Webinar: Geochemical leaching from the subsurface (Water Quality Knowledge Impulse)

Date: Tuesday, 29 March 2022
Time: 13.00 – 14.00
Online on Teams

Due to anthropogenic activities, our clean, slow-flowing groundwater is being contaminated at greater and greater depths with numerous different substances. This ‘greying’ process is an urgent problem, for example in terms of drinking water supplies. The adverse effects of human interventions on groundwater quality are not direct. The Groundwater theme of the Water Quality Knowledge Impulse (KIWK) is investigating three barriers that delay and mitigate these effects:

• Geohydrological protection by poorly permeable layers slows down the spread of substances in the vertical direction.
• Subsurface biological protection by organisms in the unsaturated subsurface and topsoil that can degrade pollutants.
• Geochemical protection through the presence of reactive minerals and sedimentary organic matter (SOM) in the subsurface that allows contaminants to be bound or biochemically degraded.

In this webinar, Falco van Driel (WML) and Bas van der Grift (KWR) will present the results of detailed research into geochemical protection around the Grubbenvorst drinking water extraction site. Experiments have been conducted with a Micro-Oxymax respirometer to identify the reactive elements in the soil and how fast they react. The results were used to make long-term predictions of the leaching and buffering capacity of the subsurface around the extraction site. In addition, country-wide maps were produced of the reactive soil constituents in the Dutch subsurface and the related buffer reactions.

The research was conducted by KWR in collaboration with Deltares, TNO, RIVM and Wageningen University and Research Centre and it is being conducted as part of the KIWK, Groundwater theme. In the KIWK, the national government, provincial authorities, water authorities, drinking water companies and research institutes are working together on a better understanding of the quality of groundwater and surface water, and the factors which influence that quality. This will allow water management authorities to take the appropriate measures to improve water quality and biodiversity.

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