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281.
Katsivela Eleftheria Moore Edward R. B. Kalogerakis Nicolas 《Water, Air, & Soil Pollution: Focus》2004,4(4-5):75-85
The biodegradation of n-alkanes and branched alkanes from waste sludge were observed in landfarming soils of Motor Oil Hellas (a petroleum refinery) and changes in the bacterial communities in the soils were monitored during the remediation. Bacterial 16S rRNA gene (rDNA)-based community fingerprint patterns were obtained from soil samples by terminal restriction fragment length polymorphism (T-RFLP) analysis. Changes in T-RFLP fingerprints, as well as in the petroleum contaminant composition of the polluted soil, correlated with degradation activities in field tests. 相似文献
282.
Martin Simard Nicolas Lecomte Yves Bergeron Pierre Y Bernier David Paré 《Ecological applications》2007,17(6):1619-1637
Long-term forest productivity decline in boreal forests has been extensively studied in the last decades, yet its causes are still unclear. Soil conditions associated with soil organic matter accumulation are thought to be responsible for site productivity decline. The objectives of this study were to determine if paludification of boreal soils resulted in reduced forest productivity, and to identify changes in the physical and chemical properties of soils associated with reduction in productivity. We used a chronosequence of 23 black spruce stands ranging in postfire age from 50 to 2350 years and calculated three different stand productivity indices, including site index. We assessed changes in forest productivity with time using two complementary approaches: (1) by comparing productivity among the chronosequence stands and (2) by comparing the productivity of successive cohorts of trees within the same stands to determine the influence of time independently of other site factors. Charcoal stratigraphy indicates that the forest stands differ in their fire history and originated either from high- or low-severity soil burns. Both chronosequence and cohort approaches demonstrate declines in black spruce productivity of 50-80% with increased paludification, particularly during the first centuries after fire. Paludification alters bryophyte abundance and succession, increases soil moisture, reduces soil temperature and nutrient availability, and alters the vertical distribution of roots. Low-severity soil burns significantly accelerate rates of paludification and productivity decline compared with high-severity fires and ultimately reduce nutrient content in black spruce needles. The two combined approaches indicate that paludification can be driven by forest succession only, independently of site factors such as position on slope. This successional paludification contrasts with edaphic paludification, where topography and drainage primarily control the extent and rate of paludification. At the landscape scale, the fire regime (frequency and severity) controls paludification and forest productivity through its effect on soil organic layers. Implications for global carbon budgets and sustainable forestry are discussed. 相似文献
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Vlasis Oikonomou Alexandros Flamos Niki-Artemis Spyridaki Wytze van der Gaast Ariane De Dominicis Nicolas Chung 《Mitigation and Adaptation Strategies for Global Change》2012,17(2):187-205
Next to energy efficiency, in the context of GHG reductions, additional policy mechanisms to the incumbent EU Emissions Trading
scheme (EU ETS) are discussed. Such is the case of Non-ETS Domestic Offset (DO) schemes, which can reduce CO2-eq.emissions in the non-ETS sectors and trade these as CO2 credits on the ETS market. Taking into account that the EU’s “Linking Directive” (EC 2004) creates the conditions to use credits generated by emission reduction projects certified by the UN Framework Convention
on Climate Change Kyoto Protocol (KP) within the EU ETS market, in this paper we employ the institutional analysis method
of interactions in order to provide insight of a combined White Certificates (WhC) and DOs cheme. Special attention is paid
to the parameters that seem to hamper harmonization of WhC and DO. Aim of this paper is to discuss whether smart market- based
instruments, such as WhC, can be complementary to the effectiveness of mechanisms fostering energy efficiency such as DOs
projects and vice versa. In this respect, the potential combined scheme is assessed (ex-ante) with the help of standard criteria
that refer to the triptych energy, environment & society. Given the outcome of the study made, it is fair to say that such
a DO/WhC combined scheme could be selected if the additionality concern is to minimize short term social costs of reaching
a certain goal. However recent information and research conducted so far cannot yet uphold an ambition that a WhC/DO scheme
of this kind could also drive technical change, keep consumer costs down and be equitable. 相似文献
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Environmental Fluid Mechanics - The flow pattern within a storage zone governs the efficiency of passive scalar accumulation, spreading and homogenization. The present paper aims at characterizing... 相似文献
289.
Nektarios Koutsourakis John G. Bartzis Nicolas C. Markatos 《Environmental Fluid Mechanics》2012,12(4):379-403
In this study the Reynolds-averaged Navier-Stokes computational fluid dynamics methodology is used, which has proved to be a powerful tool for the simulations of the airflow and pollutant dispersion in the atmospheric environment. The interest is focused on the urban areas and more specifically on the street canyons, several types of which are examined in order to evaluate the performance of various turbulence models, including a Reynolds-stress model and variations of the k-ε model. The results of the two-dimensional simulations are compared with measurements from a diversity of independent street canyon experimental datasets, covering a wide range of aspect ratios, free stream velocities and roughnesses. This way more general and reliable conclusions can be reached about the applicability, accuracy and ease of use of each turbulence model. In this work, the renormalization group k-ε presented better results in most cases examined, while the Reynolds-stress model did not stand up for the expectations and also exhibited convergence problems. 相似文献
290.
Among rewardless orchids, pollinator sampling behavior has been suggested to drive a positive relationship between population phenotypic variability and absolute reproductive success, and hence population fitness. We tested this hypothesis by constructing experimental arrays using the rewardless orchid Dactylorhiza sambucina, which is dimorphic for corolla color. We found no evidence that polymorphic arrays had higher mean reproductive success than monomorphic arrays for pollinia removal, pollen deposition, or fruit set. For pollinia removal, monomorphic yellow arrays had significantly greater reproductive success, and monomorphic red the least. A tendency for yellow arrays to have higher pollen deposition was also found. We argue that differential population fitness was most likely to reflect differential numbers of pollinators attracted to arrays, through preferential long-distance attraction to arrays with yellow inflorescences. Correlative studies of absolute reproductive success in 52 populations of D. sambucina supported our experimental results. To our knowledge this is the first study to suggest that attraction of a greater number of pollinators to rewardless orchids may be of greater functional importance to population fitness, and thus ecology and conservation, than are the behavioral sequences of individual pollinators. 相似文献