Environmental fate of pollutants is paramount to their bioavailability, and as such their potential toxicity. Soil bound fractions of persistent organic pollutants (POPs) such as chlorobenzenes are far greater than in any other environmental compartment. This thesis investigates the potential for volatilisation flux of dichlorobenzene (DCB) from soils under planted and unplanted regimes. It was found that volatilisation, not mineralization, is the main route of DCB removal from soil systems. It was also found that planted systems resulted in a significant increase in volatilisation flux from DCB contaminated soil, in comparison to unplanted systems. It is concluded that the plants have two main interactions with the soil that may lead to this increased volatilisation. These are: (i) the plants transpirational influence dries out the soil; (ii) aromatic acids are released by the plants into the rhizosphere in the form of root exudates. It is shown in this thesis that drier soil has increased rates of volatilisation to the atmosphere than wetter soil. It is also shown in literature (Xing and Pignatello, 1998) that aromatic acids released by plant roots as exudates competitively bind to SOM resulting in the displacement of DCB that may subsequently be volatilised from the soil. Both of these factors in combination explain the resulting flux of volatiles from the soil under planting. It is of critical important to recognise volatilisation as a main route of POP flux from soil systems. Many previous studies may have overlooked volatilisation fluxes from soil in favour of the opinion that mineralization is the main route for removal. This may have important implications for the phytoremediation of contaminated soils.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:440067 |
| Date | January 2006 |
| Creators | Baughn, Heulwen M. |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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