Iodine isotopes in surface water in the Northeast Asia

Iodine isotopes ( 129 I and 127 I) in the fresh and sea water of Lake Khanka and the Sea of Japan (Peter the Great Bay) were determined. The measured concentration of 129 I in the seawater is (1.87–2.33) × 10 7 atoms/L and (29.0–39.9) × 10 7 atoms/L in the lake water. The 129 I/ 127 I atomic ratios in the fresh water [(0.87–1.13) × 10 −8 ] are two orders of magnitude higher than those in the sea water [(0.91–1.15) × 10 −10 ]. 129 I was flowed into sea from the river, deposited and quickly diluted in the seawater, causing a declined 129 I concentration. The orders of magnitude higher stable 127 I concentration in seawater compared to the fresh water enlarged the difference on the 129 I/ 127 I atomic ratios.