: Location map of the pilot test . The direction of groundwater flow is shown with the blue arrow . Figure S2 . Measured changes in water table depth during the injection of nanoparticles . Time 0 is the starting time of the pre - flushing phase ( same 0 as Figure 6 in the main text ) . Figure S3 . Adsorption isotherms of Zn to Goethite nanoparticles in ultrapure water ( circles ) and groundwater ( diamonds ) as well as to bulk goethite in ultrapure water ( squares ) at pH 7 . Data points and error bars show means and standard deviations of three replicate incubations . The lines depict fittings of the data with Langmuir adsorption isotherms .     