983 resultados para Benthocosm D2


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Microscopic and electron probe examination of some manganese nodules show that they consist of segregations of manganese-iron oxides in an interstitial material almost free of manganese but rich in iron and silicates. The segregations are widely spaced in the volcanic cores of the nodules but become more abundant towards their outer crusts where they form the centres of linked polygons of interstitial materials. Most of the minor elements are concentrated in the segregations compared to the interstitial materials. It is suggested that the structures observed result partly from solution and reprecipitation of elements in the original volcanic cores of the nodules and partly from the replacement and coating of these cores by manganese-iron oxides precipitated from sea water.

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The purpose of the expedition was to test new techniques to determine thickness, distribution and quality of mineral deposits on the Blake Plateau with special reference to manganese nodules and manganese-phosphate pavements.

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This report gives a comprehensive general description of the scientific activities of Cruise 2 of R. R. S. 'Discovery'. These were largely geological and geophysical and were part of the British contribution to the International Indian Ocean Expedition. In addition to the thirteen geophysicists and geologists on board, there were five scientists involved in ocean chemistry, temperature measurements and ornithology making continuous observations - their accounts are also included. The report of a geological expediton ashore in the Seychelles is given in section 6.

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The Kiel Outdoor Benthocosm infrastructure (Kiel, Germany,N 54°19.8'; E 010°09.0') allows combining natural in-situ fluctuations on all environmental variables with the controlled manipulation of treatment factors. The environmental fluctuations are admitted by a continuous flow-through of fjord water. The treatment is applied by delta-treatments which shift the mean of target variables (temperature and pH in this case) while maintaining the frequency and amplitude of natural fluctuations. The data presented here show the treatment levels and the continuously logged temperature and pH conditions in the experimental tanks. The dynamics of temperature and pH are driven by (i) in situ variability, (ii) the treatments imposed and (iii) the biology of the biota in the tanks. These contained macroalgal communities with associated mesograzers, mussels, and sea stars. The data set comprised 5 experimental runs: spring experiment (4.4.-19.6.2013), summer experiment 1 (4.7.-17.9.2013), autumn experiment (10.10-17.12.2013), winter experiment (16.1. - 1.4.2014), summer experiment 2 (10.7. - 26.9.2014).

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The perception of the present state of trade relations with Chile is obscured by a lack of adequate understanding of its legal framework as well as of the policy behind it. This study attempts to clarify the present state of and future prospects for trade between the EU and Chile through an examination of previous agreements and the EU’s new approach to trade liberalisation. The authors agree with the large consensus existing on both the EU and Chilean sides regarding the efficacy of the Association Agreement, but note that any extension of an agreement with Chile should capture the spirit of older EU agreements rather than simply following the ‘NAFTA route’. The study also includes a comparative analysis between the EU-Chile agreement and current trade agreements being negotiated by the EU and Chile with third countries.

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The first part of this thesis includes some topics of a non-geochemical nature but which are of importance in interpreting the geochemistry of nodules. The points covered include their distribution, petrography, structure, mineralogy and internal compositional variations. Part Two includes the geochemistry of both nodules and that of their surrounding sediments, This geochemical study has been divided into firstly, a general geochemical study of both nodules and sediments using a statistical approach to the interpretation of the data, secondly, the regional geochemistry of Pacific and Indian Ocean nodules and sediments, the latter entirely uninvestigated in the past, and thirdly, local variations in the composition of nodules. Throughout, emphasis has been placed on the geochemistry of nodules in terms of their environment of formation.