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Title: Impact of biochar on the biodegradation and bioaccessibility of organic contaminants of soil
Author: Ogbonnaya, Ogbonnaya Uchenna
Awarding Body: Lancaster University
Current Institution: Lancaster University
Date of Award: 2013
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This thesis investigated the fate of organic contaminants (naphthalene, phenanthrene and azoxystrobin) in soils amended with biochar. This research considered both microbial biodegradability and chemical extractability. In order to assess the risk posed by organic contaminants in soils, knowledge of the bioavailable and bioaccessible fractions of the organic contaminants are of prime importance rather than the total concentrations. The bioavailable and bioaccessible fractions were defined and determined using respirometry assay and chemical extractions using methanol, calcium chloride (CaCl2) and hydroxypropyl-~ - cyclodextrin (HPCD). In different experiments, biochar was amended in soils at varying doses, particle size and types. The findings of this thesis illustrated that the rates and extents of mineralisation of 14C_PAHs and 14C-azoxystrobincan be controlled by application of biochar varying in dose and type. Furthermore, this study validated the HPCD extraction technique in predicting the bioaccessible fraction of PAHs and azoxystrobin in soil. Results indicated that the presence of biochar in soil reduced the bioaccessibility but did not alter the ability to estimate bioaccessible fractions. This was shown by linear correlations between extents of mineralisation and HPCD single extractions of PAHs in soils. Notably, the presence of biochar in the soils enhanced sorption of contaminants to reduce bioaccessibility but did not inhibit catabolic activities of indigenous microorganisms. The ability of biochar to control bioaccessibility of organic contaminants in soils could be related to difference in biochar intrinsic properties that were determined using nuclear magnetic resonance cryoporometry.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available