Cd contamination in rice grains has become a topic of great concern because of the high health risks associated with the long-term consumption of Cd-contaminated rice. Identification of Cd sources in rice grains by scientific methods is important for controlling heavy metal pollution and protecting human health. Here, the Cd concentrations and Cd isotopic compositions of rice plants (root, stem, leaf, and grain) and topsoil, and possible pollution sources (agricultural fertilizers, industrial dust, and automobile exhaust) were analyzed using an instrument of inductively coupled plasma mass spectrometry (ICP-MS) and multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The results showed variations in the Cd isotopes of different components of rice plants and the fractionation coefficient of rice grains relative to topsoil (Δ^114/110Cd_{rice grains−topsoil} = 0.25‰). The contributions of pollution sources to rice grains were realized by combining the Cd isotopic composition with an isotopic mixing model (Isosource). The analysis showed that all three possible pollution sources contributed to the Cd in the rice grains in the field, the average Cd contribution of industrial dust, agricultural fertilizers and automobile exhaust was 87%, 9%, and 4%, respectively. Our study provides a feasible method for the identification of pollution sources of Cd in rice grains at the field scale and demonstrates that Cd isotopic composition is one of the powerful tools to trace the pollution sources of Cd in crops.

由于长期食用受Cd污染的大米会带来很高的健康风险，因此大米中Cd的污染已成为人们高度关注的话题。用科学方法鉴定稻米中的Cd来源对于控制重金属污染和保护人体健康至关重要。在这里，使用电感耦合等离子体质量仪分析了水稻植物（根，茎，叶和谷粒）和表土的镉浓度和镉同位素组成，以及可能的污染源（农业肥料，工业粉尘和汽车尾气）。质谱（ICP-MS）和多收集器电感耦合等离子体质谱（MC-ICP-MS）。结果表明，水稻植物不同成分的Cd同位素变化以及水稻籽粒相对于表层土壤的分馏系数（Δ^114/110 Cd_{水稻籽粒-表土}= 0.25‰）。通过将Cd同位素组成与同位素混合模型（Isosource）相结合，实现了污染源对水稻籽粒的贡献。分析表明，三种可能的污染源均对稻田中的Cd产生了影响，工业粉尘，农业肥料和汽车尾气中Cd的平均贡献分别为87％，9％和4％。我们的研究提供了一种在田间范围内鉴定水稻籽粒中Cd污染源的可行方法，并证明了Cd同位素组成是追踪作物中Cd污染源的有力工具之一。