Protective role of fine silts for PAH in a former industrial soil

Pernot, Audrey; Ouvrard, Stéphanie; Leglize, Pierre; Faure, Pierre

Protective role of fine silts for PAH in a former industrial soil

2013

Pernot, Audrey | Ouvrard, Stéphanie | Leglize, Pierre | Faure, Pierre

An original combined organic geochemistry and soil science approach was used to elucidate PAH availability controlling factors in a multi-contaminated industrial soil. Water granulodensimetric fractionation was applied to obtain five water-stable material fractions. These were characterized by elemental, molecular and mineral analysis, and microscopic observations. Among the different fractions, fine silts distinguished themselves by higher carbon and nitrogen contents, lower C/N ratio, an enrichment in total PAH and especially high molecular weight compounds, a coal tar signature and the lowest PAH availability. This fine silt fraction seemed to play a protective role for PAH that might be explained by its size and/or its specific reactivity. The mineral phases present in this fraction were proposed to explain the protection of organic matter. This led to a specific molecular signature of OM, having higher sorption properties both processes (sorption and mineral-bound protection) resulting in a lower PAH availability.

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