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1.
Algal biomass, in addition to cell numbers, is a measure of the successful conversion of inorganic to organic carbon. Consequently, carbon is the main currency used in aquatic models and in flux and budget studies. On the other hand, microscopic observation and counts remain the only means for determining species composition and biomass, which is relevant to many aspects of aquatic ecology. In this study, we focus on the way to convert biovolume to carbon biomass for algal assemblages of two rivers, using a computerized system that records dimensions of phytoplankton (Gosselain & Hamilton, 2000). We first compare different equations found in the literature for converting algal cell volume to cellular carbon content. We then evaluate the accuracy of a biomass estimate based on less time-consuming measurements, using pre-determined biovolume values instead of measuring cells in all samples. Biovolume/carbon equations are evaluated using total phytoplankton carbon biomass determined from measured chlorophyll a. Equations established for freshwater taxa seem to provide better estimates of algal biomass in the two case studies presented here, the Rideau and Meuse rivers (Canada and Belgium, respectively) than do more numerous equations defined for marine taxa. Furthermore, equations that make a distinction between diatoms and other algae appear more appropriate than those considering all algal groups as a whole. Finally, mean values of algal biovolumes, determined using sufficient measurements of cell dimensions from representative sampling series, may prove sufficient for carbon estimates of taxa in relatively homogenous size ranges. The careful choice of appropriate volumetric shapes and taxa categories remains of prime importance to get precise results.  相似文献   

2.
基于协整分析的安徽省能源消费碳排放库兹涅茨曲线   总被引:2,自引:0,他引:2  
碳排放环境库兹涅茨曲线研究,能预判碳排放拐点出现时间,可揭示出经济发展与碳排放之间的动态关系。依据IPCC碳排放计算方法,以能源消费数据为基础,对安徽省1995—2010年碳排放及碳排放强度进行了动态测度,借助EKC模型简化式构建了安徽省碳排放总量、人均碳排放量、碳排放强度的EKC模型,基于协整OLS回归方法对安徽省碳排放、碳排放强度EKC曲线进行了探析。结果表明:安徽省碳排放总量由1995年的4420.58×104t增加到2010年的11913.32×104t,人均碳排放量由1995年的0.74t增加到2010年的1.74t,均呈持续增长态势,碳排放总量,而碳排放强度由1995年的每万元2.44t持续下降至2010年的0.97t。安徽省碳排放EKC曲线呈N型,通过作散点图并添加趋势线表明,N型关系非常微弱,短期内EKC曲线不存在拐点,拐点出现时间为2027年;安徽省碳排放强度EKC曲线也呈N型,通过作散点图并添加趋势线表明,N型关系也非常微弱,短期内EKC曲线不存在拐点,而呈递减趋势;安徽省人均碳排放量不支持EKC曲线。研究结果有利于了解未来碳排放态势,从而为制定出相应的减排政策提供依据。  相似文献   

3.

Purpose

There are many recent proposals in life cycle assessment (LCA) to calculate temporary storage of carbon in bio-based products. However, there is still no consensus on how to deal with the issue. The main questions are: how do these proposals relate to each other, to what extent are they in line with the classical LCA method (as defined in ISO 14044) and the global mass balances as proposed by the IPCC, and is there really a need to introduce a discounting system for delayed CO2 emissions?

Methods

This paper starts with an analysis of the widely applied specification of PAS 2050 and the ILCD Handbook, both specifying the credit for carbon sequestration as ‘optional’ in LCA. From this analysis, it is concluded that these optional calculations give rather different results compared to the baseline LCA method. Since these optional calculations are not fully in line with the global carbon mass balances, a new calculation method is proposed. To validate the new method, two cases (one on wood and one bamboo products) are given. These cases show the practical application and the consequences of the new approach. Finally, the main issue is evaluated and discussed: is it a realistic approach to allocate less damage to the same emission, when it is released later in time?

Results and discussion

This paper proposes a new approach based on the global carbon cycle and land-use change, translated to the level of individual products in LCA. It is argued that only a global growth of forest area and a global growth of application of wood in the building industry contribute to extra carbon sequestration, which might be allocated as a credit to the total market of wood products in LCA. This approach is different from approaches where temporary storage of carbon in trees is directly allocated to a product itself.

Conclusions

In the proposed approach, there seems to be no need for a discounting system of delayed CO2 emissions. The advantage of wood and wood-based products can be described in terms of land-use change on a global scale in combination with a credit for heat recovery at the end-of-life (if applicable).  相似文献   

4.
Kim H  Park H 《Protein engineering》2003,16(8):553-560
The prediction of protein secondary structure is an important step in the prediction of protein tertiary structure. A new protein secondary structure prediction method, SVMpsi, was developed to improve the current level of prediction by incorporating new tertiary classifiers and their jury decision system, and the PSI-BLAST PSSM profiles. Additionally, efficient methods to handle unbalanced data and a new optimization strategy for maximizing the Q(3) measure were developed. The SVMpsi produces the highest published Q(3) and SOV94 scores on both the RS126 and CB513 data sets to date. For a new KP480 set, the prediction accuracy of SVMpsi was Q(3) = 78.5% and SOV94 = 82.8%. Moreover, the blind test results for 136 non-redundant protein sequences which do not contain homologues of training data sets were Q(3) = 77.2% and SOV94 = 81.8%. The SVMpsi results in CASP5 illustrate that it is another competitive method to predict protein secondary structure.  相似文献   

5.
6.
Abstract. The physics of ultrasonic acoustic emissions (AEs) was investigated for AE transmission through wood and transducers. The physical properties measured were velocity, attenuation and frequency composition of AEs produced by two sources: cavitation events in xylem and pencil lead breaks. The authors also measured the relative sensitivity of various combinations of ultrasound transducers and amplifiers to aid in the selection of a measuring system optimized for cavitation detection in woody plants. Some of the authors' conclusions are: (1) Softwoods ( Thuja, Pinus ) attenuate AEs more rapidly than hardwoods (maple, birch). (2) The velocity of AEs in wood exceeds that measured by others in water so the main medium of AE transmission must be the cellulose. (3) The strongest frequencies of AEs are in the range of 100–300 kHz. (4) Cavitation-induced AEs tend to shift to higher frequency as wood dehydration progresses. (5) One cannot determine the locus of origin of AEs from its frequency composition. (6) The frequency composition of the acoustic emissions probably cannot be determined at all with the sensors used because of their tendency to 'ring'. The data collected in this paper were used to aid in the design of an improved AE counter having a seven-fold increase in signal to noise ratio compared to counters previously used in our laboratory. The improved counter, model 4615 Drought Stress Monitor, is now commercially available from Physical Acoustics Corp., Princeton, NJ, U.S.A.  相似文献   

7.
The International Journal of Life Cycle Assessment - Current field emission modelling and toxicity characterisation of pesticides suffer from several shortcomings like mismatches between LCI...  相似文献   

8.
Stretching and tissue expansion for rhytidectomy: an improved approach   总被引:2,自引:0,他引:2  
D Man 《Plastic and reconstructive surgery》1989,84(4):561-9; discussion 570-1
Intraoperative expansion of the skin of the face supplies additional tissue that permits closure of the face lift incision with minimal tension. This paper presents the findings in rhytidectomy patients over the last 3 years using both intraoperative stretching and intraoperative stretching combined with tissue expansion utilizing the Man face lift expander. Sixty-seven patients underwent rhytidectomy surgery, of whom 50 were treated with stretching techniques alone and 17 were treated with the combined stretching and expansion method. The patients' ages ranged from 28 to 78 years. Results indicate that the patients treated with combined stretching and expansion had significantly more skin removed. This new technique appears to offer significant clinical advantages over usual face lifts.  相似文献   

9.

Purpose

Indoor emissions of toxic substances from products can have a negative effect on human health. These are typically not considered in a life cycle assessment (LCA), potentially underestimating the importance of the use stage. The purpose of this paper is to develop a method that, based on a set of measured emission rates, calculates the impact on human health during the use stage of products that are used indoors and that emit volatile organic compounds (VOCs).

Methods

Emissions from a product are measured in a test chamber and reported as a set of emission rates (microgrammes per hour) at specific points in time (hour/day). Constrained non-linear regression (CNLR) analysis is then used to determine parameters for three emission models, and a model is selected based on goodness of fit with the measured emission rates (R 2 and expert judgement). The emission model is integrated over a defined time period to estimate the total use stage emissions per functional unit (FU). The total emissions are subsequently integrated in a homogeneously mixed one-box model within the USEtox model. Intake fraction (iF) is calculated based on size of residential home, inhalation rate, exposure time, ventilation rate, mixing factor and number of people exposed.

Results and discussion

The method is tested in a case study of a chair, with the results showing that the impacts in the use stage are in most cases significantly higher than from the production and disposal stages combined. The sensitivity to parameter variations is evaluated. Intake fraction (factor of 761), replacement frequency (factor of 70) and emission model (factor of 24) are found to be the most important model parameters. Limiting early exposure (>14 % of emissions may occur in the first month and >50 % in the first year) and replacing furniture less frequently will reduce exposure.

Conclusions

The case study shows that the impact on human health from indoor emissions can be of significance, when compared to the impact on human health from total outdoor emissions. Without specific exposure data (e.g. ventilation rates) the uncertainty will be high. The developed method is applicable to all products that emit VOCs, provided that the emission rate can be modelled using an exponential decay model and that the product amount is related to a meaningful functional unit. It is recommended that when performing an LCA of products that emit VOCs, the indoor use stage is included in the life cycle impact assessment.  相似文献   

10.
The possibilities of adapting the Modern Analogs Technique (MAT) based on planktonic foraminifers for estimating sea-surface temperatures (SST) in the Mediterranean during the Pliocene are discussed in this article. The calibration database used comprises 684 core-top samples distributed in the North Atlantic and the Mediterranean. MAT estimates show an imperceptible bias (− 0.03 °C; σ = 0.59) and a low mean error of estimates (0.42 °C; σ = 0.42) when applied over the samples of the calibration dataset. The procedure used for assimilating the Pliocene taxonomic categories to those of the modern assemblages results in an increase from 17 to 40 in the number of samples showing an error > 2 °C when applied over the calibration database. However, the precision of MAT does not diminish when these samples are removed from the dataset. This methodology was used for obtaining SST estimates of late-middle Pliocene–earliest Pleistocene samples from ODP-site 975 (Menorca area), which have close modern analogs within the calibration database. In order to compare this technique with an additional proxy, we measured also δ18O values of G. bulloides tests from these samples. The results obtained show a good agreement on the whole, which corroborates the validity of the technical approach proposed.  相似文献   

11.
The International Journal of Life Cycle Assessment - Much progress has recently been made in modelling future background systems for LCA by including future scenario data,...  相似文献   

12.

Purpose  

The assessment of biofuels has until now mainly focused on energy demand and greenhouse gas emissions. Only little attention has been given to other impacts, although the general importance of water use for the life cycle assessment (LCA) of agricultural products has been recognized in recent publications. The aim of this work is to assess in detail the water consumption along a biofuel production chain taking into account irrigation efficiencies, levels of water scarcity, and type of feedstock, and to integrate those results in a full LCA. Furthermore, we compare the results for biofuels from various feedstocks and regions with conventional petrol.  相似文献   

13.
The capacity of a soil to sequester organic carbon can, in theory, be estimated as the difference between the existing soil organic C (SOC) concentration and the SOC saturation value. The C saturation concept assumes that each soil has a maximum SOC storage capacity, which is primarily determined by the characteristics of the fine mineral fraction (i.e. <20 µm clay + fine silt fraction). Previous studies have focussed on the mass of fine fractions as a predictor of soil C stabilisation capacity. Our objective was to compare single- and multi-variable statistical approaches for estimating the upper limit of C stabilisation based on measureable properties of the fine mineral fraction [e.g. fine fraction mass and surface area (SA), aluminium (Al), iron (Fe), pH] using data from New Zealand’s National Soils Database. Total SOC ranged from 0.65 to 138 mg C g?1, median values being 44.4 mg C g?1 at 0–15 cm depth and 20.5 mg C g?1 at 15–30 cm depth. Results showed that SA of mineral particles was more closely correlated with the SOC content of the fine fraction than was the mass proportion of the fine fraction, indicating that it provided a much better basis for estimating SOC stabilisation capacity. The maximum C loading rate (mg C m?2) for both Allophanic and non-Allophanic soils was best described by a log/log relationship between specific SA and the SOC content of the fine fraction. A multi-variate regression that included extractable Al and soil pH along with SA provided the “best fit” model for predicting SOC stabilisation. The potential to store additional SOC (i.e. saturation deficit) was estimated from this multivariate equation as the difference between the median and 90th percentile SOC content of each soil. There was strong evidence from the predicted saturation deficit values and their associated 95 % confidence limits that nearly all soils had a saturation deficit >0. The median saturation deficit for both Allophanic and non-Allophanic soils was 12 mg C g?1 at 0–15 cm depth and 15 mg C g?1 at 15–30 cm depths. Improving predictions of the saturation deficit of soils may be important to developing and deploying effective SOC sequestration strategies.  相似文献   

14.
15.

Purpose

While life cycle assessment (LCA) has standardized methods for assessing emission impacts, some comparable methods for the accounting or impact assessment of resource use exist, but are not as mature or standardized. This study contributes to the existing research by offering a comprehensive comparison of the similarities and differences of different resource indicators, in particular those based on thermodynamics, and testing them in a case study on titania (titanium dioxide pigment) produced in Panzhihua city, southwest China.

Materials and methods

The system boundary for resource indicators is defined using a thermodynamic hierarchy at four levels, and the case data for titania also follow that hierarchy. Seven resource indicators are applied. Four are thermodynamics-based??cumulative energy demand (CED), solar energy demand (SED), cumulative exergy demand (CExD), and cumulative exergy extraction from the natural environment (CEENE)??and three have different backgrounds: abiotic resource depletion potential, environmental priority strategies, and eco-indicator 99. Inventory data for the foreground system has been collected through on-site interviews and visits. Background inventory data are from the database ecoinvent v2.2. Characterizations factors are based on the CML-IA database covering all major methods. Computations are with the CMLCA software.

Results and discussion

The scores of resource indicators of the chloride route for titania system are lower than that of the sulfate route by 10?C35?%, except in terms of SED. Within the four thermodynamic indicators for resources, CED, CExD, and CEENE have similar scores, while their scores are five orders of magnitude lower than the SED score. Atmospheric resources do not contribute to the SED or CEEND score. Land resources account for a negligible percentage to the SED score and a small percentage to the CEENE score. Non-renewable resources have a dominant contribution to all seven resource indicators. The global production of titania would account for 0.12 and 0.14?% of the total anthropogenic non-renewable resource demand in terms of energy and exergy, respectively.

Conclusions

First, we demonstrate the feasibility of thermodynamic resource indicators. We recommend CEENE as the most appropriate one within the four thermodynamic resource indicators for accounting and characterizing resource use. Regarding the case study on the titania produced in China, all the resource indicators except SED show that the sulfate route demands more resource use than the chloride route.  相似文献   

16.
Rubinsten O  Sury D 《PloS one》2011,6(9):e24079
In contrast to quantity processing, up to date, the nature of ordinality has received little attention from researchers despite the fact that both quantity and ordinality are embodied in numerical information. Here we ask if there are two separate core systems that lie at the foundations of numerical cognition: (1) the traditionally and well accepted numerical magnitude system but also (2) core system for representing ordinal information. We report two novel experiments of ordinal processing that explored the relation between ordinal and numerical information processing in typically developing adults and adults with developmental dyscalculia (DD). Participants made "ordered" or "non-ordered" judgments about 3 groups of dots (non-symbolic numerical stimuli; in Experiment 1) and 3 numbers (symbolic task: Experiment 2). In contrast to previous findings and arguments about quantity deficit in DD participants, when quantity and ordinality are dissociated (as in the current tasks), DD participants exhibited a normal ratio effect in the non-symbolic ordinal task. They did not show, however, the ordinality effect. Ordinality effect in DD appeared only when area and density were randomized, but only in the descending direction. In the symbolic task, the ordinality effect was modulated by ratio and direction in both groups. These findings suggest that there might be two separate cognitive representations of ordinal and quantity information and that linguistic knowledge may facilitate estimation of ordinal information.  相似文献   

17.
18.
19.
20.

Purpose

Pesticides are applied to agricultural fields to optimise crop yield and their global use is substantial. Their consideration in life cycle assessment (LCA) is affected by important inconsistencies between the emission inventory and impact assessment phases of LCA. A clear definition of the delineation between the product system model (life cycle inventory—LCI, technosphere) and the natural environment (life cycle impact assessment—LCIA, ecosphere) is missing and could be established via consensus building.

Methods

A workshop held in 2013 in Glasgow, UK, had the goal of establishing consensus and creating clear guidelines in the following topics: (1) boundary between emission inventory and impact characterisation model, (2) spatial dimensions and the time periods assumed for the application of substances to open agricultural fields or in greenhouses and (3) emissions to the natural environment and their potential impacts. More than 30 specialists in agrifood LCI, LCIA, risk assessment and ecotoxicology, representing industry, government and academia from 15 countries and four continents, met to discuss and reach consensus. The resulting guidelines target LCA practitioners, data (base) and characterisation method developers, and decision makers.

Results and discussion

The focus was on defining a clear interface between LCI and LCIA, capable of supporting any goal and scope requirements while avoiding double counting or exclusion of important emission flows/impacts. Consensus was reached accordingly on distinct sets of recommendations for LCI and LCIA, respectively, recommending, for example, that buffer zones should be considered as part of the crop production system and the change in yield be considered. While the spatial dimensions of the field were not fixed, the temporal boundary between dynamic LCI fate modelling and steady-state LCIA fate modelling needs to be defined.

Conclusions and recommendations

For pesticide application, the inventory should report pesticide identification, crop, mass applied per active ingredient, application method or formulation type, presence of buffer zones, location/country, application time before harvest and crop growth stage during application, adherence with Good Agricultural Practice, and whether the field is considered part of the technosphere or the ecosphere. Additionally, emission fractions to environmental media on-field and off-field should be reported. For LCIA, the directly concerned impact categories and a list of relevant fate and exposure processes were identified. Next steps were identified: (1) establishing default emission fractions to environmental media for integration into LCI databases and (2) interaction among impact model developers to extend current methods with new elements/processes mentioned in the recommendations.
  相似文献   

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