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21.
Klemens Marx Johannes Bolhàr-Nordenkampf Tobias Pröll Hermann Hofbauer 《International Journal of Greenhouse Gas Control》2011,5(5):1199-1205
A semi-commercial 10 MWth chemical looping combustion (CLC) plant for power production is proposed as a next scale demonstration plant after successful operation of a 120 kW CLC pilot rig. The design criteria for the CLC boiler are derived from the experience obtained from the CLC pilot rig at Vienna University of Technology. The IPSEpro simulation environment is chosen for implementation of the process flow sheet of the CLC power plant. A single pressure steam cycle is suggested for this small scale demonstration plant. Heat exchangers and a five-stage steam turbine are arranged. Basic design parameters of the power plant are derived from detailed mass and energy investigations and discussed. It turns out that the net electric efficiency of such a small scale plant can be expected to be in the range of 32.5–35.8%. However, a demonstration of CLC at such a scale is necessary in order to gain confidence in more sophisticated CLC power generation concepts at larger scale. 相似文献
22.
Thomas K. Gottschalk Birgit AueStefan Hotes Klemens Ekschmitt 《Ecological modelling》2011,222(18):3403-3412
High resolution remote sensing data facilitate the use of small-scale habitat features such as trees or hedges in the analysis of species-habitat relationships. Such data potentially enable more accurate species-habitat mapping than lower resolution data. Here, for the first time, we systematically investigated this hypothesis by altering the spatial resolution from 1 m up to 1000 m grain size in species-habitat models of 13 bird species. The study area covered the Nidda river catchment in central Germany, a large heterogeneous landscape of 1620 km2. A high resolution habitat map of the area was converted to coarser spatial and thematic resolutions in seven steps. We investigated how model performance responded to grain size, and we compared the differential effects of spatial resolution and thematic resolution on model performance. Explained deviance (D2) of the bird models generally decreased with coarser spatial resolution of the data, although it did not decrease monotonically in all species. On average across all species, model D2 decreased from 41.5 at 1 m grain size to 15.9 at 1000 m grain size. Ten species were best modelled at 1 m, two species at 3 m and one species at 32 m grain size. Model performance degraded continuously with increasing grain size, both in habitat generalist and habitat specialist bird species, and was systematically lower in habitat generalists. The higher model performance observed at finer grain sizes was most likely caused by the combination of three factors: (1) high spatial accuracy of bird records and (2) a more precise location and delineation of habitat features and, (3) to a lesser degree, by more habitat types differentiated in maps of finer resolution. We conclude that higher spatial and thematic resolution data can be essential for deriving accurate predictions on bird distribution patterns from species-habitat models. Especially for bird species that are sensitive to specific land-use types or to small-scaled habitat features, a grain size of 1-3 m seems most promising. 相似文献
23.
Sarmiento Jon Marx P. Mendez Queenie Lynly T. Estaña Leo Manuel B. Giray Evette S. Nañola Cleto L. Alviola Pedro A. 《Environment, Development and Sustainability》2021,23(11):16786-16802
Environment, Development and Sustainability - The Philippine fisheries sector continues to play a critical role in the livelihood of coastal households; however, the country’s fisheries... 相似文献
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The Science of Nature - 相似文献
26.
D. A. Higgins A. R. Tiedemann T. M. Quigley D. B. Marx 《Journal of the American Water Resources Association》1989,25(6):1131-1149
ABSTRACT: Streamflow data for water years 1978–84 were evaluated to identify streamflow characteristics for 13 small watersheds (0.46–7.00 mi2) in the Blue Mountains of eastern Oregon and to determine differences among grazing intensities and vegetation types. The ranges for mean annual water yields, peak flows, and 7-day low flows for the 13 watersheds were 5.5–28.1 inches, 2.0–34.7 cfsm, and 0.006–0.165 cfsm, respectively. Two classes of vegetation were evaluated: (1) western larch-Douglas-fir (nine watersheds) and (2) other (four watersheds representing fir-spruce, lodgepole pine, ponderosa pine, and mountain meadow). The means for annual peak flows and the slopes of the flow.duration curve were significantly different (p=0.05) for the two vegetation classes; differences in mean annual water yield were marginallysignificant(0.05< p <0.10). After they were adjusted for precipitation, the means for annual water yield, peak flows, and slopes of the flow-duration curve were significantly different for the two vegetation classes; differences in the means for annual 7-day low flows were marginally significant. The western larch-Douglas-fir group had somewhat lower water yields but, overall, tended to have more favorable streamfiow characteristics including lower peak flows, higher low flows, and more evenly distributed flow regimes (flatter flow-duration curves) than the “other” class. Four levels of grazing intensity had no effect on streamilow characteristics. 相似文献
27.
By mainly targeting larger predatory fish, commercial fisheries have indirectly promoted rapid increases in densities of their
prey; smaller predatory fish like sprat, stickleback and gobies. This process, known as mesopredator release, has effectively
transformed many marine offshore basins into mesopredator-dominated ecosystems. In this article, we discuss recent indications
of trophic cascades on the Atlantic and Baltic coasts of Sweden, where increased abundances of mesopredatory fish are linked
to increased nearshore production and biomass of ephemeral algae. Based on synthesis of monitoring data, we suggest that offshore
exploitation of larger predatory fish has contributed to the increase in mesopredator fish also along the coasts, with indirect
negative effects on important benthic habitats and coastal water quality. The results emphasize the need to rebuild offshore
and coastal populations of larger predatory fish to levels where they regain their control over lower trophic levels and important
links between offshore and coastal systems are restored. 相似文献
28.
Samuel K. Marx Balz S. Kamber Atun Zawadzki 《Environmental pollution (Barking, Essex : 1987)》2010,158(5):1615-276
Two peat bogs from remote alpine sites in Australia were found to contain detailed and coherent histories of atmospheric metal pollution for Pb, Zn, Cu, Mo, Ag, As, Cd, Sb, Zn, In, Cr, Ni, Tl and V. Dramatic increases in metal deposition in the post-1850 AD portion of the cores coincide with the onset of mining in Australia. Using both Pb isotopes and metals, pollutants were ascribed to the main atmospheric pollution emitting sources in Australia, namely mining and smelting, coal combustion and agriculture. Results imply mining and metal production are the major source of atmospheric metal pollution, although coal combustion may account for up to 30% of metal pollutants. A novel finding of this study is the increase in the otherwise near-constant Y/Ho ratio after 1900 AD. We link this change to widespread and increased application of marine phosphate fertiliser in Australia's main agricultural area (the Murray Darling Basin). 相似文献
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Britas Klemens Eriksson Christiaan van Sluis Katrin Sieben Lena Kautsky Sonja Råberg 《Marine Biology》2011,158(4):747-756
We tested the relative strength of direct versus indirect effects of an aquatic omnivore depending on the functional composition
of grazers by manipulating the presence of gastropod and amphipod grazers and omnivorous shrimp in outdoor mesocosms. By selectively
preying upon amphipods and reducing their abundance by 70–80%, omnivorous shrimp favoured the dominance of gastropods. While
gastropods were the main microalgal grazers, amphipods controlled macroalgal biomass in the experiment. However, strong predation
on the amphipod by the shrimp had no significant indirect effects on macroalgal biomass, indicating that when amphipod abundances
declined, complementary feeding by the omnivore on macroalgae may have suppressed a trophic cascade. Accordingly, in the absence
of amphipods, the shrimp grazed significantly on green algae and thereby suppressed the diversity of the macroalgal community.
Our experiment demonstrates direct consumer effects by an omnivore on both the grazer and producer trophic levels in an aquatic
food web, regulated by prey availability. 相似文献