinghouse Savannah River Company, Aiken, SC 29808, USA. anna.knox@srs.gov
Journal of Environmental Quality
|April 24, 2003
Summary
Apatite and phillipsite effectively sequestered metal contaminants in soil, significantly improving plant growth and reducing heavy metal uptake in maize and oat crops. These amendments enhance soil remediation for contaminated sites.
Area of Science:
- Environmental Science
- Soil Science
- Geochemistry
Background:
- Industrial activities like smelting can lead to significant soil contamination with toxic metals.
- Phytoavailability of metals in contaminated soils poses risks to ecosystems and human health.
- Zeolites and apatite are minerals with potential for metal sequestration in soils.
Purpose of the Study:
- To quantify the metal sequestration capacity of apatite and phillipsite.
- To evaluate the effectiveness of these minerals in reducing metal phytoavailability and enhancing plant growth in contaminated soil.
- To compare the performance of apatite and phillipsite under greenhouse conditions.
Main Methods:
- Laboratory batch sorption experiments were conducted to determine distribution coefficients (Kd) for various metal contaminants.
- Greenhouse studies utilized contaminated soil from a Zn-Pb smelter site, amended with apatite and phillipsite at two application rates.
- Maize (Zea mays L.) and oat (Avena sativa L.) were grown in amended and unamended soils, with plant tissues and soil analyzed for metal and essential element content.
Main Results:
- Apatite exhibited higher sorption for Co2+, Pb2+, Eu3+, and UO2(2+) (Kd > 200,000 L kg(-1)), while phillipsite was more effective for Ba2+.
- Soil amendment with apatite and phillipsite significantly improved plant growth in contaminated soil, where unamended soil supported little to no growth.
- Apatite and phillipsite reduced Cd, Pb, and Zn concentrations in maize and oat tissues, with sequential extractions confirming stronger metal sorption in amended soils.
Conclusions:
- Apatite and phillipsite are effective soil amendments for sequestering metal contaminants, reducing their phytoavailability.
- These minerals enhance plant growth in metal-contaminated soils, offering a viable remediation strategy.
- Mineral amendments can alter essential element concentrations in plants, but levels generally remain sufficient for growth.
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