Wednesday, November 7, 2007
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Trace Element Contents of Ethnic Vegetables.

Edward Landa1, Kathryn Conko1, Stephan Tubene2, and R. David Myers2. (1) U.S. Geological Survey, MS 430, 12201 Sunrise Valley Dr., Reston, VA 20192, (2) University of Maryland, 7320 Ritchie Hwy, Suite 210, Glen Burnie, MD 21061

Immigrants to the U.S. from Asia, Africa, the Caribbean and Latin America are creating an increasing demand for vegetables indigenous to their native countries. To help meet this demand, ethnic vegetable production trials have been conducted since 2000 at the University of Maryland Research and Education Center (UMREC) in Upper Marlboro, Maryland on a Monmouth fine sandy loam soil (http://www.marylandethnicvegetable.com/production.html). Crops included African eggplant “Gboma”, edible African hibiscus, amaranth “Jamaican calaloo”, Solanum gilo “Jamaican bitter balls”, and a selection of basil and hot peppers. As trace element content of these crops has often not been documented in the food composition literature, we did a screening study involving composite sampling of edible tissue from 19 different crops at the 2005 harvest from UMREC test plots. Ranges and mean tissue concentrations of selected trace elements (mg/kg dry weight): As (0.04; 0.003-0.15), B (30; 1.1-83), Ba (49; 1.9-300), Cd (0.64, 0.04-1.9), Co (0.24; 0.05-1.1), Cu (12; 4.0-26), Fe (77; 27-340), Mn (110; 9.8-770), Ni (1.6; 0.40- 4.9), Pb (0.14; 0.012- 0.61) and Zn (37; 15-79). The highest tissue concentrations observed were: As (0.15) in amaranth leaves; Ba (300) in purslane leaves; B (83) in hibiscus leaves; Cd (1.9) in edible hibiscus and okra leaves; Co (1.1) in amaranth leaves; Cu (13) in Gboma; Fe (340) in purslane leaves; Mn (770) in amaranth leaves, Ni (4.9) in the seeds of Agusi [an African indigenous melon]; Pb (0.61) in Genovese basil; and Zn (79) in okra leaves. The Melich-3 extraction was used to assess available trace element concentrations in soil. Mean plant-to-soil concentration ratios for As, Fe and Pb are less than one; the highest ratios are for B>Cu>>Cd≈Zn (all >10).