Temporal dynamics of pore water concentrations of Cd, Co, Cu, Ni, and Zn and their controlling factors in a contaminated floodplain soil assessed by undisturbed groundwater lysimeters

•Flooding durations and frequency affect soil metal dynamics in undisturbed lysimeters.•Long term flooding released DOC, Co, Fe, Mn, and Ni to soil solution.•During short term cycles Cd, Cu, Zn, and SO42− tended to be mobilized at high EH.•Dynamics of Co and Ni were controlled mainly by chemistry of Fe, Mn, and DOC.•Dynamics of Cd, Cu, and Zn were governed mainly by DOC and SO42−.

We aimed to assess the dynamics of pore water concentrations of Cd, Co, Cu, Ni, Zn and their controlling factors (EH, pH, DOC, Fe, Mn, and SO42−) in a contaminated floodplain soil under different flood-dry-cycles. Two parallel undisturbed groundwater lysimeters (mean values presented) were used for long term (LT; 94 days) and short term (ST; 21 days) flood-dry-cycles. Reducing conditions under LT lead to low EH and pH, while DOC, Co, Fe, Mn, and Ni increased. Cadmium, Cu, Zn, and SO42− increased under oxidizing conditions during ST. Cobalt and Ni revealed a similar behavior which seem to governed by EH/pH, Mn, Fe, and DOC. Cadmium, Cu, and Zn reveal a similar fate; their dynamics were affected by EH/pH, DOC, and SO42−. Our findings suggest that a release of Cd, Cu, Co, Fe, Mn, Ni, and Zn under different flood-dry-cycles can assumed what might create potential environmental risks in using metal-enriched floodplain soils.

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