Improvement of certain heavy elements status in salt-affected soil irrigated with low quality water

Abstract

Wastewater, mostly without pretreatment, has been used for irrigation in some locations such as Bahr El-Baqar drain area in El-Hosinia plain, Sharkia Governorate. A survey study including wastewater, soil and plant was carried out in El-Hosinia area to identify such problem. Moreover, certain amendments i.e. gypsum, byproduct rich in Ca from citric acid company (BCC) and citric acid, were applied to contaminated studied soil columns experiment to assess their effects on the distribution of Fe and Mn among the different soil fractions as well as the bioavailability of certain heavy elements, consequently their contents in cotton seeds. The obtained results showed that Bahr El-Baqar drain water was contaminated with Fe, Mn, Zn, Cu, Pb, Ni, Co and Cd which were higher than exceeded the permissible limits, while roots of alfalfa and rice plants grown on such soil contained Fe and Mn, as well as plants shoots contained only Fe, above the normal range. Soil Fe fractions were in the following order: residual fraction> reducible bound> organically bound> carbonate fraction> exchangeable Fe, but Mn fractions were in the following order: reducible bound> residual fraction> carbonate fraction> organically bound> exchangeable Mn. The applied treatments increased the downward movement of Fe and Mn as indicated by increasing their concentrations with increasing soil depth and this point out to the possibility of reducing such heavy elements concentration at plant root zone. Gypsum amendment was superior in reducing the chemically available Fe and Mn followed by byproduct (BCC). Heavy elements content in seeds of cotton plants cultivated in soil columns were within the sufficient range.