Pollution assessment of heavy metals in roadside agricultural soils

Abstract

Soil contamination of heavy metals is widespread, raising concerns about agricultural risks. We are investigating the concentrations and forms of the heavy metals lead, zinc, chromium, cobalt, nickel, cadmium and copper in agricultural soils near intensive traffic areas in two major cities in western Algeria: Tlemcen and Sidi Bel Abbes. We analyzed four soil samples cultivated with grapes (E1 and E2) and wheat (E3 and E4). The average concentrations of lead, cadmium, chromium and copper in these agricultural lands exceeded the environmental quality standards of soil in Europe. The average of total concentrations of nickel, cobalt and zinc are less than the environmental quality standards of soil in Europe, which is consistent with the obtained results of the contamination degrees and the potential ecological risk of a single heavy metal. Eri, Eri were classified as considerable (80≤Eri<160), high (160≤Eri<320); that, Eir average for Pb in all soil samples is 68.67 and 162.91 for the Cd. As a result, the ERI of the four soil samples was high in all cases. When using sequential extraction, our results show that cadmium compounds are preferentially concentrated in the carbonate fraction, acid-extractable fraction and residual phase of the soil, causing a risk because of its high value. Co was concentrated in the phases of reducible and oxidizable, while Pb, Zn, Cu and Ni are highly concentrated in the remaining two remaining phases, which are weak in reducible and oxidizable phases. These results show that these minerals are less readily available in the examined soil. There is also a correlation between nickel-zinc (Ni-Zn), cobalt, zinc (Co-Zn), cadmium and nickel (Cd-Ni), cadmium and chromium (Cd-Cr), cadmium and lead (Cd-Pb), copper and zinc (Cu-Zn), and chromium and lead (Cr-Pb). Soil parameters such as pH, CEC, TC% and organic matter content should also be taken into consideration when determining soil pollution status.