Phytoremediation of Lead in Urban Residential Soils of Portland, Maine

Lead contamination of urban soils is a widespread problem, and traditional remediation of lead‐contaminated soils is very expensive. Thus, it is important to examine alternatives to traditional techniques. We evaluated the phytoremediation potential of spinach in 13 lead‐contaminated garden soils of residential yards in Portland, Maine. We sampled the soils before planting and after harvest, as well as the roots and shoots of the spinach. Soils were analyzed for total and plant‐available lead, particle size, pH, and organic matter; plants were analyzed for lead. Total soil lead decreased, but the difference was not statistically significant. Plant‐available lead showed a significant decrease ( p < 0.05), and after 6 wk the lead concentrations decreased 28%. Soil pH and organic carbon were weakly, but significantly correlated with plant‐available lead. Spinach plants absorbed lead, and roots always had a significantly higher concentration of lead than shoots. These data suggest that unamended phytoremediation is not an adequate remediation tool for these soils. However, these data do suggest that eating leafy greens grown in these urban soils presents a potential health hazard to residents.