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University of Arizona (1978)

THE BEHAVIOR OF LEAD AS A MIGRATING POLLUTANT IN SIX SAUDI ARABIAN SOILS

Turjoman, Abdul Mannan

Titre : THE BEHAVIOR OF LEAD AS A MIGRATING POLLUTANT IN SIX SAUDI ARABIAN SOILS

Auteur : Turjoman, Abdul Mannan

Université de soutenance : University of Arizona

Grade : Master of Science (MS) 1978

Résumé partiel
To evaluate the capability of calcareous desert soils to minimize the migration of Pb from municipal solid waste landfill leachate, Pb-containing leachate was passed through 10-cm columns of six different soils from Saudi Arabia. The volume of the outcoming effluent was recorded and analyzed for Pb/ Ca, and Fe. Leaching continued until a complete Pb breakthrough took place C/Co =1) or at the end of seven months of continuous leaching. Lead was strongly attenuated by all soils. Lead started to appear in the effluent after influent Fe attained a complete breakthrough. Fe is moderately atten uated. Ca was negatively attenuated since its concentration in the effluent was always higher than its concentration in the influent. Of the six soils, only Onaiza sand and Buraida loamy sand reached their maximum Pb-holding capacity ? i.e., a complete Pb breakthrough. Lead was, then, found to be almost evenly distributed in the columns and it was easily extracted by 0.1 N HCl. The data from these two soils behaved according to the Freundlich and the Langmuir ad sorption isotherms suggesting the prominence of Pb sorption over other attenuating mechanisms. Kharj sand and Quatif sandy loam retained the highest quantity of Pb while allowing some to pass through, indicating multiple reactions of sorption, precipitation, chelation, and organic complexation. This was asserted by the non-conformity of the data to normal Freundlich or Langmuir isotherms. After seven months the concentration of Pb was highest in the top layer decreasing gradually toward the bottom of the column. The efficiency of Pb extraction using 0.1 N HCl was low as it extracted ^4 to 13.5% of the retained Pb in the soil. Hasa and Deerab loams showed the highest potential capability of withholding Pb from passing through mainly due to the soil texture. Almost all the Pb precipitated in the surface layer and did not move to the bottom of the column. Only 10.4 to 13.2% of the retained Pb was extracted by 0.1 N HCl. Since no Pb was detected in the effluent, the Freundlich and Langmuir isotherms were not applicable.

Mots clés : Soil pollution. ; Soil permeability. ; Soils — Saudi Arabia.

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