BGS have just completed a review of emerging contaminants in groundwater. The report includes a review of previous literature and a new assessment of Environment Agency monitoring data for less commonly analysed compounds in groundwater. The Emerging contaminants in groundwater briefing note (PDF) provides a summary of our findings.
Compounds detected in groundwaters of England and Wales include caffeine, nicotine and ibuprofen.
Previously undetected organic micropollutants are being observed in the aqueous environment due to improvements in analytical techniques. These are known as emerging contaminants. Many of these are currently unregulated. Some of these contaminants can have human or ecological health effects and there is a need for better understanding of their fate in environmental systems.
Metaldehyde is an example of a compound which has relatively recently emerged as a groundwater contaminant. Metaldehyde is a selective pesticide used to control slugs. First introduced in 1940, it has been widely used in all sectors (agriculture, horticulture, recreational land and gardens) since the 1970s. Until 2007 there was not a satisfactory method for measuring metaldehyde concentrations in treated water. The development of a new methodology has enabled monitoring for metaldehyde in drinking water supply catchments. Levels in some sources have been close to or above the 0.1 microgram/Litre EU drinking water limit for pesticides.
The types of organic micropollutants which have been found in groundwater worldwide include:
There is a wide variety of sources and pathways which allow these compounds to enter the environment. Sources include agriculture, animal husbandry, industry, waste disposal and urban areas.
Pathways to groundwater include leaching from cultivated areas or animal wastes, effluent discharged from wastewater treatment works to ponds which infiltrate to groundwater or to surface water which then interacts with groundwater.
Many of the compounds are relatively small polar molecules which are not effectively removed by conventional drinking water treatment using activated carbon and can potentially persist in supplied water.
In order to assess the hazards presented by potential organic micropollutants, information on usage, persistence, leachability and a robust sensitive analytical method is required. The UK metaldehyde problem was not originally discovered due to lack of an analytical method and was exacerbated by its recalcitrance in water treatment.
Further information can be found in the Emerging contaminants in groundwater report.
Contact Marianne Stuart for further information.