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361.
Stohlgren TJ Chong GW Schell LD Rimar KA Otsuki Y Lee M Kalkhan MA Villa CA 《Environmental management》2002,29(4):566-577
Basic information on where nonnative plant species have successfully invaded is lacking. We assessed the vulnerability of
22 vegetation types (25 sets of four plots in nine study areas) to nonnative plant invasions in the north–central United States.
In general, habitats with high native species richness were more heavily invaded than species-poor habitats, low-elevation
areas were more invaded than high-elevation areas, and riparian zones were more invaded than nearby upland sites. For the
100 1000-m2 plots (across all vegetation types), 50% of the variation in nonnative species richness was explained by longitude, latitude,
native plant species richness, soil total percentage nitrogen, and mean maximum July temperature (n = 100 plots; P < 0.001). At the vegetation-type scale (n = 25 sets of four 1000-m2 plots/type), 64% of the variation in nonnative species richness was explained by native plant species richness, elevation,
and October to June precipitation (P < 0.001). The foliar cover of nonnative species (log) was strongly positively correlated with the nonnative species richness at the
plot scale (r = 0.77, P < 0.001) and vegetation-type scale (r = 0.83, P < 0.001). We concluded that, at the vegetation-type and regional scales in the north–central United States, (1) vegetation types
rich in native species are often highly vulnerable to invasion by nonnative plant species; (2) where several nonnative species
become established, nonnative species cover can substantially increase; (3) the attributes that maintain high native plant
species richness (high light, water, nitrogen, and temperatures) also help maintain nonnative plant species richness; and
(4) more care must be taken to preserve native species diversity in highly vulnerable habitats. 相似文献
362.
Mohammed Matouq 《Local Environment》2000,5(4):415-433
The ISO 14001 implementation process among certified firms in China was examined by conducting a questionnaire survey distributed to all certified firms as of December 1998. Results showed that the ISO 14001-based environmental management system (EMS) has a significant effect on firms' daily environmental activities and performance. Recycling, natural resource consumption and released pollutants have been managed in a better way and, in some cases, pollutants have been reduced. The study showed that firms' main targets for adopting the system were to: enhance the firm's public image; enhance employees' environmental awareness; improve the EMS inside the firm; improve the environmental aspects and performance inside the firm; and improve relations with government offices and local citizens. ISO 1400-based EMS implementation showed that it is a promising tool for helping build a better partnership between three main stakeholders, government, local citizens and enterprises. The system has enabled firms to consider the role of the local people in a more effective way. For example, special consideration is given to involving local citizens in health and emergency preparedness during firms' daily environmental activities. Moreover, enhancing environmental awareness among the local citizens and giving more consideration to co-operation with other firms from the same industrial groups are reported by certified firms. Finally, there are strong demands for government support to build more reliable information systems, ISO 14001-related research, more incentives for eco-labelling and tax exemptions. 相似文献
363.
Alan Mair Ali Fares Aly El‐Kadi 《Journal of the American Water Resources Association》2007,43(1):148-159
Abstract: Land‐use/land‐cover changes in Mākaha valley have included the development of agriculture, residential dwellings, golf courses, potable water supply facilities, and the introduction of alien species. The impact of these changes on surface water and ground water resources in the valley is of concern. In this study, streamflow, rainfall, and ground‐water pumping data for the upper part of the Mākaha valley watershed were evaluated to identify corresponding trends and relationships. The results of this study indicate that streamflow declined during the ground‐water pumping period. Mean and median annual streamflow have declined by 42% (135 mm) and 56% (175 mm), respectively, and the mean number of dry stream days per year has increased from 8 to 125. Rainfall across the study area appears to have also declined though it is not clear whether the reduction in rainfall is responsible for all or part of the observed streamflow decline. Mean annual rainfall at one location in the study area declined by 14% (179 mm) and increased by 2% (48 mm) at a second location. Further study is needed to assess the effect of ground‐water pumping and to characterize the hydrologic cycle with respect to rainfall, infiltration, ground‐water recharge and flow in the study area, and stream base flow and storm flow. 相似文献
364.
Kolja Rotzoll Aly I. El‐Kadi Stephen B. Gingerich 《Journal of the American Water Resources Association》2007,43(2):334-345
Abstract: In recent years the ground‐water demand of the population of the island of Maui, Hawaii, has significantly increased. To ensure prudent management of the ground‐water resources, an improved understanding of ground‐water flow systems is needed. At present, large‐scale estimations of aquifer properties are lacking for Maui. Seven analytical methods using constant‐rate and variable‐rate withdrawals for single wells provide an estimate of hydraulic conductivity and transmissivity for 103 wells in central Maui. Methods based on constant‐rate tests, although not widely used on Maui, offer reasonable estimates. Step‐drawdown tests, which are more abundantly used than other tests, provide similar estimates as constant‐rate tests. A numerical model validates the suitability of analytical solutions for step‐drawdown tests and additionally provides an estimate of storage parameters. The results show that hydraulic conductivity is log‐normally distributed and that for dike‐free volcanic rocks it ranges over several orders of magnitude from 1 to 2,500 m/d. The arithmetic mean, geometric mean, and median values of hydraulic conductivity are respectively 520, 280, and 370 m/d for basalt and 80, 50, and 30 m/d for sediment. A geostatistical approach using ordinary kriging yields a prediction of hydraulic conductivity on a larger scale. Overall, the results are in agreement with values published for other Hawaiian islands. 相似文献
365.
Charbel Mahfou Antoine El Samrani Rita Mouaw Walid Hleihel Rim El Khati Bruno S. Lartiges Na¨?m Oua¨?ni 《环境科学学报(英文版)》2009,21(1):120-126
Biofilms grown inside two sewage collecting pipes located in industrial and residential areas are studied. Bacterial biomass inside three layers of biofilms was evaluated. Biofilm cohesion under different mixing rate and ionic strength was also investigated. Effects of physical and chemical parameters in the biofilms were evaluated by monitoring turbidity, chemical and biochemical oxygen demands. Extracted organic matter from biofilms was partitioned to polar, aromatic and saturated fractions using activated silica column chromatography. Results revealed that bacterial biomass growth depending on biofilm thickness and stratification. The most loaded stratum in bacterial biomass was the sewage-biofilm interface stratum that represented 51% of the total bacterial biomass. Stirring rate and ionic strength of mono and bivalent salts showed a major influence in biofilm disruption. The stirring time enhanced the exchange dynamic and matter capture between biofilm fragments at the critical stirring rate 90 r/min. Sodium chloride showed the dispersing effect on biofilms in suspension, and decreased the BOD5 (biochemical oxygen demand) beyond the physiological salt concentration. 相似文献
366.
In the aftermath of catastrophic natural disasters such as hurricanes, tsunamis and earthquakes, emergency management agencies come under intense pressure to provide temporary housing to address the large‐scale displacement of the vulnerable population. Temporary housing is essential to enable displaced families to reestablish their normal daily activities until permanent housing solutions can be provided. Temporary housing decisions, however, have often been criticized for their failure to fulfil the socioeconomic needs of the displaced families within acceptable budgets. This paper presents the development of (1) socioeconomic disruption metrics that are capable of quantifying the socioeconomic impacts of temporary housing decisions on displaced populations; and (2) a robust multi‐objective optimization model for temporary housing that is capable of simultaneously minimizing socioeconomic disruptions and public expenditures in an effective and efficient manner. A large‐scale application example is optimized to illustrate the use of the model and demonstrate its capabilities ingenerating optimal plans for realistic temporary housing problems. 相似文献
367.
Beata Szafranek Elżbieta Synak Danuta Waligóra Janusz Szafranek Jan Nawrot 《Chemoecology》2008,18(4):205-216
Summary. The sampling behavior of the Colorado potato beetle Leptinotarsa decemlineata Say (CPB) involves examination of the surface
of potato leaves. It has been suggested that leaf surface compounds (volatiles and cuticular waxes) may be involved in host-plant
recognition, acceptance or discrimination. Here we report on the effect of leaf surface extracts of six Polish commercial
potato varieties on CPB feeding. We tested the influence of potato leaf surface extracts on CPB adult and larval feeding,
then separated the extracts with HPLC, and finally tested the effect of the HPLC-separated fractions on CPB feeding. The bioassays
were performed using potato leaf discs deprived of their original surface compounds. Applied to test discs at concentrations
ten times higher than natural (10 leaf area equivalent), the extracts deterred CPB adults and larvae from feeding. HPLC-separated
fractions composed of alkanes, sesquiterpene hydrocarbons, wax esters, benzoic acid esters, fatty acid methyl, ethyl, isopropyl
and phenylethyl esters, aldehydes, ketones, methyl ketones, fatty acids, primary alcohols, β-amyrin and sterols did not affect
adult CPB feeding. Similarly, alkanes, sesquiterpene hydrocarbons, wax esters, methyl ketones, sesquiterpene alcohols and
secondary alcohols had no effect on larval CPB feeding. The sterol fraction (cholesterol, β-sitosterol and stigmasterol) acted
as a phagostimulant to CPB larvae. We isolated a fraction demonstrating a phagodeterrent effect on CPB adults and larvae.
The qualitative composition of the deterrent fraction was quite similar in all potato extracts, but there were quantitative
differences between the varieties. Much further work is needed to identify the compounds that can produce the deterrent effect. 相似文献
368.
Kamal El Kadi Abderrezzak André Paquier Bernard Gay 《Environmental Fluid Mechanics》2008,8(2):169-198
This paper reports a numerical study on dam-break waves over movable beds. A one-dimensional (1-D) model is built upon the
Saint-Venant equations for shallow water waves, the Exner equation of sediment mass conservation and a spatial lag equation
for non-equilibrium sediment transport. The set of governing equations is solved using an explicit finite difference scheme.
The model is tested in various idealized experimental cases, with fairly good agreement between the numerical predictions
and measurements. Discrepancies are observed at the earlier stage of the dam-break wave and around the dam location due to
no vertical velocity component being taken into account. Sensitivity tests confirm that the friction coefficient is an important
parameter for the evaluation of sediment transport processes operating during a dam-break wave. The influence of the non-equilibrium
adaptation length (or the lag distance) is negligible on the wavefront celerity and weak on the free surface and bed profiles,
which indicates that one may ignore the spatial lag effect in dam-break wave studies. Finally, the simulation of the Lake
Ha!Ha! dyke-break flood event shows that the model can provide relevant results if a convenient formula for computing the
sediment transport capacity and an appropriate median grain diameter of riverbed material are selected. 相似文献
369.
Carin Jantzen Christian Wild Mohammed El-Zibdah Hilly Ann Roa-Quiaoit Christoph Haacke Claudio Richter 《Marine Biology》2008,155(2):211-221
Two species of giant clams, Tridacna maxima and T. squamosa, coexist in the Red Sea, but exhibit distinctly different depth distributions: T. maxima mostly occurs in shallow waters (reef flat and edge), while T. squamosa may occur down to the lower fore-reef slope. Giant clams have been described as mixotrophic, capable of both filter-feeding
and photosynthesis due to algal symbionts (zooxanthellae), therefore, observed depth preferences were investigated in relation
to possible differences in autotrophy vs. heterotrophy. This study was conducted from April to June 2004, at the reef near
the Marine Science Station, Aqaba, Gulf of Aqaba, Red Sea, and in May 2007, at a reef near Dahab, Sinai Peninsula, Egypt.
In situ measurements using a submersible pulse amplitude modulated fluorometer (Diving PAM), revealed no significant differences
in effective PSII quantum yield (ΔF/Fm′) and relative electron transport rates (ETR) between the two species; but rapid light curves (ETR vs. light, photosynthetically
active irradiance, PAR) showed significant differences in maximum photosynthetic rates (ETRmax), with 20% higher values in T. maxima. Chamber incubations displayed higher net and gross oxygen production by T. maxima (88.0 and 120.3 μmol O2 cm−2 mantle area day−1) than T. squamosa (56.7 and 84.8 μmol O2 cm−2 mantle area day−1); even under shading conditions (simulated depth of 20 m) T. maxima still achieved 93% of the surface gross O2 production, whereas T. squamosa reached only 44%. A correlation was found between ETR and net photosynthesis measured as oxygen production (T. maxima: R
2 = 0.53; T. squamosa: R
2 = 0.61). Calculated compensation depth (CD) (gross photosynthesis equals respiration) in T. maxima (16 m) matches the maximum depth of occurrence in this study (17 m). By contrast, the CD of T. squamosa (9 m) was much shallower than the maximum vertical range (42 m). Findings suggest T. maxima is a strict functional photoautotroph limited by light, whereas T. squamosa is a mixotroph whose photoautotrophic range is extended by heterotrophy.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
370.
Vembu Savithiri Attia Mohammed El Hadi Thangamuthu Mohanasundaram Thangamuthu Gunasekar 《Environmental science and pollution research international》2023,30(2):2597-2606
Environmental Science and Pollution Research - The phenomenon of drinking water scarcity has turned into the foremost issue that the world’s populace is facing today. The Algerian desert... 相似文献