New approaches for low-invasive contaminated site characterization, monitoring and modelling

Helen K. French 0 1 3 4 Matthias Kstner 0 1 3 4 Sjoerd E. A. T. M. van der Zee 0 1 3 4 0 H. K. French Environmental Sciences, Norwegian University of Life Sciences , P.O.Box. 5003, 1432 s, Norway 1 Responsible editor: Philippe Garrigues 2 ) The Norwegian Institute for Agricultural and Environmental Research , BioforskFrederik A Dahlsv. 20, 1430, s, Norway 3 S. E. A. T. M. van der Zee Ecohydrology Soil Physics and Land Management , ESG, Wageningen University , P.O.Box 47, 6700 AA Wageningen, The Netherlands 4 M. Kstner Department of Environmental Biotechnology, Helmholtz-Centre for Environmental Research-UFZ , Permoserstrae 15, D-04318 Leipzig, Germany Previously, conventional techniques for characterizing contaminated sites were often applied with limited strategic planning, resulting in time-consuming and costintensive investigation campaigns, which did not effectively support decision-making. The need for remediation, and the optimal way of doing so in terms of environmental beneficial effect and cost effectiveness, involves problem owners, the authorities, and consultants. Each of these stakeholders has to deal with lack of knowledge and broad-bands of uncertainty regarding subsurface contaminant distribution and processes. The primary cause is the spatiotemporal variability both of the subsurface, its structure and processes such as flow, transport, and biodegradation, and the pollution event. This variability leads to highly erratic patterns of - contaminant concentrations, which cannot be captured experimentally with conventional techniques that provide point measurements. An obvious solution to deal with the invisible subsoil is to develop new ways of monitoring. The need for this innovation was identified by the US EPA and by the European Commission, to be based on step-by-step site characterization strategies, allowing for smart feedback loops (Fig. 1). The identified needs were laid down in a call in the FP 7 program which then acted as the starting point for the overall project approaches. The research presented in this special issue is centred around two European Commission 7th Framework program projects: ModelPROBE - Model-driven Soil Probing, Site Assessment and Evaluation (Grant agreement No. 213161; www.modelprobe.eu ) and to a much higher extent, SoilCAM Soil Contamination: Advanced Integrated Characterisation and Time Lapse Monitoring (Grant agreement No. 212663; www.soilcam.eu ). The research activities were dedicated to both the primary development of emerging methods and, equally important, the improvement and combination of previously developed methods, interdisciplinary efforts for the investigation, and assessment of contaminated sites. Negotiations with the European Commission started in 2008, and led to the establishment of collaboration links between the two projects selected in the competitive call for proposals within Soil Technology topic, in order to make use of the possibly synergistic approaches and to ensure the transfer of knowledge between the projects. The overlap of personnel within the partners of both consortia facilitated the collaboration. The cluster of Soil Technology Research, which is a coalition of research projects funded by the European Commission, Fig. 1 Dynamic work flow to select most appropriate monitoring techniques for a contaminated site was formed mid-way in the project and an overview of these projects can be found here: http://www.ufz.de/ soiltechnologyresearch . The SoilCAM project aimed at improving current methods for monitoring contaminant distribution and biodegradation in the subsurface. Currently, proven technology and methods that are based on invasive sampling of soil, soil water, and gaseous phase are unable to provide a sufficiently accurate database with high enough resolution as well as subsoil volume coverage, resulting in inability to assess bioremediation progress and quantification of the processes involved in such bioremediation at field sites. Two European sites were taken into consideration, i.e. the Trecate site in Italy where there was a crude oil blow out in 1994, and Oslo airport, Norway, where similar to other airports with winter maintenance, large quantities of easily degradable de-icing chemicals are supplied to the soil surface every winter. The common denominator of the two sites was their contamination by mobile degradable compounds in highly permeable subsurface. The SoilCAM project facilitated collaborative work between microbiologist, modellers, geophysicists, and geochemists. Focus on practical field situations and strong communication with stake-holders was also central. The Trecate site was used as a case study site by both the SoilCAM and the ModelPROBE projects. One of the leading ideas of the ModelPROBE project was to evaluate the techniques against the best practise of conventional methods at fully equipped and characterized European reference sites. However, due to the large variety of methods and their specific results, this idea was recognized as being very ambitious, and finally, it turned out that the evaluation goal could only be achieved in a limited set of cases. The simple reason for this lower-than-expected outcome was that techniques which are based on different physical or biogeochemical principles cannot be directly compared in all details. Another basic idea of the project was to develop and apply integrated statistical analysis and modelling at various stages of the approach in order to extract as much information as possible from the raw data. Six years later, we can now state that the majority of the development goals have been achieved. Nevertheless, developments outside of the project also evolve, so the outcomes of several developments are punctual but no longer totally new in the field of site assessment. In order to publish parts of the final outcome of 6 years of research, activities of the EU funded ModelPROBE parts of the results are presented in this special issue and the full details of the outcomes were provided in a handbook (Kstner et al. 2012). The methods presented there are non- to lowinvasive, aim for cost-effectiveness, and comprise advanced geophysical site characterization techniques, new types of vegetation analysis, and improved or new biogeochemical methods, mostly combined with direct push applications. Focusing on a wide potential readership, the book contains general introduction chapters concerning the principles of site assessment combined with an overview about recent methods and detailed application manuals with an annex providing additional information of general relevance. It was published to present the outcomes understandable and available to all potential users: stakeholders, consultants and authorities, and, last but not least, scientists. In this special issue, examples are given of noninvasive technology and methods, and how these can be used for a proper characterization of the contaminated subsurfac (...truncated)