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511.
Jeffrey H. R. Goddard Maria C. Schaefer Craig Hoover Ángel Valdés 《Marine Biology》2013,160(6):1497-1510
Felimare californiensis (=Hypselodoris californiensis) was once common throughout the Southern California Bight (SCB) and California Channel Islands. This well-known shallow-water nudibranch, which specializes on dysideid sponges, has persisted for decades in Mexico, but in California disappeared from its entire range by 1984. Since reappearing in 2003, it has been found only at Santa Catalina Island, plus sightings of single individuals in 2011 at Santa Cruz Island and San Diego. The decline of F. californiensis in California was documented using published historical records, museum collections, unpublished field accounts, and images posted online. The loss of this emblematic species is unique among Californian nudibranchs, including (1) its congener Felimare porterae (=Mexichromis porterae), with which it appears to overlap in diet, and (2) opisthobranch species with similar historical geographic ranges and mode of development. The decline in F. californiensis is not predicted by warming trends and climate variation over the past 40 years, including the strong El Niño events of 1983 and 1998. Coastal pollution from the large human population in southern California may have impacted Dysidea amblia, the primary reported prey of F. californiensis. Historical overcollecting of the nudibranch and habitat loss through the development of major ports likely also contributed to its decline. Sightings since 2003 are consistent with a nascent recovery, as elements of water quality have improved in the SCB in recent decades. 相似文献
512.
Human impacts on fire occurrence: a case study of hundred years of forest fires in a dry alpine valley in Switzerland 总被引:2,自引:1,他引:1
Thomas Zumbrunnen Patricia Menéndez Harald Bugmann Marco Conedera Urs Gimmi Matthias Bürgi 《Regional Environmental Change》2012,12(4):935-949
Forest fire regimes are sensitive to alterations of climate, fuel load, and ignition sources. We investigated the impact of human activities and climate on fire occurrence in a dry continental valley of the Swiss Alps (Valais) by relating fire occurrence to population and road density, biomass removal by livestock grazing and wood harvest, temperature and precipitation in two distinct periods (1904–1955 and 1956–2006) using generalized additive modeling. This study provides evidence for the role played by humans and temperature in shaping fire occurrence. The existence of ignition sources promotes fire occurrence to a certain extent only; for example, high road density tends to be related to fewer fires. Changes in forest uses within the study region seem to be particularly important. Fire occurrence appears to have been negatively associated with livestock pasturing in the forest and wood harvesting, in particular during the period 1904–1955. This study illustrates consistently how fire occurrence has been influenced by land use and socioeconomic conditions. It also suggests that there is no straightforward linear relationship between human factors and fire occurrence. 相似文献
513.
Celia Arenas Carlos Leiva Luis F. Vilches Héctor Cifuentes 《Waste management (New York, N.Y.)》2013,33(11):2316-2321
The present study aims to determine and evaluate the applicability of a new product consisting of coal bottom ash mixed with Portland cement in the application of highway noise barriers. In order to effectively recycle the bottom ash, the influence of the grain particle size of bottom ash, the thickness of the panel and the combination of different layers with various particle sizes have been studied, as well as some environmental properties including leachability (EN-12457-4, NEN-7345) and radioactivity tests. Based on the obtained results, the acoustic properties of the final composite material were similar or even better than those found in porous concrete used for the same application. According to this study, the material produced presented no environmental risk. 相似文献
514.
X. Qu V.A. Vavilin L. Mazéas M. Lemunier C. Duquennoi P.-J. He T. Bouchez 《Waste management (New York, N.Y.)》2009,29(6):1828-1837
Utilizing stable carbon isotope data to account for aceticlastic and non-aceticlastic pathways of methane generation, a model was created to describe laboratory batch anaerobic decomposition of cellulosic materials (office paper and cardboard). The total organic and inorganic carbon concentrations, methane production volume, and methane and CO2 partial pressure values were used for the model calibration and validation. According to the fluorescent in situ hybridization observations, three groups of methanogens including strictly hydrogenotrophic methanogens, strictly aceticlastic methanogens (Methanosaeta sp.) and Methanosarcina sp., consuming both acetate and H2/H2CO3 as well as acetate-oxidizing syntrophs, were considered. It was shown that temporary inhibition of aceticlastic methanogens by non-ionized volatile fatty acids or acidic pH was responsible for two-step methane production from office paper at 35 °C where during the first and second steps methane was generated mostly from H2/H2CO3 and acetate, respectively. Water saturated and unsaturated cases were tested. According to the model, at the intermediate moisture (150%), much lower methane production occurred because of full-time inhibition of aceticlastic methanogens. At the lowest moisture, methane production was very low because most likely hydrolysis was seriously inhibited. Simulations showed that during cardboard and office paper biodegradation at 55 °C, non-aceticlastic syntrophic oxidation by acetate-oxidizing syntrophs and hydrogenotrophic methanogens were the dominant methanogenic pathways. 相似文献
515.
Andrés Planas 《Natural resources forum》1991,15(3):228-234
This paper concentrates on two aspects of the vast subject of '… water projects and services'. Even though the questions tackled may affect different water uses, this analysis is focused on operation and maintenance of water supply systems and the institutions that service them. The paper seeks to analyse some of the obstacles which impede the attainment of better performance in the operation and maintenance of water projects. It tackles the institutional problems and restrictions which must be overcome to speed up the adoption of operational patterns which will lead to a better use of available capacities. 相似文献
516.
This paper describes how the Carajas iron ore project was set up in February 1985 at a time of deep recession in the iron ore and steel industries. Development of the project was met with much criticism, mainly from North American steel makers, who argued that the project would only be successful through the support of a Third World government, highly dependent on foreign exchange, without any consideration being given to its economic feasibility or to the fundamentals of the market. The authors explain why the World Bank took the step of setting up the project and how its development can be partly explained by the interests of the Japanese and European steel makers. The role of the Brazilian government is explained and the authors conclude that the relatively low rate of investment anticipated by the project will be overshadowed by the high gains in foreign exchange. 相似文献
517.
We followed selection guidelines commonly used by management agencies to select mountain quail (Oreortyx pictus) as an indicator species for an ecological guild of birds. We then evaluated the ability of mountain quail to indicate the presence of other species from the guild and to index the quality of the habitat for other species. The ability of quail to indicate the presence of species from the ecological guild varied widely within and among vegetation types. Species compositions of the ecological guild were more consistent in comparisons of sites within vegetation types than they were in comparisons of sites between vegetation types. Mountain quail habitat was significantly different from the habitats of sympatric species from the guild for 14 of 15 multivariate contrasts. We suggest that managers use indicator species with caution. If indicators are used, they should be applied to guilds composed of species that closely share ecological affinities. The habitat of the indicator species should overlap extensively with those of all other guild members. The use of indicators should be restricted to very similar sites within the same general vegetation type. 相似文献
518.
In reaction to a paper inEnvironmental Management in which the sense and sensibility of environmental assessments of packaging were questioned, it is argued that these types
of assessments may be very useful, provided the relevant types of questions are posed. These boundary conditions are discussed,
along with an overview of more recent methodological developments with respect to environmental assessment of products. 相似文献
519.
520.
For about 50 years the desertion of areas by traditional activities has led to an important evolution of landscapes and environments
on the island of Ouessant. The study of this evolution has been undertaken at different spatial and temporal scales. On one
part of the island, a scientific investigation carried out at the scale of the parcel enabled the form of the landscape in
1850 to be compared with that of 1985. On the whole island, the evolution of spatial organization and land use was compared
between 1950 and 1985. For each of three main ecological environments, vegetational successions after the decrease of agriculture
have been studied along with their future potential changes. This work highlights some considerations about the present management
of the environment in relation to the major objectives of island environmental policies. 相似文献