Investigation of Optimal Operational Conditions in Phytoremediation of Soils Contaminated with the Heavy Metal Zinc by Spinaciaoleracea L. Plant

The gradual increase in the concentration of heavy metals in soil poses serious hazards to human health and other living organisms. Accordingly, the current study aimed to assess the optimal operating conditions of phytoremediation of soils contaminated with zinc by Spinaciaoleracea L. plant.

In this experimental study, different concentrations of zinc chloride (0, 100, 250, 500, 1000, 1500, and 2000 μM) were applied to Spinaciaoleracea L. plant in the four-leaf stage in hydroponic culture medium for four weeks. Thereafter, the growth and physiologic parameters, as well as the amount of the zinc accumulated on the root and aerial organs of the plants were measured. The experiment was carried out with a completely randomized design at three treatment levels.

In Spinaciaoleracea L. plant, the increase in the concentration of zinc chloride in nutrient solutions led to a significant decrease in the biomass of the root and aerial part, chlorophyll a, total chlorophyll, and leaf surface, with the highest reduction being related to the treatment with 2000 μM zinc chloride. In the aerial part of Spinaciaoleracea L.plant, proline accumulation increased significantly with elevated zinc concentration. This being the case, the zinc accumulation rate in treatment with 2000 μM zinc was 2.57 times higher than the control treatment. In addition, the zinc accumulation rate in treatment with 2000 mM was measured at 324.02 and 355.46 mg/kg of dry weight in aerial and root sections, respectively.

As evidenced by the obtained results, Spinaciaoleracea L. plant can be used to refine zinc-contaminated soil since it is resistant to low concentrations of zinc in terms of indices of growth, chlorophyll a, total chlorophyll, carbohydrates, and leaf surface. The other underlying rationales include the relatively short growth period and high performance of this plant