Comparison of cadmium and zinc accumulation in onion and radish irrigated with municipal wastewater

This study has investigated the accumulation of cadmium (Cd) and zinc (Zn) in onion (Allium cepa) and radish (Raphanus sativus) grown in municipal wastewater irrigated pots. The study was aimed at determining the phytoaccumulation of heavy metals in order to identify health risks associated with wastewater irrigation. The root tissues of both the plants were subjected to metal analysis. Cd accumulation was significantly higher (P<0.001) in onion plants (1.87 mg kg–1) as compared to radish (1.33 mg kg–1). Onion plants also had significantly higher concentration (P<0.0001) of Zn (3.93 mg kg–1) than radish (1.29 mg kg–1). The accumulation of Cd and Zn in higher concentrations in monocotyledon plants may be a matter of concern since onion is used more extensively for edible purposes than radish, a dicot plant. The study reveals that municipal wastewater irrigation may pose risk of food chain contamination, especially where fresh water availability is a limiting factor.