Water managers can now make a more accurate assessment of whether they are complying with the standard for heavy metals in surface water with the new computer model developed by Deltares: PNEC.pro.
This model takes the local water chemistry into account, making it possible to calculate local standards for permitted concentrations of heavy metals and precluding the need to implement the generic standard from the Water Framework Directive (WFD), which is usually conservative.
The model is based on the research conducted by Anja Verschoor for Deltares as part of her doctoral thesis ‘The power of biotic ligand models: Site-specific impact of metals on aquatic communities’. Her doctoral award ceremony will be on 4 December at Leiden University.
Model targets zinc, copper and nickel
PNEC.pro looks at concentrations of zinc, copper and nickel because these metals often exceed the permitted levels set by the Water Framework Directive (WFD).
Jos Vink, a researcher with Deltares who is closely involved with the development of the new model: ‘ The exceedances are caused by the fact that the WFD standard often fails to take location-specific conditions into account, such as acidity or the presence of organic compounds or calcium. These factors affect the impact that heavy metals such as zinc, copper and nickel have on aquatic flora and fauna. PNEC.pro does take specific conditions into account, making it possible to calculate the right permitted level in a specific location. The WFD allows more refined standards but a practically applicable model has not been available until now.’
PNEC.pro available free of charge
The new model was developed and tested on the basis of field trials with the De Dommel water authority, where people were very enthusiastic. PNEC.pro is available from Deltares free of charge. It can be downloaded from www.pnec-pro.com, which also provides more background information about the model and the issues it addresses.
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Press Release, November 28, 2013