Abstract
Cleaning of pollutants from contaminated soils is a public matter to prevent their access to the food chain. There are many technological methods that are used in the remediation of contaminated soils, but phytoremediation technology is the new trend in the world because it does not cause damage on soil quality and it is an environmentally friendly method. This study aims to use one of the halophytic plants [Atriplex lentiformis (Torr.) S.Wats] to clean a soil contaminated with cadmium (Cd) and lead (Pb). Furthermore, the study aims to explore the mechanism of compost and nitrogen fertilization in the phytoremediation capacity of quail bush plants. A pot experiment was conducted for a year to evaluate the effect of compost and nitrogen fertilization on the efficiency of quail bush [Atriplex lentiformis (Torr.) S.Wats] in removing Cd and Pb from the contaminated soil. The experiment contained four treatments including control without any fertilization (C), compost (COM) at a rate of 10 g kg(-1) soil, nitrogen fertilization (N) at a rate of 150 mg N kg(-1) soil, and combined application of compost and nitrogen (COM + N). The application of N, COM, and COM + N significantly (P < 0.05) enhanced the growth of quail bush plants. The growth of quail bush plants as affected by N and COM treatments can be arranged in the descending order: COM + N > N > COM > C. N, COM, and COM + N increased the Cd in shoots by 40, 33, and 60%, respectively, compared to C, and increased Pb by 17, 7, and 23%. Quail bush plants removed 6.6-14.1% of the total soil Cd and 1.0-1.7% of the total soil Pb. Quail bush removed 11, 10, and 14% of the total soil Cd when the soil was amended with N, COM, and COM + N, respectively, while it removed 1.48, 1.28, and 1.74% of the total Pb as results of the same treatments. The addition of COM and N led to an increase in the synthesis of chlorophyll and a decrease in the synthesis of proline and oxalate which are used to control the osmosis of plant cells. The single addition of N and COM led to significant improvement in alleviating the toxicity stress, while adding them together significantly outperformed the individual additions. The ability of quail bush plants in cleaning the polluted soil increased as a result of nitrogen and compost application due to the increase in the metal concentration in the shoot and the increase in the total plant biomass. The studied quail bush plants have a high ability to withstand Cd and Pb in polluted soil, but their ability to remove Pb from the contaminated soils is weak, while they remove large amounts of Cd. Quail bush plants grown on metal-contaminated soils removed 14% of the total soil Cd during a year when amended with both compost and nitrogen.