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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