The streambed sediments of the Suez Canal have been analyzed for determining the natural radionuclides and long-lived radionuclides such as uranium by gamma and alpha spectrometric techniques. The specific activities ...The streambed sediments of the Suez Canal have been analyzed for determining the natural radionuclides and long-lived radionuclides such as uranium by gamma and alpha spectrometric techniques. The specific activities of 238U series, 232Th series and 40K (Bq/kg) were measured by gamma spectrometry based on Hyper-Pure Germanium detector (HPGe). The average specific activities of 226Ra(238U) series, 232Th series and 40K were ranged from 3.04 ± 1.10 to 14.70 ± 1.24 Bq/kg, from 1.12 ± 0.66 to 16.10 ± 1.30 and from 77 ± 4.90 to 350.50 ± 8.90 Bq/kg respectively. The concentration of 238U and 234U in the streambed sediments are ranged from 3.24 ± 0.21 to 13.34 ± 0.61 ppm and from 3.18 ± 0.02 to 13.77 ± 0.03 ppm in dry weight respectively. 234U/238U ratios of the sediments are relatively lower than unity in many locations indicating the preferential uranium leaching process. The results with the high ratios for 234U/238U were observed in the sediment collected from Port Said. This may be attributed to the sorption of uranium by sediment which has a relatively high content of organic matter. The geochemical behavior of sediment, the chemistry of uranium and the flow rates of water are considered as the most important factors controlling uranium isotopic composition of the streambed sediment. The result of radioactivity in sediment samples can be used to distinguish any future changes due to non-nuclear industries on the Suez Canal area.展开更多
This paper describes a radioactive tracer experiment carried out at the landward spoil site of the North Passage in the Yangtze Estuary in June, 1991. Scandium -46 was selected as the tracer, the total activity releas...This paper describes a radioactive tracer experiment carried out at the landward spoil site of the North Passage in the Yangtze Estuary in June, 1991. Scandium -46 was selected as the tracer, the total activity released was 179.45 GBq and the amount of the Sandium-46 glass was 495 g. The purpose of the experiment was to determine the sediment movement direction, path, velocity and transport rate, and therefore, to provide direct evidence for using the landward spoil site in the future. The experimental results showed that the sediment movement was governed by the ebb tide current during the period of mean and neap tides when the radioactive tracer was injected both on the flood and ebb tides, and the sediment moved from the release point to the middle of the North Passage near navigation buoy No. 269. The direciton of the sediment movement was 110 ° , the particle velocity was 758 m/d, and the sediment transport rate per unit width was 47.8 m3 / md.展开更多
In this study, iridium (Ir) was selected as a signal element, the chemical adsorption tagging method was adopted to make the tracer sediments, the neutron activation analysis method was used to determine the signal el...In this study, iridium (Ir) was selected as a signal element, the chemical adsorption tagging method was adopted to make the tracer sediments, the neutron activation analysis method was used to determine the signal element content in sediments, and the sediment transport law was judged according to the movement characteristics of the signal elements. This method overcomes the shortcomings of the fluorescent sediment technique and radioactive tracer sediment technique. It is capable of simulating truly the movement characteristics of natural sediments. Therefore, it is an advanced technique for observation of the sediment movement. The expectant effects were obtained in the experiment on the first domestic practical application of this method carried out in Tianjin Port.展开更多
文摘The streambed sediments of the Suez Canal have been analyzed for determining the natural radionuclides and long-lived radionuclides such as uranium by gamma and alpha spectrometric techniques. The specific activities of 238U series, 232Th series and 40K (Bq/kg) were measured by gamma spectrometry based on Hyper-Pure Germanium detector (HPGe). The average specific activities of 226Ra(238U) series, 232Th series and 40K were ranged from 3.04 ± 1.10 to 14.70 ± 1.24 Bq/kg, from 1.12 ± 0.66 to 16.10 ± 1.30 and from 77 ± 4.90 to 350.50 ± 8.90 Bq/kg respectively. The concentration of 238U and 234U in the streambed sediments are ranged from 3.24 ± 0.21 to 13.34 ± 0.61 ppm and from 3.18 ± 0.02 to 13.77 ± 0.03 ppm in dry weight respectively. 234U/238U ratios of the sediments are relatively lower than unity in many locations indicating the preferential uranium leaching process. The results with the high ratios for 234U/238U were observed in the sediment collected from Port Said. This may be attributed to the sorption of uranium by sediment which has a relatively high content of organic matter. The geochemical behavior of sediment, the chemistry of uranium and the flow rates of water are considered as the most important factors controlling uranium isotopic composition of the streambed sediment. The result of radioactivity in sediment samples can be used to distinguish any future changes due to non-nuclear industries on the Suez Canal area.
文摘This paper describes a radioactive tracer experiment carried out at the landward spoil site of the North Passage in the Yangtze Estuary in June, 1991. Scandium -46 was selected as the tracer, the total activity released was 179.45 GBq and the amount of the Sandium-46 glass was 495 g. The purpose of the experiment was to determine the sediment movement direction, path, velocity and transport rate, and therefore, to provide direct evidence for using the landward spoil site in the future. The experimental results showed that the sediment movement was governed by the ebb tide current during the period of mean and neap tides when the radioactive tracer was injected both on the flood and ebb tides, and the sediment moved from the release point to the middle of the North Passage near navigation buoy No. 269. The direciton of the sediment movement was 110 ° , the particle velocity was 758 m/d, and the sediment transport rate per unit width was 47.8 m3 / md.
基金the National Natural Science Foundation of China
文摘In this study, iridium (Ir) was selected as a signal element, the chemical adsorption tagging method was adopted to make the tracer sediments, the neutron activation analysis method was used to determine the signal element content in sediments, and the sediment transport law was judged according to the movement characteristics of the signal elements. This method overcomes the shortcomings of the fluorescent sediment technique and radioactive tracer sediment technique. It is capable of simulating truly the movement characteristics of natural sediments. Therefore, it is an advanced technique for observation of the sediment movement. The expectant effects were obtained in the experiment on the first domestic practical application of this method carried out in Tianjin Port.
基金supported by the Science and Technology Plan Project of Qinghai Province(2022-ZJ-732)“Kunlun Talents·High-end Innovative and Entrepreneurial Talents”Plan Project(Grant to Chunliang Gao)the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0805)。
