Citation:
Frédéric Coulon, Michael J. Whelan, Graeme I. Paton, Kirk T. Semple, Raffaella Villa, Simon J.T. Pollard, Multimedia fate of petroleum hydrocarbons in the soil: Oil matrix of constructed
biopiles, Chemosphere, Volume 81, Issue 11, December 2010, Pages 1454–1462.
Abstract:
A dynamic multimedia fugacity model was used to evaluate the partitioning and
fate of petroleum hydrocarbon fractions and aromatic indicator compounds within
the soil: oil matrix of three biopiles. Each biopile was characterised by four
compartments: air, water, soil solids and non-aqueous phase liquid (NAPL).
Equilibrium partitioning in biopile A and B suggested that most fractions
resided in the NAPL, with the exception of the aromatic fraction with an
equivalent carbon number from 5 to 7 (EC5-7). In Biopile C, which had the
highest soil organic carbon content (13%), the soil solids were the most
important compartment for both light aliphatic fractions (EC5-6 and EC6-8) and
aromatic fractions, excluding the EC16-21 and EC21-35. Our starting hypothesis
was that hydrocarbons do not degrade within the NAPL. This was supported by the
agreement between predicted and measured hydrocarbon concentrations in Biopile B
when the degradation rate constant in NAPL was set to zero. In all scenarios,
biodegradation in soil was predicted as the dominant removal process for all
fractions, except for the aliphatic EC5-6 which was predominantly lost via
volatilization. The absence of an explicit NAPL phase in the model yielded a
similar prediction of total petroleum hydrocarbon (TPH) behaviour; however the
predicted concentrations in the air and water phases were significantly
increased with consequent changes in potential mobility. Further comparisons
between predictions and measured data, particularly concentrations in the soil
mobile phases, are required to ascertain the true value of including an explicit
NAPL in models of this kind.