4 resultados para WATER-VAPOR PERMEABILITY
em Aquatic Commons
Resumo:
Executive Summary: Observations show that warming of the climate is unequivocal. The global warming observed over the past 50 years is due primarily to human-induced emissions of heat-trapping gases. These emissions come mainly from the burning of fossil fuels (coal, oil, and gas), with important contributions from the clearing of forests, agricultural practices, and other activities. Warming over this century is projected to be considerably greater than over the last century. The global average temperature since 1900 has risen by about 1.5ºF. By 2100, it is projected to rise another 2 to 11.5ºF. The U.S. average temperature has risen by a comparable amount and is very likely to rise more than the global average over this century, with some variation from place to place. Several factors will determine future temperature increases. Increases at the lower end of this range are more likely if global heat-trapping gas emissions are cut substantially. If emissions continue to rise at or near current rates, temperature increases are more likely to be near the upper end of the range. Volcanic eruptions or other natural variations could temporarily counteract some of the human-induced warming, slowing the rise in global temperature, but these effects would only last a few years. Reducing emissions of carbon dioxide would lessen warming over this century and beyond. Sizable early cuts in emissions would significantly reduce the pace and the overall amount of climate change. Earlier cuts in emissions would have a greater effect in reducing climate change than comparable reductions made later. In addition, reducing emissions of some shorter-lived heat-trapping gases, such as methane, and some types of particles, such as soot, would begin to reduce warming within weeks to decades. Climate-related changes have already been observed globally and in the United States. These include increases in air and water temperatures, reduced frost days, increased frequency and intensity of heavy downpours, a rise in sea level, and reduced snow cover, glaciers, permafrost, and sea ice. A longer ice-free period on lakes and rivers, lengthening of the growing season, and increased water vapor in the atmosphere have also been observed. Over the past 30 years, temperatures have risen faster in winter than in any other season, with average winter temperatures in the Midwest and northern Great Plains increasing more than 7ºF. Some of the changes have been faster than previous assessments had suggested. These climate-related changes are expected to continue while new ones develop. Likely future changes for the United States and surrounding coastal waters include more intense hurricanes with related increases in wind, rain, and storm surges (but not necessarily an increase in the number of these storms that make landfall), as well as drier conditions in the Southwest and Caribbean. These changes will affect human health, water supply, agriculture, coastal areas, and many other aspects of society and the natural environment. This report synthesizes information from a wide variety of scientific assessments (see page 7) and recently published research to summarize what is known about the observed and projected consequences of climate change on the United States. It combines analysis of impacts on various sectors such as energy, water, and transportation at the national level with an assessment of key impacts on specific regions of the United States. For example, sea-level rise will increase risks of erosion, storm surge damage, and flooding for coastal communities, especially in the Southeast and parts of Alaska. Reduced snowpack and earlier snow melt will alter the timing and amount of water supplies, posing significant challenges for water resource management in the West. (PDF contains 196 pages)
Resumo:
As the global population has increased, so have human influences on the global environment. ... How can we better understand and predict these natural and potential anthropogenic variations? One way is to develop a model that can accurately describe all the components of the hydrologic cycle, rather than just the end result variables such as precipitation and soil moisture. If we can predict and simulate variations in evaporation and moisture convergence, as well as precipitation, then we will have greater confidence in our ability to at least model precipitation variations. Therefore, we describe here just how well we can model relevant aspects of the global hydrologic cycle. In particular, we determine how well we can model the annual and seasonal mean global precipitation, evaporation, and atmospheric water vapor transport.
Resumo:
Physical properties of linear low density polythene film of 60 gauge thickness and its suitability as packaging material in frozen fish industry was studied in comparison with conventional 100 gauge low density polythene film. Both were comparable in water vapor transmission rate both at 38°C and -20°C, overall migration test and :flexibility at low temperatures. ·Even though the tearing strength was inferior to the conventional one, it is of no significance in its use in frozen fish industry. The new film worked out to be more economical than the other one.
Resumo:
Biodegradable protein-based film was developed by incorporating cinnamon essential oil (CEO) into whey protein concentrate (WPC) at level of 0.8% and 1.5% v/v. Then physical and mechanical properties of the films were evaluated. Adding CEO to the WPC matrix decreased the water vapour permeability of the films and water solubility. Films containing CEO showed significant antibacterial activity both gram-positive and gram-negative strains and exhibited significant inhibitory effect on the studied fungi. In continue, the effect of whey coating and whey coating incorporated with 1.5% CEO on quality and shelf life of Huso huso fillet during refregrated (4±1°C) storage period were also investigated. The control and treated fish samples were analyzed for microbiological (total viable count, psychrophilic counts), chemical (PV, TBA, FFA, pH, TVB-N), and sensory characteristics in 4-day intervals up of microbial, chmical and sensoy analyses indicated lower levels of PV, TBA, FFA, pH, TVB-N in coasted sampels and specially, those with CEO while were kept in refrigerator. Based on results, whey protein edible coating contain 1.5% cinnamon essential oil could enhance preserving ability Huso huso during storage cold.