Tesis doctoral de Manuela Peschka
Organic pollutants in the aquatic environment are affected by biotic and abiotic factors which can causa transformation and degradation. Such processes widen the spectrum of the total amount of organic pollutants. Further, their structure remains unknown, if not throughly investigated by means of adequate envirnmental simulating degradation tests and appropriate analytical technology. several compounds have been selected to investigate their persistence potential. The selection was based on (i) their classification as a priority substance and (ii) with respect to the time frame of their application. Barbiturates (start of application approximately 100 years ago until 1970s) and clotrimazole (ospar list; still applied since 1970s) have been chosen from the class of pharmaceuticals. The pesticides bentazone, atrazine (including two metabolites) and acetochior have been selected. Bentazone was revealed to be persistent towards microbial attack and is still applied since the late 1960s. Atrazine is included on the list of priority substances of the water framework directive (wfd) whereas acetochlor serves as a substitutte after atrazines ban in the european union in 2004 (application for approximately 60 years). Partially fluorinated surfactants have been investigated for their potential to be completely degraded, i.E. Mineralised by ubiquitous microorganisms. They are prototypes and potential substitutes for the harmful perfluiorinated surfactants such as perfluorooctanessulfonate (pfos, ospar list). the selected compunds have been subjected to different degradation tests and have been monitored in the envirnment. The carried out experiments are complementary to existing studies described in literature. For aerobic degradation a fixed bed bioreactor (fbbr) and a bottle test have been employed. In order to test the abiotic degradability, a photodegration test (suntest) or hydrolysis experiments were carried out. If the persistence potential could be confirmed or degradates could be successfully identifie, environmental samples were screened for the parent compounds or the degradate in order to study their occurrence and to verify the test results. for the purpose of monitoring and structure elucidation of unknowns, gas and liquid chromatography coupled to mass sepctrometry was employed. The barbituirates were found to be persistent in the performed degradation tests. Hence, they were detected in the aquatic environment even years after their peak of consumption. Further, they were found to be still present in groundwater. The obtained results impressively demostrate the drawbacks of missing environmental legistaltions and the application of persistent compounds. On the other hand, clotrimazole was classified to be persistent by the ospar commission. In a carried bottle test clotrimazole was found to be primary biodegradable. After hydroxylation, it was presumably conjugated with an amino acid. Envirnmental concentrations of clotrimazole were found to be at the low ng l range. Since the conversion of clotrimazole was not complete in the bottle test, the metabolite concentration would be expected to be even lower. grounwater of the bréville catchment (france) is still contaminated with atrazine though its application was stopped in 2002. The soil was expected to act as a reservoir for atriazine. Arfter implementation of a sensitive analytical method and analysis of soil samples with gc-ms, it was refvealed that atrazine is solely present in the upper soil. The concentration of atrazine and acetochlor decrease proportional with depth. Both pesticides are presumably bound to organic matter. Dealdylates metabolites have not been detected in the soil but in groundwater.. the partially fluorinated surfactants have been exposed to biodegradation tests. They have been developed with respect to biodegreadability which was realised by taking advantage of the inherent biodegradability of n-alkylsulfonates and the instability of certain fluorinated compounds like trifoluoromethanol. Both have been connected to obtain the prototypes of biodegradable fluorinated surfactants. The aim was the release and decay of instable fluorinated compound after degradation of the n-alkysulfonates resulting in complete mineralization. Two surfactants out of 12 were found to be completely mineralised. Others formed dead-end metabolites or did not degrade during the performe test. It was possible to distinguish between two major degradation pathways: (i) a desulfonation and subseqí¼ent oxidation and degradation of the alkyl chain being predominant and (ii) an insertion of oxygen with a subsequen cleavage and degradation of the molecule. Degradation of the surfactants was dependent on the chain length and on the fluorinated rest.
Datos académicos de la tesis doctoral «Persistence evaluation of selected priority and emerging contaminants«
- Título de la tesis: Persistence evaluation of selected priority and emerging contaminants
- Autor: Manuela Peschka
- Universidad: Barcelona
- Fecha de lectura de la tesis: 23/03/2009
Dirección y tribunal
- Director de la tesis
- Damia Barcelo Culleres
- Tribunal
- Presidente del tribunal: johannes Barth
- mira Petrovic (vocal)
- (vocal)
- (vocal)
