28 research outputs found

    Environmentally Sound Desludging Concept for Hoan Kiem Lake in Hanoi Vietnam

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    AbstractDue to urbanization, more and more lakes are being swallowed up by the catchments of growing cities. The ecosystem of shallow, small to mid-sized lakes reacts very sensitively to changing environmental conditions. Water quality deteriorates as a result of sewage discharge, higher water extraction, and the growing inflow of urban suspended solids. Since water bodies and, in particular, lakes are very important for the microclimate, urban beautification and recreational purposes, they need to be protected. Therefore, many growing cities are developing management concepts for urban lakes. A Vietnamese–German research project developed and applied a sustainable concept to remediate urban shallow lakes in tropical regions. This paper provides an insight into the current situation of Hoan Kiem Lake in the center of Hanoi as well as other urban water bodies in Asia, and presents approaches for environmentally sound remediation and sustainable water management

    Enceladus as a potential oasis for life: Science goals and investigations for future explorations

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    International audienceEnceladus is the first planetary object for which direct sampling of a subsurface water reservoir, likely habitable, has been performed. Over a decade of flybys and seven flythroughs of its watery plume, the Cassini spacecraft determined that Enceladus possesses all the ingredients for life. The existence of active eruptions blasting fresh water into space, makes Enceladus the easiest target in the search for life elsewhere in the Solar System. Flying again through the plume with more advanced instruments, landing at the surface near active sources and collecting a sample for return to Earth are the natural next steps for assessing whether life emerges in this active world. Characterizing this habitable world also requires detailed mapping and monitoring of its tidally-induced activity, from the orbit as well as from the surface using complementary platforms. Such ambitious goals may be achieved in the future in the framework of ESA large or medium-class missions in partnership with other international agencies, in the same spirit of the successful Cassini-Huygens mission. For all these reasons, exploring habitable ocean worlds, with Enceladus as a primary target, should be a priority topic of the ESA Voyage 2050 programme

    Enceladus as a potential oasis for life: Science goals and investigations for future explorations

    Get PDF
    Enceladus is the first planetary object for which direct sampling of a subsurface water reservoir, likely habitable, has been performed. Over a decade of flybys and seven flythroughs of its watery plume, the Cassini spacecraft determined that Enceladus possesses all the ingredients for life. The existence of active eruptions blasting fresh water into space, makes Enceladus the easiest target in the search for life elsewhere in the Solar System. Flying again through the plume with more advanced instruments, landing at the surface near active sources and collecting a sample for return to Earth are the natural next steps for assessing whether life emerges in this active world. Characterizing this habitable world also requires detailed mapping and monitoring of its tidally-induced activity, from the orbit as well as from the surface using complementary platforms. Such ambitious goals may be achieved in the future in the framework of ESA large or medium-class missions in partnership with other international agencies, in the same spirit of the successful Cassini-Huygens mission. For all these reasons, exploring habitable ocean worlds, with Enceladus as a primary target, should be a priority topic of the ESA Voyage 2050 programme

    Taxonomy of the heavily exploited Indo-Pacific sandfish complex (Echinodermata: Holothuriidae)

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    Two commercially valuable holothurians, the sandfish and golden sandfish, vary in colour and have a confused taxonomy, lending uncertainty to species identifications. A recent molecular study showed that the putative variety Holothuria (Metriatyla) scabra var. versicolor Conand, 1986 (‘golden sandfish’) is a distinct species from, but could hybridize with, H. (Metriatyla) scabra Jaeger, 1833 (\u27sandfish\u27). Examination of the skeletal elements and external morphology of these species corroborates these findings. The identity of H. (M.) scabra is unambiguously defined through the erection and description of a neotype, and several synonyms have been critically re-examined. The nomenclaturally rejected taxon H. (Metriatyla) timama Lesson, 1830 and H. (M.) scabra var. versicolor (a nomen nudum) are herein recognized as conspecific and are allocated to a new species, Holothuria lessoni sp. nov., for which type specimens are described. The holotype and only known specimen of H. aculeata Semper, 1867, has been found and is redescribed. It is considered to be a valid species. Taxonomic clarification of this heavily exploited species complex should aid its conservation and permit species-specific management of their fisheries
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