Phytoremediation has been promoted as a promising tool to clean soils without having to remove large amounts of soil from a site or to invest in expensive technical equipment. However, the extent to which phytoremediation currently is applicable on the field scale remains largely unclear due to the fact that the majority of studies have been performed on a very small scale only. Also, the side effects of chelate-enhanced phytoremediation under field conditions have not been examined yet. Addition of EDGA (glycolether diamine tetra acetic acid, C_(14)H_(24)N_2O_(10)) to a moderately Cd- and Zn-polluted sandy soil resulted in a marked increase in metal solubility in both laboratory and lysimeter studies, which resulted in an increase in metal uptake by the three crops included in the study as well. Citric acid, on the other hand, did not affect metal solubility nor uptake, which was due to microbial degradation of citric acid. Under field conditions, additions of non-degradable EDGA resulted in serious leaching losses of Cd, Cu, Pb, and Zn. From this it is concluded that chelate-enhanced phytoremediation can be applied only if the drainage water can be collected and cleaned. Otherwise, metal mobilization due to chelate addition will solve one problem - pollution of the soil - and create another - pollution of groundwater -which is perhaps even more difficult to treat.
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