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91.
92.
Lemkau KL Peacock EE Nelson RK Ventura GT Kovecses JL Reddy CM 《Marine pollution bulletin》2010,60(11):2123-2129
Understanding the fate of heavy fuel oils (HFOs) in the environment is critical for sound decisions regarding its usage and spill cleanup. To study weathering of HFOs, we examined the M/V CoscoBusan spill (November 2007; San Francisco Bay, CA, USA). In this baseline report, we identified which ruptured tank (port tank 3 or 4) was the source of the spilled oil and characterized changes in the oil composition across location and time. Samples from three impacted shorelines, collected within 80 days of the spill, were analyzed using one- and two-dimensional gas chromatography (GC and GC × GC, respectively). Weathering varied across sites, but compounds with GC retention times less than n-C16 were generally lost by evaporation and dissolution. Changes in n-C18/phytane and benz[a]anthracene/chrysene ratios indicated some biodegradation and photodegradation, respectively. 相似文献
93.
ABSTRACTThis article analyses the nexus of technocracy–peacebuilding and its implications on water conflicts and hydropolitics. It is a conceptual exploration which advances an interdisciplinary approach by combining theories from two distinct research fields: peacebuilding and transboundary water management. It probes the argument that synergies between water management, development and peacebuilding frequently lead to technocratic and functional solutions. As empirical case illustration, the transboundary project, the Red Sea–Dead Sea Water Conveyance (RSDSWC) is analysed regarding its peacebuilding and peace promoting potential. Three concluding remarks are drawn from the conceptual and empirical analysis. First, strong emphasis on technocratic solutions is inclined to favour supply-oriented options rather than solutions based on ethics of sustainable development and rights-based distribution. Second, functional solutions to water conflicts downplay at times complex hydro-political and asymmetrical relations between adversaries. Third, wider trends of privatization in the water sector coincide with similar developments in the field of peacebuilding, where new transnational actors are gaining influence as “new peacemakers”, which are likely to have long-term consequences on power relations and the resolution of water conflict.
EDITOR D. Koutsoyiannis; ASSOCIATE EDITOR not assigned 相似文献
94.
Stabilisation of soil organic matter by interactions with minerals as revealed by mineral dissolution and oxidative degradation 总被引:4,自引:0,他引:4
Karin Eusterhues Cornelia Rumpel Markus Kleber Ingrid Kgel-Knabner 《Organic Geochemistry》2003,34(12):1591-1600
Soil organic matter is known to contain a stable fraction with an old radiocarbon age. Size and stabilisation processes leading to the formation of this old soil carbon pool are still unclear. Our study aims to differentiate old organic matter from young and labile carbon compounds in two acid forest soils (dystric cambisol, haplic podzol). To identify such fractions soil samples were exposed to oxidation with Na2S2O8 and to dissolution by hydrofluoric acid (HF). A negative correlation between 14C activity and carbon release after dissolution of the mineral matrix by HF indicates a strong association of stabilised carbon compounds with the mineral phase. A negative correlation between the 14C activity and the relative proportion of carbon resistant to oxidation by Na2S2O8 shows that young carbon is removed preferentially by this treatment. The fraction remaining after oxidation represents a certain stabilised, long residence time carbon pool. This old fraction comprises between 1 and 30% of the total soil organic carbon in the surface horizons, but reaches up to 80% in the sub-surface horizons. Old OC is mainly stabilised by organo-mineral associations with clay minerals and/or iron oxides, whereas intercalation in clay minerals was not found to be important. 相似文献
95.
Karin M. Borenäs 《地球物理与天体物理流体动力学》2013,107(1-4):115-132
Abstract The stability of a rotating, stationary flow of zero potential vorticity in a slowly varying channel is examined using the method of multiple scales. This technique can be applied when the variations of the basic flow occur on a length scale which is much larger than the one associated with the perturbation. To lowest order the disturbance is described by a propagating part multiplied by a slowly changing amplitude. It is shown that when the phase speed of a disturbance approaches zero, the growth of the amplitude becomes unbounded. This happens when a perturbation superimposed upon a flow which is slightly sub/supercritical, or which alters from a super- to a subcritical state, propagates over a shoaling bottom. If, however, the change of the basic flow is from a sub- to a supercritical state, the phase speed is quite large and the amplitude of the perturbation will just show minor variations along the channel. The same holds true if the steady flow is only moderately affected by the changing topography. The problem has also been analyzed using wave-action formalism, and the outcome of this alternative approach to the stability problem proved to conform to the previously obtained results. Finally, an interpretation of the calculated growth rates is undertaken in terms of “convective” amplification and “absolute” instability. 相似文献
96.
Abstract: Coastal research and monitoring on New Zealand beaches have typically examined seasonal and event-driven (storms) changes in the coast. However, historical records are now of sufficient length to indicate that change occurs at longer timescales. This paper presents examples of multi-decadal change at three case-study locations around New Zealand. Results show that morphological adjustment of the coast occurs at multi-decadal scales and is much larger than short-term dynamics. Physical mechanisms driving changes are ill defined but may be associated with El Niños and La Niña episodes which modulate waves and sea level, as well as changes in sediment supply. 相似文献
97.
Karin Antonsson Heikki Seppä 《Boreas: An International Journal of Quaternary Research》2007,36(4):400-410
Inferred mean annual temperatures (Tann) from a radiocarbon-dated fossil pollen stratigraphy obtained from Lake Trehörningen, southwest Sweden, provide evidence of climate variability during the Holocene in the boreal-nemoral zone of Sweden. The record indicates low early Holocene temperatures, followed by a rising trend and maximum temperature values from about 7000 to 4000 cal. yr BP. During the later part of the Holocene until present day, a cooling trend is reflected in the temperature record. At about 8200 cal. yr BP, temperatures temporarily drop, and at 8000 cal. yr BP the rising temperature trend is recovered. Inferred mid-Holocene temperatures are about 2.5-3°C higher than at present, and also higher than other pollen-inferred mid-Holocene temperatures of 1.5-2.5°C further to the north and east in Scandinavia. The reconstructed long-term climate pattern in Trehörningen has an overall consistency with temperature reconstructions from Scandinavia, suggesting a regional climate link for the Holocene variability in Sweden. Holocene climate trends in Trehörningen also show a remarkably similar pattern with the classic work on postglacial climate change by Sernander (1893, Sernander 1909), Andersson (1909) and von Post (1924). 相似文献
98.
Wave energy is a renewable source, which has so far not been exploited widely. Many of the various schemes in the past consist of large mechanical structures, often located near the sea surface. This article presents a range of systems with point absorbers on the surface and linear generators placed on the seabed, converting the wave motion into electrical power. Electrical power components are combined in different ways to obtain solutions suitable for various conditions. Different topologies for the electrical system transmitting power to the grid are discussed. Qualitative case studies are used to exemplify system options and connection schemes. 相似文献
99.
Adrian M. Hall Karin Ebert Clas Hättestrand 《Geografiska Annaler: Series A, Physical Geography》2013,95(1):33-49
We seek to quantify glacial erosion in a low relief shield landscape in northern Sweden. We use GIS analyses of digital elevation models and field mapping of glacial erosion indicators to explore the geomorphology of three granite areas with the same sets of landforms and of similar relative relief, but with different degrees of glacial streamlining. Area 1, the Parkajoki district, shows no streamlining and so is a type area for negligible glacial erosion. Parkajoki retains many delicate pre‐glacial features, including tors and saprolites with exposure histories of over 1 Myr. Area 2 shows the onset of significant glacial erosion, with the development of glacially streamlined bedrock hills. Area 3 shows extensive glacial streamlining and the development of hill forms such as large crag and tails and roches moutonnées. Preservation of old landforms is almost complete in Area 1, due to repeated covers of cold‐based, non‐erosive ice. In Area 2, streamlined hills appear but sheet joint patterns indicate that the lateral erosion of granite domes needed to form flanking cliffs and to give a streamlined appearance is only of the order of a few tens of metres. The inheritance of large‐scale, pre‐glacial landforms, notably structurally controlled bedrock hills and low relief palaeosurfaces, remains evident even in Area 3, the zone of maximum glacial erosion. Glacial erosion here has been concentrated in valleys, leading to the dissection and loss of area of palaeosurfaces. Semi‐quantitative estimates of glacial erosion on inselbergs and palaeosurfaces and in valleys provide mean totals for glacial erosion of 8 ± 8 m in Area 1 and 27 ± 11 m in Area 3. These estimates support previous views that glacial erosion depths and rates on shields can be low and that pre‐glacial landforms can survive long periods of glaciation, including episodes of wet‐based flow. 相似文献
100.
Anne Karin Hufthammer John Inge Svendsen Pavel Pavlov 《Boreas: An International Journal of Quaternary Research》2019,48(2):387-406
Here, we present and discuss results from geo‐archaeological and palaeo‐zoological investigations at the Palaeolithic site Pymva Shor, in the Russian Arctic. As many as 3324 vertebrate fauna remains were recovered during two excavations. This includes bones of mammals, birds and fish. Radiocarbon dates were obtained from 26 specimens. The results show ages in the range 30–3 cal. ka BP. Hare and reindeer are the best represented amongst the identified mammalian species, whilst ptarmigan and various wader species dominate the avian bones. The Pleistocene assemblage includes herbivorous herd animals such as horse, bison and musk ox. These species are typical of the treeless tundra‐steppe landscape that existed during the Lateglacial. Of particular interest is a cave lion specimen that has been radiocarbon dated to approximately 15.5 cal. ka BP. According to our knowledge, this is one of the latest dated examples of this species in Eurasia. The faunal composition in the Holocene assemblage is strikingly different and includes distinct forest taxa such as beaver and pine marten. The avifauna also supports a forested environment with the presence of black grouse. A few stone artefacts were found within the strata, and have been radiocarbon dated to 16–15 cal. ka BP, suggesting that there were humans in the Pymva Shore area at that time. We identified impact notches and cut marks on some radiocarbon‐dated reindeer and bison bones, showing that humans were present twice during the Younger Dryas period. A fourth occupation phase is identified during the mid‐Holocene (6–5 cal. ka BP). We also investigated river terraces and obtained a series of luminescence dates. These have been used to reconstruct the geological history and the relationship to the find‐bearing strata. 相似文献