Effect of brackish water irrigation on cadmium migration in a soil-maize system

The effects of irrigation with high-salinity water on phytoremediation efficiency have not yet been fully investigated. Here, a pot experiment was conducted to explore the effects of irrigation with three water resources (T1: deionized water, T2: natural brackish water, T3: NaCl salt water with salinity equal to that of natural brackish water) on cadmium (Cd) uptake by maize grown under different Cd pollution conditions (exogenous Cd: 0, 5, 10, 15 mg kg − 1 ). Salt stress and cation antagonism caused by brackish water both affected maize plant growth and Cd uptake. When exogenous Cd was added to the soil at 5, 10, and 15 mg kg − 1 , Cd accumulated in maize shoots at 5.55, 7.08, and 5.71 µg plant –1 in the T1 treatment, 4.08, 3.04, and 5.38 µg plant –1 in the T2 treatment, and 2.48, 3.44, and 5.33 µg plant –1 in the T3 treatment, respectively. Shoot Cd accumulation was significantly lower for treatments T2 and T3 than T1 at exogenous soil Cd concentrations of 5 and 10 mg kg − 1 , whereas no significant differences were observed among treatments T1, T2, and T3 when the exogenous Cd concentration was 15 mg kg − 1 . These findings indicate that there was decreased phytoremediation efficiency in response to both salt stress and cation antagonism caused by brackish water when there were low soil Cd concentrations, but that this effect was negligible under high Cd pollution. Accordingly, brackish water irrigation can be considered during phytoremediation of soils contaminated with high levels of Cd to save freshwater resources.