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901.
In this study, synthesis and speciation of polyaluminum chloride (PAC) for application in water treatment was investigated using a colorimetric speciation method. It was possible to produce stable preparations of PAC solutions in which a relatively stable cationic polymer predominated. The mode of preparation has a dramatic effect on the composition of PAC preparation. Some important parameters such as hydroxyl ligand number, mixing intensity, base injection rate and method, and aging were identified in this study. 相似文献
902.
This article covers the strategic, organizational, and operational decisions involved in one automobile manufacturer's efforts to balance its goals of productivity and high quality with the more elusive goal of environmental responsibility. The case material is based on the real-life experiences of Honda of America's two manufacturing plants in East Liberty and Marysville, Ohio. The case unfolds as the environmental manager in charge of the two plants faces the pending visit of her corporate boss from Tokyo, who has made it clear that environmental issues are of growing importance in Honda's overall direction. ISO 14000, the new environmental quality standards being adopted by some other manufacturers, serves as a focusing issue for the environmental manager's thinking, but this issue is really representative of a wider challenge facing the Ohio plants: balancing Honda's core mission of producing the best cars at the lowest cost possible, and being a responsible actor in the environmental arena. Complicating this challenge, the environmental manager has to negotiate another tension common in global manufacturing firms today: balancing the influence of Honda's corporate headquarters in Japan with the local and regional context at its American plant sites. 相似文献
903.
Brian D. Smith A. K. M. Aminul Haque M. Shakhawat Hossain Anisuzzaman Khan 《Environmental management》1998,22(3):323-335
Platanista gangetica ) are threatened in Bangladesh from the effects of dams, large embankment schemes, dredging, fisheries bycatch, directed hunting,
and water pollution. Visual surveys of the section of the Jamuna River located between the divergence of the Old Brahmaputra
River and the confluence of the Padma River and the section of the Kushiyara River located between the Bangladesh–India border
and the confluence of the Korangi River recorded a sighting rate of 0.13 sightings/km (mean group size = 1.8 dolphins) and
0.08 sightings/km (mean group size = 3.8 dolphins), respectively. These sections of river were considered to be priority areas
for investigation because several water development projects have already been constructed and more are planned for the areas.
During the surveys we examined the remains of dolphins caught accidentally in plastic gillnets and observed fishermen catching
the fish species Clupisoma garua using dolphin oil and body parts as a fish attractor. Additional studies are needed to assess the status of dolphins and
effects of water development and fisheries bycatch. Feasibility studies should be conducted on designating dolphin/fish sanctuaries
and creating artificial habitat or enhancing existing habitat in eddy countercurrent scour pools to mitigate deleterious impacts.
The environmental requirements of river dolphins reflect the needs of productive and biotically diverse tropical rivers. 相似文献
904.
Robert W. Kates Michael W. Mayfield Ralph D. Torrie Brian Witcher 《Local Environment》1998,3(3):279-297
This paper reports on two efforts to develop methods for quantifying and analysing greenhouse gas emissions from local places. The International Council for Local Environmental Initiatives-Cities for Climate Protection (ICLEI-CCP) campaign and the Association of American Geographers-Global Change in Local Places (AAG-GCLP) project represent independent efforts with differing origins and objectives. There is a rich and dynamic fine structure to the causal patterns that determine the level of greenhouse gas emissions in the society. This fine structure is essentially opaque to national and state-level inventories and analyses, and yet understanding it is necessary to understanding how human communities can be organised and human enterprise structured in environmentally sustainable ways. Simplified inventory methods that account for most but not all emissions, use readily available local data and, most important, inform efforts at emission reduction are currently available for cities and could be made available for larger or more diverse local regions or areas. 相似文献
905.
Carbon values,reforestation, and `perverse' incentives under the Kyoto protocol: An empirical analysis 总被引:3,自引:0,他引:3
Economic incentives for sequestering atmospheric carbon dioxide (CO2) in forests may be an effective way to meet greenhouse gas (GHG) reduction commitments under the Kyoto Protocol (KP). But concerns have been raised that the KP may create unintended incentives to excessively harvest existing forests if regenerated forests qualify for carbon (C) credits under the reforestation provision of Article 3.3. This paper combines an analytical model of the optimal forest rotation with both timber and C as priced outputs with data on timber and C growth and yield to different forest settings in the U.S. C prices of $50 per megagram (Mg) – the highest price evaluated– can considerably lengthen forest rotations (40 years or more), raise forest land values (as much as $1,900 per hectare), and sequester more C in the long run (up to 60 percent per acre), relative to the base case of no C compensation. However, if C payments are made for the regenerated stand only, in some situations, it is optimal to immediately harvest an otherwise premature stand at C prices as low as $20/Mg. The strength of perverse incentives to accelerate harvesting of existing forest varies by forest type, region, C price level, and institutional factors relevant to the compensation system. If C compensation were extended to existing stands, as may be possible under Article 3.4 of the KP, the perverse incentives for prematurely harvesting existing stands would not exist. 相似文献
906.
Terry V.Callaghan Lars Olof Bjrn Yuri Chernov Terry Chapin Torben R.Christensen Brian Huntley Roll A.Ims Margareta Johansson Dyanna Jolly Sven Jonasson Nadya Matveyeva Nicolai Panikov Walter Oechel Gus Shaver Sibyll Schaphoff Stephen Sitch Christoph Zckler 《Ambio-人类环境杂志》2004,33(7):445-449
在评价北极陆地生态系统影响时,人们常常强调物种和生态系统对环境变化响应的地理变化,这种变化往往与气候、生物多样性、植被带、生态系统结构和功能的南-北梯度相关联,可是,环境、生态系统的功能和结构上,以及环境史和当前气候变化的明显东-西变化显然也很重要.尽管一些地方变得温暖,但另一些地方却降温了,海洋、群岛和山脉等地理屏障的东西差异过去也对物种和植被带响应气候变化而改变分布区的能力产生了很大影响,同时,这些地理屏障为种群遗传分化和生物多样性热点区的形成提供了必要的隔离条件,这些屏障在未来气候变暖时,也将影响物种重新分布的能力.为了说明这种东西向的变化,同时也避免过分笼统或过于专业化,基于大尺度的天气和气候形成因素,北极气候影响评价项目确定了4个主要亚区.通过模拟与4个北极气候影响评价亚区有关的主要信息,导致物种分布区发生改变的地理屏障,特别是大陆的分布和海洋产生的隔离,明显会影响植被带的向北移动.对植被区向北移动的地理限制或者促进将影响将来碳的贮存和释放,以及生物圈与大气之间水和能量的交换.此外,气候变化使受威胁物种数量在各个亚区之间差别很大(白令海地区别尤其是热点),各个植被亚区重新分布的能力差异将影响每个区的生物多样性.总而言之,亚区分析表明,在整个北极地区水平上概括生态系统结构和功能的反应、物种的丧失,以及生物圈对气候系统的反馈的趋势是困难的,说明需要对北极陆地生态系统对于气候变化响应的空间变化性有深刻的认识. 相似文献
907.
In Ireland, mussels on exposed rocky shores constitute an interbreeding mixture of two forms of mussels, the blue mussel,
Mytilus edulis, and the Mediterranean mussel, M. galloprovincialis. Results from an Irish study in the 1980s, using partially diagnostic allozyme markers, indicated that mussels higher up
the shore were more galloprovincialis-like than those lower down. In this study we set out to test two hypotheses: (a) recruits arriving on the shore are composed
of genetically distinct cohorts that settle preferentially at different levels on the shore, and maintain genetic distinctiveness
into adulthood; (b) recruits are genetically homogeneous, but once settled they diverge genetically over time, due to within-habitat
site specific-selection. The diagnostic Me 15/16 DNA marker was used to analyse the genetic composition of newly-settled spat recruiting to artificial substrates, which were
placed at two-week intervals from May–October 2002, on the mid- and low shore areas of two exposed sites in Galway Bay. Adult
mussels were also collected on each sampling date. Results did not support the preferential settlement hypothesis, i.e., the
genetic composition of primary settlers (≤ 500 μm) was similar between tidal heights and shores. Neither was there evidence
of post settlement selective mortality, as adults were genetically similar to settling spat. In spat and adults the frequency
of the M. galloprovincialis allele was high (0.56–0.80), due to high frequencies of M. galloprovincialis (> 37%) and hybrid (> 33%) genotypes, and correspondingly low frequencies of the M. edulis genotype (< 11%). Adult mussels from a nearby sheltered estuarine site, while significantly different to exposed shore mussels,
still had low frequencies of the M. edulis genotype (< 17%), indicating no apparent advantage for the genotype in this environment. There are indications that the genetic
composition of mussels may be changing on the Atlantic coasts of Ireland. 相似文献
908.
Simulating forest structure, timber production, and socioeconomic effects in a multi-owner province.
K Norman Johnson Pete Bettinger Jeffrey D Kline Thomas A Spies Marie Lennette Gary Lettman Brian Garber-Yonts Tad Larsen 《Ecological applications》2007,17(1):34-47
Protecting biodiversity has become a major goal in managing coastal forests in the Pacific Northwest--an area in which human activities have had a significant influence on landscape change. A complex pattern of public and private forest ownership, combined with new regulations for each owner group, raises questions about how well and how efficiently these policies achieve their biodiversity goals. To develop a deeper understanding of the aggregate effect of forest policies, we simulated forest structures, timber production, and socioeconomic conditions over time for the mixture of private and public lands in the 2.3-million-ha Coast Range Physiographic Province of Oregon. To make these projections, we recognized both vegetative complexity at the stand level and spatial complexity at the landscape level. We focused on the two major factors influencing landscape change in the forests of the Coast Range: (1) land use, especially development for houses and cities, and (2) forest management, especially clearcutting. Our simulations of current policy suggest major changes in land use on the margins of the Coast Range, a divergence in forest structure among the different owners, an increase in old-growth forests, and a continuing loss of the structural elements associated with diverse young forests. Our simulations also suggest that current harvest levels can be approximately maintained, with the harvest coming almost entirely from private lands. A policy alternative that retained live trees for wildlife would increase remnant structures but at a cost to landowners (5-7% reduction in timber production). Another alternative that precluded thinning of plantations on federal land would significantly reduce the area of very large diameter (>75 cm dbh) conifer forests 100 years into the future 相似文献
909.
Brian M. Steele David A. Patterson Roland L. Redmond 《Environmental and Ecological Statistics》2003,10(3):333-356
The time and effort required of probability sampling for accuracy assessment of large-scale land cover maps often means that probability test samples are not collected. Yet, map usefulness is substantially reduced without reliable accuracy estimates. In this article, we introduce a method of estimating the accuracy of a classified map that does not utilize a test sample in the usual sense, but instead estimates the probability of correct classification for each map unit using only the classification rule and the map unit covariates. We argue that the method is an improvement over conventional estimators, though it does not eliminate the need for probability sampling. The method also provides a new and simple method of constructing accuracy maps. We illustrate some of problems associated with accuracy assessment of broad-scale land cover maps, and our method, with a set of nine Landsat Thematic Mapper satellite image-based land cover maps from Montana and Wyoming, USA. 相似文献
910.
William J Lindberg Thomas K Frazer Kenneth M Portier Frederic Vose James Loftin Debra J Murie Doran M Mason Brian Nagy Mary K Hart 《Ecological applications》2006,16(2):731-746
Many exploited reef fish are vulnerable to overfishing because they concentrate over hard-bottom patchy habitats. How mobile reef fish use patchy habitat, and the potential consequences on demographic parameters, must be known for spatially explicit population dynamics modeling, for discriminating essential fish habitat (EFH), and for effectively planning conservation measures (e.g., marine protected areas, stock enhancement, and artificial reefs). Gag, Mycteroperca microlepis, is an ecologically and economically important warm-temperate grouper in the southeastern United States, with behavioral and life history traits conducive to large-scale field experiments. The Suwannee Regional Reef System (SRRS) was built of standard habitat units (SHUs) in 1991-1993 to manipulate and control habitat patchiness and intrinsic habitat quality, and thereby test predictions from habitat selection theory. Colonization of the SRRS by gag over the first six years showed significant interactions of SHU size, spacing, and reef age; with trajectories modeled using a quadratic function for closely spaced SHUs (25 m) and a linear model for widely spaced SHUs (225 m), with larger SHUs (16 standardized cubes) accumulating significantly more gag faster than smaller 4-cube SHUs (mean = 72.5 gag/16-cube SHU at 225-m spacing by year 6, compared to 24.2 gag/4-cube SHU for same spacing and reef age). Residency times (mean = 9.8 mo), indicative of choice and measured by ultrasonic telemetry (1995-1998), showed significant interaction of SHU size and spacing consistent with colonization trajectories. Average relative weight (W(r)) and incremental growth were greater on smaller than larger SHUs (mean W(r) = 104.2 vs. 97.7; incremental growth differed by 15%), contrary to patterns of abundance and residency. Experimental manipulation of shelter on a subset of SRRS sites (2000-2001) confirmed our hypothesis that shelter limits local densities of gag, which, in turn, regulates their growth and condition. Density-dependent habitat selection for shelter and individual growth dynamics were therefore interdependent ecological processes that help to explain how patchy reef habitat sustains gag production. Moreover, gag selected shelter at the expense of maximizing their growth. Thus, mobile reef fishes could experience density-dependent effects on growth, survival, and/or reproduction (i.e., demographic parameters) despite reduced stock sizes as a consequence of fishing. 相似文献