Abstract
In this study, we measured the activity concentrations of Cs-137 and Sr-90 in surface seawater and surface sediments at the Tra Co, Bach Long Vi, and Ky Anh locations in the Gulf of Tonkin, Vietnam, from December 2018 to October 2019. The average activity at the selected locations was 1.22, 1.43, and 1.33 Bq/m3 for Cs-137 and 0.88, 1.17, and 1.09 Bq/m3 for Sr-90 in surface seawater samples and 0.74, 1.01, and 0.81 Bq/kg dry for Cs-137 and 0.49, 0.49, and 0.43 Bq/kg dry for Sr-90 in sediment samples. The ratio of the average activity concentration (Cs-137/Sr-90) in the surface seawater was 1.42, 1.22, and 1.22 at the Tra Co, Bach Long Vi, and Ky Anh locations, respectively. These are somewhat low compared to the global ratios (1.6 and 1.8). Meanwhile, Cs-137/Sr-90 ratios in the sediment samples at the selected locations were 1.51, 2.06, and 1.88, respectively, which is equal to or greater than the corresponding value for global sedimentation according to the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Correlations between Sr-90, Cs-137, and organic carbon content were detected in this study. The results showed that Cs-137 has a high correlation with the organic carbon content in sediment, while Sr-90 has a low correlation.
Highlights
Introduction e Gulf ofTonkin is located at the coordinates of 17°00ʹ–21°40ʹ north latitude and 105°40ʹ–109°40ʹ east longitude, stretching to nearly 5 geographical latitudes with a distance from north to south of approximately 500 km from the coast of Vietnam. e Gulf of Tonkin is one of the major bays in Southeast Asia and the world, with an area of approximately 126,250 km2, widest width of approximately 320 km, and narrowest width of approximately 220 km
Due to the accident at the Fukushima nuclear power plant, as well as an increase in the commercial activity of nuclear power plants around the Gulf of Tonkin from China (4 NPPs operational and 2 NPPs under construction) [3], there is a risk of introducing radioactive pollutants Cs137 and Sr-90 into the marine environment in general and the Gulf of Tonkin in particular. us, artificial radioisotopes (Cs-137 and Sr-90) contribute to the public dose due to human consumption of marine food. us, studies and Journal of Chemistry surveys must produce a database of radioisotopes in marine environmental objects in order to assess the impact of these radioactive nuclei on human health and the environment [2]
The average ratios of Cs-137/ Sr-90 in surface seawater at Tra Co, Bach Long Vi, and Ky Anh are 1.42, 1.22, and 1.22, respectively, which is somewhat low compared to the global fallout ratio of 1.6–1.8 [2, 6, 7]
Summary
Seawater samples and marine sediments were collected from 3 locations (1 offshore location and 2 nearshore locations) in the Gulf of Tonkin. Depending on the flow of seawater in the Gulf of Tonkin, the samples were collected at times when the flow moved from north to south, and vice versa [1]. Ese samples were collected in December 2018, April 2019, June 2019, and October 2019 Depending on the flow of seawater in the Gulf of Tonkin, the samples were collected at times when the flow moved from north to south, and vice versa [1]. ese samples were collected in December 2018, April 2019, June 2019, and October 2019
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