Development of Analysis Methods for Chemical Substances and Long-term Monitoring of Radioactivity in Farm Products

Background and Objectives

The agricultural environment contains trace quantities of environmental chemicals, heavy metals and other hazardous substances. In order to ensure a supply of safe farm products to the people, it is necessary to measure such substances with accuracy and carry out analysis promptly and with relative ease. We are conducting research with the aim of developing such analytical methods and use them for monitoring purposes as well. Another matter of concern is radioactivity in the agricultural environment. Monitoring of farm products for radioactivity began when a number of nuclear tests were carried out in the atmosphere. By now, radioactive substances floating in the atmosphere have diminished considerably, but the number of nuclear reactors and other nuclear facilities has increased substantially including those in our neighboring countries. The public continues to have deep concerns about the radioactive aspect of food safety. We are making background studies in preparation for nuclear reactor accidents and other emergencies, and are also promoting research to clarify the behavior of radioactive substance in the environment.

Project Outline

Relevant Outcomes to Date

1. We have developed a method to analyze organic arsenic by HLPC-ICP-MS. This allows analysis of organoarsenic compounds in soil and crops, derived from abandoned chemical weapons.
2. We have successfully analyzed cadmium in rice promptly and easily by the immunochromato assay method. We are continuing our research so that this method will be widely used by those who are involved in agricultural production.
3. We have dramatically increased the sensitivity of ICP-MS analysis for radioactive iodine (¹²⁹ I) that is characterized by a long half-life. It is hoped that this will permit collection of background data on radioactive iodine in the neighborhood of nuclear fuel reprocessing facilities.
4. We are accumulating environmental radioactivity measurement data over a long period of time. While it is reasonably believed that hardly any radioactive substances land on soil from the atmosphere today (except for nuclear reactor accidents and similar exceptional situations), trace amounts of ¹³⁷Cs and ⁹⁰Sr are still detected at times in rice, wheat and their cultivated soil on account of the radioactivity that has been accumulated in soil over the years.
5. An analysis of the long-term monitoring data has revealed that exchangeable radioactive strontium in upland field soil is less susceptible to transfer to lower soil layers and to absorption by common wheat at spots where the cation exchange capacity (CEC) of the soil is higher.