Training Area I: Bottlenecks of contaminant degradation in groundwater
WP 2 examines the role of spatial heterogeneity as a limiting factor for pesticide biodegradation in contaminated aquifers. There is evidence suggesting that spatial isolation of microorganisms and the heterogeneous distribution of resources (e.g. inorganic nutrients, carbon sources and organic C) are key elements in controlling population dynamics, microbial community diversity and structure. We hypothesize that the fate of organic pollutants in aquifers is controlled by the heterogeneous sediment environment including the heterogeneous distribution of resources. The main aim of fellow 2 (SV: J. Aamand/ S.R. Sørensen, GEUS) will be to address how aquifer heterogeneity affects overall degradation rates, accumulation of metabolites and transport of contaminants to e.g. drinking water wells. The research will focus on dichlobenil/BAM and phenoxy acid herbicides, which are major groundwater contaminants. The fellow will study whether potential bottlenecks of degradation may be created by heterogeneities in the distribution of degrader organisms and contaminant concentrations. The heterogeneity will be studied at different scales: from micro-scale the size of few millimetres to the aquifer scale. Heterogeneities in transition zones between different redox-environments will be studied in collaboration with fellow 15 (DTU). Pesticide metabolism will be investigated using micro-scale degradation assays, micro-scale chemical and immunochemical analysis and advanced monitoring of degrader populations in collaboration with fellow 3 (GEUS). Fellow 2 will be trained in the use of DNA and RNA-SIP (fellow 8, HMGU) as well as CSIA (fellow 7, HMGU) during a 3-month visit to HMGU (January-March 2009). These techniques will be used to determine the spatial distribution of degrader organisms and their activity. Effects of spatial distributions of microorganisms and resources will be studied using model aquifer biofilms. The model biofilms will be set up in collaboration with fellow 13 (K.U.Leuven) during a 2-month visit at K.U.Leuven (September-October 2009). Mathematical modelling of contaminant transport will be carried out in collaboration with the ER fellow 11 (HMGU). Fellow 2 will be trained in groundwater resource management and legislation by Copenhagen Energy (KE) (G. Brandt) who will also co-supervise the fellow through at least 3 meetings during the project period. In addition, KE will provide access to drinking water wells and monitoring data to be used by both, fellow 2 and 3.