Growth and accumulation of heavy metals in turnip (Brassica rapa) irrigated with different concentrations of treated municipal wastewater

The present study has been carried out by irrigating turnip plants with different concentrations of treated municipal wastewater in order to see the effect on heavy metals accumulation and growth of plants. The turnip plants were watered with normal water and the results compared with results obtained by using treated municipal wastewater. The treatments used were: control (tap water) with 0, 25, 50 and 75% wastewater, and 100% wastewater, in three replications. The results indicated a substantial build-up of heavy metals in turnip irrigated with wastewater. The heavy metals content in the dry matter of the plants increased significantly with increase in wastewater concentration. Analysis of plant samples indicated the maximum accumulation of Fe (1,835 mg/kg in roots and 1,247 mg/kg in leaves) followed by Mn, Zn, Ni, Cu and Cd. The findings of this study regarding daily intake of metals suggest that the consumption of plants grown in wastewater is high, compared to consumption of those grown in tap water, but is nearly free of risks.