Bioaccumulation of chromium by Zea mays in wastewater-irrigated soil: An experimental study

摘要

The use of wastewater to irrigate plants is a common in many countries. This study aims to compare thebioaccumulation of chromium in Zea mays that irrigated with wastewater and tap water. The study was carriedout in the field of waste water treatment plant in Birjand for 4 successive months from 16 August 2011 to 16November 2011. 0.5 kg soil and 5 g of the root, stem and leave of Z. mays were collected monthly. Z. mayssamples were digested by cloridric acid and soil samples were digested with nitric acid. Chromiumconcentration in the samples was determined by AA-7000 series of atomic absorption spectrophotometer. Theaverage concentrations of chromium in wastewater and tap water were 12 ppb and 5 ppb respectively. Theconcentration of chromium in soils, which is irrigated with wastewater and tap water, were 26.68 ppm and11.15 ppm respectively. The mean concentration of chromium in roots of Z. mays that is irrigated withwastewater and tap water were 10.28 ppm and 3.92 ppm respectively. The mean concentration of chromium inthe stem of Z. mays which is irrigated with wastewater and tap water were 4.19 ppm and 1.17 ppm respectivelywhile the mean concentration of chromium in leaves of Z. mays which is irrigated with wastewater and tapwater were 2.27ppm and 0.44ppm respectively. The Study showed higher accumulation of chromium in soilsand Z. mays plants which irrigated by wastewater. Cr is immobilized mainly in roots. The ratio of transferfactor of root:leaves is more than ratio of transfer factor of root:stems. It is noticeable that the transfer factor ofCr is decreasing with increase of Cr concentration. The transfer factor between roots and shoots of Z. maysirrigated with wastewater was lower than Z. mays irrigated with tap water. Cr was accumulate and immobilizedmainly in roots than the other parts.