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61.
A key challenge in ecology is to find ways to obtain complete and accurate information about the diets of animals. To respond to this challenge in seabirds, traditional methods (usually stomach content analysis or observations of prey at nests) have been supplemented with indirect methods or molecular trophic markers. These techniques have the potential to extend the period of investigation outside the few short months of breeding and avoid biases. Here, we use an analysis of fatty acids (FAs) and fatty alcohols (FALs) from blood, adipose tissue and stomach oil to investigate how the diets of male and female common guillemots (Uria aalge), black-legged kittiwakes (Rissa tridactyla) and northern fulmars (Fulmarus glacialis) differed through the sampling period (prelaying and breeding season) and by sex. Diets of both sexes of all three species generally varied across the season, but sex differences were apparent only in fulmars during prelaying. Our study shows that FA/FAL analysis can provide significant insights into diets of seabirds, in particular periods of the annual cycle which are not readily studied using traditional methods.  相似文献   
62.
In the South West of the UK, a growing number of rural and urban communities are exploring various pathways to a more sustainable living. The village of Belstone is among these pioneers of change through its Green Village project. It is a relatively affluent community and it has been a major challenge to engage people that are reticent to change their lifestyle and suspicious of the motives of the initiators. Based on a process of action research, this paper explores the attitudes and perceptions towards sustainability and how they influenced the people's engagement. We demonstrate that the partnership was effective in enabling the villagers engaged in the project to take control over the process. Behaviour changes were reported by the villagers actively engaged with the initiative. The Green Village did not “snowball” to the entire community; however, many of those who chose not to engage associated the word “Green” with traits that they did not identify with.  相似文献   
63.
Radiation-induced adaptive response in fish cell lines   总被引:1,自引:0,他引:1  
There is considerable interest at present in low-dose radiation effects in non-human species. In this study gamma radiation-induced adaptive response, a low-dose radiation effect, was examined in three fish cell lines, (CHSE-214 (Chinook salmon), RTG-2 (rainbow trout) and ZEB-2J (zebrafish)). Cell survival after exposure to direct radiation with or without a 0.1 Gy priming dose, was determined using the colony forming assay for each cell line. Additionally, the occurrence of a bystander effect was examined by measuring the effect of irradiated cell culture medium from the fish cell lines on unexposed reporter cells. A non-linear dose response was observed for all cell lines. ZEB-2J cells were very sensitive to low doses and a hyper-radiosensitive (HRS) response was observed for doses <0.5 Gy. A typical protective adaptive response was not detected in any of the three fish cell lines tested. Rather, it was found that pre-exposure of these cells to 0.1 Gy radiation sensitized the cells to subsequent high doses. In CHSE-214 cells, increased sensitivity to subsequent high doses of radiation was observed when the priming and challenge doses were separated by 4 h; however, this sensitizing effect was no longer present when the interval between doses was greater than 8 h. Additionally, a "protective" bystander response was observed in these cell lines; exposure to irradiated medium from fish cells caused increased cloning efficiency in unirradiated reporter cells. The data confirm previous conclusions for mammalian cells that the adaptive response and bystander effect are inversely correlated and contrary to expectations probably have different underlying mechanisms.  相似文献   
64.
A sustainable national policy on waste electronic and electrical equipment reuse has to ensure an integrated environmental economic and social approach. In this paper, a quantitative model is developed that permits a comparative analysis of re-use and non-re-use scenarios from an environmental and economic perspective. The model demonstrates the importance of considering user consumption profiles and the changing national electricity generation portfolio in determining the best end-of-life strategy, whether it should be reuse or recycling. A case study of Ireland is used to demonstrate the model. From a social perspective, qualitative aspects of reuse, such as the job creation potential and the impact on prosperity for low income families, are also considered. Reuse of white goods, if conducted through social enterprises, will create more employment than an equivalent amount of recycling for those most vulnerable to unemployment. Any environmental and social dividends from re-use can be realized only in the context of an economically sustainable system. This would include such factors as a secure supply of suitable equipment, a competitive cost base and sufficient revenues from sales and other sources in order for the business to survive. In an attempt to examine whether a white goods re-use program could possibly operate in a competitive manner with new appliances, this study has examined examples of comparable businesses operating in the EU as well as interpreting data on consumer demand.  相似文献   
65.
We make a theoretical study of nitrogen cycling in a model of a grazing system with five compartments. The rates of uptake of nutrient by plants and herbivores are allowed nonlinear forms which involve no a priori assumptions about whether the system is subject to top-down or bottom-up control. We derive a method of piecewise linear approximation which allows analytical study of the system. We then use this method to investigate the properties of the equilibrium states of the system, and in particular whether the system favours donor- or recipient-control, the grazing optimization problem, and the potential benefits of herbivory to plant growth. We are able to generalise our results to all uptake functions of the same qualitative class as those considered, and to show that in general the system will tend to a stable equilibrium state of donor-controlled herbivory. In this model, the presence of the ‘right’ class of herbivore is not only beneficial to plant growth in certain circumstances, but can be essential to their survival, allowing plants to co-exist with herbivores under conditions in which they would be unable to survive alone.  相似文献   
66.
The distribution and composition of hydrocarbons in sediment from the Fladen Ground oilfield in the northern North Sea have been investigated. The total PAH concentrations (2- to 6-ring parent and alkylated PAHs, including the 16 US EPA PAHs) in sediments were relatively low (<100 microg kg(-1) dry weight). The PAH, the Forties crude and diesel oil equivalent concentrations were generally higher in sediment of fine grain size and higher organic carbon concentration. PAH distributions and concentration ratios indicated a predominantly pyrolytic input, being dominated by the heavier, more persistent, 5- and 6-ring compounds, and with a high proportion of parent PAHs. The n-alkane profiles of a number of the sediments contained small, high boiling point, UCMs, indicative of weathered oil arising from a limited petrogenic input. The geochemical biomarker profiles of the sediments that contained UCMs showed a small bisnorhopane peak and a high proportion of norhopane relative to hopane, indicating that there was contamination from both Middle Eastern and North Sea oils. Therefore contamination was not directly as a result of oil exploration activity in the area. The most likely source of petrogenic contamination was from general shipping activity.  相似文献   
67.
Regional Environmental Change - Landscapes are changing rapidly in regions where rural people live adjacent to protected parks and reserves. This is the case in highland East Africa, where many...  相似文献   
68.
In cost-benefit analysis, natural resources, like other factors of production, should be costed as a mixture of marginal social cost of exploiting additional resources and lost marginal social benefit of forgone alternative uses, according to the way in which extra resources are made available to a project. For a nonrenewable resource, changes in future marginal social cost and marginal social benefit are likely to add significantly to the immediate elements of cost, as successively less tractable resource stocks are exploited. Of the several reasons given for ignoring these future costs, the most plausible is that technological advance justifies a heavy discount on the future. However, neither historical nor logical arguments demonstrate the inevitability of efficacious technological advance.  相似文献   
69.
Jones CG  Wyser K  Ullerstig A  Willén U 《Ambio》2004,33(4-5):211-220
The Rossby Centre regional climate model (RCA2) has been integrated over the Arctic Ocean as part of the international ARCMIP project. Results have been compared to observations derived from the SHEBA data set. The standard RCA2 model overpredicts cloud cover and downwelling longwave radiation, during the Arctic winter. This error was improved by introducing a new cloud parameterization, which significantly improves the annual cycle of cloud cover. Compensating biases between clear sky downwelling longwave radiation and longwave radiation emitted from cloud base were identified. Modifications have been introduced to the model radiation scheme that more accurately treat solar radiation interaction with ice crystals. This leads to a more realistic representation of cloud-solar radiation interaction. The clear sky portion of the model radiation code transmits too much solar radiation through the atmosphere, producing a positive bias at the top of the frequent boundary layer clouds. A realistic treatment of the temporally evolving albedo, of both sea-ice and snow, appears crucial for an accurate simulation of the net surface energy budget. Likewise, inclusion of a prognostic snow-surface temperature seems necessary, to accurately simulate near-surface thermodynamic processes in the Arctic.  相似文献   
70.
Laboratory studies were carried out to investigate solute leaching at different times from application in relation to temperature and initial soil moisture. Aggregates of a heavy clay soil were treated with a non-interactive solute (bromide) and the herbicides chlorotoluron, isoproturon and triasulfuron. The soil was incubated at 90% field capacity and either 5 or 15 degrees C. The influence of application to initially dry and initially wet aggregates on the behaviour of isoproturon was also investigated. At intervals, samples were either leached in small columns, centrifuged to characterise the fraction of chemical available in pore water under natural moisture conditions or extracted with organic solvents to assess total residues in soil. Bromide concentrations in leachate and in pore water extracted by centrifugation were constant with time. In contrast, availability for leaching and concentration in pore water of the herbicides decreased with increasing time from application in soil incubated at 15 degrees C. The effect of residence time was much smaller at 5 than at 15 degrees C. At the higher temperature, pesticide concentrations in leachate and pore water declined faster than would be expected from degradation alone, probably due to slow diffusion of the pesticides into soil aggregates where they are less available for leaching and/or slow sorption-desorption. The faster decline in availability for leaching at 15 than at 5 degrees C was attributed to faster degradation of the readily available fraction. There was no significant influence of initial soil moisture on either the leaching behaviour of isoproturon or its availability in soil water.  相似文献   
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