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711.
This study investigates the relationship between characteristics of environmental policy statements and the reputations of ISO 14001 registrars who had performed certification audits of firms operating in mainland China. Three characteristics of environmental policy statements were examined: (1) The conformance of the policy to strict interpretations of the international standard; (2) The policy statement's adherence to the good practice guidelines specified in ISO 14004; and, (3) Self-reported evaluations of the policy statement's effectiveness as implemented. Data from 106 facilities in Beijing, Shanghai and Guangzhou reveal that registrar quality has a relatively weak, positive relationship with conformance to both ISO 14001 standards and to ISO 14004 guidelines, but no relationship was observed with the self-reported data. Additional findings are that the use of foreign registrars is significantly associated with the adoption of ISO 14004 guidelines and that conformance with ISO 14001 standards is somewhat higher for international joint ventures and foreign-owned firms than for state-owned enterprises.  相似文献   
712.
Organisms exposed to suboptimal environments incur a cost of dealing with stress in terms of metabolic resources. The total amount of energy available for maintenance, growth and reproduction, based on the biochemical analysis of the energy budget, may provide a sensitive measure of stress in an organism. While the concept is clear, linking cellular or biochemical responses to the individual and population or community level remains difficult. The aim of this study was to validate, under field conditions, using cellular energy budgets [i.e. changes in glycogen-, lipid- and protein-content and mitochondrial electron transport system (ETS)] as an ecologically relevant measurement of stress by comparing these responses to physiological and organismal endpoints. Therefore, a 28-day in situ bioassay with zebra mussels (Dreissena polymorpha) was performed in an effluent-dominated stream. Five locations were selected along the pollution gradient and compared with a nearby (reference) site. Cellular Energy Allocation (CEA) served as a biomarker of cellular energetics, while Scope for Growth (SFG) indicated effects on a physiological level and Tissue Condition Index and wet tissue weight/dry tissue weight ratio were used as endpoints of organismal effects. Results indicated that energy budgets at a cellular level of biological organization provided the fastest and most sensitive response and energy budgets are a relevant currency to extrapolate cellular effects to higher levels of biological organization within the exposed mussels.  相似文献   
713.
This study details the investigations of the effect of temperature and the presence of predators on the vertical distribution of the ctenophore Pleurobrachia pileus. Previous studies had suggested that P. pileus moves to the sediment when exposed to colder temperatures as an energy saving strategy. Although we did observe an effect of temperature on the movement of the ciliate combs, the effect of temperature on the average depth of animals in the water column was not significant, but a significant interaction was found between temperature and exposure time. In the presence of benthic predators or of water previously inhabited by these predators P. pileus changed its vertical distribution significantly, and moved away from the sediment, thus reducing the risk of being predated. We conclude that P. pileus can sense the presence of its predators, and changes its behaviour accordingly.Communicated by O. Kinne, Oldendorf/Luhe  相似文献   
714.
Plutonium in Polish forest soils and the Bór za Lasem peat bog is resolved between Chernobyl and global fallout contributions via inductively coupled plasma mass spectrometric measurements of 240Pu/230Pu and 241Pu/239Pu atom ratios in previously prepared NdF3 alpha spectrometric sources. Compared to global fallout, Chernobyl Pu exhibits higher abundances of 240Pu and 241Pu. The ratios 240Pu/230Pu and 241Pu/239Pu co-vary and range from 0.186 to 0.348 and 0.0029 to 0.0412, respectively, in forest soils (241Pu/239Pu = 0.2407 x [240Pu/239Pu] - 0.0413; r2 = 0.9924). Two-component mixing models are developed to apportion 239+240Pu and 241Pu activities; various estimates of the percentage of Chernobyl-derived 239+240Pu activity in forest soils range from < 10% to > 90% for the sample set. The 240Pu/230Pu - 241Pu/239Pu atom ratio mixing line extrapolates to estimate 241Pu/239Pu and the 241Pu/239+240Pu activity ratio for the Chernobyl source term (0.123 +/- 0.0007; 83 +/- 5; 1 May 1986). Sample 241Pu activities, calculated using existing alpha spectrometric 239+240Pu activities, and the 240Pu/230Pu and 241Pu/239Pu atom ratios, agree relatively well with previous liquid scintillation spectrometry measurements. Chernobyl Pu is most evident in locations from northeastern Poland. The 241Pu activities and/or the 241Pu/239Pu atom ratios are more sensitive than 240Pu/239Pu or 238Pu/239+240Pu activity ratios at detecting small Chernobyl 239+240Pu inputs, found in southern Poland. The mass spectrometric data show that the 241Pu activity is 40-62% Chernobyl-derived in southern Poland, and 58-96% Chernobyl in northeastern Poland. The Bór za Lasem peat bog (49.42 degrees N, 19.75 degrees E), located in the Orawsko-Nowotarska valley of southern Poland, consists of global fallout Pu.  相似文献   
715.
An airborne gamma-ray spectrometry survey of nuclear sites in Belgium   总被引:1,自引:0,他引:1  
As part of a wider study to define the existing background levels in Belgium an airborne gamma-ray survey was conducted in two areas associated with nuclear sites. In the Mol area, the survey zone included areas surrounding the SCK-CEN nuclear research centre, and its associated neighbourhood which includes radioactive waste stores, fuel manufacture and fabrication facilities and an international accelerator laboratory. In the vicinity of Fleurus, the survey included the IRE complex with radiochemical laboratories, irradiation facilities and stores, and isotope production accelerators. The survey was conducted using a twin engined helicopter equipped with a combined scintillation and semiconductor spectrometer. The system was installed and tested in the UK, and then transferred to Belgium for operations. The complete survey was conducted successfully within 1 week. The results provide a comprehensive record of the radiation environment of the nuclear sites at time of survey, and show a range of signals associated with the types of activity present in each area. They confirm that radiation fields are largely confined to the operational sites, and provide a traceable record against which future changes could be assessed. The demonstration of efficient deployment between two European countries, coupled with rapid mapping of many different radiometric signals around these sites confirms the utility of the airborne gamma spectrometry approach for accurate definition of enhanced radiation fields. This has important implications for emergency response.  相似文献   
716.
Daily dietary intakes of two naturally occurring long-lived radionuclides, 232Th and 238U, were estimated for the adult population living in a number of Asian countries, using highly sensitive analytical methods such as instrumental and radiochemical neutron activation analysis (INAA and RNAA), and inductively coupled plasma mass spectrometry (ICP-MS). The Asian countries that participated in the study were Bangladesh (BGD), China (CPR), India (IND), Japan (JPN), Pakistan (PAK), Philippines (PHI), Republic of Korea (ROK) and Vietnam (VIE). Altogether, these countries represent more than 50% of the world population. The median daily intakes of 232Th ranged between 0.6 and 14.4 mBq, the lowest being for Philippines and the highest for Bangladesh, and daily intakes of 238U ranged between 6.7 and 62.5 mBq, lowest and the highest being for India and China, respectively. The Asian median intakes were obtained as 4.2 mBq for 232Th and 12.7 mBq for 238U. Although the Asian intakes were lower than intakes of 12.3 mBq (3.0 ug) 232Th and 23.6 mBq (1.9 ug) 238U proposed by the International Commission on Radiological Protection (ICRP) for the ICRP Reference Man, they were comparable to the global intake values of 4.6 mBq 232Th and 15.6 mBq 238U proposed by the United Nation Scientific Commission on Effects of Radiation (UNSCEAR). The annual committed effective doses to Asian population from the dietary intake of 232Th and 238U were calculated to be 0.34 and 0.20 microSv, respectively, which are three orders of magnitude lower than the global average annual radiation dose of 2400 microSv to man from the natural radiation sources as proposed by UNSCEAR.  相似文献   
717.
Environmental changes in Sepetiba Bay,SE Brazil   总被引:2,自引:0,他引:2  
Sepetiba Bay is an example of an aquatic environment that has been severely impacted by human occupation and industrial activities in its basin. Some 400 industries including metallurgical, petrochemical and pyrometallurgical smelters, which emitted pollutants to air, soil and water, were established in Sepetiba Basin during the past 30 years. Apart from these point sources, changes in land use have also resulted in a large remobilization of pollutant deposition on Sepetiba Bay Basin. Studies have pointed out significant changes in sedimentation rates, concentrations of inorganic pollutants (Zn, Cd, Pb and Hg) and more recently, eutrophication, pointing to this area as an example of an impacted coastal zone. Notwithstanding local sources, Sepetiba Bay also suffers environmental impacts caused by diversion of river waters from adjacent basins, with some 30% of the total Hg flux to Sepetiba Bay and a 10-fold increase in water and sediment fluxes resulting from this. Decreasing environmental quality compromises both the large biodiversity and the potential economic uses of Sepetiba Bay, including fisheries and tourism. Monitoring of heavy metal levels in organisms (algae, mollusks, crustaceans and oysters) often shows concentrations well above the limits allowed following Brazilian legislation for food quality. Historical evolution of these concentrations suggests a worsening of the situation. Failure to monitor the effect of land-based activities, including those from other basins artificially associated with Sepetiba Bay has resulted in poor scenario construction and proper management planning.  相似文献   
718.
The effects of grazing by feral horses on vegetation and dune topography at Assateague Island National Seashore were investigated using color-infrared imagery, lidar surveys, and field measurements. Five pairs of fenced and unfenced plots (300 m2) established in 1993 on sand flats and small dunes with similar elevation, topography, and vegetation cover were used for this study. Color-infrared imagery from 1998 and field measurements from 2001 indicated that there was a significant difference in vegetation cover between the fenced and unfenced plot-pairs over the study period. Fenced plots contained a higher percentage of vegetation cover that was dominated by American beachgrass (Ammophila breviligulata). Lidar surveys from 1997, 1999, and 2000 showed that there were significant differences in elevation and topography between fenced and unfenced plot-pairs. Fenced plots were, on average, 0.63 m higher than unfenced plots, whereas unfenced plots had generally decreased in elevation after establishment in 1993. Results demonstrate that feral horse grazing has had a significant impact on dune formation and has contributed to the erosion of dunes at Assateague Island. The findings suggest that unless the size of the feral horse population is reduced, grazing will continue to foster unnaturally high rates of dune erosion into the future. In order to maintain the natural processes that historically occurred on barrier islands, much larger fenced exclosures would be required to prevent horse grazing.  相似文献   
719.
720.
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