Cs-134, Cs-137, and I-129 dissolved in seawater im MR20-05C

(1) Radiocesium (Cs-134 and Cs-137)Seawater samples for radiocesium were collected using 12-liter PVC bottles. Surface seawater was collected from continuous pumped-up water at about 4-m depth. The sample volumes is 40 L (two 20-L plastic containers).The seawater sample for radiocesium measurement was not filtered and was acidified by adding nitric acid. Radiocesium in the seawater sample is concentrated using ammonium phosphomolybdate (AMP) that forms an insoluble compound with cesium. The radiocesium in the compound is measured using Ge gamma-ray spectrometers. We collected 34 seawaters for the radiocesium measurements in the Arctic Ocean, Bering Sea, and northern North Pacific Ocean during this cruise.(2) I-129Seawater samples for 129I were collected using 12-liter PVC bottles. Surface seawater was collected from continuous pumped-up water at about 4-m depth. The seawater sample was collected into a 1-L plastic bottle after two-time rinsing. Iodine in the seawater samples is extracted by the solvent extraction technique. Extracted iodine is then precipitated as silver iodide by the addition of the silver nitrate. Iodine isotopic ratios (I-129/I-127) of the silver iodide are measured by the Accelerator Mass Spectrometry (AMS). To evaluate the I-129 concentration in the seawater samples, iodine concentration (I-127) will be measured by the inductively coupled plasma mass spectrometry (ICP-MS) and/or the voltammetry. We collected 80 seawater samples for I-129 measurements in the Arctic Ocean, Bering Sea, and northern North Pacific Ocean during this cruise.