School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, PR China.
School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, PR China; Key Laboratory of Ecological Geochemistry, Ministry of Natural Resources, Beijing 100037, PR China.
Ecotoxicol Environ Saf. 2021 Jan 15;208:111505. doi: 10.1016/j.ecoenv.2020.111505. Epub 2020 Oct 28.
It is well-known that Cd concentration in the soil, Cd bioavailability, and Cd bioaccumulation in rice (Oryza sativa L.) grains vary greatly in different soil parent materials. Therefore, the classification of agricultural land environmental quality and agricultural land safe usage based on the Cd content in the soil has a wide deviation. By the application of systematic sampling and analysis of soil and rice samples, and in comparison with the different soil parent materials in Heng County, it was found that soil derived from carbonate rocks has higher total Cd and lower mobile Cd proportion than soil from the non-karst areas. This result indicated that soil carbonates raised soil pH and the adsorption of Fe/Mn oxide/hydroxide on Cd significantly reduced the bioavailability of Cd in karst areas. In contrast, acidic soils with relatively lower CaO, TFeO, Mn and total Cd contents, the grown rice plants accumulated higher Cd in their grains. Further research confirmed significant differences in Cd bioaccumulation abilities in the soil between karst and non-karst areas. On this basis, the bioaccumulation factor prediction models of Cd in rice grains were developed in karst and non-karst areas. According to the total concentration of Cd in topsoil samples obtained from the area survey and the predicted Cd content in rice grains, an agricultural land safe usage scheme was put forward. The results showed that the agricultural land classification method based on Cd concentration in the soil and rice grains was more accurate and scientific than that based on the Cd contents in the soil alone.
众所周知，土壤中的镉浓度、镉生物有效性以及水稻（Oryza sativa L.）籽粒中的镉积累在不同的土壤母质中差异很大。因此，基于土壤中镉含量对农业土地环境质量和农业土地安全利用进行分类存在很大偏差。通过对土壤和水稻样品进行系统采样和分析，并与横县不同的土壤母质进行比较，发现来源于碳酸盐岩的土壤总镉含量较高，而可移动镉的比例较低。这一结果表明，土壤碳酸盐提高了土壤 pH 值，同时显著降低了 Fe/Mn 氧化物/氢氧化物对 Cd 的吸附，从而降低了喀斯特地区镉的生物有效性。相比之下，酸性土壤中 CaO、TFeO、Mn 和总镉含量相对较低，种植的水稻植株在其籽粒中积累了更高水平的镉。进一步的研究证实了喀斯特和非喀斯特地区土壤中镉生物积累能力的显著差异。在此基础上，建立了喀斯特和非喀斯特地区水稻籽粒中镉的生物积累因子预测模型。根据该地区调查获得的表层土壤样品中总镉浓度和预测的水稻籽粒中镉含量，提出了一个农业土地安全利用方案。结果表明，基于土壤和水稻籽粒中镉浓度的农业土地分类方法比仅基于土壤中镉含量的方法更加准确和科学。
