Thesis (M.S.)--Texas State University--San Marcos, 2009. / Vita. Includes bibliographical references (leaves 52-54). Also available on microfilm.

Thesis (Ph.D.)--University of Ottawa, 2008. / Includes bibliographies. Also available via the World Wide Web.

Thesis (Ph.D.)--University of Ottawa, 2008. / Includes bibliographies.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves 173-180).

Thesis (Ph. D.)--Miami University, Dept. of Microbiology, 2004. / Title from second page of PDF document. Includes bibliographical references (p. 133-140).

Thesis (Ph. D.)(Microbiology)--University of Pretoria, 2007. / Includes bibliographical references. Available on the Internet via the World Wide Web.

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Made available in DSpace on 2014-10-09T12:27:05Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:15Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

For widespread use of biochar in agriculture and horticulture, it must be ensured that application will neither adversely affect soil and plants, nor exceed legislated contaminant concentrations. The most relevant groups of contaminants in biochar are potentially toxic elements (PTEs), polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOC). In this thesis, the concentrations of these groups of contaminants were analysed in 90 different biochars produced by slow pyrolysis. Subsequently, the concentrations were compared to legislation/guideline threshold values and linked to production conditions. The risk these contaminants pose to plant growth was also assessed, to give recommendations on production of safe biochar. PTEs can neither be formed nor destroyed, which means their presence in biochar is predominantly determined by feedstock type. However, significant levels of Cr, Fe and Ni were introduced into biochar from the furnace steel, whilst PTEs with low boiling points, such as As, Cd and Zn, partially evaporated during pyrolysis. PTEs were not responsible for phytotoxic effects observed for PTE-rich biochars despite biochar’s exceedance of available and total PTE threshold values for soil and soil amendments. Although initial tests were promising, the risk that PTE-rich biochars as amendment for soil and growing media pose, needs further investigation. The PAH concentration in biochar was markedly reduced by increasing carrier gas flow rate, and the type of feedstock also influenced the PAH content. However, there was no clear dependence of pyrolysis temperature on PAH concentrations, which was attributed to PAHs being increasingly formed and evaporated at higher pyrolysis temperatures. Ultimately, condensation of pyrolysis vapours and deposition on biochar was identified as the main risk for biochar contamination with PAHs, as this resulted in elevated concentrations of high-risk, higher molecular weight PAHs. Weaknesses in the pyrolysis unit design, such as cold zones, resulted in elevated concentrations of VOCs, as well as PAHs, in biochar. Comparing concentrations and phytotoxic potential of both compound groups, it was concluded that observed toxic effects were much more likely caused by VOCs in biochars containing both contaminants. Overall, formation of VOCs and PAHs cannot be prevented, but their presence in biochar resulting from retention and deposition can be minimised.

Les hydrocarbures aromatiques polycycliques (HAP) sont des polluants ubiquitaires cancérogènes émis dans l’atmosphère sous forme gazeuse ou particulaire et constituent des mélanges complexes issues de sources multiples. Les biomarqueurs d’exposition urinaires sont le plus couramment utilisés pour effectuer la surveillance biologique de l’exposition (SBE) aux HAP, notamment le 1-hydroxypyrène (1-OHP). Sa seule utilisation pour estimer l’exposition aux mélanges de HAP est aujourd’hui controversée. Le 3-hydroxybenzo(a)pyrène (3-OHBaP) est récemment utilisé car il est issu du benzo(a)pyrène (BaP), le seul HAP classé cancérogène certain pour l’homme. Les métabolites monohydroxylés des HAP gazeux les plus abondants sont utilisés pour la SBE. Ce travail a pour objectif de développer et sélectionner un ensemble de biomarqueurs permettant une SBE pertinente et efficace de l’exposition aux HAP tant au niveau professionnel qu’environnemental. Dans un premier temps, les biomarqueurs d’exposition aux HAP cancérogènes (essentiellement contenus dans la phase particulaire) qui sont le 1-OHP et le 3-OHBaP ont été étudiés. La variabilité des mélanges atmosphérique émis, notamment l’abondance relative de la phase gazeuse par rapport à la phase particulaire font que le 1-OHP n’est pas spécifique de l’exposition aux HAP cancérogènes qui sont contenu dans la phase particulaire. En effet, les concentrations urinaires de 1-OHP dépendent des niveaux atmosphériques de pyrène, un HAP non cancérogène émis sous forme gazeuse et particulaire. L’étude de la cinétique d’élimination urinaire du 3-OHBaP a permis de confirmer que le prélèvement d’urine dans le cadre de la SBE en milieu professionnel soit réalisé en fin de poste plus 16h de par la cinétique d’élimination urinaire atypique. Ainsi, il est recommandé de l’effectué en début de poste du dernier jour travaillé. L’étude des modes de correction de la diurèse a confirmé la nécessité de prendre en compte le degré de dilution des urines pour le 1-OHP et le 3-OHBaP et que la correction par la créatinine urinaire est un moyen adapté. La faible abondance urinaire du 3-OHBaP ne permet pas d’effectuer de la SBE dans des milieux professionnels avec de faibles niveaux d’expositions. Dans un deuxième temps, nous avons sélectionné des biomarqueurs pour les faibles expositions professionnelles parmi les différents métabolites monohydroxylés des HAP gazeux. Parmi les métabolites comparés, le 2-hydroxyfluorène et le 2-hydroxyphenanthrène sont ceux qui reflètent au mieux l’exposition professionnelle mais ne sont pas spécifiques de l’exposition aux HAP cancérogènes contenus dans la phase particulaire. Enfin, nous avons développé une méthode de dosage urinaire du (±)trans-anti-BaP-tétraol (Tetraol-BaP) applicable en routine avec un limite de quantification de 0,02 ng/L. Le Tetraol-BaP urinaire est au moins aussi abondant que le 3-OHBaP. Les premières analyses indiquent que le Tetraol-BaP pourrait être un biomarqueur d’exposition intéressant pour estimer le risque cancérogène. En effet, il est plus proche de l’effet toxique que le 3-OHBaP car il est issu des voies de métabolisation toxique du BaP. Ce travail de thèse souligne que l’évaluation de l’exposition aux mélanges de HAP à partir d’un seul métabolite est difficilement interprétable à cause de la variabilité des mélanges émis et propose différents biomarqueurs qui permettraient de caractériser l’exposition à l’échelle du mélange de HAP. / Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous carcinogenic pollutants emitted into the atmosphere in complex mixtures constituted of gaseous PAHs and particulate PAHs. Urinary exposure biomarkers are most commonly used in order to perform human biomonitoring (HB) to PAHs, especially the 1-hydroxypyrene (1-OHP) that is considered as the golden standard. However, its use to characterized mixture exposure is controversial. The 3-hydroxybenzo(a)pyrene (3-OHBaP) is recently used because it is a metabolite of the benzo(a)pyrene (BaP), the only PAH classified as carcinogenic to humans. Monohydroxylated metabolites of the most abundant gaseous PAHs are also used to perform HB. The aim of this thesis was to develop and select a set of exposure biomarkers that enables a relevant and effective HB for both environmental and occupational exposures. Firstly, the 1-OHP and the 3-OHBaP which are used as exposure biomarkers of carcinogenic PAHs (mainly contained in the particulate phase) were studied. The variability of the emitted atmospheric mixtures, especially the relative abundance between the gaseous and the particulate phases complicates the use of the 1-OHP to assess specific carcinogenic PAH exposure. Indeed, 1-OHP urinary concentrations depend on atmospheric pyrene concentrations (a non-carcinogenic PAH) which is present in both phases. The study of urinary elimination kinetic of the 3-OHBaP revealed atypical elimination kinetics (as in rats) and confirmed that sampling time should be done 16 hours after the end of the shift. Thus, sampling is recommended at pre-shift of the last day worked. The study of diuresis adjustment confirmed the need to take into account the urine’s degree of dilution and that urinary creatinine adjustment is suitable to correct concentrations of the 1-OHP and the 3-OHBaP. HB in occupational sectors with low exposure can’t be performed with 3-OHBaP due to its low urinary abundance. Secondly, monohydroxylated metabolites of gaseous PAHs were compared to select relevant biomarkers for low occupational exposure. Among the compared metabolites, the 2-hydroxyfluorene and the 2-hydroxyphenanthrene were proposed because they are those that best reflect occupational exposure. However, these two metabolites were not specific of carcinogenic PAH exposure in the particulate phase. Finally, an analytical method of the (±)trans-anti-BaP-tetraol (Tetraol-BaP) was developed for routine application (the limit of quantification was 0,02ng/L). The first urinary analysis indicated that the Tetraol-BaP is at least as abundant as the 3-OHBaP and that it could be a relevant biomarker to assess carcinogenic risk. Indeed, the Tetraol-BaP is a product of toxic metabolism pathways of the BaP, which allows it to be closer to the toxic effect than the 3-OHBaP. This thesis highlights the difficulty to use a single biomarker to assess PAH mixture exposure due to their important variability and suggests different biomarkers that would characterize mixture PAH exposure.