摘要:

The paper describes isotope studies carried out in Tattapani, Puga and Manikaran geothermal areas in India.

ISSN:0021-1915    

DOI:10.1080/10256019108622498

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The boron isotopic ratios,11B/10B, of a hot spring water and a rock which were expected to have been in direct contact with each other in nature were measured mass spectrometrically. The water showed a larger11B/10B value than the rock and the value of the separation factor between the two was 1.013. The observed result was consistent with what was theoretically expected.

ISSN:0021-1915    

DOI:10.1080/10256019108622499

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

An application of stable isotope distribution of bioelements to ecogeochemical and archaeological studies requires precise knowledge on the relationship between available field samples and diet. As the nature of birds makes it possible to set up an isotopically well defined experiment, nitrogen and carbon isotope relationships between various tissues of a cormorant and its constant diet was studied. The tissues were collected after more than 23 years on the same diet. The two stable isotope ratios for the diet and the tissues showed a high correlation (r = 0.92). The linear regression analysis gave the slope of 1.1. Among the tissues examined, skin showed the highest enrichment in both15N (4.8‰) and13C (4.2‰), while brain gave the lowest enrichments (0.8‰ for15N and 1.1‰ for13C).

ISSN:0021-1915    

DOI:10.1080/10256019108622500

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Groundwater samples collected from a number of localities, in Al-Maghara area, north central part of Sinai, were subject to various chemical and isotopic analysis. The purpose of the study is to determine whether the groundwaters are recently recharged or not in order to adopt an efficient water management policy. The hydrochemical results indicate that they are mainly of primary marine origin, dilution of this water by meteoric water changes its chemical composition to be mixed water type, which has the major chemical components:

ISSN:0021-1915    

DOI:10.1080/10256019108622501

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A hydrochemical and environmental isotopes study was undertaken for Mallawi area in El-Minia province in upper Egypt. The results of hydrochemical analysis indicate that the salinity ranges from 200–950 ppm and that the predominate water type is meteoric and mixed water. The interrelation between different anions and cations were discussed in terms of probable different contribution of dissolution of either halide minerals or gypsum or limestone rocks. The correlation between the deuterium content and the salinity as well as the major anions has been studied to determine the recharge source. The results indicate a trend of decrease of salinity chloride and sulphate content with increasing deuterium concentration, while the bicarbonate shows the opposite relationship. The hydrochemical and environmental isotopes data point out a recent recharge of groundwater with some contribution of palaeowater (characterized by low content of deuterium, oxygen 18 and no tritium). This contribution is different from well to another and is clearer in the Eastern fringe than in the Western Part of the River Nile Valley.

ISSN:0021-1915    

DOI:10.1080/10256019108622502

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

As a contribution of safety assessment of the underground repository for radioactive wastes (ERA) in Morsleben isotope investigations in the hydrosphere has been carried out. The measured tritium concentrations of brines infiltrating into the mine cannot be interpreted in a conventional way due to contamination of mine air with tritium. However, modelling the isotope exchange allows conclusions regarding the water balance of the dripping brines. A complex interpretation which includes hydrogeochemical data results in a qualitative assessment of the infiltrating brines in regard to their hazard potential. An acute danger cannot be derived from the data available up to the present. The natural input of cosmogenic radionuclides (tritium, radiocarbon) into the aquifers above the salt level permits to study radionuclide migration at the ERA site. Tritium from the nuclear weapon tests is detectable up to a depth of 50 m below groundwater level with a maximum in about 20 m. From these data infiltration velocities of 1.6 m/a at maximum and 0.9m/a in avarage arc derived. The14C measurements of samples from more than 100 m depth yield model ages in the order of 104years. This indicates a significantly reduced groundwater dynamic in the deeper horizons.

ISSN:0021-1915    

DOI:10.1080/10256019108622503

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

CR-39 and LR-115 plastic detectors were used in air volume of several sealed cylinderical plastic tubes (can-technique) for time integrated long term measurement of radon activity concentrations. Dried soil samples, collected from the Egyptian Nile delta, were used. The tubes, 3.8 cm inner diameter and 20–170 cm in heights, were filled at the bottom with the dry soil samples up to different thicknesses (10–160 cm). The registeration sensitivities of CR-39 and LR-115 nuclear plastic detectors in the sealed tube, taking into consideration the plated-out activity on the walls, are discussed. The porosity of the soil samples, the diffusion length, the effective and real radium-226 contents were estimated. The results showed that the sealed tube technique could be used as a useful tool for the measurement of the radium concentration with reasonable accuracy.

ISSN:0021-1915    

DOI:10.1080/10256019108622504

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

CR-39 and LR-115 plastic nuclear track detectors in the can-technique have been employed in the field measurements of radon exhalation, Ra-226 and U-238 content in dry-soil air at numerous regions in Sudan (the Blue and White Nile and Mogran regions). Measurements gave an average radon exhalation from the soil to the atmosphere and Ra-226 content of (23.4 ± 2.60) kBq · m−2and (123 ± 13.65) Bq · kg−1respectively. A polyethylene permeable membrane cover was used to eliminate the contribution of thoron activity inside the can. Assuming a radioactive equilibrium between the U-series, the average U-238 content in the soil was found to be (9.92 ± 1.01) ppm. This survey may be used for uranium prospection in soil.

ISSN:0021-1915    

DOI:10.1080/10256019108622505

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The plate-out of radon progeny on the surface of CR-39 track detector and the walls of an aluminium can is investigated. Radium chloride solution is used as a radon source inside a can containing CR-39 nuclear track detector at the top and wall of the can. As a result, Rn daughter products will be airborne inside the can. These isotopes will quikly plated-out on the can surface and the detector. The degree of the platedout activity on the walls is estimated to be 50% in a can of radius 5 cm and height 11 cm. The effect of the electrostatic charge on the walls and the detector surfaces are also discussed.

ISSN:0021-1915    

DOI:10.1080/10256019108622506

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Sealed can- and alpha-autoradiography techniques were used to estimate the effective and real contents of Ra-224 respectively in Egyptian black sand samples collected from Rosetta City in the Nile Delta at the North Coast of Egypt. The effective Ra-224 content was found to be 15 ± 3 Bq · kg−1. From the average chemical composition of the black sand samples, the range-energy relation for the alpha-particles of the thorium series was calculated. Assuming radioactive equilibrium, the real Ra-224 content for samples collected from different regions were found to range from 90 to 900 Bq · kg−1. As a result, the total emanation power was measured and then used to estimate grain diameter of the black sand. The average mass exhalation rate of the different locations in Rosetta City was also estimated.

ISSN:0021-1915    

DOI:10.1080/10256019108622507

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor