土壤性质对小白菜吸收铬(Cr)的影响及预测模型研究

摘要

采集我国15个省份理化性质差异很大的耕作土壤,利用温室试验,以小白菜为研究对象,通过外源添加铬(Cr),研究Cr从土壤向植物的运移,探索影响Cr生物有效性的主要土壤因素,并建立预测模型.结果表明,土壤总Cr含量、pH值和有机碳(OC)含量对小白菜吸收Cr有显著影响.小白菜Cr含量与土壤Cr含量呈正相关,而与土壤pH值、OC含量呈负相关.相比于土壤总Cr含量的单因素回归分析,将土壤总Cr含量、pH值和有机碳(OC)含量纳入逐步多元线性回归(SMLR)后评价Cr生物有效性时,相关性更高,决定系数由0.861提高到0.927.Cr在酸性土壤中生物富集系数(BCF)较碱性土壤中更大.利用合并CK、Cr1、Cr2处理3个处理的数据(n=45)得到Freundlich预测方程(R2=0.927,RMSE为0.12),较单独使用CK处理数据(R2=0.572,RMSE为0.25,n=15)和使用Cr1和Cr2处理结合的数据(R2=0.745,RMSE为0.17,n=30)得出的方程,能更准确地评估Cr在土壤中生物有效性,试验结果可用于预测Cr从土壤到小白菜的转移.%Estimating heavy metal bioavailability,mobility and transfer is important to environmental and food safety.A greenhouse study was conducted by using Brassica chinensis to investigate the movement of chromium (Cr) from soil to plants and predict the main factors influencing Cr bioavailability.The result showed that soil organic carbon (OC) content,pH value and total Cr content had a significant impact on Cr uptake.The plant Cr contents were positively correlated to total soil Cr contents and negatively correlated to soil OC and pH value.Stepwise multiple linear regression (SMLR) (pH value,OC and total soil Cr contents) relationships (R2 was 0.927) could more accurately estimate Cr bioavailability relative to single-factor (total soil Cr contents) equations (R2 was 0.861).The maximum bioconcentration factor (BCF) was measured in acidic soils.The most accurate Freundlich equation for estimating Cr bioavailability was developed by using data from combined CK,Cr1 and Cr2 treatments (R2 was 0.927,RMSE was 0.12,n was 45) compared with the Freundlich equation developed by using the date CK treatment alone (R2was 0.572,RMSE was 0.25,n was 15) and using data from only combined Cr1 and Cr2 treatments (R2 was 0.745,RMSE was 0.17,n was 30).The results can be used to predict Cr transfer from soil to plant systems.