Abstract:

The biogeochemical behaviors of Cr in soil-plant system and their impacts that high concentration of Cr in ecological environment have received a wide attention. This study takes Zhuzhou City in Hunan Province as the study area. Totally, 490 surface soil samples and 60 pairs of rice grains and rhizosphere soil samples were collected. The concentrations of Cr in the soil and rice grains were analyzed and thereafter the pollution degree of Cr in the soil was evaluated. At the end, we ide.pngied the influencing factors of Cr bio-concentration factor (BCF) of rice grains and established the prediction model BCF of Cr in rice grains. The Cr concentrations of the surface soils range from 48.50 to 240.60 mg/kg, with an average value of 91.45 mg/kg. Comparing with the background values in soil of nationwide and Hunan Province, the concentration of Cr in the study area significantly exceeded the background, indicating mainly being affected by parent materials and anthropogenic activities. The Cr concentrations in rice grains vary from 0.09 to 0.11 mg/kg, with an average of 0.10 mg/kg. The Cr concentration doesn’t exceed the critical limit of Cr in food. The BCF of Cr in the rice grains is closely related to the concentration of Cu and TFe₂O₃, and SiO₂/Al₂O₃ in the rhizosphere soils, and was affected by the weathering degree, iron oxides and antagonism between elements in the rhizosphere soil. The prediction model for BCF of Cr in the rice grains is established by using multiple linear regression analysis and the prediction results are convincing. The predicted Cr concentration in the rice grains in the study area is below its critical limit.

Key words: Zhuzhou, rice grain, Cr, influencing factor, prediction model