Starting with a worst-case scenario of lead contamination of soil, a scientist at Mie University in Japan has demonstrated the use of poultry waste amendment in combination with plant growth to immobilize soil Pb and restore degraded vegetation in shooting range sites.

Remediation of Pb-contaminated soils in a shooting range is generally very difficult the site is extensively contaminated with high levels of Pb, and therefore the local ecosystem has deteriorated. In situ chemical immobilization is a practical remediation technology for metal-contaminated soils.

The scientist measured Pb speciation of the soil using X-ray absorption spectroscopy at SPring-8, the world’s largest synchrotron radiation facility in Japan, and soil enzyme activity along with the changes in soil Pb immobilization. Results from the study were published in the July-August 2009 issue of the Journal of Environmental Quality. Lead speciation and enzyme activity were measured in shooting range soils treated with a grass plant and/or poultry waste in a large column setting. The research is targeted at the changes in Pb speciation along with enzyme activity and downward solute transport.

The use of amendment with less adverse impacts on soil biological properties could be a prerequisite for a comprehensive and long-term restoration program of shooting range areas, according to a Mie University press release.

The study revealed that the amendment reduced the proportion of cerussite (PbCO{-3}) and Pb-organic complexes and transformed them into a more geochemically stable species of chloropyromorphite [Pb{-5}(PO{-4})3Cl] with 30 to 35 per cent of the total Pb species. Applications of plant and amendment decreased downward Pb transport and increased activities of dehydrogenase and phosphatase in the surface soil.