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Growing global trade with organic products has increased the demand for environmental impact assessments during both production and transport. Environmental hotspots of organic soybeans produced in China and imported to Denmark were identified in a case study using a life cycle assessment approach. Furthermore, environmental impacts of organic and conventional soybeans at farm gate were compared in the case study. The total global warming potential (GWP) per ton organic soybeans imported to Denmark revealed that 51% came from transportation and 35% from the farm level. Comparing organic and conventional soybean at farm gate showed that GWP, non-renewable energy use, acidification and eutrophication was lower per ton organic soybeans, whereas land use was slightly higher.  相似文献   
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Using kriging, a statistical technique, the National Crop Loss Assessment Network (NCLAN) program estimated growing season 5-month (May-September) ambient 7-h mean O3 concentrations for each of the major crop growing areas of the United States for 1978-1982. The O3 estimates were used to predict economic benefits anticipated by lowering O3 levels in the United States. This paper reviews NCLAN’s use of kriging to estimate 7-h seasonal mean O3 concentrations for crop growing regions. Although the original kriging program used by NCLAN incorrectly calculated the diagonal elements of the kriging equations, this omission did not result in significant errors in the predicted estimates. Most of the data used in estimating the 7-h seasonal values were obtained from urban areas; the use of these data tended to underestimate the 7-h seasonal O3 concentrations in rural areas. It is recommended that only O3 data that are representative of agricultural areas and have been collected under accepted quality assurance programs be used In future kriging efforts.  相似文献   
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Oil spill contingency planners need an improved approach to understanding and planning for the human dimensions of oil spills. Drawing on existing literature in social impact assessment, natural hazards, human ecology, adaptive management, global change and sustainability, we develop an integrative approach to understanding and portraying the human dimensions impacts of stressors associated with oil spill events. Our approach is based on three fundamental conclusions that are drawn from this literature review. First, it is productive to acknowledge that, while stressors can produce human impacts directly, they mainly affect intermediary processes and changes to these processes produce human impacts. Second, causal chain modeling taken from hazard management literature provides a means to document how oil spill stressors change processes and produce human impacts. Third, concepts from the global change literature on vulnerability enrich causal models in ways that make more obvious how management interventions lessen hazards and mitigate associated harm. Using examples from recent spill events, we illustrate how these conclusions can be used to diagrammatically portray the human dimensions of oil spills.  相似文献   
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To elucidate the effects of temperature and algal cell concentration on pumping of water in the ascidian Ciona intestinalis a number of different experiments were performed. Beat frequency of the lateral cilia in the openings of the branchial sac was measured in intact specimens using a microprojection objective and a monochrome CCD video camera. At constant low algal cell concentration, beat frequencies increased linearly with temperature from 4.0 Hz (±0.5) at 7.4 °C to 13.6 Hz (±1.6) at 20.1 °C. At a constant temperature of 15 °C, beat frequency decreased with increasing algal cell concentration from approximately 3000 to >10 000 Rhodomonas sp. cells ml−1. The decrease was observed both in experiments where the ascidians had been acclimated to a fixed algal cell concentration and in experiments with changing concentrations. Effect of algal cell concentration on squirting/siphon closure and flow velocity in the exhalent siphon was measured using a thermistor. At low algal cell concentrations, flow velocity in the exhalent siphon was stable, apart from a few short squirts. At very high algal cell concentrations, the flow velocity was reduced and much less stable, with prolonged squirting. The effect of gut content on filtration was studied in experiments with specimens acclimated to high algal cell concentrations. Results showed a close relation between gut clearance and filtration rate. From the experimental results and a qualitative analysis of the Ciona-pump it was concluded that the ciliary beat frequency is proportional to the water flow through the sea squirt and that changes in pumping caused by temperature or algal cell concentration are under nervous control or governed by enzyme kinetics, rather than being a result of physico-mechanical properties, i.e. pump efficiency versus flow resistance, of the ascidian pump. Received: 6 October 1997 / Accepted: 8 October 1998  相似文献   
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Containment of genetically modified (GM) microorganisms such as Escherichia coli is a legal requirement to protect the environment from an unintended release and to avoid horizontal gene transfer (HGT) of recombinant DNA to native bacteria. In this study, we sampled the laboratory wastewater (LWW) at a large Swiss university from three sources over 2 years and cultured ampicillin-resistant, presumptive GM E. coli. From a total of 285 samples, 127 contained presumptive GM E. coli (45%) at a mean concentration of 2.8 × 102 CFU/ml. Plasmid DNA of 11 unique clones was partially or entirely sequenced. All consisted of cloning vectors harboring research-specific inserts. To estimate the chance of HGT between GM E. coli and native bacteria in LWW, we identified taxa representative for the bacterial community in LWW using 16S rRNA amplicon sequencing and measured conjugation frequencies of E. coli with five LWW isolates. At optimal conjugation conditions, frequencies were between 3.4 × 10−3 and 2.4 × 10−5. Given the absence of transferable broad-host range plasmids and suboptimal conjugation conditions in the LWW system, we conclude that the chance of HGT is relatively low. Still, this study shows that the implementation of robust containment measures is key to avoid the escape of GM microorganisms.

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This study is anchored in a contractor company providing well services for platform drilling on the Norwegian (NCS) and the UK Continental Shelves (UKCS). The research project has as its point of departure the potential influences of group level characteristics, structural work factors, trust, and safety behaviour on safety performance. Do perceptions and performance differ across Shelves? Are “nomadic” groups or employees that have more unpredictable shift rotations more exposed to accidents than others? Is high trust and sound safety behaviour enhancing good safety performance? The results are based on questionnaire data from two samples of personnel distributed across three installations on the UKCS and nine on the NCS with a response rate of 67%: N = 170 (UKCS) and N = 621 (NCS). In addition, two focus group interviews were held in each country, with 15 participants in each. The results show that our model makes sense. Shelf shows a significant influence on safety performance in all but the final stage in our five-step logistic regression model, indicating that the effect may be mediated by safety compliance and safety participation. Installations and different work teams have different exposure and structural work factors matter significantly. Somewhat counter-intuitively, employees who have a “nomadic” status and who hold the least regular shift rotations appear to have a lower risk of being involved in incidents. High trust in workmates buffers against incident involvement and the same applies for high safety compliance. The results, challenges and implications for research and safety practitioners are discussed.  相似文献   
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