Environmental fate models

The environmental fate of chemicals describes the processes by which chemicals move and are transformed in the environment. Environmental fate processes that should be addressed include: persistence in air, water, and soil; reactivity and degradation; migration in groundwater; removal from effluents by standard waste water treatment methods; and bioaccumulation in aquatic or terrestrial organisms. Environmental fate models are by no means compulsory for managing priority substances. Efficient source control can be done without them, i.e. by reducing emissions gradually and monitoring the environment to track changes. However the environmental fate models are proposed for use for two main reasons: (i) because the quantitative models can improve the understanding of the managed system and (ii) because the models can be used to predict long term impacts of planned actions. Furthermore the residence times of some of the priority substances may be very long (e.g. 50 years for mercury in water column), therefore only monitoring can be not enough to detect if the taken measures are enough to reach the good ecological status. The use of environmental fate models in decision making is not a new concept. They are routinely used in the framework of environmental risk assessment. The output of environmental fate models can be expressed as time series of predicted concentrations in different medium of both indoor and outdoor environments.