Monitoring 137Cs and 134Cs at marine coasts in Indonesia between 2011 and 2013

•In response to the Japan Fukushima Daiichi nuclear accident.•The monitoring have been carried out in some Indonesia coasts.•137Cs in the eastern and western Indonesia coasts originated from global fallout.

Environmental samples (seawater, sediments and biota) were collected along the eastern and western Indonesian coasts between 2011 and 2013 to anticipate the possible impacts of the Fukushima radioactive releases in Indonesia. On the eastern coasts (south and north Sulawesi), the 137Cs concentrations in the seawater and sediments were 0.12-0.32 Bq m−3 and 0.10-1.03 Bq kg−1, respectively. On the western coasts (West Sumatra, Bangka Island, North Java, South Java and Madura island), the 137Cs concentrations in the seawater and sediments were 0.12-0.66 Bq m−3 and 0.19-1.64 Bq kg−1, respectively. In general, the 137Cs concentrations in the fish from several Indonesian coasts were