Baseline concentrations of a substance in groundwater may be defined in several different ways. For present purposes the definition is given as the concentration of a given element, species or chemical substance present in solution which is derived naturally from geological, biological or atmospheric sources.

How good is our water quality?

Groundwater is traditionally looked on as pure water, excellent for drinking as well as feeding rivers and streams - but this perception seems to be changing. The BaSeLiNe programme seeks to answer some of the questions about the current state of European groundwater quality, highlighting changes in recent decades.

BaSeLiNe concept

The BaSeLiNe project aims to establish criteria for defining the natural groundwater quality background (Figure 1) and to develop a standardised Europe-wide approach which may be used in the emerging Water Framework Directive. Such a standard, based on geochemical principles, is needed as a reference to be able to assess quantitatively whether or not anthropogenic pollution is taking place.

Diagram showing how the natural baseline concentration varies spatially in relation to many factors such as geology and temporally with residence time

Existing water quality limits may be breached by entirely natural processes for elements such as fluoride and arsenic.

The project will also focus on timescales influencing the natural processes and the rates at which natural processes are occurring. The extent to which pristine waters are being depleted by contaminated waters moving into the aquifer will also be assessed.