首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   7篇
  免费   0篇
环保管理   2篇
综合类   1篇
基础理论   2篇
污染及防治   1篇
评价与监测   1篇
  2019年   1篇
  2013年   2篇
  2001年   1篇
  1988年   1篇
  1986年   2篇
排序方式: 共有7条查询结果,搜索用时 31 毫秒
1
1.
Residues of organochlorine pesticides, polychlorinated biphenyls (PCBs), and mercury were measured in eggs of Swainson's hawks (Buteo swainsoni) and ferruginous hawks (B. regalis) collected in North and South Dakota during 1974–79. DDE was the most common compound detected in the eggs, but residues were below levels known to have adverse effects on reproduction. Other organochlorine compounds and mercury were found at low levels. Eggs of ferruginous hawks tended to contain more compounds with higher residues than eggs of Swainson's hawks.  相似文献   
2.
From 1983 to 1985 we studied the in-situ feeding behavior of fourteen species belonging to nine genera of thecosomatous pteropods, one in the family Limacinidae, seven in the family Cavoliniidae, and one in the family Peraclididae. All the euthecosomes we examined fed with a large spherical mucous web. Peraclis reticulata (D'Orbigny), however, uses a funnel-shaped mucous sheet, resembling that of other pseudothecosomes. Although the feeding mechanisms are similar in all the animals we examined closely, we found great differences in the size and morphology of the external part of the mantle. In species of Diacria and Cavolinia the external mantle attains its greatest complexity, and appears to be used for the sorting or rejection of food and for flotation. Species of the other five cavoliniid genera we studied have greatly reduced external mantles and sink slowly while feeding. Species of Limacina have no external mantle but appear to arrest sinking by setting their mucous webs. P. reticulata, which also appears to be neutrally buoyant, has an extensive external mantle that completely covers the shell. We conclude that feeding with a large mucous web explains the presence of fragments of large, fast moving prey in the stomach contents of both pseudothecosomes and euthecosomes. At present, it is impossible to decide whether thecosomes should be regarded as carnivorous trappers of prey or as suspension feeders. The use of an external mucous web for feeding is probably common to all thecosome pteropods and is the fundamental andaptation that enables them to live holoplanktonically.  相似文献   
3.
Air emissions from gas-fired combustion devices such as boilers, process heaters, gas turbines and stationary reciprocating engines contain hazardous air pollutants (HAPs) subjected to consideration under the federal clean air act (CAA). This work presents a recently completed major research project to develop an understanding of HAP emissions from gas-fired boilers and process heaters and new HAP emission factors based on field emission tests of gas-fired external combustion devices used in the petroleum industry. The effect of combustion system design and operating parameters on HAP emissions determined by both field and research tests are discussed. Data from field tests of gas-fired petroleum industry boilers and heaters generally show very low emission levels of organic HAPs. A comparison of the emission data for boilers and process heaters, including units with and without various forms of NOx emission controls, showed no significant difference in organic HAP emission characteristics due to process or burner design. This conclusion is also supported by the results of research tests with different burner designs. Based on field tests of units fired with natural gas and various petroleum industry process gases and research tests in which gas composition was intentionally varied, organic HAP emissions were not determined to be significantly affected by the gas composition. Research data indicate that elevated organic HAP emission levels are found only under extreme operating conditions (starved air or high excess air combustion) associated with poor combustion.  相似文献   
4.
Rather than exploring how indigenous people have been alienated from resources by environmental policies, this paper explores how indigenous peoples have worked with environmental organizations to use the broad protections provided by environmental laws to protect cultural resources. The Eastern Band of Cherokee Indians, along with other concerned groups, partnered with environmentalists in opposing the destruction of the endangered snail darter’s critical habitat by the Tennessee Valley Authority’s Tellico Dam. The dam had been opposed by a shifting alliance of Cherokees, local farmers, trout fisherman, and environmentalists since it was announced in 1963. A previous lawsuit by this coalition delayed the project from 1972 to 1974 under the National Environmental Policy Act. The Endangered Species Act provided this coalition with a powerful tool for opposing the destruction of burial grounds and sacred village sites throughout the lower Little Tennessee River valley. The coalition of environmental organizations, Cherokees, and others was ultimately unsuccessful in stopping the dam from being built, but was successful in establishing a strict precedent for the enforcement of the Endangered Species Act. The lawsuit also created a space for the Eastern Band to negotiate for the return of Cherokee remains and halt the removal of any additional burials. In this situation, the strategic support of environmental regulation enabled the Eastern Band to exert some degree of control over the fate of cultural resources in the valley, and also demonstrates the significant role American Indian peoples played in one of the seminal events of the environmental movement during the 1970s.  相似文献   
5.
Measurements of respiration and excretion at 25°C were made for five species of ctenophores collected during five cruises to the Bahamas (1982–1984). The mean element-specific respiration and ammonium excretion rates of freshly collected specimens of all species ranged from 4 to 16% d-1, the mean atomic O:N ratios were 10 to 16, and ammonium averaged 60 to 90% of the total dissolved nitrogen excreted. For adult ctenophores, the carbon content ranged from 0.6% carbon (as percent of dry weight) for Bolinopsis vitrea to 3.7% carbon for Beroë ovata. There was a marked increase in the organic content (% carbon of dry weight) of small Bolinopsis vitrea with tentacles compared to fully lobate adults. B. vitrea had increasingly higher metabolic rates when held at food concentrations up to 100 copepods 1-1 (about 250 g C 1-1). The overall range between starved and well-fed B. vitrea was about two times for respiration and a factor of three for ammonium excretion. B. vitrea decreased from well-fed to a starved metabolic rate in about a day after removal from food. The metabolic rate of Eurhamphaea vexilligera was not measurably affected by short-term starvation or feeding (maximum 25 copepods 1-1). In feeding experiments, E. vexilligera of 20 to 56 mm length fed at rates equivalent to clearance rates of 250 to 1 800 ml h-1.  相似文献   
6.
Mitigation and Adaptation Strategies for Global Change - Rapid population growth, urbanization, and concentration of valuable assets and strategic infrastructure in coastal regions make coastal...  相似文献   
7.
This article describes the increasing connections between the fields of Indigenous studies and environmental management and examines some of the ways that an Indigenous studies perspective can guide thinking about environmental management. Indigenous groups have been involved in the management of environmental and natural resources on their lands since time immemorial. Indigenous groups have also become increasingly involved in Western practices of environmental management with the advent of co-management institutions, subsistence boards, traditional ecological knowledge forums, and environmental issues affecting Indigenous resources. Thus, it is an important time for scholarship that explores how Indigenous groups are both shaping and being affected by processes of environmental management. This article summarizes key findings and themes from eight papers situated at the intersection of these two fields of study and identify means by which environmental managers can better accommodate Indigenous rights and perspectives. It is the authors’ hope that increased dialog between Indigenous studies and environmental management can contribute to the building of sustainable and socially just environmental management practices.  相似文献   
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号