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41.
The study of climate impacts on Living Marine Resources (LMRs) has increased rapidly in recent years with the availability of climate model simulations contributed to the assessment reports of the Intergovernmental Panel on Climate Change (IPCC). Collaboration between climate and LMR scientists and shared understanding of critical challenges for such applications are essential for developing robust projections of climate impacts on LMRs. This paper assesses present approaches for generating projections of climate impacts on LMRs using IPCC-class climate models, recommends practices that should be followed for these applications, and identifies priority developments that could improve current projections. Understanding of the climate system and its representation within climate models has progressed to a point where many climate model outputs can now be used effectively to make LMR projections. However, uncertainty in climate model projections (particularly biases and inter-model spread at regional to local scales), coarse climate model resolution, and the uncertainty and potential complexity of the mechanisms underlying the response of LMRs to climate limit the robustness and precision of LMR projections. A variety of techniques including the analysis of multi-model ensembles, bias corrections, and statistical and dynamical downscaling can ameliorate some limitations, though the assumptions underlying these approaches and the sensitivity of results to their application must be assessed for each application. Developments in LMR science that could improve current projections of climate impacts on LMRs include improved understanding of the multi-scale mechanisms that link climate and LMRs and better representations of these mechanisms within more holistic LMR models. These developments require a strong baseline of field and laboratory observations including long time series and measurements over the broad range of spatial and temporal scales over which LMRs and climate interact. Priority developments for IPCC-class climate models include improved model accuracy (particularly at regional and local scales), inter-annual to decadal-scale predictions, and the continued development of earth system models capable of simulating the evolution of both the physical climate system and biosphere. Efforts to address these issues should occur in parallel and be informed by the continued application of existing climate and LMR models.  相似文献   
42.
The objective of the paper is to investigate the links between the patterns of incidents, the amount of hazardous materials locally present and capability of local emergency preparedness in rural local government councils. Four states Abia, Akwa Ibom, Bayelsa and Rivers State were used to examine the nature and pattern of oil-spill disasters in rural Nigeria. It is argued that oil-spill hazards are more than isolated engineering malfunctions. They can be alternatively understood as reflections of the social, economic and political contexts in which they occur. Discriminant analysis is used to examine the relationship between 71 country risk-related and preparedness variables and incident frequency. The findings illustrate the usefulness of contextual analysis in examining the restructuring of rural life and the capacity of fiscally and socially stressed rural communities to respond to environmental change.  相似文献   
43.
A three-dimensional GIS-based groundwater flow model for the Nubian Sandstone Aquifer in the eastern Sahara was developed and calibrated under steady-state and transient conditions. The model was used to simulate the response of the aquifer to climatic changes that occurred during the last 25,000 years. The simulation results indicated that the groundwater in this aquifer was formed by infiltration during the wet periods 20,000 and 5,000 years b.p. The recharge of groundwater due to regional groundwater flow from more humid areas in the south was excluded. It also indicates that the Nubian Aquifer System is a fossil aquifer, which had been in an unsteady state condition for the last 3,000 years.
Resumen Fue desarrollado un modelo de flujo de agua subterránea en tres dimensiones, basado en un SIG, para el Acuífero Arenisca Nubian en el Sahara Oriental, el cual fue calibrado para condiciones de estado estacionario y transitorio. El modelo se usó para simular la respuesta del acuífero a los cambios climáticos que ocurrieron durante los últimos 25000 años. Los resultados de esta simulación indicaron que el agua subterránea en este acuífero, se formó por infiltración, durante los períodos húmedos que hubo hace 20000 y 5000 años, antes del presente. Fue excluida la recarga del acuífero debida a un flujo regional de agua subterránea proveniente de áreas con un clima más húmedo en el sur. El modelo también muestra, que el Sistema Acuífero Nubian es un acuífero fósil, el cual ha permanecido en una condición de estado no estacionario, durante los últimos tres mil años.

Résumé Pour laquifère gréseux Nubien de Sahara -Est on a mis au points un modèle tridimensionnel, basé sur GIS. Le modèle a été calibré tant pour lécoulement stationnaire que pour lécoulement transitoire. On a simulé après la réponse de laquifère aux changements climatiques des derniers 25000 ans. Les résultats des simulations indiquent que la nappe a été rechargée par des infiltrations pendant une période humide qui sétend 5000 et 20000 ans, dès temps actuel. On na pas pris en compte la recharge de laquifère par la zone plus humide située dans sa partie sud. Le modèle indique aussi que leau de laquifère Nubien est une eau fossile qui a eu un écoulement transitoire pendant les derniers 3000 ans.
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44.
For centuries, Bermuda has been challenged with wastewater management for the protection of human and environmental health. By quantifying the δ15N of the common sea fan Gorgonia ventalina sampled from 30 sites throughout Bermuda we show that sewage-derived nitrogen is detectable on nearshore coral reefs and declines across the lagoon to the outer rim. We also sampled gorgonians from two museum collections representing a 50y time-series (1958–2008). These samples revealed an increase in δ15N of > 4.0‰ until the mid-1970s, after which δ15N values slowly declined by ~ 2.0‰. A δ15N chronology from a gorgonian skeleton exhibited a similar decline over the last 30–40 years of approximately 0.6‰. We conclude that policies have been effective in reducing sewage impacts to Bermudian reefs. However, significant sources of sewage pollution persist and are likely have a strong impact on harbor and nearshore coral communities and human health.  相似文献   
45.
Tracer Test Evaluation of a Drainage Ditch Capture Zone   总被引:1,自引:0,他引:1  
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48.
Excavations in 1980–1981 at sites (32MZ319 and 32MZ380) along Cinnamon Creek Ridge in the Little Missouri River Badlands of McKenzie County, North Dakota, unexpectedly revealed at each locality the presence of one or more deeply buried paleosols with associated cultural materials. At both sites, 32MZ319 and 32MZ380, multiple paleosols are present, each of which is terminated by an episode of aeolian deposition. Fifteen radiocarbon dates on these paleosols establish an incipient chronology for paleosol development in the study area and permit correlation with other High Plains archaeological complexes. Geological and archaeological data for the two multiple paleosol sites are summarized.  相似文献   
49.
The REE distribution patterns and Nd whole-rock and mineral isotope ratios of the Kingash ultramafic-mafic massif enabled us to propose a multistage history for its evolution at 1410 and 875 Ma. These stages reflect the magmatic evolution of the Siberian paleocontinent margin during the Late Precambrian. The age of metamorphism of the massif during collision and accretion in the Early Paleozoic (∼500 Ma) was obtained based on a Sm-Nd mineral isochron from rheomorphic veined albitite. The Nd and Sr isotopic compositions of rocks from the Kingash massif suggest mantle sources for picritic and basic magmas, which are thought to have originated by mixing of different proportions of depleted (PREMA or DM) and enriched (EM) melts. The initial isotope ratios of the parental melts transformed during interaction with Sr-rich material from the host metasedimentary complexes.  相似文献   
50.
All proposed gravitational explanations of the Pioneer anomaly must crucially face the Equivalence Principle. Thus, if Pioneers 10 and 11 were influenced by anomalous gravitational effects in regions containing other Solar System bodies, then those bodies should likewise be influenced, irrespective of their shape, composition or mass. Although the lack of any observed influence upon planetary orbits severely constrains such explanations, here we aim to construct by computer modeling, hypothetical gravitating annuli having no gravitational impact on planetary orbits from Mercury to Neptune. One model has a central zone, free of radial gravitation in the annular plane, and an ‘onset’ beyond Saturn’s orbit, where sunward annular gravitation increases to match the Pioneer anomaly data. Sharp nulls are included so that Uranus and Neptune escape this influence. Such models can be proportionately reduced in mass: a 1 % contribution to the anomaly requires an annulus of approximately 1 Earth mass. It is thus possible to comply with the JPL assessment of newly recovered data attributing 80 %, or more, of the anomaly to spacecraft heat, which appears to allow small contributions from other causes. Following the possibility of an increasing Kuiper belt density at great ranges, another model makes an outward small anomalous gravitation in the TNO region, tallying with an observed slight indication of such an effect, suggesting that New Horizons may slightly accelerate in this region.  相似文献   
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