Extraction of cesium in seawater off Japan using AMP-PAN resin and quantification via gamma spectroscopy and inductively coupled mass spectrometry

The March 2011 earthquake off the Japanese coast and subsequent tsunami that devastated the Fukushima Dai-Ichi nuclear power plant resulted in the largest accidental release of cesium 137 and 134 to the oceans. Seawater samples were collected in June 2011 from 30 to 600 km off the coast of Japan as part of initial mapping of the spread of contamination in the ocean. Cesium was extracted from unfiltered and filtered (<1.0 μm) seawater using an absorber based upon an organic polymer polyacrylonitrile (PAN) containing ammonium molybdophosphate (AMP) Sebesta and Stefula (J Radioanal Nucl Chem 140:15-21, 1990). The AMP-PAN resin can be counted directly using gamma spectroscopy for 134Cs and 137Cs. Stable 133Cs was added to evaluate extraction efficiency and quantified by ICP-MS. Our 5 mL AMP-PAN resin column was on average 95 % efficient in the removal of cesium from 20 L samples at an average flow rate of 35 mL min-1. Measured activities of 134Cs and 137Cs ranged from a few Bq m-3 to >300 Bq m-3. The extraction column can be adapted to different sample volumes and easily used in the field. (author)