Isotopic Composition And Distribution Of Plutonium In The Beibu Gulf Sediments And Transport Of PU

The increasing human activities had led to increasingly serious to the environment. Radioactive isotopes, which is widely used in the assessment of soil erosion, migration of river and coastline and other dynamic process and ecological process. The Beibu Gulf is a semi-closed gulf with good water quality, marine resources and marine ecosystems. Simultaneously, the marine sports in the gulf is weak, lead to pollutant enrichment and ecologically fragile. At present, the rapidly developing of The Beibu Gulf economic zone, such as petrochemical, nuclear power and other industrial building caused tremendous pressure on environment. It is very necessary to assess the environment of the Beibu Gulf.To analyze plutonium distribution sources in the Beibu Gulf can help to discussing the characteristics of sedimentary environment of the coast in different areas, erosion of the coastline changes caused by oceans and rivers,the influence of human activities on the coastal zone, and the source of the sediments in different historical period. The Hongsha Nuclear Power Plant has been came into service.It may impact the plutonium distribution of the Beibu Gulf. This research provides a data base when evaluating plutonium pollution caused by the Nuclear Power Plant.In this paper,239+240Pu concentrations and 240Pu/239Pu atom ratios in Beibu Gulf were measured by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS).Space and vertical distribution of plutonium were discusses.The interference of human activities on the coastal zone environment and the source of the plutonium pollutants were explored.The main result of the thesis is as follows:(1)The soil sediments in the whole beibu gulf have a relatively stable 239+240Pu activities and 240Pu/239Pu atom ratios. Terrain and seawater velocity cause greater influence in plutonium isotopes, on the contrary, human activity cause little influence.(2) The vertical distribution of plutonium in San Niang Wan column sample is:plutonium are mainly concentrated on the close distance of surface, with the peak appear in 14-20 cm. Activities of plutonium fell sharply when it comes to 23 cm depth.(3) The plutonium inventory in San Niang Wan sediment is 61.09 Bq/m2, slightly bigger than inland lakes, less than the coastal area such as pearl river estuary, Yangtze river estuary.(4) Most of the Pu in the surface sediments of the Beibu Gulf are attributed to the direct global fallout and the land-origin Pu transported by the rivers. The relative contributions of the PPG close-in fallout within 20 cm depth in San Niang Wan column are 8.220%～17.267%.