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Terry W. Rothermel Milton S. Sachs Frank O'Shaughnessy 《Journal of the American Water Resources Association》1971,7(4):867-877
ABSTRACT The Office of Saline Water, which has federal responsibility for developing low-cost, saline sources of fresh water, has recognized the need for an improved method of forecasting the future potential of desalting in this country. The magnitude of the role of desalting will influence the plans of federal, state, and local water resource agencies and the research and development programs of manufacturers. A dynamic simulation model has been developed by Arthur D. Little, Inc. under contract by OSW to translate relevant factors of water supply and demand into a forecast of desalting potential. The model projects the needs for desalting in 20 hydrologic regions of the U.S. Model performance has thus far been demonstrated by the development of a forecast and a battery of related sensitivity tests. Current results indicate the following potential desalting capacities: 225 MGD in 1980; 2,250 MGD in 2000; and 7,000 MGD in 2020. Significant improvements in desalting economics promise to increase these potentials by a factor of four or five by 2000-2020. Model inputs and results are continuing to be refined. When completed, OSW will have a dynamic tool with which to guide its R&D program. 相似文献
293.
S. A. Power M. R. Ashmore A. C. Terry S. J. M. Caporn M. G. Pilkington D. B. Wilson C. G. Barker J. A. Carroll N. Cresswell E. R. Green G. W. HEIL 《Water, Air, & Soil Pollution: Focus》2004,4(6):259-267
The results from three long-term field manipulation studies of the impacts of increased nitrogen deposition (0–120 kg N ha–1 yr–1) on lowland and upland heathlands in the UK were compared, to test if common responses are observed. Consistent increases in Calluna foliar N content and decreases in litter C:N ratios were found across all sites, while increases in N leaching were not observed at any site over the range 0–80 kg ha–1 yr–1. However, the response of Calluna biomass did vary between sites, possibly reflecting site differences in nutrient status and management histories. Five versions of a simulation model of heathland responses to N were developed, each reflecting different assumptions about the fate and turnover of soil N. Model outputs supported the deduction from mass balance calculations at two of the field sites that N additions have resulted in an increase in immobilisation; the latter was needed to prevent the model overestimating measured N leaching. However, this version of the model significantly underestimated Calluna biomass. Model versions, which included uptake of organic N by Callunaand re-mobilisation of N from the soil organic store provided some improvement in the fit between modelled and field biomass data, but re-mobilisation also led to an overestimation of N leaching. Quantification of these processes and their response to increased N deposition are therefore critical to interpreting experimental data and predicting the long-term impacts of atmospheric deposition on heathlands and moorlands. 相似文献
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Terry J. Dillon Abraham Horowitz John N. Crowley 《Atmospheric environment (Oxford, England : 1994)》2010,44(9):1186-1191
Although NF3, a trace gas of purely anthropogenic origin with a large global warming potential is accumulating in the Earth's atmosphere, little photochemical data exists from which to calculate its atmospheric removal rate. In this study, photodissociation quantum yields, Φ1, were derived following 193.3 nm laser photolysis of NF3, and quantitative conversion of the F-atom photoproducts to OH, which was detected by laser induced fluorescence. Values of Φ1(P, T) = (1.03 ± 0.05) were determined at pressures between 28 and 100 mBar of He or N2 and at either room temperature or 255 K. Absorption cross-sections, σ, obtained between 184 and 226 nm were combined with the values of Φ1(P, T) to confirm a long (≈700 year) photolysis lifetime for NF3. No evidence for reaction of OH with NF3 was found, indicating that this process makes little or no contribution to NF3 removal from the atmosphere. These results underpin recent calculations of an NF3 atmospheric lifetime τ ≈ 550 years, largely controlled by photolysis in the stratosphere. In the course of this work the rate coefficient k2(298 K) = (1.3 ± 0.2) × 10?11 cm3 molecule?1 s?1 was obtained for the reaction F + H2O. 相似文献
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Participatory learning and action (PLA) methodology was used at the village level in Fiji to identify and understand factors that influence two selected communities in implementing changes to current pig-waste management practices. The focus area was the Coral Coast in the south of Viti Levu island, where international tourism is expanding but stream and coastal waters are under threat of pollution from the largely uncontrolled release of pig waste into the local environment. The investigation found that participatory approaches are effective at the village level if correct tools are used and if the research process adapts to community needs. In particular, PLA methods in the two study villages (Komave and Votua) were able to assist different demographic groups to identify and then prioritise a range of pig-waste problems, including deteriorating water quality, public health and agricultural sustainability. Encouragement by PLA facilitators for communities to take ownership of these problems led eventually to one village installing a new pig-management system. This has become a showcase as a successful local-scale rural development project with long-term benefits for the local environment and the continuing growth of tourism in the area. 相似文献
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Terry Sohl Ryan Reker Michelle Bouchard Kristi Sayler Jordan Dornbierer Steve Wika 《Journal of Land Use Science》2016,11(4):476-499
The landscape of the conterminous United States has changed dramatically over the last 200 years, with agricultural land use, urban expansion, forestry, and other anthropogenic activities altering land cover across vast swaths of the country. While land use and land cover (LULC) models have been developed to model potential future LULC change, few efforts have focused on recreating historical landscapes. Researchers at the US Geological Survey have used a wide range of historical data sources and a spatially explicit modeling framework to model spatially explicit historical LULC change in the conterminous United States from 1992 back to 1938. Annual LULC maps were produced at 250-m resolution, with 14 LULC classes. Assessment of model results showed good agreement with trends and spatial patterns in historical data sources such as the Census of Agriculture and historical housing density data, although comparison with historical data is complicated by definitional and methodological differences. The completion of this dataset allows researchers to assess historical LULC impacts on a range of ecological processes. 相似文献