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Title: Solid organic matter in UK aquifers : its role in sorption of organic contaminants
Author: Steventon-Barnes, Hannah
ISNI:       0000 0004 2716 5825
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 2000
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A major control on the attenuation of organic contaminants dissolved in groundwater is their sorption onto solid organic matter (OM) in the rock. Sorption modelling is currently based on the amount of solid organic carbon in the rock. However, there are very few available data on the total organic carbon (TOC) content in common UK geological materials. A significant new set of TOC measurements on a range of important formations is presented. Methods to measure TOC in geological, especially carbonate-rich, samples are reviewed and evaluated. The impact of the type of OM on its sorption capacity is not understood. Non-linear isotherms measured on seven samples (of Lincolnshire Limestone, Glacial Till from Norfolk and unconsolidated deposits) had a wide range of organic carbon normalised distribution coefficients (Koc from 7.85 1/g to 767 1/g at 0.01 g/1 trichloroethene). This indicates the impact of characteristics of the OM. Bulk geochemistry and micro-morphology characteristics of the OM that could be important predictors for sorption capacity are investigated and identified. Organic matter has been isolated, and the isolation technique evaluated. The major element composition of the isolated OM has been determined; elemental results were found to correlate with results of a pyrolysis analysis applied to whole rock samples. Morphological analysis of microscope slides of isolated organic matter provided information on the physical types (visually) and size (by image analysis) of the organic particles. Measured KOC values correlated with the elemental H/O content of the sample's OM and with the pyrolysis measurements, but not with morphological results. The effect of selected empirical isotherms on solute transport was simulated: use of an accurate disitribution coefficient is essential, but non-linearity was found not to make a major impact on arrival results. Recommendations are made for the improvement of sorption modelling, and for appropriate analysis methods to supply relevant data on the type of OM in this context.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available