Reducing Heavy Metals Uptake by Lettuce from Contaminated Soils Using Organic and Inorganic Amendments

Heavy metal pollution in soil and water is a global environmental concern. In Vietnam, accumulation of
heavy metals in soil, water and plant biomass has been widely reported. Cultivation of crops on
contaminated areas can lead to inhibition of growth and accumulation of heavy metals in tissues,
leading to possible risks to human health. In this paper, the effect of heavy metal contamination on
plant growth and the accumulation of Cu, Pb and Zn in Lettuce (Lactuca sativa L.) were evaluated
both in the pots and field experiments. There is a large difference in the accumulation of heavy metals
in roots and leaves of lettuce. The concentration of heavy metals in roots is much higher than that
accumulated in leaves, usually 1.5 to 2 times higher. Lettuce plants always have a higher soil to roots
cumulative coefficient of heavy metals than that from roots to leaves. In which, Zn always has the
highest cumulative coefficient, followed by Cu and Pb. The use of organic and inorganic amendments
such as phosphate fertilizer, lime and sawdust to minimize heavy metal uptake in lettuce plants has
also shown positive results. The lettuce plant has ability to accumulate more Zn than Cu and Pb. More
effects to reduce the accumulation of Cu, Pb and Zn in Lettuce were observed in all experiments with
phosphate fertilizer, lime and sawdust applied. However, the application of lime and phosphate
fertilizer are more effective than sawdust to reduce Cu, Pb and Zn uptake by Lettuce, especially for
Cu and Pb.