Slightly polluted sludge can be used in the Netherlands for reconstruction of deep freshwater pools. Potentially, metals from the soil or sludge may enter the surface water in the pools, and the groundwater. The metal concentrations in groundwater near these pools should not increase too much on the long term. RIVM research yields background concentrations in groundwater in order to determine if there are risks for the adjacent groundwater is acceptable.
For this project RIVM investigated to which degree twelve metals occur naturally in groundwater (background concentrations) and which concentrations may cause problems (quality criteria). Most of the metals (antimony, arsenic, barium, cadmium, cobalt, copper, mercury, lead, molybdenum, nickel and zinc) occur naturally in relatively high concentrations in groundwater. In a proposed methodology to derive quality standards for soil and sludge, the groundwater risk limits and background concentrations are used that were also used for deriving so-called threshold values. These threshold values are a specific type of quality standards in groundwater stemming from the European Water Framework Directive. This type of standards includes natural background concentrations.
The applied methodology includes risks for humans (drinking water standards) and the environment (surface water standards). The most stringent one is applied, unless the natural background concentration is higher; in that case the background concentration determines the final value. This turns out to be the case for most metals.
Home/Documents and publications/2017/November/Background concentrations and quality criteria for groundwater: data for antimony, arsenic, barium, cadmium, cobalt, copper, mercury, lead, molybdenum, nickel and zinc