稻米镉的生物富集系数与其影响因素的量化关系

Quantitative Relationship Between the Bioconcentration Factor of Rice Cadmium and Its Influencing Factors

为进一步明确田间环境中稻米镉的生物富集系数(BCF)与其影响因素的定量关系,以原农业部环境监测总站对我国南方水稻产地的例行监测数据为基础,系统分析了土壤有效镉、pH、土壤有机质(SOM)及阳离子交换量(CEC)与稻米镉BCF的相关关系,并通过多元线性回归构建了二者间的定量关系模型。结果表明:研究区域土壤全镉范围为0.25~10.34 mg/kg,平均值为1.94 mg/kg,是我国《土壤环境质量农用地土壤污染风险管控标准(试行)》(GB15618—2018)中镉污染风险筛选值(0.4 mg/kg)的4.85倍;简单线性相关分析表明,稻米镉的BCF与土壤有效镉和SOM呈极显著正相关(P<0.01),相关系数分别为0.395和0.474,与pH呈极显著负相关(P<0.01),相关系数为–0.470,与CEC呈显著负相关(P<0.05),相关系数为–0.200;通过多元线性回归得到土壤有效镉、pH和SOM构建的三因子量化关系模型lgBCF=–0.346pH+0.013lgSOM+0.181lgCdavailable+2.001(R^(2)=0.560,P<0.01,n=112)达到了极显著水平,能较好预测我国南方水稻产地稻米镉含量及土壤镉的生态安全阈值。

To further determine the quantitative relationship between the bioconcentration factor(BCF)of rice cadmium(Cd)and influencing factors,this study was carried out based on the routine monitoring data of the southern rice-producing areas provided by the Agro-Environmental Monitoring Center of China.The correlations between soil available Cd content,pH,soil organic matter(SOM),cation exchange capacity(CEC)and rice BCF were systematically analyzed,and the quantitative relationship models were established by multiple linear regression.The results showed that soil total Cd content ranged from 0.25 to 10.34 mg/kg with the average of 1.94 mg/kg,which was 4.85 times of the risk screening value(0.4 mg/kg)for Cd contamination in Soil Environment Quality Risk Control Standard for Soil Contamination of Agriculture Land(GB15618—2018).The results of linear correlation analysis showed that BCF of rice Cd had significant positive correlations with soil available Cd and SOM(P<0.01),the correlation coefficients were 0.395 and 0.474,respectively,while significant negative correlations with soil pH(P<0.01)and CEC(P<0.05),the correlation coefficients were–0.470 and–0.200,respectively.The model constructed by multiple linear regression was lgBCF=–0.346pH+0.013lgSOM+0.181lgCdavailable+2.001(R^(2)=0.560,P<0.01,n=112),which can better predict Cd content in rice and the safety threshold of soil Cd in rice production areas in southern China.