Combined chelate induced phytoextraction and in situ soil washing of Cu

摘要

In this study we examined the feasibility of new combined method for remediation of Cu contaminated soil. In a soil columns experiment, we investigated the effect of 5 mmol kg~(-1) soil addition of citric acid, ethylenediamine tetraacetate (EDTA), diethylenetriamine-pentaacetate (DTPA) and EDDS on phytoextraction of Cu from a vineyard soil with 162.6mg kg~(-1) Cu, into the test plant Brassicca rapa var. pekinensis. We also examined the use of a horizontal permeable barrier for reduction of chelate induced Cu leaching and in situ soil washing. The addition of all chelates, except citric acid, enhanced Cu mobility and caused leaching. However, Cu plant uptake did not increase accordingly; the most effective was the EDDS treatment, in which the test plants accumulate only 0.85% of the total chelate mobilized Cu. Plant Cu concentration reached 37.8 +- 1.3 mg kg~(-1) Cu and increased by 3.3-times over the control treatment. The addition of none of the chelates in the concentration range from 5 to 15 mmol kg~(-1) exerted any toxic effect on respiratory soil microorganisms. When EDDS was applied into the columns with horizontal permeable barriers, only 0.53 +- 0.32% of the initial total Cu was leached. 36.7% of Cu was washed from the 18 cm soil layer above the barrier and accumulated in the barrier.