不同土壤镉提取方法预测稻米富集镉性能评估

为筛选土壤镉(Cd)有效态提取方法并建立其与稻米Cd污染之间的累积模型,采用大田协同采样方式收集了土壤-水稻140对样品,分别研究了土壤Cd总量及土壤溶液Cd含量和化学浸提(醋酸HAc、复合有机酸、乙二胺四乙酸EDTA、CaCl2)、梯度扩散薄膜(DGT)技术提取的Cd含量与水稻糙米Cd含量的相关性,以评估不同提取方法预测稻米Cd累积模型的可行性。结果表明,研究区所在的长株潭地区存在较为明显的土壤及稻米Cd污染风险,EDTA提取Cd含量与土壤Cd总量显著正相关,模型拟合决定系数R2达到0.908 4,以总量预测稻米Cd污染存在37.2%~39.8%的误判率,0.01 mol·L^-1CaCl2提取的土壤Cd有效态含量存在明显的适用范围限制,在0.04~0.13 mg·kg^-1范围内,效果明显差于其他数据区域,模型决定系数R2仅为0.006。DGT技术能较好地预测稻米对Cd的吸收富集性能,且能区分土壤库供给能力差异对稻米富集Cd的影响,与传统化学浸提方法比较,DGT技术提取的土壤Cd有效态含量与稻米Cd含量具有更好的相关性(R^2=0.585 4,0.900 9),是预测稻米富集Cd较为理想的土壤有效态提取方法。

Screening and evaluation of soil cadmium extraction methods for predicting cadmium accumulation in rice

Screening of extraction methods for available Cd in soils and establishing prediction models for Cd accumulation in rice are essential for assessing and classifying soil environmental quality. In this study, a total of 140 pairs of brown rice and soil samples were collected from Cd-contaminated paddy fields in the Changsha-Zhuzhou-Xiangtan area in Hunan Province. Total Cd concentrations in the soils and soil solutions, concentrations determined via chemical extraction methods using acetic acid (HAc), composite organic acid, ethylene diamine tetraacetic acid (EDTA), and CaCl₂, respectively, and available fraction analyzed via diffusion gradient in thin-film (DGT)technology were obtained and used to establish soil-rice Cd accumulation models. The results indicated the Cd pollution risk for soil and rice in the study region. The Cd concentration extracted using EDTA was significantly correlated with total soil Cd content (R²=0.908 4). False rates of predicting rice Cd concentration using total soil Cd content were 37.2%~39.8%. The performance of the prediction model was significantly concentration-dependent for the CaCl₂ extraction method, with a low determination coefficient (R²=0.006)for concentrations of 0.04~0.13 mg·kg^-1 compared to that for the other concentrations. However, DGT technology proved to be a better tool for extracting available Cd to establish the prediction models (R²=0.585 4, 0.900 9)for rice Cd accumulation than chemical extraction methods were as well as for distinguishing the effect of the soil bank supply capacity on Cd enrichment by rice.