Effect of Arsenic Concentration in Irrigation Water and Soil on the Arsenic Content of Vegetables in Bangladesh

Two pot experiments were conducted to examine the effect of arsenic (As) concentration both in irrigation water and in soil on the As content in vegetables grown in a glass greenhouse. In the first experiment, spinach (Spinacia oleracea), green amaranth (Amaranthus viridis) and gima kalmi (Ipomoea aquatica) were grown in soil containing 10 mgAskg-1, where the irrigation water contained two As levels (0.1 and 0.5 mg L-1). In the second experiment, gima kalmi (Ipomoea aquatica) was grown in As spiked soil at different levels [10 (control), 15, 20, 30, and 50 mgAskg-1 soil] and with irrigation water without As contamination. The As concentration (mg kg-1 DW) and As accumulation (µg plant-1) in the edible part of the plants increased significantly with increasing As concentrations in irrigation water and/or soil. When plants were irrigated with As contaminated water, the As concentration of the edible part exceeded its maximum limit (0.5 mg kg-1) in spinach and green amaranth at 0.5 mg L-1 of As, but gima kalmi had a smaller amount than the other vegetables. Gima kalmi had the characteristics of a lower As accumulation. Therefore, the risk level of As in irrigation water was suggested to be 0.1 mg L-1 for vegetables. When gima kalmi was grown in elevated levels of As contaminated soil, the As concentration of gima kalmi, even being a low As accumulator, exceeded the maximum limit at the level above 20 mgAskg-1 soil. The risk level of As in soil, therefore, was suggested to be 20 mg kg-1. The risk value of As concentration in irrigation water and/or in soil needs to be investigated in detail by using many vegetables and/or soils.