GEOC 15 |
| Amir H. Khoshgoftar1, Hossein Shariatmadari2, David R. Parker1, and Suzanne M. Reichman1. (1) Department of Environmental Sciences, University of California, Riverside, Riverside, CA 92521, (2) Department of Soil Science, Isfahan University of Technology, Isfahan, 84154, Iran |
| Both soil salinity and plant genotype may affect bioavailability of Cd and Zn to wheat. A greenhouse experiment with four bread wheat genotypes (Triticum aestivum L. cvs. Rushan, Kavir, Cross, and Falat), one durum wheat (Triticum durum L. cv. Durum), and four salinity levels of irrigation water (0, 60, 120 and 180 mM NaCl) was conducted to study effects of salinity on Cd and Zn speciation in soil solution and their concentrations in wheat shoots. A Typic Calcigypsid soil with the total Cd of 3.2 mg/kg was used. Wheats were seeded in pots and after 45 days, shoot was harvested. Zinc and Cd concentrations were determined in the shoots. After plant harvest, total concentrations of Cd and Zn in soil saturation extracts determined by GFAAS, and speciation was modeled using the MINTEQA2. Total Cd in soil saturation extracts significantly increased with increasing NaCl while total Zn concentration decreased. Cadmium and Zn speciation in soil extracts was affected by salinity treatment, but not by wheat genotype. The major Cd species present in soil solutions were free Cd2+, CaCl+, and CdSO40. The ratio of Cd2+/total-Cd was decreased by NaCl treatments; although free Cd2+ concentration increased with increasing salinity. Increase in NaCl significantly increased concentration of CdCl+ complex in soil extracts. In contrast to Cd, free Zn2+ was the dominant species in all NaCl rates, with lesser amounts of ZnSO40. Increasing soil salinity level resulted in significant increases in shoot Cd concentration of Zn-inefficient wheat genotypes Durum and Kavir, while it decreased shoot Zn concentration in these genotypes. Total, free Cd2+ and CdCl+ concentrations were significantly (P>0.05) related to shoots Cd concentrations of Zn-inefficient wheat genotypes but there was no relationship between shoot Cd concentration in Cross, Rushan, and Falat to total, free Cd2+ or CdCl+ complex concentrations. Free Zn2+ concentrations in soil solution were significantly related to shoots Zn concentrations in Cross, Rushan, and Falat but not in Durum or Kavir. The results show that in saline conditions, the importance of heavy metals speciation for assessing their bioavailability depends on plant genotype and the metal of interest. |
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Chemistry of Metals in Terrestrial and Aquatic Systems
1:25 PM-5:05 PM, Sunday, March 28, 2004 Marriott -- Marquis NE, Oral
Division of Geochemistry |