Preliminary investigation of the use of Silybum marianum (L.) Gaertn. as a Cd accumulator in contaminated Mediterranean soils: the relationships among cadmium (Cd) soil fractions and plant Cd content

The plant Silybum marianum (L.) Gaertn. has been used in a preliminary study to investigate its phytoremediation potential in moderately and heavily Cd-polluted Greek soils. For this purpose, a pot experiment was carried out using four soil treatments, two from agricultural and two from urban areas, contaminated with 3 and 30 mg of Cd per kg of soil. The modified Bureau of Community Reference (BCR) fractionation method was used to determine Cd levels in the soil fractions. The water-soluble, available-DTPA extractable, total and pseudo-total concentrations of Cd were also evaluated and attempts to find relationships between Cd soil fractions and Cd levels in the parts of the cultivated plants were made. Significant correlations among Cd soil fractions, Cd plant parts, and soil physicochemical parameters were obtained and discussed. High Cd translocation and accumulation rates were observed mainly in the root and the lower part of the stems, while in flowers and seeds no Cd was detected, leading to the conclusion that the high-value product contained in the seeds maintains its quality and is free of contaminants. The results are satisfactory indicating Silybum marianum (L.) Gaertn. as a promising plant for remediation practices in Cd-contaminated Mediterranean soils, promoting the principles of circular economy.