1000 resultados para Bottom grab (Smith-McIntyre)


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Food security is important. A rising world population coupled with climate change creates growing pressure on global world food supplies. States alleviate this pressure domestically by attracting agri-foreign direct investment (agri-FDI). This is a high-risk strategy for weak states: the state may gain valuable foreign currency, technology and debt-free growth; but equally, investors may fail to deliver on their commitments and exploit weak domestic legal infrastructure to ‘grab’ large areas of prime agricultural land, leaving only marginal land for domestic production. A net loss to local food security and to the national economy results. This is problematic because the state must continue to guarantee its citizens’ right to food and property. Agri-FDI needs close regulation to maximise its benefit. This article maps the multilevel system of governance covering agri-FDI. We show how this system creates asymmetric rights in favour of the investor to the detriment of the host state’s food security and how these problems might be alleviated.

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Analysis of composition and distribution of benthic foraminifers in six samples of bottom sediments obtained in the southeast Kandalaksha Bay of the White Sea at water depths of 20 to 155 m revealed their dependence on lithology and different hydrological characteristics. It is shown that living foraminifers populating relatively shallow areas of the bay (20-60 m), which are bathed by seasonally warmed intermediate water with temperature 0.7-1.5°C and salinity 26 per mil, are characterized by high abundance (250-750 specimens/10 ccm of wet sediment) and prevalence of agglutinated species (Eggerella advena, Recurvoides turbinatus, and others). Deeper (155 m) where cold and relatively saline deep water occurs (-1.4°C, 29.5 per mil), abundance is an order lower (30 specimens/10 ccm) and is dominated by calcareous taxa Cassidulina reniforme, an Arctic cold resistant species.

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Contents of labile (acid-soluble) sulfides were determined in the upper layer of bottom sediments at 80 stations on the Caucasian shelf of the Black Sea. Maximum values of this parameter occurred in black mud accumulated in zones of intense pollution in the Gelendzhik and Tsemess bays and in shelf areas adjacent to large health resort objects and to seaports. Contents of acid-soluble sulfides in sediments varied from 400 to 900 mg S/dm**3 of wet mud. In zones of moderate pollution they varied from 200 to 400 mg S/dm**3. Rate of sulfate reduction was 10-40 mg S/dm**3 of wet sediment per day. Obtained data show that accumulation of labile sulfides in the upper layer of shelf bottom sediments is directly related to anthropogenic pollution and is one of the most hazardous environmental aftereffects.

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Two shelf communities from the central part off the California Peninsula are described. The community of Amphiodia urtica - Nephtys ferruginea develops in the central part of the shelf within the depth range 95-105 m. The community of Nephtys ferruginea - Amphiura acrystata develops on the shelf edge at depth 110 m. Biomasses of both communities are very low (about 10 g/m**2). Species richness of the shelf community is high; more than 60 species occur in samples (43-51 species per a community). Various echinoderms and some other groups are abundant on the Californian shelf; these groups are absent in shelf areas of Peruvian and Benguela upwellings. Species structures of the communities were analyzed; the communities were shown to consist of coexisting, but not interacting guilds; this indicates that the communities are undersaturated with individuals. At the same time values of ABC-indices indicate that the communities are stable. We suggest that in this case adaptation to unfavorable but stable environment is observed (selection of species-stressolarents). An explanation seems to lie in the penetrating type of the upwelling in the Californian upwelling zone. Low biomass values seem to result from mass development of necto-benthic carnivorous crustaceans-galateids Pleuroncodes planiceps.

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Two radiolarian assemblages are distinguished: an equatorial sub-assemblage of the tropical assemblage in the East Pacific Ocean, which differs somewhat from association of radiolarians in the western part of the ocean, and an assemblage close to transitional one between the tropical and the boreal. The latter is characterized by presence of considerable number of species typical for cold-water regions. Some criteria are presented for distinguishing radiolarian associations in nearshore regions from similar associations in regions of the open ocean.

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Distribution and composition of lipids and contents of alkanes and polycyclic aromatic hydrocarbons(PAHs) in bottom sediments of the Scotia and Weddell seas are discussed. Comparatively low concentrations of organic carbon (average 0.35%) and lipids (average 0.024%) result from rapid decomposition of organic matter in upper layers of the water column. Composition of alkanes indicates that lipids are of autochthonous origin, and stable concentrations of PAHs (average 25.8 ppb, sigma 15.3 ppb) indicate that they represent the background level for bottom sediments. Higher concentrations of PAHs in sediments near the King George Island (252.1 ppb) and different distributions of individual polyarenes are produced there by the heating systems of the Polish Antarctic Station.

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Macrobenthos biomass and bottom biocoenoses were studied in the sublittoral zone of the southern East Siberian Sea. The macrobenthos is characterized by relatively high abundance (from 30 to 2680 #/m**2), biomass (from 0.25 to 578.8 g/m**2), and diversity (83 species in total). Lateral distribution of macrobenthos biomass correlates with a substrate type and salinity and is substantially higher in areas washed by the Arctic water mass than in estuaries with mixed fresh and Arctic waters and shows a tendency to decreasing in the convergence zone of different water masses. The highest macrobenthos biomass is observed in cores of water masses in the Long Strait area and in the eastern part of the sea.

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This work was based on a study of the upper layer of recent carbonate bottom sediments of the Atlantic Ocean. Biogenic carbonate of recent sediments is represented by metastable and stable minerals. In the ocean metastable phases can exist indefinitely long, but the structure of polymorphism determines inevitability of transformation of metastable phases into stable ones. This transformation occurs in the solid phase. In the absence of a critical point between the two phases of the transition process is not available for study by microscopic methods. It is estimated indirectly by studying the nature and extent of changes in mineral and chemical compositions. With aging of sediments their mineral composition alters in direction of increasing contents of resistant minerals. Fine grained sediments and fractions are subject to more intensive effects of early diagenesis processes, rather than coarse ones; this is reflected in their mineral composition. Regularities of distribution of carbonate minerals in size fractions consistent with the direction of polymorphic transformations in calcium carbonate. Such transformations can occur in a particular dimension of grains. Concrete grain size depends on environmental conditions. This situation explains presence of metastable biogenic carbonates at different depths of the ocean and suggests presence of diagenetic calcite in sediments occurring below expected for each case depth of the transition.