Global climate change induced by the emission of greenhouse gases may pose challenges to energy security. The vulnerability of energy sources, in particular of renewable sources, to climate change raises the need to identify adaptation measures. This paper applies an integrated resource planning approach to calculate least-cost adaptation measures to a set of projected climate impacts on the Brazilian power sector. The methodology used has the advantage of finding optimal solutions that take into consideration the whole energy chain and the interactions between energy supply and demand. Results point in the direction of an increased installed capacity based, mostly, on natural gas, but also sugarcane bagasse, wind power and coal/nuclear plants, to compensate for a lower reliability of hydroelectric production, amongst other impacts. The indirect effect of these results is the displacement of natural gas from other consuming sectors, such as industry, in favor of its use for power generation. Results obtained are, however, based on the techno-economic premises used in the simulation, which may vary in the long term. 相似文献
Underground hard coal mining usually disrupts the mechanical equilibrium of rock sequences, creating fractures within minor permeable rocks. The present study employs a dual-continuum model to assess how both fractured and porous sandstone media influence the percolation process in postmining setups. To test the approach, the software TOUGH2 was employed to simulate laminar fluid flow in the unsaturated zone of the Ibbenbüren Westfield mining area. Compared to other coal mining districts in Germany, this area is delineated by the topography and local geology, leading to a well-defined hydrogeological framework. Results reveal good agreement between the calculated and measured mine water discharge for the years 2008 and 2017. The constructed model was capable of reproducing the bimodal flow behavior of the adit by coupling a permeable fractured continuum with a low-conductivity rock matrix. While flow from the fractured continuum results in intense discharge events during winter months, the rock matrix determines a smooth discharge limb in summer. The study also evaluates the influence of individual and combined model parameters affecting the simulated curve. A detailed sensitivity analysis displayed the absolute and relative permeability function parameters of both continua among the most susceptible variables. However, a strong a priori knowledge of the value ranges for the matrix continuum helps to reduce the model ambiguity. This allowed for calibration of some of the fractured medium parameters for which sparse or variable data were available. However, the inclusion of the transport component and acquisition of more site-specific data is recommended to reduce their uncertainty.
Natural Hazards - Recife Metropolitan Region, in the northeast of Brazil, is formed by a coastal plain bounded by hills and by the Atlantic Ocean. Recife Metropolitan Region has about 4 million... 相似文献
The main objective was to study the seasonal variation of mercury concentrations in different tissues (muscle, hepatopancreas and gills) of Carcinus maenas from low and high Hg contaminated areas, a valuable resource in temperate estuaries and a possible pathway for human uptake. Individuals of two size classes (around 35 and 55 mm cephalothorax wide) were captured monthly between March 1999 and May 2000 in two areas of Ria de Aveiro: in the main navigation channel that connects the lagoon to the sea, and in the inner lagoon area heavily contaminated by mercury (maximum Hg in sediments of 5.4 microg g(-1)). Pronounced decreases in salinity and temperature and reduced food availability in winter seemed to be the responsible for the decline of the crab condition index (0.75-0.45) in larger individuals. Muscle and hepatopancreas exhibited higher mercury concentrations than gills, with concentrations in the contaminated site ranging from 0.03 to 0.63 microg g(-1) and 0.02 to 0.34 microg g(-1), respectively. Linear regressions between muscle and hepatopancreas (r=0.94, p<0.001) and muscle and gills (r=0.97, p<0.001) suggested a rapid redistribution of mercury inside the organism. During winter, a rapid elimination of mercury was found in the three analysed tissues followed by uptake. Larger crabs presented elimination rates from 18 to 34 ng g(-1) per week, while the smaller crabs showed lower elimination rates (10-24 ng g(-1) per week). The uptake was similar in both size classes (11-15 ng g(-1) and 8.1-15 ng g(-1) per week, respectively for large and small crabs). Our results suggest that C. maenas harvested in the contaminated areas must be considered with caution, since Hg concentrations were found to exceed the threshold concentration allowed for human consumption (0.5 microg g(-1)). 相似文献
In urban areas traffic is the major contributor to atmospheric particulate matter and exposure to these particles currently
represents a serious risk to human health. The attention has been recently focused more on the particles of smaller sizes
(PM2.5) which penetrate deeper in respiratory system causing severe health effects. Therefore, more information on PM2.5 should be provided, namely concerning morphological and chemical characterization. Aiming further evaluation of the impact
of traffic emissions on public health, this work evaluated the influence of traffic on the chemical and morphological characteristics
of PM10 and PM2.5, collected at one site influenced by traffic emissions and at one reference site. Chemical and morphological characteristics
of 1,000 individual particles were determined by scanning electron microscopy combined with energy dispersive spectrometer
(SEM–EDS). Cluster analysis (CA) was used to identify different types of particles that occurred in PM, aiming the identification
of the respective emission sources. Traffic PM2.5 were dominated by particles composed of Fe oxides and alloys (67%) which were related to traffic emissions (this percentage
was 3.7 times higher than at the background site); in PM2.5–10 the abundance of Fe oxides and alloys were 20% and 0% for the traffic and background sites, respectively. Background PM2.5 were mainly constituted by aluminum silicates (63%) related to natural sources (this percentage was 2.5 times higher than
at the traffic site); the abundances of aluminum silicates in PM2.5–10 were 74% and 73% for traffic and background sites, respectively. It was concluded that traffic emissions were mainly present
in PM2.5 (the percentage of particles associated to these emissions was 3.4 times higher than in PM2.5–10), while coarse particles were dominated by material of natural origin (the percentage of particles associated was 1.2 and
3.0 times higher than in PM2.5 for traffic and background sites, respectively). Previous results obtained by proton induced X-ray emission (PIXE) were consistent
with SEM–EDS analysis that showed to be very useful to complement elemental analysis of different PM2.5 and PM2.5–10. 相似文献