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1.
In newly burnt and unburnt pine and eucalyptus forest in Portugal, overland flow and soil losses were monitored to assess the impacts of the following post-fire treatments: application of different quantities of logging litter; rip-ploughing compared with minimum tillage prior to planting eucalyptus seedlings; and clearance of pine needles and vegetation. Eucalyptus logging litter reduced soil losses by up to 95 per cent. The impact of pine logging litter was equivocal, but removal of pine needles increased soil losses elevenfold. Implications for soil longevity, soil quality and land management strategy are discussed.  相似文献   
2.
The origin of the Serguza lead-zinc deposit of the Northern Thrust Zone has been suggested to be epigenetic, hydrothermal, structurally controlled by a post Tertiary major fault zone. Reinterpretation of previously obtained data and the evaluation of the present results have provided enough evidence to argue for a different mode of formation. Based upon trace element content of the ore minerals, dating of galena, ore and country rock texture, and the results of the detailed geochemical and geophysical prospecting in the area, it seems that the deposit is strata-bound, stratigraphically controlled within the Triassic dolomites. Its simple mineralogy, chemistry, and other features are comparable with other early Alpine strata-bound leadzinc deposits of the Mediterranean Belt.  相似文献   
3.
Climate change could have major implications for the global tourism industry if changing environmental conditions alter the attractiveness of holiday destinations. Countries with economies dependent on tourism and with tourism industries reliant on vulnerable natural resources are likely to be particularly at risk. We investigate the implications that climate-induced variations in Atlantic hurricane activity may have for the tourism-dependent Caribbean island of Anguilla. Three hundred tourists completed standardised questionnaires and participated in a choice experiment to determine the influence hurricane risk has on their risk perceptions and decisions regarding holiday preferences. The hurricane season had been considered by 40?% of respondents when making their holiday choice, and the beaches, climate and tranquility of the island were more important than coral reef-based recreational activities in determining holiday destination choice. Choice models demonstrated that respondents were significantly less likely to choose holiday options where hurricane risk is perceived to increase, and significantly more likely to choose options that offered financial compensation for increased risk. However, these choices and decisions varied among demographic groups, with older visitors, Americans, and people who prioritize beach-based activities tending to be most concerned about hurricanes. These groups comprise a significant component of the island’s current clientele, suggesting that perceived increases in hurricane risk may have important implications for the tourism economy of Anguilla and similar destinations. Improved protection of key environmental features (e.g. beaches) may be necessary to enhance resilience to potential future climate impacts.  相似文献   
4.
Islands are often considered to be a priority for conservation, because of their relatively high levels of biodiversity and their vulnerability to a range of natural and anthropogenic threats. However, the capacity of islands to conserve and manage biodiversity may depend upon their governance structures. Many island states are affiliated to other countries through an ‘overseas territory’ status, which may provide them with access to resources and support mechanisms, but which may also influence the capacity for local-scale management of environmental issues. The United Kingdom has 12 island Overseas Territories (UKOTs), most of which support biodiversity of high conservation concern. This study investigates perceptions of current and future threats to marine ecosystems and constraints to environmental protection on the six Caribbean UKOTs, through semi-structured interviews with officials from UK and UKOT government departments and non-governmental organisations. Coastal development, pollution and over-fishing were perceived as threats of most concern for the next decade, but climate change was perceived as by far the greatest future threat to the islands' marine ecosystems. However, a series of common institutional limitations that currently constrain mitigation and conservation efforts were also identified, including insufficient personnel and financial support, a lack of long-term, sustainable projects for persistent environmental problems and inadequate environmental legislation. These findings highlight the need for regional cooperation and capacity-building throughout the Caribbean and a more concerted approach to an UKOT environmental management by the UK and UKOTs' governments.  相似文献   
5.
The effects of small fractions ( < 30%) of open water covering a grid element are currently neglected even in atmospheric general circulation models (AGCMs) which incorporate complex land surface parameterization schemes. Here, a method for simulating sub-grid scale open water is proposed which permits any existing land surface model to be modified to account for open water. This new parameterization is tested as an addition to an advanced land surface scheme and, as expected, is shown to produce general increases in the surface latent heat flux at the expense of the surface sensible heat flux. Small changes in temperature are associated with this change in the partitioning of available energy which is driven by an increase in the wetness of the grid element. The sensitivity of the land surface to increasing amounts of open water is dependent upon the type of vegetation represented. Dense vegetation (with a high leaf area index) is shown to complicate the apparently simple model sensitivity and indicates that more advanced methods of incorporating open water into AGCMs need to be considered and compared against the parameterization suggested here. However, the sensitivity of one land surface model to incorporating open water is large enough to warrant consideration of its incorporation into climate models.  相似文献   
6.
The Thukela Bank, KwaZulu-Natal, supports a diverse ecosystem and South Africa’s only prawn fishery. Oceanographic studies suggest riverine input is not important for the biology of this system, whereas biological studies suggest the contrary, with prawn catches increasing with increased fluvial run-off. The aim of this study was to determine (i) the importance of riverine and marine organic matter for the Thukela Bank food web; and (ii) whether there are seasonal changes in the Thukela River stable isotope values, and, if so, whether these are reflected in the isotope values of demersal organisms. Estuarine organic matter, sediments and demersal organisms were collected from several sites across the bank in the wet and dry seasons of 2008, 2009 and 2010. Marine particulate organic matter was also collected in 2010 and analysed for δ13C and δ15N, as well as C/N ratios. There were strong seasonal changes in isotopic values of organic matter and fauna, especially faunal δ13C. There was an apparent time-lag in organisms assimilating riverine organic matter isotopic values, with the isotopic signature of demersal organisms reflecting that of riverine organic matter from the previous season, which is likely the result of tissue turnover time. In 2010, Thukela Bank sediment organic matter was of riverine origin and this maintained the demersal food web. We conclude that Thukela River organic matter is an important input to the food web of the Thukela Bank, indicating that any future damming of the catchment area could have serious consequences for this ecosystem.  相似文献   
7.
Model experiments were specifically designed to test the effect of different profile shapes of early folds on refolding patterns. Comparison of natural examples with experimental results and analogy with engineering information on buckling of fold shapes suggest that, when layers are mechanically active during refolding, the profile shape of the early folds markedly affects the patterns of fold interference. Open rounded folds tend to refold to form dome and basin patterns of interference whereas isoclinal folds tend to refold by folding their axial plane, forming type 2 patterns of interference. Hence, the dimensions and shape of the profile of the early folds control the preferred buckling mode during refolding.  相似文献   
8.
Summary Platinum-group minerals (PGM) project into fluid inclusions that occur in chalcopyrite and cubanite from the Marathon deposit, Two Duck Lake gabbro, Coldwell Complex, Ontario. Semi-quantitative analyses of the micron-sized PGM were made by SEM-EDS; they reveal Ag-bearing intermetallic compounds of Pd3Sn-Pd3Pb-Pd3Te (i.e., atokitezvyagintsevite-keithconnite) and telargpalite (Pd2AgTe) on broken, irregular surfaces of the Cu-Fe-S minerals. Halite daughter minerals, and quenched brine occur in and around some opened fluid inclusions. These data confirm the hypothesis based on petrography and mineral compositions that saline fluids remobilized PGE, Cu, and other elements and precipitated them well after crystallization of sulfide and silicate magmas in the Marathon deposit.
Platin-Gruppenminerale in Flüssigkeitseinschlüssen aus der Marathon Lagerstdtte, Coldwall Komplex, Kanada
Zusammenfassung Platin-Gruppenminerale (PGM) ragen in Flüzssigkeiteinschliisse, die im Kupferkies und Cubanit der Marathon Lagerstätte, Two Duke Lake Gabbro, Coldwell Komplex, Ontario, vorkommen, hinein. Semiqantitative Analysen der mikrongroßen PGM wurden mit einem SEM-EDS durchgeführt. Sie ergaben Ag-führende, intermetallische Verbindungen von Pd3Sn-Pd3Pb-Pd3Te (Atokit-Zvyagintsevit-Keithconnit) und Telargpalit (Pd2AgTe) auf zerbrochenen, irregulären Oberflächen der Cu-Fe-SMinerale. Steinsalz-Tochterkristalle und abgeschreckte Salzlösungen treten innerhalb und in der unmittelbaren Umgebung geöffneter Flüssigkeitseinschlüsse auf. Diese Daten bestätigen die Hypothese, basierend auf der Petrographie und der Mineralzusammensetzung, daß saline Fluida PGE, Cu und andere Elemente remobilisieren können, und daß d iese nach der Kristallisation der Sulfide und des Silikatmagmas in der Marathon Lagerstätte zur Ablagerung gekommen sind.


With 3 Figures  相似文献   
9.
Marine bioregional planning requires a meaningful classification and spatial delineation of the ocean environment using biological and physical characteristics. The relative inaccessibility of much of the ocean and the paucity of directly measured data spanning entire planning regions mean that surrogate data, such as satellite imagery, are frequently used to develop spatial classifications. However, due to a lack of appropriate biological data, these classifications often rely on abiotic variables, which act as surrogates for biodiversity. The aim of this study was to produce a fine-scale bioregional classification, using multivariate clustering, for the inshore and offshore marine environment off the east coast of South Africa, adjacent to the province of KwaZulu-Natal and out to the boundary of the exclusive economic zone (EEZ), 200 nautical miles offshore. We used remotely sensed data of sea surface temperature, chlorophyll a and turbidity, together with interpolated bathymetry and continental-slope data, as well as additional inshore data on sediments, seabed oxygen and bottom temperature. A multivariate k-means analysis was used to produce a fine-scale marine bioregionalisation, with three bioregions subdivided into 12 biozones. The offshore classification was primarily a pelagic bioregionalisation, whereas the inshore classification (on the continental shelf) was a coupled benthopelagic bioregionalisation, owing to the availability of benthic data for this area. The resulting classification was used as a base layer for a systematic conservation plan developed for the province, and provided the methods for subsequent planning conducted for the entire South African EEZ. Validation of the classification is currently being conducted in marine research programmes that are sampling benthic biota and habitats in a sampling design stratified according to the biozones delineated in this study.  相似文献   
10.
Abstract— Calcite crystals within the Kaibab limestone in Meteor Crater, Arizona, are examined to understand how calcite is deformed during a meteorite impact. The Kaibab limestone is a silty finegrained and fossiliferous dolomudstone and the calcite crystals occur as replaced evaporite nodules with impact‐induced twinning. Twinning in the calcite is variable with deformational regimes based on abundances of crystals with twins and twin densities within crystals. The twins are similar to those that are seen in low tectonically deformed regimes. Low levels of shock are inferred from minor peak broadening of the X‐ray diffraction patterns (XRD) of the calcite crystals. In addition, electron spin resonance (ESR) spectroscopy data also indicates low shock levels (<3.0 GPa). Quantitative shock pressures and correlation between the XRD and ESR results are poor due to the inferred low shock levels in conjunction with the analytical error associated in calculation of the shock pressures.  相似文献   
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