Publikationsserver der RWTH Aachen University
Heterocyclic compounds in tar oil contaminated groundwater : occurence, fate, and indications for natural attenuation
Abstract
dc:descriptionThe aim of this thesis was to assess the relevance of NSO-heterocycles in the groundwater of three tar oil contaminated sites and furthermore to search for indications for the presence of natural attenuation processes including the group of NSO-heterocycles. Therefore, as a first step, analytical methods were developed. In addition to an existing HPLC-DAD method for the detection of a huge number of NSO- heterocycles, an LC-MS-MS method for a selective and sensitive analysis of N- heterocycles as well as a Headspace-GC-MS method for the analysis of volatile analogs was performed. The site-directed survey allowed the long distance comparison of the concentration of various NSO-heterocycles. Differences in distribution and decrease over the field sites using mass loads were discussed in context to compounds physicochemical characteristics to work out indications for microbial natural attenuation processes of NSO-heterocycles. N-heterocycles like quinoline compounds were found in high concentrations near the source of contamination at all of the three sites. In comparison to S- and O-heterocycles a higher decrease of quinoline compounds with the flow line of groundwater was observed. Methylsubstituted S- and O-heterocycles were found of special relevance downstream the source. A comparison of these heterocycles with EPA-PAHs, especially with acenaphthene a persistent PAH, shows the necessity to consider these compounds. To cover indications of biodegradation, degradation studies using contaminated groundwater were performed. In addition, the microbial activity in an on-site column filled with aquifer material and contaminated groundwater was analysed. A high-resolution well provided an insight into the micro distance comparison of the concentration of various contaminants as well as electron acceptors such as sulfate across the fringe and centre zones and therefore a comparison of different contaminants plumes. Indications for the presence of microbial degradation in the plumes fringe could be worked out. Altogether, data of contaminants distribution from groundwater analyses, of decrease in concentration in degradation experiments and of the plumes width in the high-resolution well were critically interpreted. The decrease in concentration along the plumes together with the results from the more artificial degradation experiments and the high-resolution well led to the general conclusion that biodegradative processes towards hetero- and homocycles are present in the aquifers. Especially O- and S-heterocycles as well as their methylated analogs were found of high relevance downstream the source of contamination, and showed persistence in the degradation experiments. Secondly, the possibility to use the formation of anaerobic degradation products for the demonstration of biodegradation at the field sites was investigated. The aim was to explore whether hydroxylated quinoline and isoquinoline or methylquinoline found in high concentrations in the groundwaters can be used as indicator for natural attenuation. Therefore, the degradative potential of aquifer material towards quinoline compounds in single, and the formation of metabolites was studied. Hydroxylated and hydrogenated metabolites were formed in high amounts. However, the analyses of seven tar products showed that 2(1H)-quinolinone, 3,4-dihydro-2(1H)-quinolinone, 1(2H)-isoquinolinone and 3,4-dihydro-1(2H)-isoquinolinone are primary constituents. Therefore, the detection of these in groundwater was found to be a non-sufficient indicator for the occurrence of natural attenuation processes. Instead, the ratio of hydroxylated to parent compound (R-metabolite) was tested as a useful indicator. Parameters which may influence this ratio were studied: Sorption was found to influence both partners of R-metabolite in a minor extend. The main parameter influencing the ratio was found in differences in partitioning of parent and hydroxylated compound between the tar oil and water phase. With respect to the observed partition coefficient between tar oil and water of 3.5 for quinoline and isoquinoline and 0.3 for 2(1H)-quinolinone and 1(2H)-isoquinolinone, the ratio in groundwater would be approximately 10 times higher than the ratio in tar oil. When paying attention to these parameters and including a sufficient threshold factor, in a broad number of groundwater samples the highest ratio found in tar oils was clearly exceeded. This indicates that biological processes take place in the aquifer of the three sites and R-metabolite is an applicable indicator for the presence of natural attenuation. The R-metabolite concept was found to be feasible for the couples 2(1H)-quinolinone/quinoline, 3,4-dihydro-2(1H)-quinolinone/quinoline, 1(2H)-isoquinolinone/isoquinoline, and also for methylsubstituted quinolines and their hydroxylated metabolites.
Degree
thesis:*- Grantor dc:publisher
- Publikationsserver der RWTH Aachen University
- Year dc:date
- 2008
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Reineke, Anne-Kirsten
- Contributors dc:contributor
-
- Hollender, Juliane
Subjects
dc:subject × 10Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- eng