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1.
Goal, Scope, and Background Uncertainty analysis in LCA is important for sound decision support. Nevertheless, the actual influence of uncertainty on decision making in specific LCA case-studies has only been little studied so far. Therefore, we assessed the uncertainty in an LCA comparing two plant-protection products.Methods Uncertainty and variability in LCI flows and characterization factors (CML-baseline method) were expressed as generic uncertainty factors and subsequently propagated into impact scores using Monte-Carlo simulation. Uncertainty in assumptions on production efficiency for chemicals, which is of specific interest for the case study, was depicted by scenarios. Results and Discussion Impact scores concerning acidification, eutrophication, and global warming display relatively small dispersions. Differences in median impact scores of a factor of 1.6 were sufficient in the case study for a significant distinction of the products. Results of toxicity impact-categories show large dispersions due to uncertainty in characterization factors and in the composition of sum parameters. Therefore, none of the two products was found to be significantly environmentally preferable to the other. Considering the case study results and inherent characteristics of the impact categories, a tentative rule of thumb is put forward that quantifies differences in impact scores necessary to obtain significant results in product comparisons.Conclusion Published LCA case-studies may have overestimated the significance of results. It is therefore advisable to routinely carry out quantitative uncertainty analyses in LCA. If this is not feasible, for example due to time restrictions, the rule of thumb proposed here may be helpful to evaluate the significance of results for the impact categories of global warming, acidification, eutrophication, and photooxidant creation.  相似文献   

2.
Social and health care provision have led to substantial increases in life expectancy. In the UK this has become higher than 80 years with an even greater proportional increase in those aged 85 years and over. The different life stages give rise to important nutritional challenges and recent reductions in milk consumption have led to sub-optimal intakes of calcium by teenage females in particular when bone growth is at its maximum and of iodine during pregnancy needed to ensure that supply/production of thyroid hormones to the foetus is adequate. Many young and pre-menopausal women have considerably sub-optimal intakes of iron which are likely to be associated with reduced consumption of red meat. A clear concern is the low intakes of calcium especially as a high proportion of the population is of sub-optimal vitamin D status. This may already have had serious consequences in terms of bone development which may not be apparent until later life, particularly in post-menopausal women. This review aims to examine the role of dairy foods and red meat at key life stages in terms of their ability to reduce or increase chronic disease risk. It is clear that milk and dairy foods are key sources of important nutrients such as calcium and iodine and the concentration of some key nutrients, notably iodine can be influenced by the method of primary milk production, in particular, the iodine intake of the dairy cow. Recent meta-analyses show no evidence of increased risk of cardiovascular diseases from high consumption of milk and dairy foods but increasing evidence of a reduction in the risk of type 2 diabetes associated with fermented dairy foods, yoghurt in particular. The recently updated reports from the World Cancer Research Fund International/American Institute for Cancer Research on the associations between dairy foods, red meat and processed meat and various cancers provide further confidence that total dairy products and milk, are associated with a reduced risk of colorectal cancer and high intakes of milk/dairy are not associated with increased risk of breast cancer. Earlier evidence of a significant increase in the risk of colorectal cancer from consumption of red and particularly processed meat has been reinforced by the inclusion of more recent studies. It is essential that nutrition and health-related functionality of foods are included in evaluations of sustainable food production.  相似文献   

3.
Background Tools and methods able to cope with uncertainties are essential for improving the credibility of Life Cycle Assessment (LCA) as a decision support tool. Previous approaches have focussed predominately upon data quality. Objective and Scope. An epistemological approach is presented conceptualising uncertainties in a comparative, prospective, attributional LCA. This is achieved by considering a set of cornerstone scenarios representing future developments of an entire Life Cycle Inventory (LCI) product system. We illustrate the method using a comparison of future transport systems. Method Scenario modelling is organized by means of Formative Scenario Analysis (FSA), which provides a set of possible and consistent scenarios of those unit processes of an LCI product system which are time dependent and of environmental importance. Scenarios are combinations of levels of socio-economic or technological impact variables. Two core elements of FSA are applied in LCI scenario modelling. So-called impact matrix analysis is applied to determine the relationship between unit process specific socio-economic variables and technology variables. Consistency Analysis is employed to integrate unit process scenarios, based on pair-wise ratings of the consistency of the levels of socio-economic impact variables of all unit processes. Two software applications are employed which are available from the authors. Results and Discussion The study reveals that each possible level or development of a technology variable is best conceived of as the impact of a specific socio-economic (sub-) scenario. This allows for linking possible future technology options within the socio-economic context of the future development of various background processes. In an illustrative case study, the climate change scores and nitrogen dioxide scores per seat kilometre for six technology options of regional rail transport are compared. Similar scores are calculated for a future bus alternative and an average Swiss car. The scenarios are deliberately chosen to maximise diversity. That is, they represent the entire range of future possible developments. Reference data and the unit process structure are taken from the Swiss LCA database 'ecoinvent 2000'. The results reveal that rail transport remains the best option for future regional transport in Switzerland. In all four assessed scenarios, four technology options of future rail transport perform considerably better than regional bus transport and car transport. Conclusions and Recommendations. The case study demonstrates the general feasibility of the developed approach for attributional prospective LCA. It allows for a focussed and in-depth analysis of the future development of each single unit process, while still accounting for the requirements of the final scenario integration. Due to its high transparency, the procedure supports the validation of LCI results. Furthermore, it is well-suited for incorporation into participatory methods so as to increase their credibility. Outlook and Future Work. Thus far, the proposed approach is only applied on a vehicle level not taking into account alterations in demand and use of different transport modes. Future projects will enhance the approach by tackling uncertainties in technology assessment of future transport systems. For instance, environmental interventions involving future maglev technology will be assessed so as to account for induced traffic generated by the introduction of a new transport system.  相似文献   

4.
Background The Swiss chemical industry produces large amounts of organic waste solvents. Some of these solvents cannot be recovered. A common option for the treatment of such organic waste solvents is the incineration in hazardous waste incinerators. Alternatively, the waste solvents can be used as fuel in cement production. On the one hand, solvent incineration in cement kilns saves fossil fuels such as coal and heavy fuel oil. On the other hand, fuel-bound emissions may change as well. These emission changes can either have a negative or a positive net ecological impact, depending on the chemical nature of the waste solvent used.Goal and Scope The aim of our work was to develop a multi-input allocation model, which allows one to calculate life cycle inventories for specific waste solvents. These LCIs can then be used in further applications, e.g. a comparison of different waste solvent treatment options. Results and Discussion A multi-input allocation model was developed that takes into account the physico-chemical properties of waste solvents such as elementary composition and net calorific value. The model is based on a set of equations and data on fuel mix, fuel composition as well as transfer coefficients for heavy metals. The model calculates “avoided inputs” and “changes in emissions” which arise from substituting fossil fuels with waste solvents. Life cycle inventories can be calculated for specific waste solvents if the elementary composition and the net calorific value are known. The application of the model is illustrated in a case study on four waste solvents. The results show that solvent incineration in cement kilns generally reduces the overall impact of clinker production because fossil fuels are replaced. A sensitivity analysis revealed that the model is especially sensitive to the fuel mix and coal properties, such as net calorific value as well as the content of nitrogen and carbon. The transfer coefficients are also uncertain, but this uncertainty is not relevant as the amount of heavy metal emitted into the atmosphere is small. Conclusions and Outlook The proposed model serves to calculate inventory data for the combustion of liquid alternative fuels such as waste solvents in cement kilns. Although our model represents Swiss cement production conditions, it can be applied to other countries by fitting the most sensitive parameters of fuel mix and coal properties. In case the technology used is very different to the Swiss situation, the transfer coefficients also need to be adapted.  相似文献   

5.
Goal, Scope and Method The purpose of this environmental system analysis was to investigate the impact of feed choice in three pig production scenarios using substance flow models complemented by life cycle assessment methodology. The function of the system studied was to grow piglets of 29 kg to finished pigs of 115 kg. Three alternative scenarios of protein supply were designed, one based on imported soybean meal (scenario SOY); one based on locally grown peas and rapeseed cake (scenario PEA) and one based on Swedish peas and rapeseed meal complemented by synthetic amino acids (scenario SAA). The environmental impact of both feed production as such and the subsequent environmental impact of the feed in the pig production sub-system were analysed. The analysed feed ingredients were barley, wheat, peas, rapeseed meal, rapeseed cake, soybean meal and synthetic amino acids. The crude protein level of the feed affected the nitrogen content in the manure, which in turn affected nitrogen emissions throughout the system and the fertilising value of the manure, ultimately affecting the need for mineral fertiliser application for feed production. Results and Discussion The results showed that feed production contributed more than animal husbandry to the environmental burden of the system for the impact categories energy use, global warming potential and eutrophication, whereas the opposite situation was the case for acidification. The environmental impacts of scenarios SOY, PEA and SAA were 6.8, 5.3 and 6.3 MJ/kg pig growth; 1.5, 1.3 and 1.4 kg CO2-eq/kg pig growth; 0.55, 0.55 and 0.45 kg O2-eq/kg pig growth; and 24, 25 and 20 g SO2-eq/kg pig growth, respectively. The results suggested that scenario SAA was environmentally preferable, and that the reason for this was a low crude protein level of the feed and exclusion of soybean meal from the feed. Conclusions Feed choice had an impact on the environmental performance of pig meat production, not only via the features of the feed as fed to the pigs, such as the crude protein content, but also via the raw materials used, since the environmental impact from the production of these differs and since feed production had a large impact on the system as a whole.  相似文献   

6.
Goal, Scope and Background This article presents the main results from a PhD dissertation about environmental impacts from Danish fish products. The focus is on LCA results for flatfish, but the article also gives an overview of screenings of other fish species. Furthermore, it includes an analysis of the energy consumption in the fishing stage – as a function of fish species and fishing methods. Alternative impact categories that have not been included in the quantitative LCA and policy perspectives are elaborated in the discussion part of the paper. Methods The study represents a consequential LCA approach (opposed to attributional) and the functional unit is one kg consumed flatfish filet in units of 300 gram (cardboard boxes). Data are obtained from statistics, interviews, literature, and databases – mainly ETH-ESU 96 and the Danish LCA food database. The EDIP 97 method has been applied for life cycle impact assessment (LCIA) and the results have been verified by Ecoindicator 99. Results The results of the flatfish LCA show that the fishing stage has the largest impact potential for the investigated impact categories. This is mainly due to a relatively high fuel consumption and significant emissions of biocides from anti-fouling agents (contributing to ecological toxicity). But large reductions in fuel intensity (fuel consumption per kg caught fish) can be obtained by changing the type of fishing gear – particularly in flatfish fisheries. The consumption and retail stages represent significant impact potentials as well, while processing is insignificant. LCA screenings of other fish species show the same picture, but there are cases (herring, mackerel and mussels) where the fishing stage is less important, while the opposite is the case for processing – mainly due to energy intensive packaging materials. Discussion A limited number of impact categories have been investigated, but a 'qualitative' LCA, focusing on other fishery specific impacts, emphasises that the fishing stage is indeed the overall most important. In this regard, it is argued that fuel requirements in many cases are proportional to environmental impacts related to 'discard' and 'seafloor damage'. Hence, it is worth focusing on energy for many reasons. In a policy context, it is a paradox that mainly the fish processing industry has been subjected to environmental regulations. Recommendation and Perspective Future scenarios indicate that energy consumption will remain one of the most important environmental aspects in the fishing stage – partly due to regulations of anti-fouling biocides (e.g. TBT) and partly because of the continued depletion of fish stocks. From an environmental policy perspective, it is therefore recommended to broaden the perspective of existing fishery regulations and increase the focus on fishing gear and energy in the primary production (fishing stage).  相似文献   

7.
Goal, Scope and Background Although a large number of life cycle inventory (LCI) analyses for steel-making processes or steel products have been conducted, the allocation of process gases generated from the steelworks has not yet been clearly solved. The most consistent settlement for avoiding the allocation problem has been generally known as a system expansion method. However, the existing subtracted operations for the process gases in that method are inconsistent to a system in which those gases are consumed at their unbalanced consumption ratio. The goal of this study is to suggest a more reasonable substitute for the process gases in the system expansion method and a modified system expansion method resettling the amount of process gases used. Methods To seek a more suitable one as a substituted operation of the process gas, a kind of by-product gas, in the system expansion method, it is necessary to analyze the composition of whole fuel consumed within a steelworks. Because the steelworks is supplied with a gap of electricity from the national grid electricity other than home power plants, we should also consider various carbon fossil fuels consumed in the external electric-power production. From this procedure, a composite fuel, which is composed of coal, heavy fuel oil and LNG, is derived as the alternative of the process gases such as BFG, COG, CFG, and LDG. In the sequential manufacturing line, IO(gas), which is the ratio of the quantity used to the quantity produced of each process gas, is increased as a functional unit proceeds to a following steel product of the next process. In the LCI system, where IO(gas) is higher than one, the IO(gas) is adjusted to nearly one. The adjustment of IO is conducted in the order of the amount of process gas used in the whole steelworks on the basis of the functional unit. Results and Discussion LCI analyses were carried out focusing on the alternative of the process gases for five steel products. As a functional unit goes down a lower stage, IO(gas) is increased due to the high consumption of those gases. We found a phenomenon that IO(gas) had a critical influence on the LCI results between no allocation and system expansion for the process gases through sensitivity analysis. To reduce this influence and adjust for the real situation of IO(gas), we applied an improved system expansion method to the process gases. That is, we partly substituted a process gas with LNG and rearranged the ratio between internal and external electricity (RIEE) as close as the values of IO(gas) to one. Conclusion As the alternative fuel for the process gases, a composite fuel was derived in the system expansion method. In addition to the composite fuel, which consisted of coal, HFO and LNG, an improved system expansion method was revised by adjusting a modified IO(gas) to nearly one, not the high value of IO(gas) for each process gas. Recommendation and Outlook This improved system expansion method can be applicable in the chemical industry as well as the steel industry, which have multi-function systems. Optimal LCI analysis may be achieved through the redistribution and optimization in the usage of process gases.  相似文献   

8.
- Part 1: Present Situation and Future Perspectives Part 2: Application on an Island Economy Goal, Scope and Background In the first part of this paper, we developed a methodology to incorporate exposure and risk concepts into life cycle impact assessment (LCIA). We argued that both risk assessment and LCIA are needed to consider the impacts of increasing insulation for single-family homes in the US from current practice to the levels recommended by the 2000 International Energy Conservation Codes. In this analysis, we apply our model to the insulation case study and evaluate the benefits and costs of increased insulation for new housing. Results and Discussion The central estimate of impacts from the complete insulation manufacturing supply chain is approximately 17 premature deaths, 470 asthma attacks, and 8.100 restricted activity days nationwide for one year of increased fiberglass output. Of the health impacts associated with increased insulation manufacturing, 83% are attributable to the supply chain emissions from the mineral wool industry, which is mostly associated with the direct primary PM2.5 emissions from the industry (98%). Reduced energy consumption leads to 1.3 premature deaths, 36 asthma attacks, and 610 restricted activity days avoided per year, indicating a public health 'payback period' on the order of 13 years. Almost 90% of these benefits were associated with direct emissions from power plants and residential combustion sources. In total, the net present value of economic benefits over a 50-year period for a single-year cohort of new homes is $240 million with a 5% discount rate, with 49 fewer premature deaths in this period. Conclusion Recommendation and Outlook. We have developed and applied a risk-based model to quantify the public health costs and benefits of increased insulation in new single-family homes in the US, demonstrating positive net economic and public health benefits within the lifetimes of the homes. More broadly, we demonstrated that it is feasible to incorporate exposure and risk concepts into I-O LCA, relying on regression-based intake fractions followed by more refined dispersion modeling. The refinement step is recommended especially if primary PM2.5 is an important source of exposure and if stack heights are relatively low. Where secondary PM2.5 is more important, use of regression-based intake fractions would be sufficient for a reasonable risk approximation. Uncertainties in our risk-based model should be carefully considered; nevertheless, our study can help decision-makers evaluate the costs and benefits of demand-side management policy options from a combined public health and life cycle perspective.  相似文献   

9.
10.
Goal, Scope and Background This paper gives an overview on how the wood and packaging material production is inventoried in ecoinvent. Packaging materials have been a very important topic in the area of Life Cycle Assessment for more than twenty years. Wood is the most important renewable material and regenerative fuel used worldwide, and an important raw material for paper / board. Several methodological problems arising when inventorying wood for material and energetic uses in a generic database are discussed in more detail. Within the ecoinvent project, the Swiss data base for life cycle inventory data, two reports are dedicated to these two important topics – report No. 9 for wood and report No. 11 for packaging materials. Methods The whole wood chain has been modeled in a consistent way. This allows one to use this data for LCAs of building materials, bioenergy or paper production. The data represent average technologies used in Central Europe in the year 2000. A revenue-based co-product allocation approach is used for the different outputs. Correction factors are introduced for the consistent modeling of mass-based, material inherent wood properties such as solar energy, carbon uptake and land use. For packaging materials, the datasets represent European average data for the most often used materials as well as specific datasets for the production of actual packaging boxes and containers.Results and Discussion For wood, revenue-based allocation and the use of the correction factors for mass-related wood properties are shown and explained. For packaging materials, the importance of the raw material wood to the total load is shown. Furthermore trends in the data inventories for board packaging materials over the last two decades are discussed: mainly due to the increased comprehensiveness of the data, higher cumulative emissions can be observed. Conclusion For wood, the database ecoinvent provides consistent datasets for the entire chain from forestry to intermediate products such as timber, different types of wood-based boards, chips, pellets, etc. For packaging materials, the number of datasets of basic materials has been extended. A modular concept for actual packaging container datasets allows the user an easy modeling of various types of packaging containers/boxes. In the area of paper and board, a comprehensive database for the production of various types of pulp, paper and board is provided, which is representative for the average European production situation. Outlook Since wood is only limited and representative data for Europe is therefore not included, an update in the near future would be reasonable. Possible further extensions in the future could include various, final wooden products. For the data on paper/board, different levels of quality are observed, requiring a selective up-date of these data. Future extensions could include datasets for the import of pulp from overseas – especially from South America and Canada.  相似文献   

11.
Goal, Scope and Background Calculating LCA outcomes implies the use of parameters, models, choices and scenarios which introduce uncertainty, as they imperfectly account for the variability of both human and environmental systems. The analysis of the uncertainty of LCA results, and its reduction by an improved estimation of key parameters and through the improvement of the models used to convert emissions into regional impacts, such as eutrophication, are major issues for LCA. Methods In a case study of pig production systems, we propose a simple quantification of the uncertainty of LCA results (intra-system variability) and we explore the inter-system variability to produce more robust LCA outcomes. The quantification of the intra-system uncertainty takes into account the variability of the technical performance (crop yield, feed efficiency) and of emission factors (for NH3, N2O and NO3) and the influence of the functional unit (FU) (kg of pig versus hectare used). For farming systems, the inter-system variability is investigated through differentiating the production mode (conventional, quality label, organic (OA)), and the farmer practices (Good Agricultural Practice (GAP) versus Over Fertilised (OF)), while for natural systems, variability due to physical and climatic characteristics of catchments expected to modify nitrate fate is explored. Results and Conclusion For the eutrophication and climate change impact categories, the uncertainty associated with field emissions contributes more to the overall uncertainty than the uncertainty associated with emissions from livestock buildings, with crop yield and with feed efficiency. For acidification, the uncertainty of emissions from livestock buildings is the single most important contributor to the overall uncertainty. The influence of the FU on eutrophication results is very important when comparing systems with different degrees of intensification such as GAP and OA. Concerning the inter-system variability, differences in farmer practices have a larger effect on eutrophication than differences between production modes. Finally, the physical characteristics of the catchment and the climate strongly affect the results for eutrophication. In conclusion, in this case study, the main sources of uncertainty are in the estimation of emission factors, due both to the variability of environmental conditions and to lack of knowledge (emissions of N2O at the field level), but also in the model used for assessing regional impacts such as eutrophication. Recommendation and Perspective Suitable deterministic simulation models integrating the main controlling variables (environmental conditions, farmer practices, technology used) should be used to predict the emissions of a given system as well as their probabilistic distribution allowing the use of stochastic modelling. Finally, our simulations on eutrophication illustrate the necessity of integrating the fate of pollutants in models of impact assessment and highlight the important margin of improvement existing for the eutrophication impact assessment model.  相似文献   

12.
物种分布范围的形成是进化生态学研究的基本问题之一,但植物的资源分配策略是否与物种边界形成有关一直没有相关研究。青藏高原特有植物露蕊乌头在末次最大冰期时有4个避难所,但冰期后只有一个避难所的种群发生了扩张并最终形成了现代分布格局。以露蕊乌头的避难所种群(同仁种群)和扩张后邻近分布区边缘的两个种群(兴海种群和海北种群)为研究对象,通过比较避难所种群和边缘种群的资源分配方式,探讨露蕊乌头的资源分配与该植物分布区及边界形成的关系。结果发现:1)兴海和海北种群的营养结构(包括根、植株高度和茎叶生物量)均显著低于同仁种群,海北种群的繁殖结构(花数量和花生物量)显著低于同仁和兴海种群,但海北和兴海的繁殖分配均显著高于同仁种群;2)3个种群的繁殖资源与个体大小呈现显著的正相关关系,投入到繁殖资源的比例(繁殖分配)与个体大小呈显著的负相关关系。对露蕊乌头的研究结果一方面进一步证明了个体大小依赖的繁殖分配,但不符合“植物开始繁殖必须达到一定的大小(阈值)”这一结论,这可能与露蕊乌头的生活史特征有关;而另一方面,露蕊乌头在扩张过程中逐渐增加了对繁殖资源投资的比例,说明胁迫生境中有性繁殖对该植物具有更为重要的意义,且露蕊乌头在扩张过程中可能逐渐实现繁殖产出最大化,并可能在边缘种群实现最优繁殖分配进而最终形成该物种分布区的边界,但这一结论仍需在更多的植物类群中验证。  相似文献   

13.

Background

Ethiopia has the largest cattle population in Africa. The vast majority of the national herd is of indigenous zebu cattle maintained in rural areas under extensive husbandry systems. However, in response to the increasing demand for milk products and the Ethiopian government''s efforts to improve productivity in the livestock sector, recent years have seen increased intensive husbandry settings holding exotic and cross breeds. This drive for increased productivity is however threatened by animal diseases that thrive under intensive settings, such as bovine tuberculosis (BTB), a disease that is already endemic in Ethiopia.

Methodology/Principal Findings

An extensive study was conducted to: estimate the prevalence of BTB in intensive dairy farms in central Ethiopia; identify associated risk factors; and characterize circulating strains of the causative agent, Mycobacterium bovis. The comparative intradermal tuberculin test (CIDT), questionnaire survey, post-mortem examination, bacteriology, and molecular typing were used to get a better understanding of the BTB prevalence among dairy farms in the study area. Based on the CIDT, our findings showed that around 30% of 2956 tested dairy cattle from 88 herds were positive for BTB while the herd prevalence was over 50%. Post-mortem examination revealed gross tuberculous lesions in 34/36 CIDT positive cattle and acid-fast bacilli were recovered from 31 animals. Molecular typing identified all isolates as M. bovis and further characterization by spoligotyping and MIRU-VNTR typing indicated low strain diversity within the study area.

Conclusions/Significance

This study showed an overall BTB herd prevalence of 50% in intensive dairy farms in Addis Ababa and surroundings, signalling an urgent need for intervention to control the disease and prevent zoonotic transmission of M. bovis to human populations consuming dairy products coming from these farms. It is suggested that government and policy makers should work together with stakeholders to design methods for the control of BTB in intensive farms in Ethiopia.  相似文献   

14.
A fundamental goal of ecology and evolution is to explain patterns of species distribution and abundance. However, the way in which stable distribution ranges are shaped by natural selection is still poorly understood, especially whether patterns of resource allocation have contributed to the range size and the formation of range boundary received little attention. For annual herb, the maximum reproductive allocation is predicted to be 50%, and thus we predicted that reproductive allocation might contribute to the formation of range boundary since plant will enhance allocations to reproduction in stressful environments. In this study, we presented our data on resource allocation between population from the glacial refegium and those from the marginal populations in Gymnaconitum gymnandrum, an alpine biennial native to the Qinghai Tibet Plateau, aiming to find the contribution of resource allocation to the formation of range boundary. Our results showed that resource allocations to vegetative organs, including roots, plant height and stem leaf biomass, were significantly higher in the refugium population that in the two marginal populations, and allocations to reproductive organs, including flower number and flower biomass, were significantly lower in one marginal population (Haibei population) than in the other marginal population (Xinghai population) and the refugium population (Tongren population). However, reproductive allocation was significantly higher in the marginal populations than in the refugium population. In addition, in each of the three populations, we found a positive relationship between the plant size and flower biomass but a negative relationship between the plant size and reproductive allocation. Our results indicated a size dependent reproductive allocation in Ggymnandrum, but we did not find a size threshold for reproduction in each of the three populations of this plant, which might be attributed to the life history of this biennial herb. We also suggested that reproductive allocation was increased during the process of range expansion and may rise to the optimal reproductive allocation in the marginal populations, which suggested the important role of sexual reproduction for plants in more stressful environments and the formation of range boundary. However, these conclusions need to be further proved in other plant species.  相似文献   

15.
16.
Several market research studies have shown that consumers are primarily concerned with the provenance of the food they eat. Among the available identification methods, only DNA‐based techniques appear able to completely prevent frauds. In this study, a new method to discriminate among different bovine breeds and assign new individuals to groups was developed. Bulls of three cattle breeds farmed in Italy – Holstein, Brown, and Simmental – were genotyped using the 50K SNP Illumina BeadChip. Multivariate canonical discriminant analysis was used to discriminate among breeds, and discriminant analysis (DA) was used to assign new observations. This method was able to completely identify the three groups at chromosome level. Moreover, a genome‐wide analysis developed using 340 linearly independent SNPs yielded a significant separation among groups. Using the reduced set of markers, the DA was able to assign 30 independent individuals to the proper breed. Finally, a set of 48 high discriminant SNPs was selected and used to develop a new run of the analysis. Again, the procedure was able to significantly identify the three breeds and to correctly assign new observations. These results suggest that an assay with the selected 48 SNP could be used to routinely track monobreed products.  相似文献   

17.
In order to describe the lactation curves of milk yield (MY) and composition in buffaloes, seven non-linear mathematical equations (Wood, Dhanoa, Sikka, Nelder, Brody, Dijkstra and Rook) were used. Data were 116 117 test-day records for MY, fat (FP) and protein (PP) percentages of milk from the first three lactations of buffaloes which were collected from 893 herds in the period from 1992 to 2012 by the Animal Breeding Center of Iran. Each model was fitted to monthly production records of dairy buffaloes using the NLIN and MODEL procedures in SAS and the parameters were estimated. The models were tested for goodness of fit using adjusted coefficient of determination root means square error (RMSE), Durbin–Watson statistic and Akaike’s information criterion (AIC). The Dijkstra model provided the best fit of MY and PP of milk for the first three parities of buffaloes due to the lower values of RMSE and AIC than other models. For the first-parity buffaloes, Sikka and Brody models provided the best fit of FP, but for the second- and third-parity buffaloes, Sikka model and Brody equation provided the best fit of lactation curve for FP, respectively. The results of this study showed that the Wood and Dhanoa equations were able to estimate the time to the peak MY more accurately than the other equations. In addition, Nelder and Dijkstra equations were able to estimate the peak time at second and third parities more accurately than other equations, respectively. Brody function provided more accurate predictions of peak MY over the first three parities of buffaloes. There was generally a positive relationship between 305-day MY and persistency measures and also between peak yield and 305-day MY, calculated by different models, within each lactation in the current study. Overall, evaluation of the different equations used in the current study indicated the potential of the non-linear models for fitting monthly productive records of buffaloes.  相似文献   

18.
尖叶拟船叶藓营养元素生殖配置格局   总被引:3,自引:0,他引:3  
为了揭示尖叶拟船叶藓营养元素生殖配置规律,本文对其12种营养元素的生殖配置格局和季节动态进行了研究。其结果如下:成熟孢子体的生物量配置为6.67%;在成熟孢子体中12种营养元素的含量顺序是:C(452mg/g)〉N(35mg/g)〉K(8439.9μg/g)〉Ca(7012.9μg/g)〉P(2129.2μg/g)〉Mg(1482.9μg/g)〉Na(432.9μg/g)〉Mn(196.3μg/g)〉Fe(177.7μg/g)〉Al(174.8μg/g)〉Zn(68.1μg/g)〉Cu(19.4μg/g);成熟孢子体中营养元素生殖配置顺序是:K(17.7%)〉P(15.1%)〉Cu(13.3%)〉N(11.6%)〉Na(10.5%)〉Mn(7.8%)〉Zn(7.5%)〉C(6.9%)〉Mg(6.8%)〉Ca(5.4%)〉Fe(1.3%)〉Al(1.2%)。  相似文献   

19.
重庆四面山常绿阔叶林建群种种子雨、种子库研究   总被引:1,自引:2,他引:1  
对重庆四面山常绿阔叶林建群种种子雨、种子库的研究表明,建群种早期和晚期的种子雨无活力;种子偏早或偏晚成熟及大籽粒的树种,其种子雨被取食的比例大;种子雨、有活力种子雨、种子库三者的数量变化不一致;有活力种子雨量较大的栲、石栎、小叶青冈、扁刺栲、香桂等,其种子库密度在早期以近几何级数的方式增长,元江栲、银木荷种子库小,存在时间短,翌年无一年生萌发苗;种子库数量动态、消减率动态决定于种子被取食的强度、种子衰老的速度以及种子对病菌、逆境的抗性和种子萌发的整齐性.  相似文献   

20.
Goal, Scope and Background Many disciplines, amongst them LCIA, environmental impact and external cost assessments, are often faced with evaluating trade-offs between two or more alternative options in terms of a range of incommensurable indicators. Using process modeling and valuation, these indicators are quantified at mid- or endpoint levels. Recent discussion amongst LCA experts showed that because of the mutually exclusive aspects of uncertainty and relevance, the midpoint/endpoint debate is controversial and difficult to reconcile. This article is aimed at a more quantitative analysis of mid- and endpoint impacts, and the implications of uncertainty for decision-making. Methods The consequences for decision-making of uncertainties of endpoints are analysed quantitatively for the example of ExternE results, by employing statistical hypothesis testing. The Analytic Hierarchy Process (AHP) is then used to demonstrate the use of multi-criteria techniques at midpoint levels. Results and Discussion Statistical hypothesis testing at the endpoint level shows that for the ExternE example, probabilities of mistakenly favouring one alternative over another when they are in reality indistinguishable can be as high as 80%. Therefore, the best estimate of external cost is inadequate for most policy making purposes. Indicators at midpoint levels are more certain, but since they are only \proxy attributes\, they carry a hidden uncertainty in their relevance. Conclusion If endpoint information is too uncertain to allow a decision to be made with reasonable confidence, then the assessment can be carried out in midpoint terms. However, midpoint indicators are generally further removed from people's experience, and less relevant to the question that people actually want to solve. Nevertheless, if this ultimate question is unanswerable (within the certainty required by the decision-maker), a decision can be made on the basis of stakeholders' subjective judgments about the more certain midpoint levels. The crucial point is that these judgments are able to intuitively incorporate many aspects that impact modeling and valuation has trouble quantifying, such as perceived risk, distribution of burdens and benefits, equity, ethical, moral, religious and political beliefs and principles, immediacy and reversibility of potential impacts, voluntariness, controllability and familiarity of exposure, or perceived incompleteness of human knowledge.  相似文献   

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