Chemically Induced Phytoextraction of Lead (Pb) Contaminated Soil by Switchgrass (Panicum virgatum L.), assisted with BAP and NTA applications

The accumulation of lead (Pb) deposits in soil is a growing global concern. Phytoextraction of Pb-contaminated soil can be enhanced by soil chelation to increase the bioavailability of Pb. In the initial study nitrilotriacetic acid (NTA) 5mM, the alkylpolyglucoside (APG) Triton X-100 (2%), and nano-silica were applied to switchgrass (Panicum virgatum L.) growing in 5L pots of Pb-contaminated soil. The second experiment used 10mM NTA, the alkylpolyglycoside Triton X-100 (2%), foliar application of the plant growth regulator 6-benzylaminopurine (BAP) twice per week, Triple-12® nutrients, and Infuse™ a soil fungicide which were applied to switchgrass Plants were grown in a controlled greenhouse environment in 5L pots with Pb-contaminated soil (5802.5 mg kg-1) collected from a former Superfund site in Cedartown, GA. Following harvest, plant material was dried, acid digested and chemically analyzed for lead (Pb), aluminum (Al) and iron (Fe) using an ICP-OES. Switchgrass treated with 5mM NTA showed an increased average Pb concentration of 858 mg kg-1, but this was further improved with applications of 10mM NTA, with an average concentration of 3196.5 mg kg-1 in plants foliage. Combined applications of NTA and APG and foliar applications of BAP and nutrients resulted in the highest average Pb concentration of 5,355 mg kg-1. The results suggested that soil applications of 10 mM NTA and Triton X-100, Infuse™ and foliar applications of BAP could be a beneficial technique for phytoremediation of Pb contaminated soils