Journal of the Saudi Society of Agricultural Sciences (Sep 2021)

Guideline references to levels of heavy metals in arable soils in upper Egypt

  • Salah Hassanien Abd El-Aziz

Journal volume & issue
Vol. 20, no. 6
pp. 359 – 370

Abstract

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Four soil profiles were selected from four different locations in upper Egypt including Tushka, Wadi El-Nuqra, El-Kharga, and El-Dakhla to evaluate the total and dithionate-citrate-bicarbonate (DCB) extractable heavy metals (Fe, Mn, Zn, Cu, Pb, Cr and Ni) levels in these soils. The heavy metal distributions in bulk soil samples and their size fractions (clay, silt and very fine sand) were also investigated. The studied soils had a coarse texture in all locations with mildly to moderately alkaline, slightly saline and low contents of calcium carbonate and organic matter. Clay and silt fractions of these soils showed the highest total and DCB-extractable levels of these metals; whereas the very fine sand fraction contained the lowest. In comparison with the average levels of heavy metals in the world soils, the studied soils displayed levels of heavy metals within the range or less than those of world soils. A moderate or moderately severe enrichment factor (EF) values were recorded in Tushka, El-Kharga and El-Dakhla soils for Pb and moderate EF ones for Zn were found in Tushka and El-Kharga ones. On the contrary, the values of EF for other heavy metals such as Mn, Cu, Cr, and Ni at most locations were <2, showing deficient to minimal enrichment in the soils. However, the calculated contamination factor (Cf) and geo-accumulation index (Igeo) indicated that the soil samples are characterized by uncontaminated levels of all heavy metals (Igeo of < 0). Positive correlations among the total Fe, Mn, Cu and Ni suggest that these metals may be originated from the same source, mainly from a lithogenic origin. The contents of soil heavy metals in all locations were less than the globally allowable concentrations, which indicate no harmful effect of these metals. Therefore, the contents of these heavy metals can be taken as a guide reference to the levels of the heavy metals in uncontaminated Egyptian soils.

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