Water Leaching of Chelated Pb Complexes from Post-Phytoremediation Biomass

• Published in: Water, air, and soil pollution air, and soil pollution, 2013-08, Vol.224 (8), p.1-11, Article 1615
• Main Authors: Krueger, Erik, Darland, Joseph, Goldyn, Stanislaw, Swanson, Rebecca, Lehmann, Robert, Shepardson, Sally, Karpovich, David
• Format: Article
• Language: English
• Subjects: Acetic acid; Acidic soils; Acids; Applied sciences; Atmospheric Protection/Air Quality Control/Air Pollution; Biodegradation of pollutants; Biological and medical sciences; Biomass; Biotechnology; Brassica rapa; Chelating; Climate Change/Climate Change Impacts; Composting; Earth and Environmental Science; Edetic acid; EDTA; Electron microscopy; Environment; Environment and pollution; Environmental cleanup; Environmental monitoring; Environmental risk; Exact sciences and technology; Extraction plants; Fundamental and applied biological sciences. Psychology; Groundwater; Groundwater pollution; Hydrogeology; Immobilization; Industrial applications and implications. Economical aspects; Leaching; Lead; Lead (metal); Liquid chromatography; Mass spectrometry; Metals; Microscopy; Phytoremediation; Plant biomass; Plant extracts; Plant tissues; Plants (organisms); Pollution; Risk; Scientific imaging; Soil (material); Soil amendment; Soil contamination; Soil pollution; Soil remediation; Soil Science & Conservation; Studies; Waste materials; Water pollution; Water Quality/Water Pollution; Xylem
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/s11270-013-1615-0

There is a pollution risk when disposing of post-remediation biomass from chelate-assisted metal phytoremediation. To assess this risk, we measured water extractable lead (Pb) in Brassica rapa tissues with ICP-MS, determined if chelated Pb was present with HPLC-MS, and identified Pb storage locations using electron microscopy with x-ray microanalysis. Ethylenediaminetetraacetic acid (EDTA) and ethylenediaminedisuccinic acid (EDDS) were used to enhance Pb movement from contaminated soil to above ground B. rapa tissues. With Pb-EDTA, 92 % (+/−5) of Pb was water extractable from dried tissues and complexed as Pb-EDTA. Electron microscopy and x-ray microanalysis showed Pb stored in xylem vessels. After composting of plant tissues, 79 % (+/−2) of Pb was water extractable and complexed as Pb-EDTA. Total plant Pb accumulation was lower from soils amended with EDDS, but only 6.7 % (+/−0.3) of Pb was water extractable from dried tissues and 55 % (+/−25) from wet tissues of plants grown in EDDS-amended soils. Pb-EDDS was detected in tissues but not at quantifiable levels. This work emphasizes the need for proper treatment and disposal of contaminated post-remediation plant tissues, especially when using EDTA. Composting of plant tissues containing Pb-EDTA was shown to significantly reduce waste material volume and slightly reduce the water extractable fraction, but further immobilization of Pb would be necessary to minimize transport risk. Amending Pb-contaminated soils with EDDS can result in plant biomass with a lower potential to leach Pb into groundwater, but the lower Pb accumulation with EDDS would require longer phytoremediation time compared with EDTA.