Phytoremediation of Lead-Contaminated Soil in the Westside of Atlanta, GA

Phytoremediation has been explored as a cost-effective method to remediate soil Pb contamination. A greenhouse study was conducted to evaluate the efficacy of Vigna unguiculata, Brassica pekinensis, Gomphrena globose, and Helianthus annuus for removing and immobilizing Pb in soil collected from the Westside Lead Superfund site in Atlanta. Plants were cultivated in sampled soil with a Pb concentration of 515 +/- 10 mg/kg for 60 days. Soils growing H. annuus were additionally treated with ethylenediaminetetraacetic acid (EDTA) (0.1 g/kg) or compost (20% soil blend) to assess their capabilities for enhancing phytoremediation. Mean post-phytoremediation Pb concentrations in the four plant species were 23.5, 25.7, 50.0, and 58.1 mg/kg dry weight (DW), respectively, and were substantially higher than 1.55 mg/kg DW in respective plant species grown in control soils with no Pb contamination. The highest Pb concentration, translocation factor, and biomass were found in V. unguiculate among four species without soil amendments. H. annuus treated with EDTA and compost resulted in a significant increase in the total Pb uptake and larger biomass compared to non-treated plants, respectively. Although this study found that V. unguiculata was the best candidate for Pb accumulation and immobilization among four species, soil remediation was limited to 54 mg/kg in a growing season. We find that it is critically important to perform phytostabilization in a secure manner, since Pb bioavailability of edible plant parts implies the potential risk associated with their unintentional consumption. Efficiently and effectively remediating Pb-contaminated soils in a low-cost manner needs to be further studied. Plain Language Summary Exposure to lead can cause well-documented adverse health effects, especially on children. Contaminated soil is a major source of lead exposure. This study investigated a potential intervention involving a remediation method of lead-contaminated soil, called phytoremediation, using four common plants: cowpea, Chinese cabbage, globe amaranth, and sunflower. We studied the ability of these plants to either take up or stabilize lead in soil and also examined the effect of two soil amendments, including EDTA and compost, on facilitating plants to remediate soil contaminants. Results showed that cowpea was the most promising candidate for taking up and stabilizing lead in soil among four species, although one growing season was not sufficient to bring down the lead concentration to the regulatory threshold. Furthermore, cowpea and Chinese cabbage accumulated lead in their tissues and can be absorbed in the body upon ingestion, the unintentional consumption of plants grown in contaminated soil can be dangerous. We also found that the application of soil amendments could facilitate further remediation, but the remediation methods need to be performed in a safe manner and more research is needed.

Automated summary

Phytoremediation, a cost-effective method for remediating soil Pb contamination, was studied using four common plant species: cowpea, Chinese cabbage, globe amaranth, and sunflower. The results showed that cowpea was the most promising candidate for Pb accumulation and immobilization among the four species, although a single growing season was not sufficient for reaching the regulatory threshold. Therefore, further research is needed to study low-cost and efficient methods for remediating Pb-contaminated soils.