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61.
    
Water quality trends in streams and rivers are impacted by several factors including land use of the watershed; however, it is unclear what influence changes in the land use of a watershed subsequently have on changes in discharge and water quality in streams and rivers. This study seeks to fill this gap by evaluating the relationship between changes in land use and changes in discharge and water quality at United States Geological Survey (USGS) stream gages over the period of 2008–2016. Using land cover data and discharge and water quality data from 60 USGS gages, regression methods were applied to determine the strength of relationship between land use changes and changes in water quality and quantity. Trends in discharge and water quality were mixed, with a majority of watersheds demonstrating a decrease in dissolved oxygen and turbidity, no overall trend for discharge, and increases in specific conductance. A regression analysis revealed that discharge, turbidity, and specific conductance were correlated with changes in individual land use types with an R2 between 0.12 and 0.25. Combining the influences of multiple land uses in multivariate regression improved the predictions for discharge (R2 0.58) and specific conductance (R2 0.47), highlighting the magnitude for which land cover changes influence trends in water quality. Overall, this study demonstrates the impact that large-scale land use changes have on surface water quality.  相似文献   
62.
The linear production of consumer goods is characterised by mass manufacture by multinational enterprises and globally dispersed supply chains. The current centralised model has created a distance between the manufacturer and end user, limiting the opportunity for intelligent circular approaches for production and consumption. Through a mixed method approach, opportunities of circularity are explored for the consumer goods sector. The study presents four lenses to analyse three enterprises through a multi-case study approach to explore the potential of digital intelligence and redistributed manufacturing (RDM) as enablers of circular business models. In addition, the study examines whether Discrete Event Simulation can be used to evaluate the circular scenarios identified through quantifying flows of material that determine traditional economic value (cost/tonne). The mixed method approach demonstrates that, a qualitative systemic analysis can reveal opportunities for circularity, gained through implementing ‘digital intelligence’ and distributed models of production and consumption. Furthermore, simulations can provide a quantified evaluation on the effects of introducing circular activities across a supply chain.  相似文献   
63.
The advantages and disadvantages of several possible control strategies for particulate emissions from vehicular diesel exhaust are discussed. The evaluation of the potential usefulness of the various control strategies is based on available data concerning the mass loading and particle size distribution and on anticipated control standards. Several studies have been made on devices for removing particulate emissions from vehicular diesel exhaust. These studies, which include the techniques of filtration, wet scrubbers, and electrostatic precipitation, are summarized. A comparison of the various control devices is made based on such factors as size, efficiency, and maintenance requirements.  相似文献   
64.
Previous projects specifically aimed at performing radiological assessments in the vicinity of North Wales, investigating the presence and transfer of radionuclides from sea to land, were in 1986 and 1989. Since then, changes have occurred in the radioactive discharges from the British Nuclear Group Sellafield site. Annual discharges of (137)Cs, (238)Pu, (239,340)Pu and (241)Am have decreased markedly whereas, up until recent years, discharges of (99)Tc have increased. It is therefore desirable to quantify current transfer processes of radionuclides in the North Wales region and thus provide an update on 15-year-old studies. A field campaign was conducted collecting soil samples from 10 inland transects and air particulates on air filters from three High Volume Air Samplers, along the northern coast of Wales at Amlwch, Bangor Pier and Flint. Complementary field data relating to external gamma dose rates were collected at the soil sites. The field data generated for (137)Cs, (238)Pu, (239,340)Pu and (241)Am were consistent with what had been reported 15 years previously. Therefore, there has been no increase in the supply of these Sellafield-derived radionuclides to the terrestrial environment of the North Wales coast. The (99)Tc data in sediments were consistent with reported values within annual monitoring programmes, however, a relatively high activity concentration was measured in one sediment sample. This site was further investigated to determine the reason why such a high value was found. At present there is no clear evidence as to why this elevated concentration should be present, but the role of seaweed and its capacity in accumulating (99)Tc and transferring it to sediment is of interest. The analysis of the field samples for (99)Tc, (137)Cs, (238)Pu, (239,240)Pu and (241)Am has provided a data set that can be used for the modelling of the transfer of anthropogenic radionuclides from sea to land and its subsequent radiological implications and is reported in an accompanying paper.  相似文献   
65.
The predictions from MEAD, a model that simulates the transport of radionuclides in the marine environment, are presented for the Irish Sea. MEAD predictions for (137)Cs and Pu(alpha) are presented following discharges from BNFL Sellafield and the predictions compared to measured data from near the discharge location and further a field in the Irish Sea. The model performs well in most circumstances given the uncertainties involved in both modelling and data collection although some inconsistencies in the predictions are found. MEAD is also compared to other models of radionuclide transport in the Irish Sea.  相似文献   
66.
Uptake and depuration experiments of (131)I from labelled seaweed (Chondrus crispus) by the edible periwinkle Littorina littorea have been performed. Radioiodine concentrations in winkles during uptake followed first-order kinetics with an uptake half-time of 1 day, and a calculated equilibrium concentration (C(infinity)) of 21 000 Bq kg(-1) resulting in a transfer factor of 0.07 with respect to the labelled seaweed used as food. For depuration, a biphasic sequence with biological half-lives of 1 and 24 days was determined. The results suggest that in general, iodine turnover in periwinkles is slower than observed for other molluscs (monophasic biological half-lives in the order of 2-3 days). Both environmental media, food and seawater, can be significant sources of radioiodine for the winkle.  相似文献   
67.
Application of radioisotope sediment dating models to lakes subjected to large anthropogenic sediment inputs can be problematic. As a result of copper mining activities, Torch Lake received large volumes of sediment, the characteristics of which were dramatically different from those of the native sediment. Commonly used dating models (CIC-CSR, CRS) were applied to Torch Lake, but assumptions of these methods are violated, rendering sediment geochronologies inaccurate. A modification was made to the CRS model, utilizing a distinct horizon separating mining from post-mining sediment to differentiate between two focusing regimes. (210)Pb inventories in post-mining sediment were adjusted to correspond to those in mining-era sediment, and a sediment geochronology was established and verified using independent markers in (137)Cs accumulation profiles and core X-rays.  相似文献   
68.
A mathematical model (MEAD) that simulates the transport of radioactivity in shelf-sea environments is presented. In the model it is assumed that the radioactivity can be present in three phases and transport both within and between the phases is captured. The set-up of the model for the Irish Sea is described and results from a simple discharge scenario are presented for (137)Cs and (239)Pu. From these results it appears that MEAD provides a good representation of the transport of radionuclides in the Irish Sea.  相似文献   
69.
    
Participation has long been considered important for post‐disaster recovery. Establishing what constitutes participation in post‐disaster shelter projects, however, has remained elusive, and the links between different types of participation and shelter programme outcomes are not well understood. Furthermore, recent case studies suggest that misguided participation strategies may be to blame for failures. This study analysed 19 shelter projects implemented in the Philippines following Typhoon Haiyan in November 2013 to identify the forms of participation employed. Using fuzzy‐set qualitative comparative analysis, it assessed how household participation in the planning, design, and construction phases of shelter reconstruction led to outcomes of household satisfaction and safe shelter design. Participation was operationalised via eight central project tasks, revealing that the involvement of households in the early planning stages of projects and in construction activities were important for satisfaction and design outcomes, whereas engagement during the design phase of projects had little impact on the selected outcomes.  相似文献   
70.
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