Plutonium isotopes in the northwestern South China Sea: Level, distribution, source and deposition. (1st April 2022)

• Record Type: Journal Article
• Authors: Zhang, Mengting; Qiao, Jixin; Zhang, Weichao; Zhu, Liuchao; Hou, Xiaolin
• Is Part Of: Environmental pollution. Volume 298(2022)
• Publication Date: 2022-04-01
• Subjects: Plutonium -- South China Sea -- Pacific Proving Ground -- Deposition -- 240Pu/239Pu atomic ratio; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2022.118846
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: The spatial distribution of plutonium isotopes ( 239 Pu, 240 Pu) in the surface sediments collected from the northwestern South China Sea (SCS) in 2018 was investigated. The 239, 240 Pu concentrations in surface sediments vary from 0.048 to 0.960 mBq/g (with mean of 0.282 ± 0.242 mBq/g) depending on the geographical feature of the sampling location such as the river estuary, continental shelf, slope and deep basin. Higher 240 Pu/ 239 Pu atomic ratios (0.24–0.31) in the surface sediment of the SCS compared to the global fallout value of 0.18 were observed, this is attributed to the input of close-in fallout of the Pacific Proving Ground (PPG) transported by the North Equatorial Current and Kuroshio Current to the northern SCS. The contribution of the PPG derived plutonium in the SCS sediment was estimated to be 39%–78% using a simple two-end member mixing model based on the measured 240 Pu/ 239 Pu atomic ratios in the sediment. Besides the soluble 239, 240 Pu level in seawater, load of suspended particulate matter from the river runoff and biological debris, hydrographic and hydrodynamic conditions are key parameters influencing the deposition process of plutonium to the sediment. Graphical abstract: Image 1 Highlights: Distribution of 239, 240 Pu and 240 Pu/ 239 Pu ratio in the SCS sediment were reported. The close-in fallout of PPG contributed 39–78% of Pu in the SCS. PPG derived Pu was transported to the SCS through NEC and KC. Pu in the estuary sediment dominated by the global fallout Pu from the catchment. Suspended particles and hydrodynamics influenced the deposition of Pu in the shelf.