We are using an ion-exchange material (IEM) to prevent lead uptake by leafy greens. Soil in the area upwind from a power plant in Madison Indiana has relatively high levels of lead. We measured levels of lead in leafy greens grown in this area and found the lead uptake into the plants was high. Because of this we have been researching for a method to reduce the uptake of lead in the plants using an IEM. The IEM is a 1:1 co-precipitate of polyvinyl alcohol (PVA) and polyacrylic acid (PAA) where the PVA is an inert substrate used to make the film insoluble and the PAA is the active material. The IEM is made insoluble by crosslinking the PVA with an aldehyde, typically formaldehyde. This IEM has several advantages over other ion exchange materials such as it is reusable, uses relatively cheap starting materials, and, most important, it is preferential for lead over calcium. In fact, the IEM we used in this research starts in the calcium form and exchanges calcium in favor of lead at the active sites. The preference for lead over calcium is important in this southern Indiana due to the high levels of calcium in the soil and water supply. Preliminary results on lab scale trials have been impressive. We grew lettuce in soil adjusted to 100 ppm lead. In half of the containers we placed an IEM film with a mass of about one gram, the other containers were left untreated. When the leafy greens where mature, they were picked and dried in an oven. 10g of the dried material was extracted with 20 mL of 10% HNO3 vortexed and centrifuged. Lead levels were determined by ICP. Results of the preliminary studies showed that samples planted in soil with the IEM had a reduction of lead uptake in the leafy greens of at least 50% and as high as 95% when compared to the untreated control.

Reduction of lead uptake in leafy green vegetables using an ion exchange material

253rd National Meeting (2017)

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