Natural abundance and background of cadmiun in river water, soil and rice grain in Japan

从人类健康和环境污染的角度来看，镉和汞可能是最关键的元素。特别是日本人的肾皮质镉含量和日摄入量已被证明是被调查国家中最高的，因此公布其在河流、土壤和农产品中镉的自然丰度范围和本底，以便制定一些有效的措施来防止镉在环境和人体中的积累，显得尤为重要。对土壤和农产品的消化方法进行了技术考察，用ICP ms对土壤和农产品的消化液进行预处理，可以有效地减少土壤和农产品中微量元素的含量，但对镉的检测却不是必需的。螯合滤池预处理对去除碱土元素非常有用，碱土元素是影响ppt检测的主要基质元素。根据上述技术检查，在日本全国范围内检测了大量的河水、地下水、温泉水、不同类型母岩的各种土壤、不同类型土壤生产的稻米等样品中的镉含量。

Cadmium and mercury might be most critical elements from view point of human health and environmental pollution. Particularly for Japanese whose cadmium concentration in kidney cortex and daily intake had been proved to be highest among the surveyed countries, it may be much more important to declare the range of natural abundance and background of cadmium in running river water, soil and agricultural products in order to establish some effective measure to prevent accumulation of cadmium in environment and human body.Technical check had been done about proper method of digestion of soil and agricultural product, and pretreatment of the digested solution for detection of ppt level of elements with ICP MS.Ultra-pure reagents as HNO_3 and HCl were of course effective to reduce the contaminants during the procedure but not essential for detection of cadmium. Pretreatment with Chelate Filter was very much useful to remove alkali and alkali earth elements which are major matrix elements disturbing detection of ppt level of heavy metal elements.Based on the technical check above written, cadmium levels in large number of samples as river waters, ground waters, hot spring waters, varieties of soils originated from different types of parent rocks, and rice grains produced on different types of soils all over Japan were detected.