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Biochar as a soil amendment to enhance petroleum hydrocarbon degradation in northern landfarms



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Extreme environmental conditions in northern regions slows efforts to remediate petroleum hydrocarbon (PHC) contaminated soils through conventional landfarming practices. Thus, cost-effective soil remediation strategies that are active under frozen conditions and specific to cold regions are in strong demand. Biochar amendments have been added to soil to sequester carbon, immobilize organic contaminants, and improve long-term soil productivity; however, there is little information regarding their use and effectiveness under cold climate conditions. The purpose of this research was to determine if locally produced biochars can enhance PHC degradation at northern landfarms. This was accomplished by examining biochar additions to PHC contaminated soils under laboratory and field conditions. The degradation of F2 and F3-PHCs increased in bonemeal biochar-amended soils incubated under frozen conditions, but there was little difference in PHC degradation between biochar-amended and control soils under field conditions. Biochars selectively increased nutrient availabilities, but results varied between study location and year. Certain biochars increased liquid water content (θliquid), soil temperature, and pH, but this was dependent on factors such as incubation temperature, biochar feedstock, and application method. A combination of increased aromatic (C2,3O and nahAc) functional gene abundance and total PHC-degraders was linked to the reduction of F3-PHCs in bonemeal biochar amended soil incubated under frozen conditions. Bone derived biochars stimulated PHC degradation and influenced the physical, chemical, and biological properties of soil to a greater extent than wood derived biochar, which was linked to inherent physicochemical properties of biochar such as ash content, pore size, pore volume, and surface area. Incorporated, rather than injected, fertilizer and/or biochar slurries effectively enhanced F2 and F3-PHC degradation, NO3-N availability, θliquid, and aromatic catabolic gene abundance in field studies. Charosphere soil, which immediately surrounds biochar particles, was identified as a spatially unique niche that supported higher 13C-phenanthrene mineralization, aromatic catabolic gene abundance, and relative abundances of PHC degrading bacteria (i.e., Bosea and Caulobacter). This research provides evidence that bone derived biochars selectively enhanced PHC degradation and improved several physical, chemical, and biological properties of northern soils.



biochar, frozen soil, petroleum hydrocarbons, bioremediation



Doctor of Philosophy (Ph.D.)


Soil Science


Soil Science


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