Dublin City University. School of Chemical Sciences
Abstract
Polycyclic aromatic hydrocarbons (PAH) have been regulated as priority pollutants
since the 1970’s. Since then, there has been increasing recognition that oxygenated
PAH transformation products may present a greater risk than parent PAH. This is a
concern for soil remediation sites where formation of oxygenated PAH can be
accelerated. Currently, routine monitoring is challenged due to a lack of standard
analytical protocols. This thesis applies new analytical methods to investigate the
formation and distribution of oxygenated PAH in contaminated soil-water systems
under different remediation scenarios. High performance liquid chromatography and
gas chromatography - mass spectrometry were used to investigate the effect of lignin
phenol amendments on PAH transformation processes in a simulated soil-water system.
Samples with highest PAH attenuation were characterised by increased utilisation of
lignin phenols and distinct patterns of oxygenated PAH removal/formation, suggesting a
potential approach to enhance PAH biodegradation. Challenges for analysing soilbound
oxygenated PAH were addressed through the development of a novel
aminopropylsilica solid phase extraction method. Strong recoveries of ketone- and
hydroxyl-modified PAH were obtained, and the method also supported limited
qualitative analysis for acid and aldehyde products. In addition, contamination level and
clay content were shown to influence recovery of targeted compounds from different
soils. Combining analytical methods for total extractable, leachate, and readily available
soil fractions, the distribution of oxygenated PAH in gasworks soils undergoing
remediation was monitored over a six-month period. Biochar, compost, and no
amendment treatments were compared for effects on contaminant
degradation/formation, and contaminant lability. It was shown that the biochar
amendment was most likely to increase, and compost amendment most likely to
decrease, risks associated with oxygenated PAH in these soils. Together, these studies
show how new analytical techniques for the detection of oxygenated PAH can be used
to enhance remediation science and support decision making at remediation sites
