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1.
The present work presents a study of the biological treatment of fish processing wastewater at salt concentration of 55 g/L. Wastewater was treated by both continuous stirred-tank reactor (CSTR) and membrane bioreactor (MBR) during 50 and 100 days, respectively. These biological processes involved salt-tolerant bacteria from natural hypersaline environments at different organic loading rates (OLRs). The phylogenetic analysis of the corresponding excised DGGE bands has demonstrated that the taxonomic affiliation of the most dominant species includes Halomonadaceae and Flavobacteriaceae families of the Proteobacteria (Gamma-proteobacteria class) and the Bacteroidetes phyla, respectively. The results of MBR were better than those of CSTR in the removal of total organic carbon with efficiencies from 97.9% to 98.6%. Nevertheless, salinity with increasing OLR aggravates fouling that requires more cleaning for a membrane in MBR while leads to deterioration of sludge settleability and effluent quality in CSTR. 相似文献
2.
Jantsje M. van Loon-Steensma Pieter A. Slim Mathieu Decuyper Zhan Hu 《Journal of Coastal Conservation》2014,18(4):415-430
This paper explores the impact of erosion and restoration measures on habitat development and on wave damping by a small salt marsh nestled alongside a dike on the Wadden island of Terschelling. The aim is to advance knowledge about the benefits and possible side-effects of salt-marsh restoration. Analysis of a time series of aerial photographs from 1944 to 2010 indicates that the salt marsh decreased steadily in size after maintenance of accretion works was terminated. In the western part of the marsh, which is accessible to sheep, vegetation is low (5–15 cm) and dominated by Salicornia europaea and by Spartina anglica. In the most intensively grazed parts, vegetation is very scarce. The eastern, inaccessible part of the salt marsh is covered by dense patches of the shrubby perennial Atriplex portulacoides and Spartina anglica (15–25 cm in height). SWAN wave models show that wave height at this location is significantly affected by the areal extent of the salt marsh as well as by the vegetation. High or dense vegetation are in the models nearly as effective in damping waves (with an initial height of 0.15 and 0.5 m) as widening the salt-marsh area by 350 m. A low density of low plants, as observed in the grazed part of the marsh, has almost no wave-damping effect. Even under conditions of sea level rise, a broader salt marsh vegetated with high plants significantly affects modelled wave height. Therefore, salt-marsh restoration is an adaptation measure worth exploring, though an array of effect types must be considered. 相似文献
3.
Hugo Slim 《Disasters》1997,21(3):244-257
In recent years a new generation of relief workers and relief agencies has become embroiled in the heat of civil wars and political emergencies, and the humanitarian community has had to revisit its fundamental principles and address the ethics of what it does. This paper sets out to continue this important debate by emphasising that ethical analysis should always be an essential part of humanitarian practice. The paper seeks to recognise the difficult moral choices relief agencies are facing today and gives some practical guidelines to relief agency staff when confronting the ethics of a given situation. In particular, it hopes to introduce some ethical principles into the debate about humanitarianism and contribute to the moral vocabulary which is being developed to improve relief agencies' ethical analysis. The paper starts by looking at the essential characteristics of a moral dilemma, and the way in which other types of tough choice can masquerade as moral dilemmas. It then introduces some basic moral principles surrounding the key ethical notions of action, consequences and moral responsibility in an effort to show how relief agencies might begin to develop a process of ethical analysis in their work. Finally, it explores how relief agencies might develop a more intuitive form of ethical analysis based on an organisational conscience and moral role models. 相似文献
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5.
J.K. Adou D.A. Brou J.-L. Consalvi A. Kaiss B. Porterie L. Zekri 《Ecological modelling》2010,221(11):1463-1471
This paper presents the development and validation results of a weighted small-world network model designed to simulate fire patterns in real heterogeneous landscapes. Fire spread is simulated on a gridded landscape, a mosaic in which each cell represents an area of the land surface. In this model, the interaction between burning and non-burning cells (here, due to flame radiation) may extend well beyond nearest neighbors, and depends on local conditions of wind, topography, and vegetation. An approach based on the coupling of the solid flame model with the Monte Carlo method is used to predict the radiative heat flux from the flame generated by the burning of each combustible cell to its neighbors. The weighting procedure takes into account latency (a combustible cell will only ignite when it has accumulated enough energy along time) and flaming persistence of burning cells. The model is applied to very different fire scenarios: a historical Mediterranean fire that occurred in southeastern France in 2005 and experimental fires conducted in arid savanna fuels in South Africa in 1992. Model results are found to be in agreement with real fire patterns, in terms both of rate of spread, and of the area and shape of the burn. This work also shows that the fractal properties of fire patterns predicted by the model are similar to those observed from satellite images of three other Mediterranean fire scars. 相似文献
6.
Farhat Ameny Elleuch Jihen Ben Amor Faten Barkallah Mohamed Smith Kirsty F. Ben Neila Idriss Abdelkafi Slim Fendri Imen 《Environmental science and pollution research international》2022,29(59):88699-88709
Environmental Science and Pollution Research - Karlodinium veneficum is a toxic benthic globally distributed dinoflagellate which has direct impacts on human health and the environment. Early and... 相似文献
7.
Increasing demand for water to develop non-agricultural activities is causing water to be diverted to high-value uses at the
expense of irrigation. However, agriculture provides a flow of amenities in the desert environment which are not either accounted
or paid. Oases are spread all over the globe and are threatened for various reasons among which is the high pressure of demand
for fresh water. This paper estimates the recreation use value of an oasis. The paper is based on the Misfat Al-Abryeen oasis
in Oman, a man-made area of streams and woodland. The travel cost method is used through an on-site questionnaire distributed
to 230 visitors. Around 75% of visitors to the oasis also visited other historical or ecological sites during the same day-trip.
The econometric model is estimated using negative binomial regression with endogenous stratification. The average consumer
surplus, or benefit, from visiting Misfat Al-Abryeen is estimated at US104.74 per individual per trip. The total social benefit from this oasis is estimated at 104.74 per individual per trip. The total social
benefit from this oasis is estimated at 366,590 per year. These results underscore the importance of the role played by irrigated
agriculture in the provision of amenity services for the tourism sector in a desert environment. The sustainability of the
irrigation activity depends on the recognition of the recreation role of oases and the transfer of part of these benefits
to the farmers who maintain the irrigation system. The implementation of an entrance fee to the oasis might increase farmers’
profit by 6–21%. 相似文献
8.
Peter Schippers Eric W.M. StienenAlex G.M. Schotman Robbert P.H. SnepPieter A. Slim 《Ecological modelling》2011,222(17):3061-3070
Most seabirds live in large colonies. This fact signifies that there is an advantage in living and breeding together. Four explanations are put fore ward for this colonial behaviour, more birds have: (1) a reduced per capita predation of chicks in colonies, (2) a better anti-predator defence, (3) a more efficient foraging in temporally patchy environments and (4) sex ratios that are more likely to be close to one. These factors induce a strong Allee-type density-dependent relation, a positive relation between density and population growth rate at low density. Nevertheless, these Allee effects are generally ignored in seabird population studies. Therefore we study the consequences of introducing Allee-type density-dependent relations in a spatially explicit metapopulation model for the Common Tern (Sterna hirundo). Simulations show that Allee effects might be responsible for a 20-fold decline in the recolonization distances, causing patches and parts of metapopulations to effectively become more isolated. This leads to long recolonization times of empty breeding patches which consequently cause slower metapopulation expansion and recovery. Additionally, we show that the typical early warning signals, that show that a population is near its critical threshold induce by Allee effects, is less pronounced in colonies that are part of a metapopulation. Hence, we offer some simple equations to estimate critical densities and thresholds in a colony. 相似文献
9.
Slim Ben Youssef 《Environmental Modeling and Assessment》2011,16(2):205-211
The impact of the investment in absorptive capacity on transboundary pollution is studied by considering two countries, each
of them regulating a firm. Firms can invest in inventive research and in absorptive research to lower their pollution intensity.
The absorptive research enables a firm to capture part of the inventive research made by the other one. We show that by means
of adequate emission taxes, original and absorptive research and development (R&D) subsidies, regulators can reach the non-cooperative
social optimum. Interestingly, we show that the investment in absorptive research enables non-cooperating regulators to better
internalize transboundary pollution. The higher is the learning parameter of absorption, the greater is the proportion of
transboundary pollution internalized. Therefore, it is recommended for the international community to make the patent laws
more flexible and enabling learning from the research made by others more interesting. Moreover, the investment in absorptive
R&D may lead to multiple equilibria necessitating non-cooperating countries to coordinate on an equilibrium, which constitutes
an incentive for them to cooperate. 相似文献
10.
Ali Fadel Bruno J. Lemaire Brigitte Vinçon-Leite Ali Atoui Kamal Slim Bruno Tassin 《Environmental science and pollution research international》2017,24(26):20934-20948
Many freshwater bodies worldwide that suffer from harmful algal blooms would benefit for their management from a simple ecological model that requires few field data, e.g. for early warning systems. Beyond a certain degree, adding processes to ecological models can reduce model predictive capabilities. In this work, we assess whether a simple ecological model without nutrients is able to describe the succession of cyanobacterial blooms of different species in a hypereutrophic reservoir and help understand the factors that determine these blooms. In our study site, Karaoun Reservoir, Lebanon, cyanobacteria Aphanizomenon ovalisporum and Microcystis aeruginosa alternatively bloom. A simple configuration of the model DYRESM-CAEDYM was used; both cyanobacteria were simulated, with constant vertical migration velocity for A. ovalisporum, with vertical migration velocity dependent on light for M. aeruginosa and with growth limited by light and temperature and not by nutrients for both species. The model was calibrated on two successive years with contrasted bloom patterns and high variations in water level. It was able to reproduce the measurements; it showed a good performance for the water level (root-mean-square error (RMSE) lower than 1 m, annual variation of 25 m), water temperature profiles (RMSE of 0.22–1.41 °C, range 13–28 °C) and cyanobacteria biomass (RMSE of 1–57 μg Chl a L?1, range 0–206 μg Chl a L?1). The model also helped understand the succession of blooms in both years. The model results suggest that the higher growth rate of M. aeruginosa during favourable temperature and light conditions allowed it to outgrow A. ovalisporum. Our results show that simple model configurations can be sufficient not only for theoretical works when few major processes can be identified but also for operational applications. This approach could be transposed on other hypereutrophic lakes and reservoirs to describe the competition between dominant phytoplankton species, contribute to early warning systems or be used for management scenarios. 相似文献