Bioavailability of heavy metals in New Orleans' community gardens
Heavy metal pollution is an increasing concern as anthropogenic activity increases their levels in the environment. When heavy metals are deposited into the soil, they become bioavailable and can persist in the environment for a long time. Once bioavailable, metals are absorbed by plants, and eventually plants are consumed by other organisms where the heavy metals bioaccumulate in the body. While some heavy metals are considered essential nutrients in small concentrations (including copper, manganese, and zinc), others are considered toxic to humans at any concentration (including arsenic, cadmium, and lead). Even essential heavy metals can become toxic when consumed in higher concentrations. Heavy metal pollution is particularly concerning when considering urban gardens, as urban soils tend to exhibit higher concentrations of heavy metals. To our knowledge, there has been no assessment of bioavailability and biotransfer of heavy metal concentration from the soil to produce in the urban gardens in New Orleans. Previous assessments of heavy metals in New Orleans have focused on soil. We collected plant and soil samples from five community gardens in New Orleans. We processed and analyzed them to determine the presence and the concentrations of 8 heavy metals (As, Cd, Cr, Cu, Pb, Ni, Mn, Zn) in the fall crops (roots, leaves, and fruits) and soils in raised beds and the ground. On average, we found edible biomass samples to have 0.035ppm As, 0.18ppm Cd, 0.51ppm Cr, 5.45ppm Cu, 0.43ppm Pb, 0.39ppm Ni, 9.48ppm Mn, and 27.55ppm Zn.