[Influencing Factors of Cadmium Bioaccumulation Factor in Crops].

The Cd bioaccumulation factor (BCF) of crops is affected by many aspects. In order to clarify the differences in the Cd bioaccumulation factor characteristics of different crops under field conditions and the influence of soil properties, point-to-point samples of soil and crop grains were collected during crop harvesting on plots with varying pollution levels in the primary production areas of rice, wheat, and maize in China. The characteristics of the Cd bioaccumulation factors of rice, wheat, summer maize, and spring maize and the effects of soil properties on the Cd bioaccumulation factors of different crops were studied, and the quantitative relationship between the Cd bioaccumulation factors and soil properties was established through multiple regression equations. The results revealed that the average BCF values of Cd in rice, wheat, summer maize, and spring maize were 0.915, 0.155, 0.113, and 0.102, respectively, with the Cd content in the field soil of 0.15-2.66 mg·kg-1. Rice is significantly higher than wheat and maize, and spring maize has the lowest Cd bioaccumulation factor. The Cd content in the soil is extremely negatively correlated with the BCF of wheat, summer maize, and spring maize. The relationship between soil organic matter (SOM) and the BCF of wheat and summer maize demonstrated a significant negative correlation. The soil pH and cation exchange capacity (CEC) also affect the BCF of crops. Introducing the soil Cd content, pH, SOM, CEC, and other factors, the Cd bioaccumulation factor prediction equations of rice, wheat, summer maize, and spring maize were established. The correlation coefficients of the BCF prediction equations for rice, wheat, summer maize, and spring maize are 0.423*, 0.796**, 0.826**, and 0.551**, respectively. The above models reached significant or extremely significant levels, which can better predict the BCF value of different crops under varying soil conditions.

[Combined Effect of Weathered Coal Based Amendments and Soil Water Management on Methylmercury Accumulation in Paddy Soil and Rice Grains].

A pot experiment and field experiment were designed to study the changes in the grain methyl mercury content in paddy soil and rice yield by sowing soil amendments that contained weathered coal, CaCO3, and Na2SeO3 as the main raw materials, combined with water management in a paddy field (80% field capacity after the heading and flowering periods). The results showed that:① In pot experiment, the content of methylmercury in rice rhizosphere soil decreased by 86.6% and the content of methylmercury in the rice grains decreased by 65.2% compared with that of the control. In field experiment, the content of methylmercury in rice rhizosphere soil decreased by 77.4% and the content of methylmercury in rice grains decreased by 60.6% upon adding the amendment+water management compared with that of CK. ② The soil pH increased by more than 0.3 in the pot experiment and 0.2 in the field experiment compared with that of the control. Furthermore, rice yield and plant biomass did not decrease in the two parts of the experiment. It can be inferred that the soil amendment and agronomic regulation measures (water management) used in this study have the advantages of quick effects, convenient use, and remarkable control effects and without secondary pollution. More, they can effectively reduce the risk of rice methylmercury exposure.