Kilder til BAM-forurening - Miljøstyrelsen

Summary and conclusions
During the past years, an increasing number of pesticide pollutions have been
encountered in Danish water supply wells. In order to investigate this problem
further, the Danish Environmental Protection Agency has initiated the present
project regarding pollution of BAM (2,6-dichlorbenzamide) in water supply
wells. BAM was chosen among the pesticides and their degradation products
as it is regarded as the most problematic pesticide-related compound for the
water supplies.
The purpose of the project is to evaluate the geological conditions under
which pollution with pesticides occur and, more specific, the types of
groundwater wells and well constructions that are especially susceptible to
pesticide pollutions. Furthermore, the aim is to describe the extent of BAMpollution
that has already infiltrated to groundwater aquifers in order to estimate
the duration of the pollution after the herbicides Prefix and Casoron are
no longer used. For this purpose, the transport ways of BAM from contaminant
sources through groundwater aquifers and via leaky wells are investigated.
The project has been divided into the subsequent sections:
- Selection and investigations of waterworks polluted with BAM
- Investigations of well constructions and their significance for BAMpollution
- Investigations and mapping of BAM contaminant sources
- Experimental studies of degradation and sorption of BAM and the parentcompound
dichlobenil
- Description and evaluation of different ways of transporting BAM to the
groundwater aquifer and analysis of the durability of BAM-pollution
based on modelling
- Preparation of guidelines for handling and remediation of BAM-pollution
at waterworks
Data regarding waterworks polluted with BAM were collected from the Danish
counties in order to establish an overview of the extent of the problem and
to point out a number of localities suitable for further investigations. Twelve
waterworks was selected for investigations, as they represent different geographical
and geological conditions in Denmark as well as big and small waterworks
and urban and agricultural catchment areas.
From the investigations knowledge was obtained about BAM contaminant
sources and spreading and leaching of BAM from the sources. Furthermore,
different types of well constructions were examined in order to evaluate their
significance for the groundwater pollution.
Studies of degradation and sorption of dichlobenil and BAM were also part of
the project, since data about BAM in the literature is generally limited. The
experiments were carried out in the laboratory using sediment and groundwater
with different contents of clay and organic matter under varying chemical
conditions of the groundwater.
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