Copper, nickel and zinc accumulations in lettuce grown in soil amended with contaminated cattle manure vermicompost after sequential cultivations

Abstract

The Cu, Ni and Zn accumulations in leaves and roots of lettuce (Lactuca sativa L) grown in soil amended with natural and contaminated cattle manure vermicompost were evaluated. The vermicompost residues containing relatively high metal concentrations used in this work were obtained from a previous experiment, in which vermicompost was applied to removing metals from electroplating wastes. Sequential lettuce cultivations were conducted in pots containing the residual substrates from the first cultivation by adding metal-enriched vermicompost residues. In general, the Cu, Ni and Zn concentrations in leaves and roots of lettuce plants grown in vermicompost enriched with these metals were higher than in the treatment using the natural vermicompost. The metal concentrations in leaves from treatments with natural vermicompost were below the critical concentrations of toxicity to plants. However, the metal concentrations in leaves of the third cultivation in which metal-enriched vermicompost was applied were greater than the upper limit that causes plant toxicity, but no visual damage was observed in the plants. Treatment with Zn-enriched vermicompost resulted in toxicity symptoms, but plant damage did not result in the death of the plant. The chemical fractionation of Cu, Ni and Zn in residues from lettuce cultivation was evaluated by using a sequential extraction procedure and metal concentrations were increased in the different chemical fractions according to the increase of vermicompost dose.

Influence of the Choice of Cultivar and Soil Fertilization on PTE Concentrations in Lactuca sativa L. in the Framework of the Regenerative Agriculture Revolution

“…S1 and S3). In L. sativa plants, Celik and Kunene [33] also highlighted higher concentrations of Cu and Pb (as well as of Cd, Cr, Fe, Mn and Zn) in roots than in leaves; similarly, Jordão et al [34] found the highest concentrations of Cu and Ni in the belowground organs, attributing this behavior to a protection mechanism. These observations put emphasis on the role that PTE bio-geochemical properties have in explaining element peculiar mobility and transfer into the soil-plant system [30].…”

“…For Cd, the remark is rather worrying, considering its carcinogenicity [36], the For Cu (55.9%), K (7.0%), Mg (16.6%), Na (14.2%) and Pb (28.0%), the organ had a relatively higher contribution in determining their concentrations (Figure 2), with the highest values observed in leaves in the case of Mg and in roots in the case of Cu, K, Na and Pb (Figures S1 and S3). In L. sativa plants, Celik and Kunene [33] also highlighted higher concentrations of Cu and Pb (as well as of Cd, Cr, Fe, Mn and Zn) in roots than in leaves; similarly, Jordão et al [34] found the highest concentrations of Cu and Ni in the belowground organs, attributing this behavior to a protection mechanism. These observations put emphasis on the role that PTE bio-geochemical properties have in explaining element peculiar mobility and transfer into the soil-plant system [30].…”