Alnus glutinosa (Alder) sapling as a phytoremediator for cadmium in contaminated soil of industrial park

Abstract

Heavy metals can contaminate soil through human activities such as mining, waste disposal, excessive use of chemical fertilizers, and fossil fuels. In Iran, uncontrolled urban growth and lack of waste collection systems have led agricultural lands to become receptors of urban and industrial waste, resulting in the contamination of soil with cadmium, which has negative consequences for the environment and health. Alder sapling may have considerable potential for phytoremediation. The soil was placed in plastic pots of 40 cm in diameter with 7 kg air-dried weight soil per pot, spiked with solutions of cadmium chloride [Cd Cl2.H2O] at rates of 0 (control), 50, 100, 150, and 200 mg/kg in a solution. The analyzed data revealed a significant reduction in vegetative growth (plant height, leaf area, chlorophyll, stem diameter growth, stem dry weight, root dry weight, and leaves dry weight). The means were compared to assess the impact of cadmium accumulation on certain biochemical and physiological characteristics. The mean separation was performed using Duncan's Multiple Range test with a p-value ≤0.05. However, there was a simultaneous significant increase in enzymatic activities (peroxidase and catalase) and an increase in proline compared to control plants. The bioconcentration factor of stem, leaves, and roots was under one. The translocation factor (TF) of cadmium was more than 1, and cadmium contents were more localized in roots compared to leaves and stems, minimizing the risk of contamination through leaves. Alnus glutinosa has defense mechanisms against cadmium up to 19.5 mg/kg soil, as the tolerance index for roots and biomass is more than 0.8. Finally, it is a good candidate for research on phytoremediation and phytoextraction.