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Evaluation of activated carbon amendment for reclamation of a DDT-contaminated site in Pakistan.

Byline: Younas Asma, Hilber I., Khwaja Mahmood, and Bucheli Thomas D.

DDT was produced from 1963 to 1994 in a factory in Nowshera, Khyber Pukhtunkhwa, Pakistan. The factory was then officially closed, but was still in operation for many years. The production and distribution of the insecticide resulted in a DDT polluted area of about 85 hectares. At the factory's site, covering about 550 m2, soils contamination is up to 10 mg g-1 DDT in dry soil.

To reduce DDT exposure of the environment and humans, this contaminated site has to be remediated. Therefore, the aim of this joint research project is to test a remediation strategy that substantially reduces the bioavailable fraction of the aged DDT in the soil. We propose to bind and immobilize the contaminant and its metabolites in the soil by activated charcoal (AC) amendment. AC has proven to significantly reduce the bioavailability of organic contaminants in solid matrices due to its high adsorption affinity and capacity. For this purpose, many researchers already successfully added AC to sediments. The novelty of this project is the application and thorough evaluation of this remediation technique to a field soil contaminated by sequestered DDT and metabolites.

Specifically, within the three years of the project, we plan the following actions: 1) Soils and sites will be selected to work with in the subsequent laboratory and field experiments. 2) In laboratory experiments with different soil contamination levels and different kinds of added AC (powdered, granulated, or reactivated charcoal), the bioavailability of DDT and metabolites will be assessed by depletive and non-depletive extraction methods which are Tenax(r) beads, a porous polymer and polyoxymethylene (POM), respectively and 3) Pilot field studies will be performed after the AC has been added to the soil according to the initial laboratory results. The chemical activity of DDT in the soil pore water will be assessed by POM and the bioaccessibility of DDT tested in the lab with Tenax(r) over a period of about two years. Overall, this technique presents, if it proves successful, a cheap, effective and feasible way to remediate other organically contaminated hotspots in South Asia.

Younas Asma, Department of Environmental Sciences, University of Peshawar, Peshawar.

Hilber I., Agroscope Reckenholz Tanikon Research Station ART, Switzerland.

Khwaja Mahmood, Sustainable Policy Development Institute (SDPI), Islamabad and

Bucheli Thomas D., Agroscope Reckenholz Tanikon Research Station ART, Switzerland.

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Author:Asma, Younas; I., Hilber; Mahmood, Khwaja; D., Bucheli Thomas
Publication:Journal of Himalayan Earth Sciences
Article Type:Report
Geographic Code:9PAKI
Date:Dec 31, 2010
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