Probability of Heavy Metals Mobility from Dumped Sediments in a Quarry

Abstract

The former Texcoco Lake was dreg to build the new international Mexico City airport were pumped in a quarry. The dredged sediments could have heavy metals (HMs) capable to pollute water bodies. The study aimed to evaluate the content of Cu, Zn, Cd, Ni, and Pb of the sediments deposited in the quarry, its transfer to the runoff water and the Cu, Zn, Ni, and Pb adsorption in the subsoil. We measured water infiltration rate, HMs concentration in sediments, water runoff, and the HM adsorption in the subsoil. The infiltration rate in sediments is low (? 10^-7 cm/h). HMs in sediments are within the maximum permissible limits by the Mexican regulations, for sewage sludge. The HM in the runoff from the sediments are in the range of the Mexican regulations for the discharge into rivers and for irrigation purposes of agricultural soils. It is also within safe limits for irrigation use considered by FAO and EPA. The materials adsorption capacity of Pb (1250 mg kg^-1), Zn (588 mg kg^-1), and Cu (1250 mg kg-1) is higher than the concentration of metals in the runoff water, so it is unlikely the movement of HM down the subsoil.