Reducing bioavailability of some heavy metals in a contaminated soil using rice straw compost and water treatment residuals
2009
Mahmoud, E.K. | El Baroudy, A.A.
The present work was carried out to evaluate the effect of rice straw compost, water treatment residuals (WTR), and their mixture (2:1 and 1:1 wet weight) on heavy metals immobilization in contaminated soils and plant growth of canola (Brassica napus). Composite surface soil samples were collected from agricultural farms of El-Mahla El-Kobra area, Gharbia Governorate, Egypt. This farm was continuously irrigated with drainage water that received raw wastewater more than 10 years. The results showed that the applications of WTR, rice compost and their mixture have significantly decreased the concentrations of lead (Pb), cadmium (Cd) and zinc (Zn) extracted from soils by DTPA- method as well as their concentrations in the root and shoot of canola plants grown in the contaminated soil compared with the control. The dry weight of canola plants were also significantly increased with the application WTR and compost treatments compared with the control. The addition of rice compost and WTR mixtures (2:1 or 1:1 wet weight ratio) at level of 10 g dry weight kg. dry soil gave the best reduction in the three heavy metals contents soils and in plant growth compared with other treatments. Thus, the interaction between rice straw compost and WTR had been successfully used to lower the bioavailability and increase the geochemical stability of the Pb, Cd and Zn in the contaminated soil and increasing the yield of canola, and also improve the efficiency of rice straw and WTR disposal.
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