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Pesticides and Groundwater, Annual Report 1998. Download INTRODUCTION the groundwater group has now been working for 2½ years within the danish environmental research programme, ´pesticides and groundwater´ (smp 96). the time has been characterised by increased findings of pesticides in danish groundwater and, due to that, an intense public debate in both the parliament and in public media. pesticides and groundwater constitute a very complex field of research, mainly due to the chemistry of the compounds and the fact that pesticides with new chemistries are introduced all the time by the agrochemical industry. in denmark, it has been decided to establish protection zones where pesticide use are either banned or restricted in certain vulnerable catchment areas, despite that our knowledge of e.g. transport mechanisms, sorption, and degradation is still too limited to accurately define the size of such zones needed to protect the drinking water resource. although such problem areas may appear too complex to expect final and definite answers of the present efforts, the ongoing research will make a strong contribution to the many questions related to transport and fate of pesticides in aquifers.
the research carried out by the groundwater group generally follows the approved programme. within project 1, "preferential transport of pesticides to groundwater" all field sites have been established and studies of pesticide transport are in progress. a thorough characterisation of the clayey tills has been carried out and it is concluded that preferential transport in macropores predominantly controls the migration of pesticides to the groundwater. heterogeneous structures were also observed at sandy soils and the importance of these structures for transport and degradation of pesticides is now being investigated. within project 2, "fate of pesticides in aquifers" sorption and degradation of several pesticides in aquifers and wetlands are studied. one pesticide field injection study has been finished and another is in progress. until now microbial degradation of the pesticides was only seen at aerobic aquifer conditions and compared to topsoil the degradation proceeds much more slowly. however, due to the long pesticide resistance time in aquifers microbial degradation is expected to control the fate of these compounds at least at aerobic conditions. pesticide degrading pure cultures of bacteria have been isolated and used in studies of factors limiting degradation in aquifers. within project 3, "large-scale modelling of pesticide transport" appropriate structures for both the catchment and regional models have been identified. furthermore, field sites to be used for validation of models have been selected, and programmes for data collection and field investigations are in progress.
an evaluation of the groundwater group activities was initiated at a meeting at sonnerupgård gods, september 11-12. at the meeting the content and basic ideas of each project were discussed with a scientific evaluation panel headed by prof. poul harremoës, and comprising prof. joseph m. suflita, prof. wolfgang kinzelbach and docent john stenström. in general, the outcome of the meeting was positive, although the panel emphasised some weaknesses e.g. in defining the pesticide input function needed for modelling pesticide transport in soil and groundwater (project 3).
based on comments from the evaluation panel the project board decided to distribute most of the reserved funds to specific projects of the programme. since the research has to be finished by the end of next year, money was allocated only to projects supporting ongoing activities. the following activities were funded (in dkk) : (1) supplementary studies of pesticide transport at the havdrup test site (200,000.-), (2) classification of fractures in clayey tills (150,000.-), (3) quantification of matrix and fracture fluxes trough a fractured till (100,000.-), (4) cfc-age dating of groundwater from the field sites (100,000.-), (5) supplementary tracer tests to identify pathways of pesticide transport in the unsaturated zone (50,000.-), (6) an additional pesticide field injection study at the vejen test site (470,000.-) (7) identification of bottlenecks for pesticide degradation in aquifers using pure cultures of pesticide degrading bacteria (380,000.-), (8) tracer test at the volby bæk wetlands (60,000.-), (9) collection of data to be used for validation of the catchment model (260,000.-), (10) mapping of redox conditions at the eggeslevmagle test site (40,000.-), and (11) purchase of radiolabelled mecoprop (100,000.-).
until now the groundwater group research activities within pesticides and groundwater have resulted in 11 international articles in peer reviewed journals, 28 contributions to conferences, workshops, and symposia, and several national articles. at present 9 ph.d. students are financed by the programme.
The Groundwater Group wishes to transfer approx. DKK 2,500,000.- to 1999. The main reasons for this transfer are the same as described in the annual report 1997, namely at the initial phase of the project period it was difficult to find qualified Ph.D. students and a general delay occurred in the selection of field sites. It should be mentioned that the amount of money to be transferred to 1999 is much smaller than the money transferred from 1997 to 1998. The Project Board of the Groundwater Group expects that most of the money originally allocated to the programme will be used during 1999, except for what is needed to finish the late initiated Ph.D. studies.
Download "Pesticides and Groundwater, Annual Report 1998"
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