Using pre-screening methods for an effective and reliable site characterization at megasites

摘要

This paper illustrates the usefulness of prescreeningmethods for an effective characterization of pollutedsites. We applied a sequence of site characterization methodsto a former Soviet military airbase with likely fuel and benzene,toluene, ethylbenzene, and xylene (BTEX) contaminationin shallow groundwater and subsoil. The methods were (i)phytoscreening with tree cores; (ii) soil gas measurements forCH4, O2, and photoionization detector (PID); (iii) direct-pushwith membrane interface probe (MIP) and laser-induced fluorescence(LIF) sensors; (iv) direct-push sampling; and (v)sampling from soil and from groundwater monitoring wells.Phytoscreening and soil gas measurements are rapid and inexpensivepre-screening methods. Both indicated subsurfacepollution and hot spots successfully. The direct-push sensorsyielded 3D information about the extension and the volume ofthe subsurface plume. This study also expanded the applicabilityof tree coring to BTEX compounds and tested the use ofhigh-resolution direct-push sensors for light hydrocarbons.Comparison of screening results to results from conventionalsoil and groundwater sampling yielded in most cases high rankcorrelation and confirmed the findings. The large-scale applicationof non- or low-invasive pre-screening can be of help indirecting and focusing the subsequent, more expensive investigationmethods. The rapid pre-screening methods also yieldeduseful information about potential remediation methods.Overall, we see several benefits of a stepwise screening and sitecharacterization scheme, which we propose in conclusion.