role of biochar, natural iron oxides, and nanomaterials as soil amendments for immobilizing metals in shooting range soil

• Published in: Environmental geochemistry and health 2015-12, Vol.37 (6), p.931-942
• Main Authors: Rajapaksha, Anushka Upamali, Ahmad, Mahtab, Vithanage, Meththika, Kim, Kwon-Rae, Chang, Jun Young, Lee, Sang Soo, Ok, Yong Sik
• Format: Article
• Language: English
• Subjects: absorption; Ambrosia - chemistry; Ambrosia trifida; antimony; Antimony - analysis; Antimony - chemistry; Bioavailability; biochar; Biomass; buffaloes; Carbon; Cation exchange; cation exchange capacity; Charcoal; Charcoal - chemistry; Copper; Copper - analysis; Copper - chemistry; Earth and Environmental Science; Environment; Environmental Chemistry; Environmental Health; Environmental perception; Environmental Restoration and Remediation; Ferric Compounds - chemistry; Geochemistry; gibbsite; Iron oxides; Land pollution; Lead; Lead - analysis; Lead - chemistry; Metal concentrations; Minerals - chemistry; Nanomaterials; nanosilver; Nanostructures - chemistry; Nanotechnology; Original Paper; Phosphates - chemistry; Phosphorus - chemistry; Public Health; Remediation; scanning electron microscopy; Silver; Soil - chemistry; Soil amendment; soil amendments; Soil conditioners; Soil pH; Soil Pollutants - analysis; Soil Pollutants - chemistry; Soil quality; Soil Science & Conservation; spectroscopy; Sport shooting; temperature; Terrestrial Pollution; toxicity; weeds; X-radiation
• ISSN: 0269-4042; 1573-2983
• DOI: 10.1007/s10653-015-9694-z

High concentration of toxic metals in military shooting range soils poses a significant environmental concern due to the potential release of metals, such as Pb, Cu, and Sb, and hence requires remediation. The current study examined the effectiveness of buffalo weed (Ambrosia trifida L.) biomass and its derived biochars at pyrolytic temperatures of 300 and 700 °C, natural iron oxides (NRE), gibbsite, and silver nanoparticles on metal immobilization together with soil quality after 1-year soil incubation. Destructive (e.g., chemical extractions) and non-destructive (e.g., molecular spectroscopy) methods were used to investigate the immobilization efficacy of each amendment on Pb, Cu, and Sb, and to explore the possible immobilization mechanisms. The highest immobilization efficacy was observed with biochar produced at 300 °C, showing the maximum decreases of bioavailability by 94 and 70 % for Pb and Cu, respectively, which were attributed to the abundance of functional groups in the biochar. Biochar significantly increased the soil pH, cation exchange capacity, and P contents. Indeed, the scanning electron microscopic elemental dot mapping and X-ray absorption fine structure spectroscopic (EXAFS) studies revealed associations of Pb with P (i.e., the formation of stable chloropyromorphite [Pb₅(PO₄)₃Cl]) in the biomass- or biochar-amended soils. However, no amendment was effective on Sb immobilization.