南方红壤小流域水稻植株中稀土元素的内稳性特征

Homeostasis of Rare Earth Elements in Paddies of Southern Red Soil Small Watershed

化学计量内稳性是维持生态系统结构、功能和稳定性的重要机制。水稻作为我国南方地区日常生活中的主要粮食和经济作物,是人们赖以生存的物质基础。本研究基于内稳性模型,以我国南方红壤小流域水稻田中的水稻植株为研究对象,探究土壤-水稻系统中稀土元素的含量及迁移累积特征和内稳性特征。结果显示：（1）本研究中水稻土的稀土元素含量的平均值为320.79 mg·kg^-1,高于福建省土壤稀土元素背景值（223.47 mg·kg^-1）以及全国土壤稀土元素背景值（187.60 mg·kg^-1）;（2）水稻植株不同器官对稀土元素累积能力大小顺序依次是：根〉叶〉稻谷,水稻植株不同器官稀土元素的生物迁移系数也呈现出根〉叶〉稻谷的规律;（3）水稻植株根部的H为1.68;叶部的H为0.44;稻谷的H为-1.31。各器官的内稳性指数呈现出根〉叶〉稻谷的规律。虽然水稻稻谷中稀土元素的含量很低,暂低于居民稀土元素摄入的安全剂量,也未超过亚临床损害剂量的临界值,但水稻稻谷的内稳控制力很弱,易受周边环境的影响,居民长期食用存在一定的潜在健康风险。

Homeostasis is an important mechanism in maintaining ecosystem structure,function and stability. Paddy,as the main food and cash crop in the daily life of southern China,is the material base for people to survive,but the study on the homeostasis of rare earth elements in soil rice system is rarely seen. Based on the homeostasis model,the rice plant of the red soil watershed of southern China was taken as the research object,and the migration and accumulation characteristics and stability characteristics of REE in the soil rice system were investigated. The results showed that：（ 1） The average content of REE content in paddy soil was 320. 79 mg·kg^-1,higher than that of Fujian province（ 223. 47 mg·kg^-1） and the national soil background value（ 187. 60 mg·kg^-1）.（ 2） Rare earth elements accumulation size order in the different organs of paddies is：root〉leaf〉rice,biological absorption coefficient of rare earth elements in different organs of paddies also showed root〉 leaf〉 rule.（ 3） The homeostasis index of different organs showed the rule of root〉leaf〉paddy. Although the content of rare earth elements in paddies is very low,the internal stability control of paddies is very weak,it is easy to be affected by the surrounding environment,so there is a certain health risk for residents to eat for a long time.