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Title: Biochar : for better or for worse?
Author: Freddo, Alessia
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 2013
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This thesis presents biochar state of the art and investigations into the environmental benefits and potential impacts of biochar application to soil. Specifically, the opportunity biochar has to increase concentrations of potentially toxic elements (PTE) and polycyclic aromatic hydrocarbons (PAHs) in soil was investigated and contextualised. Results indicated limited environmental impacts in this regard. The capacity of biochar to interact with organic compounds was studied in two contexts: PAHs absorption and partitioning; and with respect to bioavailability and potential deactivation of herbicides. Regarding PAH partitioning, sewage sludge biochar (SSBC) was established to be more efficient than sewage sludge (SS) in reducing the bioaccumulation of PAHs in Lactuca satuva L. grown in contaminated soil; while increasing significantly (p < 0.05) biomass yield, relatively to a soil only control. Regarding herbicides, biochar amended soil was observed to reduce herbicide extractability (< 2%). This extractability being far lower than that observed in the biochar free control soils (40% and 90%). 14C-radiorespirometry indicated that herbicide sequestration within biochar greatly reduced its bioavailability. Biochar influence upon weed survival indicated high biochar application rates (5%) to reduce the effectiveness of herbicides, suggesting that biochar incorporation in to soil at these levels could potentially undermine agriculture that relies upon herbicides. Finally, biochar was tested as microbial carrier. Rhizobacteria survival was established to be higher in biochar produced from redwood than in peat (a common microbial carrier) at high incubation temperatures (25°C and 35°C). In conclusion, biochar addition to soil presents limited direct environmental pollution impact. While biochar absorptivity may be beneficial in mitigating the bioavailability of organic contaminants this trait needs to be considered carefully in agricultural soils where herbicides are relied upon. Given the encouraging results regarding the potential for biochar to act as a microbial inoculant carrier, further research is warranted.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available