Heavy-metal uptake by crops from polluted river sediments covered by non-polluted topsoil

Abstract

Crop uptake of heavy metals from polluted river clay soils is shown to be reduced by covering the polluted soil with a layer of unpolluted clay soil. Plant experiments have been performed to determine the thickness of such a layer required either to comply with permissible levels for metal concentrations in foods and feeds, or to exclude any effect on plant metal levels. The experiments included cover layers up to 0.7 m and 1.6 m, respectively. Crops grown included cereals, potatoes, sugar beet, maize and various vegetables. Protection of all food crops tested against exceeding permissible levels for cadmium requires a clean topsoil of over 1.6 m; for individual crops ranging from zero (no cover layer required) for red cabbage, leek, onion, potato) to 1.2 m-1.6 m for celery tuber and leaf. Results for feed crops were variable: required topsoil depths for maize range from 0.25-l.2 m, and for wheat straw from 0.55 to 1.6 m. No-effect depths calculated for Cd, Cu and Zn demonstrate that i, many experiments the effect of the polluted soil may be observed at all topsoil depths tested. Heavy-metal concentrations in the soil profile, measured after completion of the experiments, showed no significant migration of metals from the polluted soil into the cover soil.

The Bioaccumulation and Physiological Effects of Heavy Metals in Carrots, Onions, and Potatoes and Dietary Implications for Cr and Ni: A Review

“…According to another experiment, Cd, Cu, and Zn uptake by carrots from polluted river clay soils, determined by flame atomic absorption spectrophotometry, was found to be reduced by covering the polluted soil with a layer of unpolluted clay soil: Cd, Zn, and Cu concentrations in carrot leaves (2.55, 88.40, 11.50 mg/kg, respectively) and tubers (1.48, 40.2, 9.54 mg/kg, respectively) cultivated in polluted soil were higher as compared to the ones in carrot leaves (0.1, 23.8, 8.01 mg/kg, respectively) and tubers (0.08, 17.0, 7.18 mg/kg, dry matter, respectively) grown in unpolluted clay soils (Van Driel and others ).…”

“…Likewise, heavy metal levels in the potatoes from the 2nd harvest, cultivated in contaminated soil, were considerably higher as compared to the ones of the potatoes grown in clean soil. Chemical analyses were performed using flame AAS (Van Driel and others ).…”

Uptake and Translocation of Heavy Metals in Salt Marsh Sediments by Spartina patens

“…Although considerable uptake of all heavy metals into, or adsorption to, roots was encountered in this study, translocation from below-into above-ground parts of S. patens was not significant with values in shoots remaining within normal limits for plant tissue even in treatments with Ni-amendment (Marschner 1995;van Driel et al 1995;Swaileh et al 2004). Levels were always well below those encountered in plants from more industrial areas and highly contaminated soils (Deram et al 2006).…”

“…Important salt marsh plant species such as salt-meadow grass (Spartina patens), and spike grass (Distichlis spicata) dominate portions of the marsh. The sediments of Harrier Meadow contain heavy metals at concentrations that are below regulatory action limits (e.g., cadmium (Cd) 0-1 ppm; chromium (Cr) 10-18 ppm; copper (Cu) 13-60 ppm; nickel (Ni) 7-15 ppm; lead (Pb) 0-87 ppm; zinc (Zn) 28-94 ppm) (http:// www.meri.njmeadowlands.gov/ecorisk/), but above those typically found in uncontaminated environments (van Driel et al 1995;Swaileh et al 2004).Since Spartina species have been shown to take up heavy metals into roots and translocate them into aboveground parts (see for review), we had investigated the fate and the effects of selected heavy metals (i.e., Cd, Cr, Cu, Ni, Pb, and Zn) in sediment cores that were densely covered with Spartina patens in a recent short-term study (Suntornvongsagul et al 2007). Since levels of metals taken up and translocated had been shown to vary depending on the metal concentration in the substrate (Vogel-Mikus et al 2005), and to be affected by the presence of other metals (McKenna et al 1993;Podar et al 2004), half of these cores were artificially amended with Ni in order to increase its availability, and to assess potential effects on uptake of other metals.…”

“…Important salt marsh plant species such as salt-meadow grass (Spartina patens), and spike grass (Distichlis spicata) dominate portions of the marsh. The sediments of Harrier Meadow contain heavy metals at concentrations that are below regulatory action limits (e.g., cadmium (Cd) 0-1 ppm; chromium (Cr) 10-18 ppm; copper (Cu) 13-60 ppm; nickel (Ni) 7-15 ppm; lead (Pb) 0-87 ppm; zinc (Zn) 28-94 ppm) (http:// www.meri.njmeadowlands.gov/ecorisk/), but above those typically found in uncontaminated environments (van Driel et al 1995;Swaileh et al 2004).…”