Radioactivity in the coastal waters of the Bohai and Yellow Seas of China

Abstract

The results of an extensive program to investigate radioactivity in the coastal waters of the Bohai and Yellow Seas during 1981–1982 and to monitor routinely the concentrations of 90Sr and 137Cs in both seawater and marine organisms between 1970 and 1981 are presented here. The samples collected included seawater, marine organisms and sediments and the radionuclides determined were 90Sr, 137Cs, 106Co, 144Ce, 238U, 232Th and 226Ra. The concentrations of the radionuclides in seawater, marine organisms and sediments did not differ substantially between the Bohai and Yellow Seas. The mean concentrations of 90Sr and 137Cs in seawater were 8·7 Bq m −3 and 10·7 Bq m −3 respectively in 1982; the corresonding means for 90Sr and 137Cs in the flesh of fish, shellfish, and shrimp and crab were 0·031, 0·44 and 0·33 Bq kg −1 9fresh wt_and 0·41, 0·41 and 0·59 Bq kg −1 fresh wt) respectively, in 1981, while the mean sediment concentrations for 90Sr and 137Cs in the Bohai Sea were 0·011 and 0·014 Bq g −1 (dry wt) respectively in 1981. The results show that the levels of radioactivity in the Bohai and Yellow Seas were very low; artificial radionuclides such as 90Sr, 137Cs, 144Ce, 60Co, 106Ru being mainly from weapons test fallout in the 1960s and early 1970s, and natural radionuclides such as 238U, 232Th and 226Ra reflecting the natural radiation background levels of this marine environment.