SUITMA 2005 Cairo - The biodegradation, leaching and sequestration of phenanthrene in soil

Soils of Urban, Industrial, Traffic, Mining and Military Areas
SUITMA 2005 Cairo

The biodegradation, leaching and sequestration of phenanthrene in soil

SUITMA

This abstract is about one of the papers of the Industrials, traffic, and mining pollution theme of the SUITMA 2005 symposium.

Samira Amellal,i	Arnaud Boivin,i
Corinne Perrin-Ganier,i	Michel Schiavon.i

• i - Laboratoire sols et environnement (LSE), ENSAIA, Université de Lorraine - INRA, Nancy, France.

Polycyclic aromatic hydrocarbons (PAHs) represent an important class of hydrophobic organic contaminants because of their toxicity and persistence in soils and sediments. Although natural sources affect the concentrations in local areas, PAHs are primarily due to anthropogenic inputs including the incomplete combustion or pyrolysis of organic material and the direct release of oil or its products. Previous investigations showed traffic was the major PAHs source in metropolitan areas. Soil system seems to be the important long-term repository for PAHs and is considered to be a steady indicator of the environmental pollution state. Accumulation of PAHs in soils may lead to further potential contamination of vegetables and food chains, and then cause direct or indirect exposure to human.

The purpose of the study was to follow the biodegradation, diffusion, sequestration and mobility of the ¹⁴C-phenanthrene in soil. The experiment was carried out with soil micro-columns incubated for 156 days in laboratory conditions. At intervals, samples were leached, centrifuged to characterise the fraction of chemical available in pore water or extracted with organic solvents to assess total residues in soil.

Mineralization of ¹⁴C-phenanthrene reached about 2 % after 156 days. The quantity of extractable ¹⁴C-phenanthrene residues was significantly higher during the first 64 days. However, the concentration of 14C-phenanthrene residues was low in the percolation waters. Diffusion phenomena occurred after 45 days and were simultaneous with the phenanthrene biodegradation prior to its mineralization. Results show that the production by biodegradation of hydroxylated products facilitates the transport by diffusion of the phenanthrene residues towards the intra-aggregate microporosity and their later sequestration.