Year: 2013
Type: dissertation
Abstract: This thesis presents biochar state of the art and investigations into the environmental benefits \nand potential impacts of biochar application to soil. \nSpecifically, the opportunity biochar has to increase concentrations of potentially toxic \nelements (PTE) and polycyclic aromatic hydrocarbons (PAHs) in soil was investigated and \ncontextualised. Results indicated limited environmental impacts in this regard. \nThe capacity of biochar to interact with organic compounds was studied in two contexts: \nPAHs absorption and partitioning; and with respect to bioavailability and potential \ndeactivation of herbicides. \nRegarding PAH partitioning, sewage sludge biochar (SSBC) was established to be more \nefficient than sewage sludge (SS) in reducing the bioaccumulation of PAHs in Lactuca \nsatuva L. grown in contaminated soil; while increasing significantly (p < 0.05) biomass yield, \nrelatively to a soil only control. \nRegarding herbicides, biochar amended soil was observed to reduce herbicide extractability \n(< 2%). This extractability being far lower than that observed in the biochar free control soils \n(40% and 90%). 14C-radiorespirometry indicated that herbicide sequestration within biochar \ngreatly reduced its bioavailability. \nBiochar influence upon weed survival indicated high biochar application rates (5%) to reduce \nthe effectiveness of herbicides, suggesting that biochar incorporation in to soil at these levels \ncould potentially undermine agriculture that relies upon herbicides. \nFinally, biochar was tested as microbial carrier. Rhizobacteria survival was established to be \nhigher in biochar produced from redwood than in peat (a common microbial carrier) at high \nincubation temperatures (25°C and 35°C). \nIn conclusion, biochar addition to soil presents limited direct environmental pollution impact. \nWhile biochar absorptivity may be beneficial in mitigating the bioavailability of organic \ncontaminants this trait needs to be considered carefully in agricultural soils where herbicides \nare relied upon. Given the encouraging results regarding the potential for biochar to act as a \nmicrobial inoculant carrier, further research is warranted.
Author: Alessia Freddo
Language: English
Subfield: Soil Science
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W651962289