广西镉地球化学异常区水稻籽粒镉含量预测模型研究

为了解广西镉地球化学异常区土壤对水稻籽粒镉含量的影响,更进一步从局部有限的土壤-水稻"点"的研究拓展到镉异常区域范围内"面"的研究,共采集土壤-水稻样品656件,采用逐步多元回归分析建立不同镉浓度等级下水稻籽粒重金属Cd含量预测模型。结果表明:研究区土壤呈中性(pH均值为6.8),属矿质土壤(OM均值为39.53 g·kg~(-1)),全量镉和有效态镉含量范围分别为0.078～7.893 mg·kg~(-1)和0.028～5.875 mg·kg~(-1);根据《食品安全国家标准食品中污染物限量》(GB 2762—2017),稻米Cd超标率为13.6%;不同Cd浓度等级下最佳预测模型分别为:G1(0.5 mg·kg~(-1)):lg(Cd-G)=1.561-3.782 lg(pH)+1.825 DTPA-Cd;G2(0.5～1.0mg·kg~(-1)):lg(Cd-G)=5.145-0.280 pH-2.448 lg(OM)+1.039 lg(DTPA-Cd);G3(1.0～2.0 mg·kg~(-1)):lg(Cd-G)=1.074-0.208 pH-0.029OM+0.589 DTPA-Cd;G4(2.0～3.0 mg·kg~(-1)):lg(Cd-G)=-0.897-0.026 OM+0.785 DTPA-Cd;G5(3.0 mg·kg~(-1)):lg(Cd-G)=0.791~(-1).322 lg(OM)。总体上,广西镉异常区土壤中Cd整体偏高,已经对水稻安全种植产生影响,预测模型能够较好地预测稻米中镉的累积量,为广西镉异常区内其他水稻产地的安全生产提供参考。

Prediction model for cadmium concentrations in rice grain under the geochemical background of a cadmium anomaly area in Guangxi

To understand the effect of soil cadmium(Cd)on the Cd concentrations in rice grain a large-scale study was conducted in Guangxi under the geochemical background of a Cd anomaly area, rather than evaluating the Cd effect in an identified area. Stepwise multiple regression analysis was used to establish the prediction model for Cd content in rice grain under different Cd concentrations based on a total of 656 soil and rice samples. The results showed that soil in the study area was neutral(average pH value:6.8)and could be classified as mineral soil(organic matter mean:39.53 g·kg^-1); the total Cd and available Cd content ranged from 0.078 to 7.893 mg·kg^-1 and from 0.028 to 5.875 mg·kg^-1, respectively. According to the "Food Safety National Standards for Contaminants in Foods"(GB 2762-2017), the over-standard rate of Cd in rice grain was 13.6%. The most suitable prediction models of different Cd concentration grades were:G1(<0.5 mg · kg^-1):lg(Cd-G)=1.561-3.782 lg(pH)+1.825 DTPA-Cd; G2(0.5~1.0 mg · kg^-1):lg(Cd-G)=5.145-0.280 pH-2.448 lg(OM)+ 1.039 lg (DTPA-Cd); G3 (1.0~2.0 mg·kg^-1):lg (Cd-G)=1.074-0.208 pH-0.029 OM+0.589 DTPA-Cd; G4 (2.0-3.0 mg·kg^-1):lg (Cd-G)=-0.897-0.026 OM+0.785 DTPA-Cd; G5(>3.0 mg·kg^-1):lg(Cd-G)=0.791-1.322 lg(OM). In general, the Cd concentration in Guangxi was relatively high, resulting in a significant impact on the food safety of rice planting. These prediction models effectively describe the Cd content of rice grain in the study area, which could help to determine Cd accumulation in rice in the Cd anomaly areas of Guangxi.