Quantifying the effects of hydrocarbon contamination on hybrid poplar fine root dynamics provides information about how well these trees tolerate the adverse conditions imposed by the presence of petroleum in the soil. Infection by ectomycorrhizal (ECM) fungi may benefit hybrid poplar growing in contaminated soils by providing greater access to water and nutrients and possibly inducing greater contaminant degradation. The overall objectives of this research were to: 1) investigate the relationship between the varying concentrations of total petroleum hydrocarbons (TPH) and nutrients across a hydrocarbon-contaminated site, as well as interactions between these contaminants and physical and chemical soil properties; 2) quantify the effects of these properties on the spatial and temporal patterns of fine root production for Griffin hybrid poplar (<i>P. deltoids </i> x <i>P. petrowskyana</i> c.v. Griffin); and (3) quantify the effect of ectomycorrhizal colonization on hybrid poplar fine root dynamics and N and P uptake when grown in diesel contaminated soil under controlled conditions. A minirhizotron camera provides a nondestructive approach for viewing roots in situ. This camera was used in both the field and growth chamber experiments to provide the data necessary for estimating fine root production. The field study was conducted at Hendon, SK, Canada. Twelve minirhizotron tubes were distributed across the field site and facilitated quantification of fine root production in areas of varying contamination levels. Residual hydrocarbon contamination was positively correlated with soil total C and N, which may suggest that the hydrocarbons remaining in the soil are associated with organic forms of these nutrients or increased microbial biomass. Total fine root production at the site was greater in the 0- to 20-cm depth (1.27 Mg/ha) than the 20- to 40-cm depth (0.51 Mg/ha) in 2004. Fine root production was stimulated by small amounts of hydrocarbon contamination at the field site. Nonlinear regression described fine root production as increasing linearly up to approximately 500 mg/kg TPH, then remaining constant as contamination increased. This trend was most pronounced in the 0- to 20-cm soil layer, with a (r&178; = 0.915). Stimulation of fine root production in the presence of hydrocarbons has significant implications for phytoremediation. If hybrid poplar can maintain increased root production in hydrocarbon contaminated soils, the rhizosphere effect will be exaggerated and increased degradation of contaminants is likely to occur. Under controlled conditions, colonization of hybrid poplar roots by the ectomycorrhizal fungus <i>Pisolithus tinctorius</i>increased fine root production in a diesel contaminated soil (5000 mg diesel fuel/kg soil) compared to non-colonized trees growing in the same soil. Fine root production was 56.6 g/m&178; in the colonized treatment and 22.6 g/m&178; in the non-colonized treatment. In diesel contaminated/ECM colonized treatment, hybrid poplar leaf N and P concentrations after 12 wk were 23.1 and 3.6 g/kg, respectively. In diesel contaminated/non-colonized treatment, N and P concentrations were 15.7 and 2.7 g/kg, respectively. After 12 wk, 5.0&37; of the initial concentration of diesel fuel remained in the soil of the non-colonized treatment and 6.7&37; remained in the colonized treatment. Both treatments removed more contaminants from the soil than an unplanted control, which contained 8.9&37; of the initial diesel fuel concentration after 12 wk. Significantly more hydrocarbons were found sequestered in hybrid poplar roots from the colonized treatment (354.1 mg/kg) than in the non-colonized treatment (102.2 mg/kg). The results of this study indicate that hybrid poplar may be good candidates for use in phytoremediation of petroleum hydrocarbons because of the stimulation of fine root production at low levels of hydrocarbon contamination. However, colonization of hybrid poplar growing in diesel contaminated soil by <i>P. tinctorius</i> inhibited remediation of diesel fuel.

Contamination of surface and ground water has emerged as one of the most important environmental issues in developed and developing countries. Bioremediation of groundwater takes advantage of bacteria present in the environment to transform toxic compounds to non-toxic metabolites. This biotechnology holds the potential for fast, inexpensive, and effective water decontamination. However, it is still poorly understood and usually not fully controlled due to the lack of information describing the natural phenomena involved. Therefore, a better understanding of the phenomena involved during bioremediation of groundwater could help in the design and implementation of more efficient technologies. The main objective of the present research is to assess how pore-scale physical factors, such as pore-scale velocity, affect the degradation potential of contaminants during transport in groundwater. The target chemicals studied were chlorinated ethenes because they are commonly found in contaminated groundwater sites. To achieve the research objective, the following were employed: a mathematical model that links pore scale processes to the macro-scale representation of contaminant transport; development of numerical tools to solve the mathematical model; and experimental elucidation of the influence of pore-scale flow velocity on the biodegradation of contaminants using column experiments. Results from the mathematical model and experiments were used to elucidate the inter-relationship between physical and biological phenomena at the micro scale. The influence of flow velocity through the porous media (a physical factor) on the biological structure (microbial community in the porous media) was assessed. The results of this investigation contribute to the bioremediation of contaminated groundwater understanding with new insights on the importance of physical transport factors on the biodegradation potential. For example, flow velocity is shown to have an important effect on the degradation potential of chlorinated ethenes. Additionally, the mathematical model and numerical tools have potential application to many other reactive transport problems, including: adsorption onto activated carbon, reaction in packed beds of catalyst, chemical transport in streambeds, and separation in chromatographic columns.

In this research¡Awe used three kinds of surfactant ¡Aincluding Triton X-100(nonionic surfactant)¡ATriton QS-15 and SDS(anionic surfactant) ¡Ato study the effects of PAHs degradation bacteria on phenanthrene. In addition¡A we also discussed the treatment effects of salicylate¡A which was functioned as an inducer¡Aon degradation of phenanthrene by the microorganisms with and without the three surfactants. According to the experimental results¡Athe conclusions were as following¡G 1. Biodegradation of PAHs was interfered by species surfactant¡Awhich was affected by the experimental factor¡Aspecies of surfactant and bacteria. 2. In the low level of Triton X-100 system ¡Asalicylate could enhance the degradation of phenanthrene. 3. The effect of degrading phenanthrene was obvious by adding salicylate to the system. 4. In the system containing Aluminum oxide and Triton QS-15¡A it could not enhance the degradation effects on phenanthrene. In the future study¡A we suggest to further discuss the enhancing effects of surfactant on bioremediation of PAHs.

Contamination of surface and ground water has emerged as one of the most important environmental issues in developed and developing countries. Bioremediation of groundwater takes advantage of bacteria present in the environment to transform toxic compounds to non-toxic metabolites. This biotechnology holds the potential for fast, inexpensive, and effective water decontamination. However, it is still poorly understood and usually not fully controlled due to the lack of information describing the natural phenomena involved. Therefore, a better understanding of the phenomena involved during bioremediation of groundwater could help in the design and implementation of more efficient technologies. The main objective of the present research is to assess how pore-scale physical factors, such as pore-scale velocity, affect the degradation potential of contaminants during transport in groundwater. The target chemicals studied were chlorinated ethenes because they are commonly found in contaminated groundwater sites. To achieve the research objective, the following were employed: a mathematical model that links pore scale processes to the macro-scale representation of contaminant transport; development of numerical tools to solve the mathematical model; and experimental elucidation of the influence of pore-scale flow velocity on the biodegradation of contaminants using column experiments. Results from the mathematical model and experiments were used to elucidate the inter-relationship between physical and biological phenomena at the micro scale. The influence of flow velocity through the porous media (a physical factor) on the biological structure (microbial community in the porous media) was assessed. The results of this investigation contribute to the bioremediation of contaminated groundwater understanding with new insights on the importance of physical transport factors on the biodegradation potential. For example, flow velocity is shown to have an important effect on the degradation potential of chlorinated ethenes. Additionally, the mathematical model and numerical tools have potential application to many other reactive transport problems, including: adsorption onto activated carbon, reaction in packed beds of catalyst, chemical transport in streambeds, and separation in chromatographic columns.

Cyanide-containing waste is an increasingly prevalent problem in today's society. There are many applications that utilize cyanide, such as gold mining and electroplating, and these processes produce cyanide waste with varying conditions. Remediation of this waste is necessary to prevent contamination of soils and water. While there are a variety of processes being used, bioremediation is potentially a more cost effective alternative. A variety of fungal species are known to degrade cyanide through the action of cyanide hydratases, a specialized subset of nitrilases which hydrolyze cyanide to formamide. Here I report on previously unknown and uncharacterized nitrilases from Neurospora crassa, Gibberella zeae, and Aspergillus nidulans. Recombinant forms of four cyanide hydratases from N. crassa, A. nidulans, G. zeae, and Gloeocercospora sorghi were prepared after their genes were cloned with N-terminal hexahistidine purification tags, expressed in Escherichia coli and purified using immobilized metal affinity chromatography. These enzymes were compared according to their relative specific activity, pH activity profiles, thermal stability, and ability to degrade cyanide in the presence of high concentrations of copper and silver. Although all four were relatively similar, the N. crassa cyanide hydratase (CHT) has the greatest thermal stability and widest pH range where activity remained above 50%. N. crassa also demonstrated the highest rate of cyanide degradation in the presence of both metals tested. The CHT of A. nidulans and N. crassa have the highest reaction rate of the four fungal nitrilases evaluated in this work. These data help determine optimization conditions for the possible use of these enzymes in the bioremediation of cyanide-containing waste. Similar to known plant pathogenic fungi, in vivo expression of CHT in both N. crassa and A. nidulans were induced by growth in the presence of KCN (potassium cyanide).

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xv, 160 p.; also includes graphics. Includes abstract and vita. Advisor: Warren A. Dick, Environmental Science Graduate Program. Includes bibliographical references (p. 135-160).

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisors: Lynn E. Katz and Gerald E. Speitel Jr. Vita. Includes bibliographical references. Also available from UMI.

Thesis (doctoral)--University of Helsinki, 2009. / Includes bibliographical references. Also available on the World Wide Web.

Thesis (MTech (Chemical Engineering))--Peninsula Technikon, 2001. / Word processed copy. Summary in English. Includes bibliographical references. Also available online.