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71.
Karl F. Nordstrom Ulrike Gamper Giorgio Fontolan Annelore Bezzi Nancy L. Jackson 《Environmental management》2009,44(6):1121-1135
Human actions can contribute to degradation of coastal environments or they can increase the likelihood that these environments
will be restored. Beach nourishment provides a basis for restoration, but ways must be found to add habitat improvement to
projects designed for shore protection. This study examines how beach nourishment projects can help reinstate dune landscapes
in locations where beaches and dunes had been replaced by static shore protection structures. Dune topography and vegetation
on three nourished sites on the northern Adriatic Coast of Italy are compared to a reference site to evaluate changes after
beach fill was emplaced. Results reveal how nourishment projects used for shore protection can restore the space available
for dunes to form, increase the likelihood of sediment transfers inland and increase the diversity of topography and vegetation.
Beach raking prevents formation and growth of hummocky, incipient backshore dunes that would otherwise evolve into a naturally
functioning foredune. Sand-trapping fences can speed the process of foredune development but can be counterproductive if they
interfere with transport to beach grass (Ammophila littoralis) planted landward of them. Shore protection structures can provide stability and more time for dune evolution on eroding
shores, resulting in greater species richness and longer retention of ecological niches. These structures need not be required
if re-nourishment occurs frequently enough to provide a beach wide enough to protect against storm wave uprush. 相似文献
72.
Dörfler U Cao G Grundmann S Schroll R 《Environmental pollution (Barking, Essex : 1987)》2006,144(2):695-702
In four different agricultural soils the long-term leaching behaviour of [14C]isoproturon was studied in outdoor lysimeters (2 m length, 1 m2 surface area). The herbicide was applied in spring 1997 and spring 2001. At the end of the first 4-year-investigation period between 0.13% and 0.31% of the applied radioactivity was leached. Isoproturon or known metabolites could not be detected in the leachate. However, shortly after the second application isoproturon and its degradation products 2-hydroxy-isoproturon and monodemethyl-isoproturon were leached via preferential flow in one of the lysimeters (Mollic gleysol) in concentrations of 4.5 microg L-1, 3.1 microg L-1 and 0.9 microg L-1, respectively, thus considerably exceeding the EU threshold limit of 0.1 microg L-1 for ground and drinking water. The results indicate that in soils where mass flow transfer dominates, leaching of isoproturon to groundwater is of low probability whereas in highly structured soils which have the tendency to form macropores, isoproturon can be transported via preferential flow to the groundwater. 相似文献
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74.
Land use and agricultural practices modify both the amounts and properties of C and N in soil organic matter. In order to evaluate land use and management-dependent modifications of stable and labile C and N soil pools, (i). organic C and total N content, (ii). microbial (C(mic)) and N (N(mic)) content and (iii). C and N mineralisation rates, termed biologically active C and N, were estimated in arable, grassland and forest soils from northern and southern Germany. The C/N-ratios were calculated for the three levels (i)-(iii) and linked to the eco-physiological quotients of biotic-fixed C and N (C(mic)/C(org), N(mic)/N(t)) and biomass-specific C and N mineralisation rate (qCO(2), qN(min)). Correlations could mainly be determined between organic C, total N, C(mic), N(mic) and C mineralisation for the broader data set of the land use systems. Generally, the mineralisation activity rate at 22 degrees C was highly variable and ranged between 0.11 and 17.67 microg CO(2)-C g(-1) soil h(-1) and -0.12 and 3.81 microg (deltaNH(4)(+)+deltaNO(3)(-))-N g(-1) soil h(-1). Negative N data may be derived from both N immobilisation and N volatilisation during the experiments. The ratio between C and N mineralisation rate differed significantly between the soils ranging from 5 to 37, and was not correlated to the soil C/N ratio and C(mic)/N(mic) ratio. The C/N ratio in the 'biologically active' pool was significantly smaller in soils under conventional farming than those under organic farming systems. In a beech forest, it increased from the L, Of to the Ah horizon. The biologically active C and N pools refer to the current microbial eco-physiology and are related to the need for being C and N use efficient as indicated by metabolic qCO(2) and qN(min) quotients. 相似文献
75.
Carty CL Gehring U Cyrys J Bischof W Heinrich J 《Journal of environmental monitoring : JEM》2003,5(6):953-958
Endotoxin is a toxic, pro-inflammatory compound that has been detected in indoor air and dust in homes and occupational settings, and also in outdoor air. Data on the outdoor sampling of endotoxin are limited. Currently, little is known about the seasonal variation and influence of temperature on outdoor endotoxin levels. In the present study, we report endotoxin levels in fine fraction particulate matter with a 50% aerodynamic cutoff diameter of 2.5 microm (PM2.5) and describe the seasonal variation of endotoxin in Munich, Germany. In 1999-2000, PM2.5 was collected at forty outdoor monitoring sites across Munich. Approximately four samples were collected at each site for a total of 158 samples. Endotoxin concentrations in the PM2.5 samples were determined using the kinetic chromogenic Limulus Amebocyte Lysate (LAL) assay. The geometric mean endotoxin concentration was 1.07 EU mg PM2.5(-1) (95% C.I.: 0.915-1.251) or 0.015 EU m(-3) of sampled air (95% C.I.: 0.013-0.018). Munich endotoxin levels were significantly related to ambient temperature (p < 0.0001) and percent relative humidity (p < 0.0001). Sampling periods with higher average temperatures yielded higher levels of endotoxin in PM2.5 (r = 0.641), whereas decreases in percent relative humidity were associated with increased endotoxin levels in PM2.5 (r = -0.388). Endotoxin levels were significantly higher during the warmer seasons of spring [means ratio (MR): 2.5-2.7] and summer (MR: 2.1-3.0) than during winter. Although temperature and relative humidity do not explain all of the variability in endotoxin levels, their effects were significant in our data set. Temperature effects and seasonal variation of endotoxin should be considered in future studies of outdoor endotoxin. 相似文献
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78.
Increasing empirical and theoretical evidence supports the idea that sympatric speciation is operating, for example, in species
flocks comprising several closely related fish species within one lake. Divergent natural selection (promoting spatial and
food niche partitioning) and sexual selection (assortative mating) have been identified as key selection factors in intralacustric
adaptive radiations. However, the evolution of social behaviors accompanying such adaptive radiations is less well understood.
Using a phylogenetically young species flock of pupfish (Cyprinodon spp.) as a model, we examined differences among six sympatric species and compared their shoaling, aggressive, and territorial
behaviors with that of a sister species (C. artifrons). Despite an estimated age of the species flock of less than 8,000 years, pronounced behavioral differentiation was found.
C. simus, the smallest species in the flock, shoaled more than the other species and was less aggressive and less territorial than
C. beltrani. F1-hybrids between C. simus males and C. beltrani females showed an intermediate expression of shoaling and aggressive behavior. Niche partitioning among the members of this
species flock appears to be accompanied by rapid divergent evolution of social behaviors. We discuss the potential role of
phenotypic plasticity and within-species variation of social behaviors for such rapid behavioral diversifications in sympatric
speciation processes. 相似文献
79.
What motives do companies have to make a voluntary contribution to the protection and conservation of ecosystems? Could an international market for protected area certificates (PACs)—issued for geographical areas managed in accordance with social and environmental best practices—boost private investment? What are the market opportunities and risks that influence private sector investment? These questions are evaluated based on semi-structured expert interviews conducted in 39 German companies. Triangulation is used for data analysis to combine the advantages of qualitative and quantitative methods. Qualitative interview results complemented with the exploratory factor analysis allow identifying five motives for private sector investment, of which three are key motives in the early stage of developing PACs: direct financial benefits; the social legitimacy of entrepreneurial business; and the corporate dependency on ecosystems. Opportunities for private companies arise from the high marketing potential of certificates, the international orientation of the PAC market, and the bundling of different ecosystem benefits. Identified risks include a lack of differentiation, additional costs, and green washing. Depending on the transparency of the certification scheme, companies are aware that PACs could both improve and damage their credibility and reputation. 相似文献
80.
Maren Kruse-Plass Frieder Hofmann Ulrike Kuhn Mathias Otto Ulrich Schlechtriemen Boris Schröder Rudolf Vögel Werner Wosniok 《Environmental Sciences Europe》2017,29(1):12
In this commentary, we respond to a report of the EFSA GMO Panel (EFSA EFSA Supp Publ, 1) that criticises the outcomes of two studies published in this journal (Hofmann et al. Environ Sci Eur 26: 24, 2; Environ Sci Eur 28: 14, 3). Both publications relate to the environmental risk assessment and management of Bt-maize, including maize events MON810, Bt11 and maize 1507. The results of Hofmann et al. (Environ Sci Eur 26: 24, 2), using standardised pollen mass filter deposition measurements, indicated that the EFSA Panel model had underestimated pollen deposition and, hence, exposure of non-target organisms to Bt-maize pollen. The results implied a need for safety buffer distances in the kilometre range for protected nature reserve areas instead of the 20–30 m range recommended by the EFSA Panel. As a result, the EFSA Panel revised their model (EFSA EFSA J 13: 4127, 4), adopting the slope of the empirical data from Hofmann et al. The intercept, however, was substantially reduced to less than 1% at one point by introducing further assumptions based on the estimates of mainly panel members, citing possible ‘uncertainty’. Hofmann et al. (Environ Sci Eur 28: 14, 3) published extensive empirical data regarding pollen deposition on leaves. These results were part of a larger 3-year study involving detailed measurements of pollen release, dispersal and deposition over the maize flowering period. The data collected in situ confirmed the previous predictions of Hofmann et al. (Environ Sci Eur 26: 24, 2). Mean levels and observed variability of pollen deposition on maize and four lepidopteran host plants exceeded the assumptions and disagreed with the conclusions of the EFSA Panel. The EFSA Panel reacted in a report (EFSA EFSA Supp Publ, 1) criticising the methods and outcomes of the two published studies of Hofmann et al. while reaffirming their original recommendations. We respond here point-by-point, showing that the critique is not justified. Based on our results on Urtica leaf pollen density, we confirm the need for specific environmental impact assessments for Bt-maize cultivation with respect to protected habitats within isolation buffer distances in the kilometre range. 相似文献