goodwater

WP 3 unravels the limitations for degradation of low pesticide concentrations in aquifers. Pesticides are normally detected only in the concentrations of nM to µM in groundwater aquifers. These concentrations may, however, still exceed the EU threshold limit of 0.1 µg/l for drinking water and thereby present a threat to our drinking water resource. Many studies using both, environmental samples and isolated micro-organisms, have suggested the occurrence of threshold concentrations below which no extensive degradation occurs. At this time, however, there is still a large gap in our knowledge on the importance of threshold concentrations for contaminant degradation in aquifers. The research will focus on phenoxy acid and phenylurea herbicides, both well-known groups of European groundwater contaminants. Fellow 3 (SV: S.R. Sørensen/ J. Aamand, GEUS) will investigate threshold concentrations for (i) catabolic gene expression (ii) shifts between different degradation processes and (iii) proliferation of pesticide-degrading populations. Techniques will include 14C-tracer experiments, antibody- and RT-PCR based methods, and CSIA, in collaboration with fellow 2 (GEUS) and fellow 7 (HMGU). Interactions between different microorganisms charring degradation pathways will be studied in model aquifer biofilms, taking the spatial distribution of the bacteria into account. This research will be carried out in collaboration with fellow 2 (GEUS) and fellow 13 (K.U.Leuven) during a 2-month visit at K.U.Leuven (September-October 2009). The results will be mathematically modelled to determine the effects of consortial degradation and threshold concentrations on contaminant transport in aquifers in collaboration with ER fellow 11 (HMGU). Research fellow 3 will also provide specific degrader organisms to be used by fellow 15 (DTU). The fellow will be co-supervised by DHI (C. Jørgensen) who will also train the fellow in legislation related to approval of new pesticides. In addition, KE will provide access to drinking water wells and monitoring data to be used by both, fellow 2 and 3.