30 research outputs found

    Thickness of unconsolidated sediments in the eastern Mediterranean Sea

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    The unconsolidated sedimentary layer in the eastern Mediterranean Sea becomes more variable in thickness toward the east. The distribution pattern suggests that the primary sources of sediment in Cenozoic times have been the Nile River, elevated areas of Cyrenaica, the Taurus, and the Apennines.Submitted to the Office of Naval Research under contract Nonr-4029 (00); NR 260-101, and partially supported by National Science Foundation Grants GP-2370 and GA-283

    Lake Kivu expedition : geophysics, hydrography, sedimentology (preliminary report)

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    In March 1971, seven members of the Woods Hole Oceanographic Institution were engaged in a multidisciplinary study of Lake Kivu. This expedition represents part of a long-range program concerned with the structural and hydrographical settings of the East African Rift Lakes and their relationships to the Red Sea and the Gulf of Aden Rifts. The program started in May 1963 with a geophysical study on Lake Malawi (von Herzen and Vacquier, 1967). Several expeditions of our Institution into the Red Sea and Gulf of Aden area in 1964, 1965 and 1966 (Degens and Ross, 1969) provided detailed geological information on the "northern" extension of the East African Rift. And finally our study of last year on Lake Tanganyika c1osed a major gap in the program; it allowed us to out1ine a model on the evolution of a rift which starts with (i) bulging of the earth's crust, (ii) block-faulting, (iii) volcanism and hydrothermal activity, and which has its final stage in (iv) sea floor spreading (Degens et al. 1971). In the case of Lake Tanganyika, only the second stage of this evolution series has been reached, i.e. block-faulting. In contrast, the Red Sea and the Gulf of Aden had already evolved to active sea floor spreading, almost 25 million years ago. Somewhere along the line between Lake Tanganyika and the Gulf of Aden must lie the "missing link" of this evolution series. Lake Kivu, almost 100 miles to the north of Lake Tanganyika is situated at the highest point of the Rift Valley and is surrounded by active volcanoes and geothermal springs. As recently as 1944, lava flows reached the lake shore. This lake was therefore, a natural choice to test our hypothesis on the origin and development of rifts. Furthermore, the occurrence of large quantities of dissolved gases, e.g., CO2 and methane, represented an interesting geochemical phenomenon worthwhile to investigate.Supported by the National Science Foundation with Grants GA 19262, GB 20956, and GU 3927; grants from the Petroleum Research Fund of the American Chemical Society PRF#1943A2; and by private research funds of the Woods Hole Oceanographic Institution

    Fractionation and extraction of bio-oil for production of greener fuel and value-added chemicals : Recent advances and future prospects

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    Bio-oil is a highly valuable product derived from biomass pyrolysis which could be used in various downstream applications upon appropriate upgrading and refining. Extraction and fractionation are two promising methods to upgrade bio-oil by separating the complex mixture of bio-oil compounds into distinct fine chemicals and fractions enriched in certain classes of chemical compounds. In this review, various extraction techniques for bio-oil (organic solvent extraction, water extraction, supercritical fluid extraction, distillation, adsorption, chromatography, membrane, electrosorption and ionic liquid extraction), their associated features (extraction mechanisms involved, advantages and disadvantages), the characteristics of bio-oil extracts and their applications are presented and critically discussed. It was revealed that the most promising technique is via organic solvent extraction. Furthermore, the technological gaps and bottlenecks for each separation techniques are disclosed, as well as the overall challenges and future prospects of oil palm biomass-based bio-oil value chain. This review aims to provide key insights on bio-oil upgrading via extraction and fractionation, and a proposed way forward via technology integration in establishing a sustainable palm oil mill-based biorefinery

    Hydrogen sulfide (H2S) conversion to hydrogen (H2) and value-added chemicals : Progress, challenges and outlook

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    Hydrogen sulfide (H2S) is a toxic gas released from natural occurrences (such as volcanoes, hot springs, municipal waste decomposition) and human economic activities (such as natural gas treatment and biogas production). Even at very low concentrations, H2S can cause adverse health impacts and fatality. As such, the containment and proper management of H2S is of paramount importance. The recovered H2S can then be transformed into hydrogen (H2) and various value-added products as a major step towards sustainability and circular economy. In this review, the state-of-the-art technologies for H2S conversion and utilization are reviewed and discussed. Claus process is an industrially established and matured technology used in converting H2S to sulfur and sulfuric acid. However, the process is energy intensive and emits CO2 and SO2. This calls for more sustainable and energy-efficient H2S conversion technologies. In particular, recent technologies for H2S conversion via thermal, biological, plasma (thermal and non-thermal), electrochemical and photocatalytic routes, are critically reviewed with respect to their strengths and limitations. Besides, the potential of diversified value-added products derived from H2S, such as H2, syngas, carbon disulfide (CS2), ammonium sulphate ((NH4)2SO4), ammonium thiosulfate ((NH4)2S2O3), methyl mercaptan (CH3SH) and ethylene (C2H4) are elucidated in detail with respect to the technology readiness level, market demand of products, technical requirements and environmental impacts. Lastly, the technological gaps and way forward for each technology are also outlined

    Geophysical studies of sediments in waters near Hong Kong and in the Gulf of St. Lawrence

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    Thickness of unconsolidated sediments in the eastern Mediterranean Sea

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    The unconsolidated sedimentary layer in the eastern Mediterranean Sea becomes more variable in thickness toward the east. The distribution pattern suggests that the primary sources of sediment in Cenozoic times have been the Nile River, elevated areas of Cyrenaica, the Taurus, and the Apennines.Submitted to the Office of Naval Research under contract Nonr-4029 (00); NR 260-101, and partially supported by National Science Foundation Grants GP-2370 and GA-283

    The Mud Area Southeast of Helgoland: A Reflection Seismic Study

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    In the Middle Miocene, two halotectonic depressions were formed in the German Bight. While the western depression, Helgoland Hole, still exists more or less intact today, the Eastern Depression persisted as a palimpsest structure only through the Pleistocene into the Early Holocene. About 8,000 years B.P., as sea level rose to about -40 m, a small embayment formed east and southeast of Helgoland. It was bounded to the north by the Steingrund ridge which stretched from Eiderstedt Peninsula to the Helgoland platform, so that water circulation in the north-south direction was highly restricted. The Elbe and Weser were deflected to the west to deposit their suspended material and bed load in the Eastern Depression. Before this depression could be completely filled up about 1,500 years B.P., however, the Steingrund ridge was breached with rising sea level, and the modern, basically northsouth current pattern was established. Simultaneously, the filled Eastern Depression (the Mud Area) became progressively more distal, so that sedimentation came to a halt. Today, sediment deposition is largely controlled by anthropogenic activities, in particular by the dumping of dredged fine harbour mud. This material forms a small lenticular body superimposed on the coarser, larger sediment lens of fine sand and silt
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