Response of the heavy metals lead, cadmium, copper and zinc to different exfiltration and infiltration conditions in the case of bank filtration

In a test region on the Neckar river, the dependence on local conditions of the heavy metal distribution in the gravel aquifer was established. Selective control of the drinking water wells of the test field helped to change the hydraulic conditions and to establish their effects on trace element behaviour. An analysis of the solid phase helped to differentiate between the different banding types of the heavy metals. The establishment of quasisteady exfiltration and infiltration conditions with 'constant' local conditions depended on the kinetics of the geo-chemical reactions of individual parameters. Of all the trace metals, copper showed the most pronounced differences in the reaction to changes in the local situation, while zinc reacted the least. Lead was mobilized above average, especially in the 7-month exfiltration phase. Cadmium was detected in ground-water especially in the exfiltration phases in the interface regime between the oxidic and postoxidic environments. The column experiments described here are another clear proof of the fact that organic substances, as well as iron and manganese compounds, influence the transport characteristics of the trace elements lead, cadmium, copper, and zinc. (orig./BBR)