[Effect of Chelating Agents and Organic Acids on Remediation of Cadmium and Arsenic Complex Contaminated Soil Using Xanthium sibiricum].

In order to improve the phytoextraction efficiency of Xanthium sibiricum on farmland soil that had been contaminated by Cd and As, this study explored the effects of chelating agents and organic acids (EDTA, SAP, CA, and MA) on the extraction of Cd and As heavy metals using X. sibiricum. The results showed that the four different chelating agents and organic acids had little effect on the biomass of the roots, stems, and leaves of X. sibiricum. However, they had different effects on the concentrations and accumulation of Cd and As in various organs of X. sibiricum. Compared with the those in the CK treatment, EDTA, SAP, CA, and MA significantly increased the Cd concentrations in the leaves of X. sibiricum by 44.1%, 32.4%, 41.2%, and 38.2% and the As concentrations in the roots of X. sibiricum by 89.6%, 7.4%, 94.8%, and 61.5%, respectively. The four treatments (EDTA, SAP, CA, and MA) improved the total Cd accumulation of X. sibiricum, with increasing ranges, respectively, of 70.2%, 29.4%, 28.9%, and 33.1%, and the As accumulation increased by 67.0%, 19.6%, 81.9%, and 40.8%, respectively, compared with that of the CK treatment. The four chelating agents and organic acids had different effects on the Cd and As bioconcentration factor and transfer factor of various organs of X. sibiricum. Treatments with EDTA, SAP, CA, and MA resulted in a decrease of 32.7%-38.2% in soil Cd concentrations and a decrease of 14.6%-20.5% in soil As concentrations. These four chelating agents can be used for enhancing the efficiency of extraction Cd and As heavy metals by X. sibiricum.

Combined effect of iron and zinc on micronutrient levels in wheat (Triticum aestivum L.).

A nutrient solution experiment was conducted to investigate the effect of Fe and Zn supply on Fe, Zn, Cu, and Mn concentrations in wheat plants. The experiment used a factorial combination of two Fe levels (0 and 5 mg l(-1)) and three Zn levels (0, 0.1 and 10 mg I(-1)). The supply of Fe (5 mg l(-1)) and Zn (0.1 mg l(-1)) increased plant dry weight and leaf chlorophyll content compared to the Fe or Zn deficient (0 mg 11) treatments. However, excess Zn supply (10 mg l(-1)) reduced plant dry weights and leaf chlorophyll content. Iron supply (5 mg l(-1)) reduced wheat Zn concentrations by 49%, Cu concentrations by 34%, and Mn by 56% respectively. Zinc supply (10 mg l(-1)) reduced wheat Fe concentrations by an average of 8%, but had no significant effect on Cu and Mn concentrations. Stepwise regression analyses indicated that Zn, Cu, and Mn concentrations were negatively correlated with root- and leaf-Fe concentrations, but positively correlated with stem-Fe concentrations. Leaf-Mn concentrations were negatively correlated with root-, stem- and leaf-Zn concentrations.