Document Type : Original Article
Authors
1
Department of Soil and Water, College of Agriculture (Elshatby), Alexandria University, Alexandria, 21545, Egypt.
2
Department of Soil and Water, College of Agriculture (Elshatby),Alexandria University, Alexandria, 21545, Egypt.
Abstract
Concerns over the possible increase in phytoavailability ofwater treatment residual (WTR)-applied trace metals to plants have been raised. The fate of WTR metals applied to agriculturalsoils is not well understood, particularly in the soils of thearid region. This investigation was conducted to assess the effect of WTR application rates on chemical extractabilityand concentration of Cd, Cu, Ni, and Pb in wheat plants. Five alum rates (0, 10, 20, 30 and 40g kg-1) were applied to three alkaline soils (calcareous, sandy and clayey soils). Wheat (Triticum aestivum) seeds were planted in pots after WTR application. Extractable Cd, Cu, Ni, and Pb (as measured by AB-DTPA, and soil solution) were determined after wheat harvest .No adverse effects on plant growth or excessive amounts of metaluptake were noted after application.The metal concentrationsin wheat plants were lower in the WTR treatments than inthe control and remained well within the values observed foruncontaminated soils. Noneof the trace metals attained toxic concentrations. However, it is crucial to understand the long-term effects that applicationof WTR has on metal availability.Correlations between the concentrations of Cd, Cu, Ni, and Pb in roots ,shoots and panicles of wheat plants and soil metalsextracted by AB- DTPA and soil solution were variable. The strength of the correlationbetween metal concentration in plants and extractable levelsin soil solution was greater for Pb and Cd than Cu and Ni. Copper concentrationsin plants were better predicted by the AB-DTPA extractant. The soil solution better predicted availabilityof Cd (r=0.40 , p < 0.01) and Pb (r=0.60 , p < 0.001) than AB-DTPA.
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