Neutron activation technique using a low intensity252Cf source has been applied for Mn and Na analysis in geological samples. The series of samples tested in the present work
were collected from the boreholes Nádudvar-9, Hajdúböszörmény-1 and Nagyecsed-1 in Hungary, from different strata.
The applicability of fast and thermal neutron activation analyses for the determination of gold in rock samples has been studied.
Using a Ge/Li/ detector limit of 0.45 mg g−1 was obtained for a fast neutron flux of 8.107 n cm−2.s−1. With a thermal neutron flux of 6.105 n cm−2.s−1 and the same detector a value of 35 μg g−1 was obtained. Using a NaI/Tl/ crystal a sensitivity of 14 μg g−1 was attained at the same thermal flux.
A method for simultaneous determination of uranium and thorium based on the deviation of their fission cross-section curves has been developed. Using a D-T neutron generator two different neutron spectra were produced with and without moderator around the target. The detection limits were found to be 0.044 mg and 0.25 mg in the presence of a moderator, while for fast neutrons 0.017 mg and 0.037 mg for uranium and thorium, respectively.
Authors:H. Essekhyr, K. Khalil, Z. Damsiri, G. Derhy, and K. Elkalay
The Moroccan Atlantic coast is considered as one of the richest fishing areas in the world, having rich biodiversity, and supporting the fisheries sector. However, studies have shown that the ecosystem presently suffers from overexploitation of fishery resources and environmental degradation. To quantify these impacts, the characterization of the ecosystem is essential. In this work, an Ecopath model (EwE), which assumes steady-state and mass-balanced conditions for the Moroccan Atlantic coast ecosystem, was developed and balanced. Network analysis included in the Ecopath software package was used to estimate trophic interactions and the maturity of the ecosystem. The model consisted of 29 functional groups. The results showed a Total System Throughput (TST) which is comprised mainly of flows into detritus, followed by export, consumption, and respiration. Systemic indicators, suggest that the Moroccan Atlantic coast is an immature and developing ecosystem. Further observations on the functioning and dynamics of the ecosystem are discussed.