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71.
Organic wastes have been reported to reduce saturation of the exchange complex by Al in Al-rich acid soils. For 3 years, the main soil fertility properties were studied in plots sown with mixed pasture species. These plots were fertilized with cattle slurry, dairy sludge (DS), or granulated broiler litter (BL) in comparison with mineral fertilizer. Al saturation levels were low after the initial inorganic liming treatment (19.00-33.71%) but tended to rise under all treatments (21.09-61.37%) except BL (8.45-30.98%), which was also associated with the highest average soil pH and the highest average levels of exchangeable Ca2+, Mg2+, and K+. Treatment DS performed similarly to mineral fertilizer in most respects, but it led to greater available P levels. Under the dry conditions of the second and third years of the study, BL and DS treatments were associated with significantly greater forage yields than the other treatments. Under DS treatment, available P levels were too low to allow the maintenance of mixed pasture, clover being eliminated by the less P-dependent species.  相似文献   
72.
We present a simple dynamic model to get some key insights about the substitution of renewable for nonrenewable resources and the consequences for sustainability. We highlight the role of the elasticity of substitution (technological component) to determine the adjustment of production as a response to scarcity and growing ability of resources (environmental component). In some cases, the model predicts a smooth substitution of renewable for nonrenewable resources, but this process could work in the opposite direction if renewable resources are temporarily beyond their maximum sustainable yield, so that their marginal natural growth is negative. If substitution possibilities are high enough, it may be optimal to suspend the extraction of a resource to allow the biomass to regenerate. A production process is more likely to be sustainable the more heavily it depends on renewable, rather than nonrenewable resources.  相似文献   
73.
Forest fires play a critical role in landscape transformation, vegetation succession, soil degradation and air quality. Improvements in fire risk estimation are vital to reduce the negative impacts of fire, either by lessen burn severity or intensity through fuel management, or by aiding the natural vegetation recovery using post-fire treatments. This paper presents the methods to generate the input variables and the risk integration developed within the Firemap project (funded under the Spanish Ministry of Science and Technology) to map wildland fire risk for several regions of Spain. After defining the conceptual scheme for fire risk assessment, the paper describes the methods used to generate the risk parameters, and presents proposals for their integration into synthetic risk indices. The generation of the input variables was based on an extensive use of geographic information system and remote sensing technologies, since the project was intended to provide a spatial and temporal assessment of risk conditions. All variables were mapped at 1 km2 spatial resolution, and were integrated into a web-mapping service system. This service was active in the summer of 2007 for semi-operational testing of end-users. The paper also presents the first validation results of the danger index, by comparing temporal trends of different danger components and fire occurrence in the different study regions.  相似文献   
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The Brindisi area is characterized by the presence of industries with high environmental impact, located along its eastern border. Epidemiological studies have revealed several critical situations: two short-term (2003-2005) epidemiological studies have shown that PM(10) and NO(2) are adversely associated with daily hospital admissions: one of the two pointed to the associations with wind blowing from the southern, eastern and western sectors. This study aims to expand the time span of available air quality data in order to provide a more complete and extensive epidemiological study. Multi-year series (from 1992 to 2007) of SO(2), NO(2), and TSP concentration data are presented and analyzed. Data show a significant downward trend of SO(2) from 1992 to 2007, while for the TSP series, the downward trend is limited to the period 1992-1994. Marked seasonal trends are evident for all three pollutants, especially for NO(2) and TSP. The NO(2) series shows higher levels in winter. Inversely, the TSP series shows its maximum values during the summer months, associated with a moderate correlation with temperature and a poor correlation with other pollutants. Analysis of the series for wind sectors revealed the influence of the industrial site and of the harbor. The concentration series exhibit high concentration values and stronger correlations between them and with meteorology for wind blowing from the eastern sectors. Overall analysis supports the hypothesis of a different origin for TSP during the year and for different wind regimes and therefore possible size and chemical differences in TSP, which should be further investigated due to their health implications.  相似文献   
76.
Seed dispersal is a crucial component of plant population dynamics. Human landscape modifications, such as habitat destruction and fragmentation, can alter the abundance of fruiting plants and animal dispersers, foraging rates, vector movement, and the composition of the disperser community, all of which can singly or in concert affect seed dispersal. Here, we quantify and tease apart the effects of landscape configuration, namely, fragmentation of primary forest and the composition of the surrounding forest matrix, on individual components of seed dispersal of Heliconia acuminata, an Amazonian understory herb. First we identified the effects of landscape configuration on the abundance of fruiting plants and six bird disperser species. Although highly variable in space and time, densities of fruiting plants were similar in continuous forest and fragments. However, the two largest-bodied avian dispersers were less common or absent in small fragments. Second, we determined whether fragmentation affected foraging rates. Fruit removal rates were similar and very high across the landscape, suggesting that Heliconia fruits are a key resource for small frugivores in this landscape. Third, we used radiotelemetry and statistical models to quantify how landscape configuration influences vector movement patterns. Bird dispersers flew farther and faster, and perched longer in primary relative to secondary forests. One species also altered its movement direction in response to habitat boundaries between primary and secondary forests. Finally, we parameterized a simulation model linking data on fruit density and disperser abundance and behavior with empirical estimates of seed retention times to generate seed dispersal patterns in two hypothetical landscapes. Despite clear changes in bird movement in response to landscape configuration, our simulations demonstrate that these differences had negligible effects on dispersal distances. However, small fragments had reduced densities of Turdus albicollis, the largest-bodied disperser and the only one to both regurgitate and defecate seeds. This change in Turdus abundance acted together with lower numbers of fruiting plants in small fragments to decrease the probability of long-distance dispersal events from small patches. These findings emphasize the importance of foraging style for seed dispersal and highlight the primacy of habitat size relative to spatial configuration in preserving biotic interactions.  相似文献   
77.
Environmental Science and Pollution Research - Hydrolysis is one of the most important processes of transformation of organic chemicals in water. The rates of reactions, final chemical entities of...  相似文献   
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Background, aim and scope  

Ambient air concentrations of polycyclic aromatic hydrocarbons (PAH) were determined at five elevated mountain sites on the European continent and the Atlantic Ocean. All sites can be considered remote background areas since they are situated above the timberline and they lack local emission sources of these compounds.  相似文献   
80.
In this paper we show the integration of techniques for early fault detection and diagnosis of operational faults in industrial processes, and we show an application example in a Fluid Catalytic Cracking refinery process. The early fault detection and diagnosis allow the operators in an industrial process to take the best actions during the real state of the process, avoiding incipient faults to scale to critical situations where there is risk of human lives and economical lost.  相似文献   
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