[Assessment of toxicity effects for cadmium contamination in soils by means of multi-indexes]

The genetic and eco-toxic effects of Cd (0-10 mg x kg(-1)) were studied with Vicia faba (broad bean) as the test species using meadow brown soil in pot experiments by means of several indexes, such as Vicia faba root tip micronucleus frequency (MCN), mitosis index (MI), and chromosomal aberrations frequency (CAF), antioxidant enzymes superoxide dismutases (SOD), peroxidases (POD), catalase (CAT) and phytohormone abscisic acid (ABA), gibberellic acid (GA3) and zeatin and zeatin riboside (Z&ZR). Results indicated the significant positive dose-response correlations were found between Cd2+ concentrations and the tested indexes (MI, MCN and CAF). Among of them, MCN is the most sensitive, and the MCN frequencies were 1.43-3.22 times higher in Cd treatment soils than that of in the controls. SOD and POD in seedling leaves of broad bean were response to the Cd stress, showing a trend of increase with Cd concentrations initially and then decreased. The CAT response to Cd in soils was opposite to that of SOD and POD. In addition, there were stimulation and inhabitation effects between Cd and ABA, GA3 and Z&ZR in lower and higher Cd concentrations. The highest contents of phytohormone (ABA, GA3 and Z&ZR) were found when Cd was at 2.5 mg x kg(-1), which was 6.6%, 4.0% and 12.6% higher than that in the control, respectively. Our study indicated that all indexes were response to the Cd stress in soils, but the sensitivity of each index was different from each other. All these indexes combined should be more efficiency in the diagnosis of geno-, and eco-toxicity of cadmium in soils.