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781.
Ping-Ping Shen Hong Zhou Ho-Yan Lai Ji-Dong Gu 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):575-581
Benthic infaunal communities at Mai Po Inner Deep Bay mudflat, Hong Kong were investigated between August 2002 and August
2003. A total of 55 species belonging to 8 Phyla from more than 99,074 specimens were recorded. The species richness varied
between 13 at Station B in August 2002 and 28 at Station D in August 2003 with an average of 21 across the mudflat and the
species diversity was low [H′(log2) = 0.7–3.5 with an average H′ = 2.4]. Seasonal variations were also observed through abundance and biomass across the mudflat among the seasons. The abundance
density was between 8,977 individuals m−2 at Station D in February 2003 and 77,256 individuals m−2 at Station B in November 2002 and the overall average density was 25,274 individuals m−2 for the four stations. The benthic infauna were dominated by pollution tolerant species at this wetland mudflat. 相似文献
782.
Two visitor-monitoring methods, video monitoring and counts by human observers, were compared in order to identify and evaluate their respective advantages and disadvantages. The analysis considered user numbers, user type (walkers, dog walkers, bicyclists, and joggers) and group size of visitors. Remarkable differences were found between the two methods for user type and use levels. At low use levels, evaluations based on video monitoring resulted in fewer single bicyclists compared to counts by human observers, whereas at high use levels, human observers counted fewer walkers and bikers than video-interpreters. Based on this comparative analysis, we derive recommendations for more effective visitor-monitoring approaches. All data were collected during a visitor-monitoring project in the Danube Floodplains National Park in Austria between 1998 and 1999. 相似文献
783.
Data on the species composition, abundance, and biomass of macrozoobenthos in the rapids of a small river flowing in the foothills of the southwestern Kamchatka Peninsula are considered along with the results of quantitative analysis of structural rearrangements in the lithophilic community under the effects of changes in the granulometric composition of bottom sediments. Groups of lithophilic and pelophilic invertebrates typical of the metarithral of such rivers (e.g., chironomids of subfamilies Diamesinae and Prodiamesinae) are identified.Translated from Ekologiya, No. 2, 2005, pp. 120–125.Original Russian Text Copyright © 2005 by Leman, Chebanova. 相似文献
784.
Linda Wrell 《Resources Policy》2007,32(4):191-204
The purpose of this paper is to analyse the competitive and efficiency impacts of a large merger in the world iron ore industry, using an event study approach. This method builds on an analysis of stock market reactions of the merging firms as well as close rivals at the time of the merger announcement. The event study method allows for the possibility to assess both the motivations behind as well as the welfare effects of the merger. The event study results for the merger announcement of Rio Tinto and North Ltd. show that, according to the market reactions, the main motive behind the merger was either the market power or the efficiency hypothesis. When adjusting the analysis to include several information releases about the merger, the overall result indicates that efficiency improvements were the predominant motives behind the merger. Thus, the event study results suggest that there are positive welfare effects to expect and the European Commission's decision to allow the merger is supported. 相似文献
785.
Naoto Mihara Dalibor Kuchar Yoshihiro Kojima Hitoki Matsuda 《Journal of Material Cycles and Waste Management》2007,9(1):21-26
From the point of view of a sustainable and environment-friendly society based on the recycling of material resources, it
is preferable to utilize waste gypsum as a substitute for lime, which is currently produced by the calcination of limestone.
In the present work, the reductive decomposition of CaSO4 was investigated under an atmosphere of CO: 2 vol%, CO2: 30 vol%, with N2 as a carrier gas without and with the addition of SiO2, Al2O3, or Fe2O3. It was found that the decomposition temperature of CaSO4 was significantly reduced from 1673 K to 1223 K when only 5 wt% Fe2O3 was added to CaSO4. In the case of the addition of SiO2 or Al2O3 to CaSO4, the decomposition temperature was reduced from 1673 K to 1623 K. This was due to the formation of composite oxides (calcium
ferrite, calcium silicate, or calcium aluminate) during the reaction of CaSO4 with the additives at a lower temperature. In addition, the formation of unfavorable product CaS was inhibited in the presence
of 5 wt% Fe2O3, and this inhibition effect further increased as the addition of Fe2O3 was increased. In contrast, no significant effect on the inhibition of CaS formation was observed on the addition of SiO2 or Al2O3. 相似文献
786.
Trochkine D. Iwasaka Y. Matsuki A. Yamada M. Kim Y.-S. Zhang D. Shi G.-Y. Shen Z. Li G. 《Water, Air, & Soil Pollution: Focus》2003,3(2):161-172
The Asian continent is recognized as one of the most important sources of mineral (or soil) particles. These particles have a large potential to effect global changes through the biogeochemical cycle of particulates and through radiative balance (IPCC Third Assessment Report, 2001). Therefore, comparison of particle compositions near the source region and those after long-range transport is important in understanding the long-range particle transport phenomenon. Individual aerosolparticles were collected in Dunhuang (40°09N; 94°41E), China. Particles were collected at the campus of the Meteorological Bureau of Dunhuang City (17 August 2001) and near the Mogao Grots, located approximately 30 km from Dunhuang (18 August 2001, 18 October 2001 and 13 January 2002) using a two-stage low-volume impactor. The morphology of individual aerosol particles and their elemental compositions were examined via a scanning electron microscope (Hitachi, S-3000N) equipped with an energy dispersive X-ray (EDX) analyzer (Horiba, EMAX-500). The particles collected at these locations were comprised primarily of minerals, with the exception of sulphateparticles in the submicron range that were contained in thesample collected on 18 October 2001 (likely, ammonium sulphate). The most abundant elements were found to be Si and Al. Approximately 46–77% of the collected particles were Si-richparticles (composed primarily of quartz and aluminosilicate),and 13–41% of the collected particles were Ca-rich particles,such as calcite (CaCO3), dolomite (CaMg(CO3)2),and gypsum (CaSO42H2O). The fractions of Fe-rich, Mg-rich, Ti-rich, K-rich, and Cl-rich were 3–10, 0–7, 0–3, 0–1, and 0–1%, respectively. Similar types of mineral particles were found in the free troposphere over Japan(Trochkine et al., 2002). A number of differences were found to exist between the particles collected in China and thosecollected in Japan, and these differences can be explained bychemical modification of the particles during transport fromChina to Japan. 相似文献
787.
Wanzenböck Josef Gassner Hubert Lahnsteiner Barbara Hassan Yasmin Hauseder Gudrun Doblander Christine Köck Günter 《Water, Air, & Soil Pollution: Focus》2002,2(4):227-248
In order to analyse potential influences of soda industryeffluents on the ecological integrity of Traunsee (TS) weinvestigated the fish community of the lake in comparison witha reference lake (Hallstättersee HS) and used a reconstructionfrom the (older) literature concerning the original speciescomposition of Traunsee. Published `Index of Biotic Integrity(IBI)' metrics were considered to be of limited value due tothe relatively low species number in the oligotrophic, Alpinelake. Therefore we included, in addition to speciescomposition, studies on egg distribution, larval fishdensities, life-history parameters (i.e. growth, maturity,fecundity, age and size composition), stress levels and heavymetal content of the dominant whitefish (Coregonuslavaretus), as well as overall fish density and biomass (usinghydroacoustics) to assess the ecological status of the fishcommunity. Two of the original 18 species have disappearedfrom the lake, presumably in connection with the introductionof non-native eel (Anguilla anguilla) and theconstruction of a power plant in the outflow. Silt from grindedlimestone together with highly alkaline pore waters is emittedvia industrial wastewater from Sodaworks and covers part of thelake bottom. We observed that eggs of whitefish were spawnedmainly in the main inflowing river and close to the shore, thusavoiding the silty areas and making the anticipated damage tothe reproductive potential of whitefish neglectable. This wascorroborated by larval surveys done weekly on both lakes fromJanuary to May, which showed halve the density of whitefishlarvae in TS compared to HS. Estimates of potentially spawningfish from hydroacoustic surveys resulted in a ratio of 1(TS) :3 (HS). Analysis of whitefish revealed that they are growingfaster in TS and have higher fecundity leading to somecompensation of lower abundance. High levels of fishing in TSmight have led to this pattern and to depressed yields asindicated by the age composition. Level of oxidative stress andheavy metal content were not discernible from the referencelake. Therefore we concluded that negative impacts on theecological status of the fish community resulted from fisheriesmismanagement and a power plant situated in the outflow of thelake, considered to have damaged spawning places for somespecies, but not from soda industry effluents. 相似文献
788.
地下水取水构筑物早期报废的原因错综复杂,而含铁地下水取水构筑物的早期报废问题常常比一般情况更为突出,本文对含铁地下水取水构筑的进水面上的腐蚀与沉积问题进行了初步探讨,供分析研究。 相似文献
789.
The response of forest understory vegetation to trampling applied at different temporal and spatial scales was determined
in a cliff-edge forest in Ontario, Canada. Three frequencies (0, 50, 500 passes per year) of short-term trampling (one year)
were applied to plots previously undisturbed. Existing trails that had received three frequencies (approx. 100, 500, 25,000
passes per year) of long-term trampling (18 years) were also studied. Community composition, species richness, and individual
species frequency were recorded in plots within 4 m and (or) 1 m of the patch centerline. The quantitative and qualitative
form of plant response to increased trampling was compared for short-term and long-term treatments, both within 4 m and within
1 m of the path centerline, to judge the consistency of trampling effects at different temporal and spatial scales.
As trampling frequency increased, community composition changed progressively, but consistently, in plots both within 4 m
and 1 m of the path centerline. Species richness was less affected by trampling and only decreased within 1 m of the path
centerline at the highest level of trampling (25,000 passes per season for 18 years). Effects of trampling on individual species
frequency were much less consistent at different temporal and spatial scales of trampling. The scale-dependence results suggest
that field workers and resource managers both should try explicitly to include and define multiple scale components when trying
to ascertain the response of vegetation to human disturbance factors. 相似文献
790.