Colloid-related infiltration of trace metals from a river to shallow groundwater

Abstract

The role of colloids for the transport of the trace metals Al, Cd, Cu, Fe, Mn and Zn was investigated in the River Glatt and in a groundwater infiltration zone near Glattfelden, Switzerland. Ultrafiltration techniques were applied to fractionate colloids in the size range 2–450 nm. From the analysis of the above elements, Si and total organic carbon, it was concluded that colloids play a minor role for the transport of trace metals in the river and from the river into the adjacent heterogeneous aquifer. Colloids in the river and in the aquifer show a different element distribution. It was furthermore demonstrated that filtration through 450-nm filters is in general a method adequate for the separation of solids and liquids in natural water systems. The results of this case study may be applied to other shallow heterogeneous aquifers with interstitial porosity. Extended aquifers of this composition are mainly found in Alpine and peri-Alpine locations, but also elsewhere.