Assessment of Some Heavy Metals Pollution and Bioavailability in Roadside Soil of Alexandria-Marsa Matruh Highway, Egypt

Abstract

To assess the roadside soils contamination with Pb, Cd, and Zn, 34 soil samples were collected along Alexandria-Marsa Matruh highway, Egypt, and analyzed by using the atomic absorption. The contamination with these metals was evaluated by applying index of geoaccumulation<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mo stretchy="false">(</mml:mo><mml:msub><mml:mrow><mml:mi>I</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">g</mml:mi><mml:mi mathvariant="normal">e</mml:mi><mml:mi mathvariant="normal">o</mml:mi></mml:mrow></mml:msub><mml:mo stretchy="false">)</mml:mo></mml:math>, contamination factor (CF), pollution load index (PLI), the single ecological risk index<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mo stretchy="false">(</mml:mo><mml:msub><mml:mrow><mml:mi>E</mml:mi></mml:mrow><mml:mrow><mml:mi>i</mml:mi></mml:mrow></mml:msub><mml:mo stretchy="false">)</mml:mo></mml:math>, and the potential ecological risk index (PERI). The average concentrations of Pb, Cd, and Zn were 38.2, 2.3, and 43.4 μ g/g, respectively.<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mrow><mml:msub><mml:mrow><mml:mi>I</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">g</mml:mi><mml:mi mathvariant="normal">e</mml:mi><mml:mi mathvariant="normal">o</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>indicates the pollution of soil with Pb and Cd as opposed to Zn.<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mrow><mml:msub><mml:mrow><mml:mi>E</mml:mi></mml:mrow><mml:mrow><mml:mi>i</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>shows that the roadside soils had low risk from Pb and Zn and had considerable to high risk from Cd. Most of the samples (62%) present low PERI risk associated with metal exposure and the rest of the samples (38%) are of moderate PERI. The bioavailable fraction (EDTA-Extract) was 72.5 and 37.5% for Pb and Cd contents, respectively. These results indicate the remarkable effect of vehicular and agricultural activities on Pb and Cd contents in soil.