phytoextraction and estimating optimal time for remediation of cd-contaminated soils by spinach

the so-called phytoextraction in which hyperaccumulator plants are used to remediate the contaminated soils is proven to be an efficient method. the objective of this study was to investigate the capability of spinach for phytoremediation of cadmium from cd-contaminated soils and determine the efficiency extent of spinach for phytoremediation. for this purpose, a randomized block experimental design whit five treatments including 0, 15, 30, 60 and 120 mg cd/ kg soil and three replications was established in the greenhouse. after contamination the soils with different levels of cadmium, spinach seeds were planted. when plants were fully developed, plants were harvested and their cadmium contents in shoot and roots as well as the soil-cadmium were measured. the results indicated that by increasing cd concentration in soil, the major cd accumulation was occurred in the roots rather than shoots. maximum cadmium concentration within the shoots and roots was 73.7 and 75.86 mg/kg soil, respectively. according to spinach ability to absorb high concentration of cadmium in the root zone and its high biomass and capability of cadmium accumulation in shoots, spinach can be used as hyperaccumulator plant to remediate cadmium from cd-contaminated soils. but, according to minimum remediation time and maximum dry matter for the 30 mg cd/ kg soil, maximum cd extracted by shoots in hectare/year was in 30 mg cd/ kg soil. it can be concluded that spinach is a suitable plant for phytoremediation of slightly and to moderately cadmium contaminated soils.