浙江省典型水稻产区土壤水稻系统重金属 迁移特征及定量模型

重金属在土壤?水稻系统中迁移转化规律越来越受到人们的关注。本研究采集浙江省3个不同区位(浙北南浔、浙中嵊州、浙南温岭)的水稻主产区土壤、水稻样品,基于水稻品种(杂交水稻和晚粳稻)进行重金属迁移转化的影响因子分析,明确主要驱动因子,建立定量评测模型并进行验证,以此掌握浙江省典型水稻产区重金属的迁移转化规律。研究结果表明,3个研究区土壤的理化性状存在差异,其中嵊州产区土壤的p H(均值为5.52)、有机质(均值为39.4 g?kg?1)、重金属形态含量等均低于其他两个研究区;3个产区土壤和水稻中重金属含量也存在显著性差异,温岭产区土壤重金属(Cd、Cu、Zn)含量显著高于其他两个产区(P0.05),而嵊州产区的水稻重金属含量则显著高于南浔产区(P0.05);Cd和Zn富集系数高于Cu和Ni,嵊州产区的重金属富集系数(0.018~0.521)显著高于其他两个产区(南浔为0.004~0.143,温岭为0.007~0.269)。土壤重金属形态和土壤理化性质均显著影响不同品种的富集系数,其中土壤理化性质的作用相对较大。对数线性迁移模型能够预测实际产地环境中土壤?水稻系统重金属的有效性(富集系数),晚粳稻的预测结果优于杂交水稻,重金属Ni的预测效果(杂交水稻和晚粳稻的回归系数r分别达0.61、0.70,P0.01)好于其他重金属,而杂交水稻重金属Cd的预测效果(r值为0.21,P0.05)偏低,需增加环境变量,并做进一步研究以提高预测精度。

Characteristics and quantitative model of heavy metal transfer in soil-rice systems in typical rice production areas of Zhejiang Province

The understanding of characteristics of heavy metal transfer in soil-rice systems can improve soil quality in production areas and guide the safe production of rice. We collected soil and rice samples from three typical rice production areas (Nanxun, Shengzhou and Wenling) located in the northern, central and southern parts of Zhejiang Province. The controlling factors of heavy metal transfer were studied based on a transfer model set up for hybrid rice and japonica rice. The objective of the study was to identify transfer traits of heavy metals in soil-rice systems in typical rice production areas in Zhejiang Province and to guide safe agricultural production. The results suggested that the physico-chemical properties were different in the three areas. pH (mean value of 5.52), organic matter (mean value of 39.4 g?kg-1), EC and heavy metal fractions contents in soil in Shengzhou area were lower than those in the other two production areas. Sand content of soil in Shengzhou area was higher than that in the other two areas. Heavy metals in soils and rice were significantly different from each other of rice production areas. Heavy metals (Cd, Cu and Zn) contents in soil in Wenling area were significantly higher than those in the other two areas. Then heavy metals contents in rice in Shengzhou area were significantly higher than those in Nanxun area (P < 0.05). No carbonate bound fraction of heavy metals was detected in the study. The corresponding contents of exchangeable, Fe-Mn oxide bound, organic bound, and residual fractions of heavy metals in Shengzhou were lower than those in the other two production areas due to the lowest total heavy metals contents in Shengzhou soil. The enrichment indexes (EI) of heavy metals were different in the three production areas. Generally, EIs of Cd and Zn were higher than those of Cu and Ni. Also EIs in Shengzhou area (range of 0.018-0.521) were significantly higher than those in the other two areas (range of 0.004-0.143 for Nanxun area and of 0.007-0.269 for Wenling area). Both soil physico-chemical properties and heavy metals fractions were important factors influencing heavy metal enrichment indexes. Compared with heavy metals fractions, soil physico-chemical properties contributed more to the movement of heavy metals in soil-rice systems. A log-linear model of heavy metals combined with the physico-chemical properties and heavy metal fractions well predicted the availability of heavy metals in soil-rice systems under practical production conditions. The accuracy of the model prediction for hybrid rice was better than that for japonica rice. The Ni (regression coefficient r was 0.61 and 0.70 at P < 0.01 for hybrid and japonica rice, respectively) model was better than that of other heavy metals. However, the accuracy of the model prediction of hybrid rice Cd content (r = 0.21 at P > 0.05) was poor. In that case, it was necessary to conduct further research in order to improve the accuracy of the model by either using more of the environmental variables or adjusting the variables.