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排序方式: 共有106条查询结果,搜索用时 234 毫秒
91.
The US Environmental Protection Agency conducts risk assessments of insecticide applications to wild birds using a model that is limited to the dietary route of exposure. However, free-flying birds are also exposed to insecticides via the inhalation and dermal routes. We measured azinphos-methyl residues on the skin plus feathers and the feet of brown-headed cowbirds (Molothrus ater) in order to quantify dermal exposure to songbirds that entered and inhabited an apple (Malus x domestica) orchard following an insecticide application. Exposure to azinphos-methyl was measured by sampling birds from an aviary that was built around an apple tree. Birds sampled at 36 h and 7-day post-application were placed in the aviary within 1 h after the application whereas birds exposed for 3 days were released into the aviary 4-day post-application. Residues on vegetation and soil were also measured. Azinphos-methyl residues were detected from the skin plus feathers and the feet from all exposure periods. Our results underscore the importance of incorporating dermal exposure into avian pesticide risk assessments.  相似文献   
92.
Wang D  Atkinson S  Hoover-Miller A  Li QX 《Chemosphere》2007,67(10):2044-2057
Blubber, liver and kidney samples of harbor seals (Phoca vitulina) from the northern Gulf of Alaska were collected during 2000-2001 for the analysis of polychlorinated naphthalenes (PCNs) and coplanar polychlorinated biphenyls (CoplPCBs). On the lipid weight (lw) base, the total concentrations of PCNs (Sigma PCNs) ranged from 0.3 to 27 ng/g lw, and the total concentrations of CoplPCBs (Sigma CoplPCBs) were 3.6-546 ng/g lw in all the tissue samples. Di-ortho PCBs and mono-ortho PCBs were dominant followed by non-ortho PCBs and PCNs. Sigma Mono-ortho PCBs and Sigma di-ortho PCBs in nursing seals were apparently lower than those in male adult seals, but Sigma PCNs and Sigma non-ortho PCBs in female adults were not significantly different from those in male adults. Differences in PCNs and CoplPCBs congener profiles in female and male adult seals are apparently related to their chemical structure and properties, animal's developmental stages and physiological conditions. A large quantity of mono-ortho and di-ortho PCBs might be transferred to newborns from the nursing seals during lactation, while non-ortho PCBs and PCNs were relatively accumulative in the mother seals. Sigma PCNs and Sigma CoplPCBs in the harbor seals correlated with ages, gender, body weight and blubber thickness, but the blubber Sigma PCNs and Sigma CoplPCBs in Kodiak Island and Southern Alaska Peninsula (KIAP) did not significantly differ from those in Prince William Sound (PWS). In addition to the new PCB data, this first report on PCN contamination in Alaskan harbor seal tissues is useful for the wildlife and ecosystem management and human health protection.  相似文献   
93.
This paper argues that interdisciplinary collaboration between the sciences, the arts/humanities and engineering will provide innovative responses to important changes in our natural environment. Specifically, it will introduce ??Images of Nature??, a case study on creative collaboration and a multi-level research project at Purdue University, headed by Prof. Shannon McMullen and Prof. Fabian Winkler. By bringing together scientists, engineers and artists, ??Images of Nature?? aims to convey the significance of new understandings of nature in images and tangible artifacts (e.g., data visualization, functional devices, generative and kinetic installations) for the public. It is our hope that this project will be the starting point for a flexible network connecting science, engineering and the arts on Purdue??s West Lafayette campus to enrich STEM education and provide a local model for STE(A)M (STEM disciplines plus Art), which emphasizes creativity and innovation; critical thinking and problem solving; flexibility and adaptability; cross-disciplinary communication and collaboration in the context of our changing natural environment.  相似文献   
94.
95.
A study was conducted to identify, characterize, and quantify the national particulate air pollution problem from stationary sources. Particulate emissions from stationary sources were determined from data on emission factors, grain loadings, and material balances. The principal method used for establishing the tonnage emitted by an industry utilized uncontrolled emission factors. Total tonnage emitted by a given industry was calculated from four quantities: (1) an emission factor for the uncontrolled source; (2) the total tonnage processed per year by the industry; (3) the efficiency of control equipment used; and (4) the percentage of production capacity equipped with control devices.

Particulate emissions from stationary sources in the United States currently total approximately 18 X 106 ton/yr. The major stationary sources of particulates include electric power generation plants, the crushed stone industry, the forest products industry, agriculture and related operations, the cement industry, and the iron and steel industry.

Three methods were developed to project the total quantity of particulate pollutants emitted up to the year 2000. In making these forecasts, these factors were considered (1) changes in production capacity; (2) improvements in control devices; and (3) regulatory action to enforce installation of control equipment.

These forecasts indicate that particulate emissions can be reduced from the current level of 18 X 106 ton/yr to 3 X 106 ton/yr by 2000 based on the most optimistic forecast. The projections also suggest that major reductions of particulate matter will most likely occur by installation of control equipment on uncontrolled sources and by shifts to more efficient types of collection equipment on existing controlled sources.  相似文献   
96.
Environmental and Ecological Statistics - Cetacean abundance estimation often relies on distance sampling methods using shipboard visual line-transect surveys, which assumes that all animals on the...  相似文献   
97.
Abstract: The Gully, the largest submarine canyon off the coast of eastern Canada, is currently under consideration as a marine conservation area, primarily because of the increasing interest in oil and gas production on the Scotian Shelf. Cetaceans, as a guild of abundant, large organisms that are relatively sensitive to such threats, provide a reliable means to determine the boundaries for a conservation area in this region. We compared the abundance of cetaceans between the Gully and other parts of the Scotian Shelf and Slope and found that abundance was higher in the Gully. We also assessed cetacean distribution and relative abundance within the Gully relative to search effort for several spatial and temporal parameters: depth, slope, sea surface temperature, and month. Distribution within the Gully was most strongly correlated with depth, but was also significantly correlated with sea surface temperature and month. Five of the 11 cetacean species commonly found in the Gully, and all those for which the Gully formed significant habitat on the Scotian Shelf, were concentrated in the deep (200–2000 m) mouth of the canyon. We suggest that a year-round marine protected area is necessary for the Gully. A core protection zone should be defined in the Gully based on depth and bounded by the 200-m isobath. A buffer zone around the core zone should be defined to provide protection from activities with further-reaching effects, such as noise, dredging, and chemical pollution.  相似文献   
98.
We report the results of a mail questionnaire for 312 manufacturing firms in the province of Ontario (Canada). We conducted a cross-sectional analysis of workplace level health and safety policies, practices and attitudes. Analyses were conducted across firm categories based upon lost-time frequency rate (LTFR) data. Lower LTFRs were associated with paternalistic initiatives, recording of occupational health and safety (OHS) measures, greater involvement of workers in decision-making, and better managerial attitudes concerning the importance of OHS. The composition of the Joint Health and Safety Committee (JHSC), a committee mandated in all workplaces we sampled, differed according to injury rate: the mean number of worker (vs. management) members on the JHSC was higher for lower injury sites, and the mean number of worker members attending JHSC meetings was also higher for lower injury worksites. In addition, workplaces with lower LTFR benefitted by having JHSCs with more executive functions and greater worker involvement. In conclusion, managerial and worker participation in OHS initiatives characterizes safer workplaces. Also, general concern of management towards OHS—illustrated by both attitudes and concrete actions—is also associated with lower injury rates.  相似文献   
99.
Cash for work (CFW) programmes are utilised in various disaster and emergency contexts and were a prominent component of the tsunami response in Aceh province, Indonesia. This paper describes Mercy Corps' CFW programme, discusses CFW implementation experiences and provides key recommendations for similar programmes in future emergencies. For the majority of CFW participants and their households, CFW was the only source of household income and 93 per cent of household incomes were attributable to it. The CFW programme empowered displaced populations to return to their communities; 91 per cent of participants indicated that CFW facilitated their return. Other reported psychosocial benefits included providing productive activities and giving communities an opportunity to work together. Mercy Corps' experience in Aceh demonstrates that cash disbursements can be safely delivered in a widespread manner in emergencies, and that when implemented on a short-term basis, can have positive impacts at the individual and community level.  相似文献   
100.
We report observations on spawning and early development in bone-eating worms of the genus Osedax. Individual females of Osedax rubiplumus were observed at 1820 m depth freely spawning hundreds of oocytes, and females of an undescribed species, Osedax “orange collar”, were observed spawning in laboratory aquaria. Cytological and molecular analysis of the spawned oocytes of two Osedax species revealed no evidence for the bacterial endosymbionts that the female worms require for their nutrition, suggesting that the bacteria must be acquired later from the environment, as they are in other siboglinids. Individual O. “orange collar” females released an average of 335 (±130) eggs per day, but the number of oocytes spawned per day varied greatly, suggesting that not all the females spawned daily. Fertilization rates of the spawned oocytes varied from 0 to 100%, though most females showed nearly 100% fertilization rates. Oocytes spawned in the laboratory at 4–6°C were negatively buoyant. If fertilized, these oocytes extruded polar bodies and then after at least four hours cleaved unequally. Subsequent cleavages occurred in a spiral pattern at roughly 2-h intervals, resulting in free-swimming trochophore larvae after 24 h. These lecithotrophic trochophores swam for 9–16 days before settling with several hooked chaetae, similar to those of dwarf Osedax males. The larval life span of the Osedax species studied in the laboratory appears to be shorter than in closely related Vestimentifera. Osedax rubiplumus, on the other hand, has much larger oocytes and so may have greater dispersal potential than these other Osedax species. The high fecundity and apparently continuous reproduction of Osedax boneworms permits the opportunistic exploitation of sunken vertebrate bones. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   
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