Biochar: for better or for worse?

Freddo, Alessia (2013) Biochar: for better or for worse? Doctoral thesis, University of East Anglia.

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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.

    Item Type: Thesis (Doctoral)
    Faculty \ School: Faculty of Science > School of Environmental Sciences
    Depositing User: Mia Reeves
    Date Deposited: 12 Mar 2014 14:58
    Last Modified: 12 Mar 2014 14:58

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