Status of Cs-137 concentrations in sea water at the inlets of the Indonesian Through Flow (ITF)

There is a lack of available data on 137Cs water concentrations at the Indonesian Through Flow (ITF). The
data is required for evaluation of the possible impact of the Fukushima accident in Indonesia’s marine
environment. 137Cs monitoring at inlets of ITF were conducted in order to address this possible impact.
Monitoring was performed by the Baruna Jaya III research vessel during the Sail Morotai campaign of 2012. Surface sea water (0–10 m depth) samples were collected at 7 stations. The AMP (Ammonium molybdophosphate) method was used for separating radiocesium from seawater. The radiocesium were measured by a HPGe detector of gamma spectrometer system. The measured concentrations of 137Cs in the Flores Sea ranged between 0.29–0.30 Bq m−3. At another inlet of the ITF in the Halmahera Sea which
the concentration of 137Cs were founded varied between 0.20–0.38 Bq m−3. The water concentrations of
137Cs in the Lifamatola Passage, at the Eastern of Sulawesi, ranged between 0.20–0.30 Bq m−3. There was
no detection of 134Cs at any of the monitoring stations. The result showed that the input 137Cs from the
Pacific Ocean to Indonesian Seas was not from Fukushima but was characteristic of global fallout in the
Pacific Ocean.