日本福岛核电站事故后的海洋放射化学

由于对环境影响的关注,日本福岛核电站事故后,人们进行了大气、陆地和海洋环境人工放射性核素变化监测与研究,研究的主要核素是131I、137 Cs、134 Cs和129I。除了关注浓度水平的变化外,还进行了通过大气和海流对事故释放的放射性核素运行路径的模拟研究。研究表明,受气候条件的控制,事故释放进入大气的放射性核素先经过太平洋到达北美,然后越过大西洋到达欧洲,最后绕北半球一周后到达中国。除事故核电站周边外,全球大气中131I活度浓度在mBq/m3量级,137 Cs活度浓度在0.1~1mBq/m3量级。事故释放进入海洋的放射性核素将随海流向东输运,然后在北太平洋随环流输运。研究也发现在离开源地不远的海区,由于混合进入200m水深以下的次表层水,在远离事故核电站海区水体的137 Cs活度浓度可达100Bq/m3,但大部分水体137 Cs活度浓度在Bq/m3量级,仅稍高于本底水平。

Marine Radiochemistry Progress After Fukushima Daiichi Nuclear Power Plant Accident

Because being paid close attention to environment impact from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, artificial radionuclides in the atmosphere, land and ocean were studied and monitored. The main nuclides detected are ¹³¹I, ¹³⁷Cs, ¹³⁴Cs and ¹²⁹I. When the concentration levels are measured, the transport path of radionuclides in the atmosphere and ocean were simulated. The results showed that controlling by climate condition, the airborne radionuclides released by FDNPP accident reached America via the Pacific, and then arrived to Europe over Atlantic, and finally transported to China. Over the globe the activity concentration of ¹³¹I from FDNPP accident is in the order of magnitude of mBq/m³, and 0.1-1 mBq/m³ for ¹³⁷Cs. The nuclides released to the sea headed eastward with the ocean current and then would circulate in the North Pacific. With mixing, the radionuclides went down to 200 m depth, where not very far from FDNPP. In the open ocean far from FDNPP, the ¹³⁷Cs activity concentration may be in the order of magnitude of 100 Bq/m³, but most of waters is in the Bq/m³ level, only slightly higher than background.