New approaches of groundwater management using contaminant mass flux measurement

The monitoring and management of contaminants in soil and groundwater is a challenge, especially with respect to volatile organic hydrocarbons (VOCs) that are present in up to 60% of European industrially-contaminated land. Deep and irregularly shaped dense non-aqueous phase liquid (DNAPL) sources typically produce widespread and dynamic plume zones that are difficult to monitor and difficult to remediate. In this context, the measurement and interpretation of contaminant mass fluxes instead of concentrations is gaining importance.;The research presented in this thesis aims to contribute to the more integrated and more controlled management of groundwater pollution in the near future.;To achieve this, three key components have been investigated and/or developed: I) Contaminant mass flux: evaluation of the contaminant mass flux measurement prospects of passive sampling devices in groundwater; II) Contaminant mass discharge: evaluatior of corresponding contaminant mass discharge estimation methods; III) Risk-based groundwater management: development of a clear flux- and risk-based plume management strategy and a regulatory approach.;The potential use of passive sampling devices for the determination of groundwater related VOC mass fluxes has been examined through a literature review and a lab and field experiment. Finally, one selected passive sampling device has been subjected to extensive lab and field research: the Passive Flux Meter (PFM). The PFM provides simultaneous in situ point measurements of a time-averaged contaminant mass flux and water flux. The in situ time-integrating monitoring of the contaminant mass flux, and therefore indirectly also the monitoring of the risk of soil and groundwater contamination to a receptor, is unique and a very promising technique in contaminated soil and groundwater management.;The proposed risk-based groundwater management approach, the Contaminant Mass Flux (CMF) approach, yields a clear methodology on a flux-based groundwater risk management and can be the basis for a practical guidance on this. The CMF approach has been illustrated with an example of the application at a field site in Flanders (Belgium). The results of this PhD research are valuable for authorities, consultancies and researchers.