Groundwater pollution by volatile halogenated hydrocarbons; sources of pollution and methods to estimate their relevance

An investigation was made of the prevalence of volatile halogenated hydrocrabons in groundwater used for production of drinkingwater in the Netherlands. In some cases concentrations of tri- and perchloroethylene were found at levels higher than 10/ μg/l. In 50% of the groundwatersources these substances were detected at levels than l /μg/l but higher than the detection limit of 0.01 /μg/l, even in well protected areas. Cases with levels higher than 10/μg/l and probably 1/μg/l could be argued to be due to direct (point) discharges to the ground. From data of the Dutch emission inventory system it is calculated that air pollution may be the cause of groundwater-pollution at lower levels.The emission inventory system allows sources of pollution to be classed by level of emission, industrial branche and type of installation, enabling a systematic identification of pollutants and their point sources.