The uptake of nickel and chromium from irrigation water by potatoes, carrots and onions
- Food Chemistry Laboratory, Department of Chemistry, University of Athens, 15771 Athens, Greece
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Heavy metals, in general, can migrate from polluted soil and/or irrigation water to tuber plants, leading, after chronic consumption, to health problems. The scope of this study was to investigate the uptake of chromium and nickel by carrots (Daucus carrota), onions (Allium cepa) and potatoes (Solanum tuberosum) in a greenhouse experiment simulating the open-field irrigation conditions in the two biggest tuber producing regions of Greece (Asopos river in Viotia and Messapia in Evia). The study included cultivation of tubers for a period of approximately 4 months in six irrigation lines, each one provided by a water solution containing different levels of Cr(VI) and Ni(II) ranging from 0 μg/l (control) to 250 μg/l. The soil used was obtained from a certified organic greenhouse. Uptake of Cr was observed in onion leaves between 0 and 10 μg/l water concentrations (+109.2 percent, p=0.006), 0 μg/l and 20 μg/l (+47.5 percent, p=0.006), 0 μg/l and 50 μg/l (+202.8 percent, p=0.006), 0 μg/l and 100 μg/l (+89.9 percent, p=0.028), 0 μg/l and 250 μg/l (+61.3 percent, p=0.009). Uptake of Ni was observed: (a) in onion leaves between 0 and 250 μg/l water concentrations (+90.2 percent, p=0.076), (b) in onion shoots between 0 and 10 μg/l (+39.1 percent, p=0.045), 0 and 250 μg/l (+55 percent, p=0.047) and (c) in potatoes between 0 and 20 μg/l (+28.1 percent, p=0.083). Our results suggest that irrigation water containing Cr and Ni can cross-contaminate onions and potatoes cultivated in a soil never previously polluted, anthropogenically, with heavy metals. No such results were found for carrots.
► Carrots, onions and potatoes were irrigated by water containing Cr(VI) and Ni(II). ► The soil (not polluted) was obtained from an organic greenhouse. ► Uptake of total Cr was observed in onion leaves. ► Uptake of Ni was observed in both onion leaves and shoots and potatoes. ► Polluted irrigation water can cross-contaminate onions and potatoes.