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1.
The European Variant Berkeley Trent (EVn-BETR) multimedia fugacity model is used to test the validity of previously derived emission estimates and predict environmental concentrations of the main decabromodiphenyl ether congener, BDE-209. The results are presented here and compared with measured environmental data from the literature. Future multimedia concentration trends are predicted using three emission scenarios (Low, Realistic and High) in the dynamic unsteady state mode covering the period 1970–2020. The spatial and temporal distributions of emissions are evaluated. It is predicted that BDE-209 atmospheric concentrations peaked in 2004 and will decline to negligible levels by 2025. Freshwater concentrations should have peaked in 2011, one year after the emissions peak with sediment concentrations peaking in 2013. Predicted atmospheric concentrations are in good agreement with measured data for the Realistic (best estimate of emissions) and High (worst case scenario) emission scenarios. The Low emission scenario consistently underestimates measured data. The German unilateral ban on the use of DecaBDE in the textile industry is simulated in an additional scenario, the effects of which are mainly observed within Germany with only a small effect on the surrounding areas. Overall, the EVn-BTER model predicts atmospheric concentrations reasonably well, within a factor of 5 and 1.2 for the Realistic and High emission scenarios respectively, providing partial validation for the original emission estimate. Total mean MEC:PEC shows the High emission scenario predicts the best fit between air, freshwater and sediment data. An alternative spatial distribution of emissions is tested, based on higher consumption in EBFRIP member states, resulting in improved agreement between MECs and PECs in comparison with the Uniform spatial distribution based on population density. Despite good agreement between modelled and measured point data, more long-term monitoring datasets are needed to compare predicted trends in concentration to determine the rate of change of POPs within the environment.  相似文献   

2.
Silver nanoparticles: behaviour and effects in the aquatic environment   总被引:3,自引:0,他引:3  
This review summarises and evaluates the present knowledge on the behaviour, the biological effects and the routes of uptake of silver nanoparticles (Ag NPs) to organisms, with considerations on the nanoparticle physicochemistry in the ecotoxicity testing systems used. Different types of Ag NP syntheses, characterisation techniques and predicted current and future concentrations in the environment are also outlined. Rapid progress in this area has been made over the last few years, but there is still a critical lack of understanding of the need for characterisation and synthesis in environmental and ecotoxicological studies. Concentration and form of nanomaterials in the environment are difficult to quantify and methodological progress is needed, although sophisticated exposure models show that predicted environmental concentrations (PECs) for Ag NPs in different environmental compartments are at the range of ng L(-1) to mg kg(-1). The ecotoxicological literature shows that concentrations of Ag NPs below the current and future PECs, as low as just a few ng L(-1), can affect prokaryotes, invertebrates and fish indicating a significant potential, though poorly characterised, risk to the environment. Mechanisms of toxicity are still poorly understood although it seems clear that in some cases nanoscale specific properties may cause biouptake and toxicity over and above that caused by the dissolved Ag ion. This review concludes with a set of recommendations for the advancement of understanding of the role of nanoscale silver in environmental and ecotoxicological research.  相似文献   

3.
4.
Abstract

Energy efficiency analysis has been recognised as an effective measure for the energy prediction, energy assessment and energy benchmarking in the machining system. However, study on energy efficiency of CNC hobbing machines, especially high-speed, dry-cutting CNC hobbing machines (HSDC-CHM), is still scarce. The energy consumption by HSDC-CHM is generally considered larger, and energy efficiency lower, than wet-cutting CNC hobbing machines (WC-CHM). Therefore, this paper summarises the investigation of energy efficiency of HSDC-CHM and establishes energy efficiency models of CNC hobbing machines. Energy efficiency of HSDC-CHM and WC-CHM are compared and analysed based on energy efficiency models established. Through the theory analysis, results show that, in the production line, although HSDC-CHM possess larger transient energy consumption, its energy efficiency is higher than energy efficiency of WC-CHM. Moreover, it is difficult to obtain quantitative energy efficiency of two types of hobbing machines due to massive relevant hard-to-acquire parameters using energy efficiency models; for this reason, experiments are performed to compare and analyse energy efficiency of HSDC-CHM and WC-CHM. The experiments results indicate that energy efficiency of HSDC-CHM is excellent and far higher than WC-CHM. The study results have a positive significance for the development and application of HSDC-CHM.  相似文献   

5.
A combined approach utilizing GIS, Participatory Rural Appraisal (PRA) and Focus Group Discussion (FGD) has been developed for resource mapping in a rural poverty-prone area of Bangladesh. This model integrated GIS and participatory tools to include the voices of the stakeholders in assessing available resources and needs. The resource mapping framework, developed using PRA with local community people and community gatekeepers, was aimed at sustainable resource management, and ArcView GIS was used to digitize the resource maps as a Decision Support System (DSS). A detailed assessment and analysis of the quality, quantity and physical status of resources was first mapped in the field and then digitized using GIS. FGD-based interaction with community people at each union in a subdistrict of Bangladesh revealed stakeholders’ opinions on land and water body management. The present paper demonstrates the power of this model as a policy-making tool for sustainable development and poverty eradication. It also recognized the need for collaboration between interdisciplinary policy planners and researchers to develop and implement a policy on agricultural resource management for poverty-prone areas.  相似文献   

6.
7.
The purpose of this study was to investigate the climate change impacts, vulnerability and adaptive capacity of the electrical energy sector in Cyprus. Spatial vulnerability of the island was assessed using the degree-day indicator to investigate heating and cooling demands in the near future using daily temperature projections from regional climate models (RCMs). Using daily electrical energy consumption data for the present climate, an impact model linking consumption and temperature was constructed and this relationship was projected to the future climate using the data from the RCMs and assuming the same technology use. Our impact model results showed that for the period between November and April (‘cold period’), a decreasing trend in electrical energy consumption is evident due to warmer conditions in the near future, while for the period between May and October (‘warm period’), an increasing trend in electricity consumption is evident as warmer conditions dominate by 2050. Regarding the spatial vulnerability assessment, the cooling degree-day indicator testified that major increases in cooling demand, between 100 and 200 degree-days, are expected in inland and southern regions during the summer in the near future. In addition, increases of about 20–50 degree-days are anticipated during autumn. Conversely, energy demand for heating is projected to decrease during spring and winter, especially in the higher elevation parts of the island. More precisely, reductions of about 30–75 degree-days are projected during spring, while greater reductions of about 60–90 degree-days are expected during winter in heating demand, especially for in the near future. The ability of the energy sector to adapt and follow these changes was deemed to be satisfactory reducing the overall vulnerability of the sector to future climate change.  相似文献   

8.
基于MODIS数据的地表组分温度反演研究   总被引:3,自引:0,他引:3  
组分温度的反演是当前定量遥感的一个难点。与众多的陆面温度遥感模型相比,成熟的组分温度遥感模型相对较少。通过对近地面热红外辐射能量的线性展开,建立了MODIS多波段植被、土壤组分温度反演模型。该模型将组分温度与地表温度定量联系起来,模型中所涉及到的参数充分考虑到研究区湿地环境的特点。在计算组分温度时,首先利用单窗算法得到的MODIS陆面温度反演模型计算地表温度,然后由所建立的组分温度模型计算植被、土壤温度。选用2005年10月31日的鄱阳湖地区MODIS数据试验,与实测的植被、土壤温度相比,反演的组分温度的误差在15~21℃;通过对模型参数的敏感性分析,表明该模型具有一定的稳定性。实践证明,该方法能够有效实现组分温度的分离,是一种组分温度反演的较好方法。  相似文献   

9.
Analysing drug residues in wastewater (wastewater analysis) to monitor the consumption of those drugs in the population has become a complementary method to epidemiological surveys. In this method, the excretion factor of a drug (or the percentage of drug metabolites excreted through urine) is a critical parameter for the back-estimation of the consumption of a drug. However, this parameter is usually derived from a small database of human pharmacokinetic studies. This is true for methadone and codeine, the two most commonly used opioids and also common substances of abuse. Therefore, we aimed to refine the current excretion factors used for estimating methadone and codeine by analysing published data from the literature on the excretion of methadone, its main metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), and codeine. Our review included both human drug pharmacokinetic studies and wastewater analysis studies. We found that while the commonly used excretion factor of methadone (~ 27.5%) was relatively accurate, the excretion factor of EDDP, a better biomarker for methadone consumption in sewer epidemiology, should be twice that of methadone (i.e. 55%) instead of the current equal or half values. For codeine, the excretion factor should be ~ 30% instead of 63.5% or 10% as previously used in wastewater analysis studies. Data from wastewater analysis studies could be used in this way to refine the excretion factors of the drugs of interest.  相似文献   

10.
A simplified means of probabilistic risk assessment (PRA) for long-range atmospheric transport based on a K-diffusion model is presented. In a case study, model parameters are estimated by comparing with the results of long-range atmospheric dispersion model calculations using one-year numerical weather prediction model data. It is found that the estimated ensemble mean provides a reasonable first approximation to the total dry and wet deposition from the one-year continuous release.  相似文献   

11.
While the U.S. EPA has issued a draft report with a 1% TCDD effective dose (ED01) of 87.9 pg/kg/day based on continuous integration of key scientific evidence, a detailed and comprehensive uncertainty analysis has not been well documented. In this study, a new estimate for ED01 was derived based on uncertainty analysis by quantitatively assessing the potential bias arising from the selection of kinetic models, dose–response models and cohorts. The cumulative serum lipid concentration (CSLC) and cumulative body burden (CBB) were reconstructed as dose metrics using a concentration- and age-dependent pharmacokinetic model (CADM), physiologically based pharmacokinetic model (PBPK), and age-dependent half-life model (FV), and the reconstructed dose metrics based on CADM and PBPK were generally higher than those based on the FV model. Three dose–response curves (linear, multiplicative and power) were used to link dose metrics and cancer risk to estimate ED01, and the linear model resulted in the lowest ED01, followed by the power model and multiplicative model, for the same cohort. Meanwhile, ED01 based on the CADM model was the highest, followed by those based on the PBPK model and first-order model. Finally, the ED01 was estimated to be 17.03 ± 7.83 pg/kg/day by statistically analyzing the distribution of ED01 values based on various kinetic models, cohorts and dose–response models. The study presented here strengthens the scientific basis for understanding the potential health implications of TCDD exposure.  相似文献   

12.
Produced water, discharged from offshore oil and gas operations, contains chemicals from formation water, condensed water, and any chemical added down hole or during the oil/water separation process. Although, most of the contaminants fall below the detection limits within a short distance from the discharge port, a few of the remaining contaminants including naturally occurring radioactive materials (NORM) are of concern due to their bioavailability in the media and bioaccumulation characteristics in finfish and shellfish species used for human consumption. In the past, several initiatives have been taken to model human health risk from NORM in produced water. The parameters of the available risk assessment models are imprecise and sparse in nature. In this study, a fuzzy possibilistic evaluation using fuzzy rule based modeling has been presented. Being conservative in nature, the possibilistic approach considers possible input parameter values; thus provides better environmental prediction than the Monte Carlo (MC) calculation. The uncertainties of the input parameters were captured with fuzzy triangular membership functions (TFNs). Fuzzy if-then rules were applied for input concentrations of two isotopes of radium, namely (226)Ra, and (228)Ra, available in produced water and bulk dilution to evaluate the radium concentration in fish tissue used for human consumption. The bulk dilution was predicted using four input parameters: produced water discharge rate, ambient seawater velocity, depth of discharge port and density gradient. The evaluated cancer risk shows compliance with the regulatory guidelines; thus minimum risk to human health is expected from NORM components in produced water.  相似文献   

13.
浮游动物常作为水体富营养化程度的指示生物,但多集中于湖泊和水库等大型自然水体中。基于放养密度和搭配水生植物不同,中华鳖有不同的池塘养殖模式,而呈现出不同的水生态环境。通过调查鳖-单养、鳖-莲、鳖-生态和鳖-菱4种主要的池塘养殖模式水质指标和浮游甲壳动物的群落结构,了解不同养殖池塘中浮游甲壳动物的群落结构与富营养化程度之间的关系。研究结果显示,鳖-单养模式DO、NH_4~+-N、NO_2~--N、TN、TP、COD、Chl a、综合营养状态指数(TLI)均显著高于鳖-莲、鳖-生态和鳖-菱模式,SD显著低于鳖-莲、鳖-生态和鳖-菱模式(P0.05);养殖池塘中共记录枝角类6属7种,哲水蚤3属3种,剑水蚤6属6种,共同优势种为毛饰拟剑水蚤(Paracyclops fimbriatus)、广布中剑水蚤(Mesocyclops leuckarti)和台湾温剑水蚤(Thermocyclops taihokuensi);聚类分析结果显示鳖-单养模式单独聚为一类,鳖-莲、鳖-菱和鳖-生态模式聚为一类;线性回归分析显示枝角类丰度和TLI呈负相关(P0.05),哲水蚤丰度和TLI呈正相关(P0.05),剑水蚤和浮游甲壳动物丰度与TLI呈显著正相关(P0.05);RDA显示Chl a、NO_2~--N、SD、WT和COD显著影响了浮游甲壳动物组成(P0.05)。该研究不仅可以为中华鳖池塘养殖模式的开发提供技术指导,而且可以为渔业生产影响淡水生态系统结构与功能的研究提供理论支持。  相似文献   

14.
This study considers the implications and research needs arising from anticancer (also referred to as antineoplastic) drugs being released into the aquatic environment, for the entire therapeutic classes used: cytotoxic, cytostatic and endocrine therapy drugs.A categorization approach, based on French consumption amounts, allowed to highlight parent molecules and several metabolites on which further occurrence and ecotoxicological studies should be conducted.Investigations of consumption trends at a national and a local scale show an increase in the use of anticancer drugs between 2004 and 2008, thus leading to increased levels released in the environment. It therefore appears necessary to continue surveying their presence in surface waters and in wastewater treatment plant (WWTP) effluents.Furthermore, due to the rise of anticancer home treatments, most of the prescribed molecules are now available in town pharmacies. Consequently, hospital effluents are no longer the main expected entry route of anticancer drugs into the aquatic environment.Concerning ecotoxicological risks, current knowledge remains insufficient to support a definitive conclusion. Risk posed by cytotoxic molecules is still not well documented and it is not possible to conclude on their long-term effects on non-target organisms. To date, ecotoxicological effects have been assessed using standardized or in vitro assays. Such tests however may not be suitable for anticancer drugs, and further work should focus on full-life cycle or even multigenerational tests.Environmental significance (i.e. occurrence and effects) of cytostatics (protein kinases inhibitors and monoclonal antibodies), if any, is not documented. Protein kinases inhibitors, in particular, deserve further investigation due to their universal mode of action.Finally, concerning endocrine therapy drugs, molecules such as antiestrogen Tamoxifen and its active metabolites, could be of concern.Overall, to accurately assess the ecotoxicological risk of anticancer drugs, we discuss the need to break away from tests on isolated molecules and to test effects of mixtures at the low ng.l− 1 range.  相似文献   

15.
In this paper, some of the main processes and parameters which affect metal bioavailability and toxicity in the aquatic environment and its implications for metal risk assessment procedures will be discussed. It has become clear that, besides chemical processes (speciation, complexation), attention should also be given to physiological aspects for predicting metal toxicity. The development of biotic ligand models (BLMs), which combine speciation models with more biologically oriented models (e.g. GSIM), has offered an answer to this need. The various BLMs which have been developed and/or refined for a number of metals (e.g. Cu, Ag, Zn) and species (algae, crustaceans, fish) are discussed here. Finally, the potential of the BLM approach is illustrated through a theoretical exercise in which chronic zinc toxicity to Daphnia magna is predicted in three regions, taking the physico-chemical characteristics of these areas into account.  相似文献   

16.
宜昌站1900~2004年生态水文特征变化   总被引:2,自引:0,他引:2  
基于宜昌站1900~2004年共105年的日径流量资料,分别采用Mann Kendall法、Mann Whitney法分析该站水文特征与变化。跳跃性检验表明,宜昌站年平均流量的跳跃点出现在1969年,置信度超过99%。宜昌站1970年前的平均流量是14 375 m3/s,1970年后的平均流量是13 438 m3/s,相差937 m3/s,相当于295.5 m3/a,流量减少主要集中在下半年(7~12月),以8~10月最为明显。以1970年为界,将宜昌站105年水文序列划分为“近自然状态河流” 的1970年前和“人工干扰状态河流”的1970年后两个分析水文变动序列,基于Richter提出的生态水文变动指标体系,应用变动范围法,计算了长江中游的生态水文目标,分析了长江流域宜昌站的生态水文特征变化。结果表明,1970年以后,人类活动与自然变动对长江宜昌站生态水文特征的改变并不明显,仅在1月、11月平均流量上有中等程度的改变。  相似文献   

17.
The energy analysis of injection moulding processes is influenced by complex interactions amongst the moulded part, its material, the injection machine, the process parameters and the environmental conditions. The availability of energy usage analyses that comprehend information on specific materials and machine kind is limited. This paper reports a study that estimates and analyses the power usage profile (PUP), the specific energy consumption (SEC), and the energy distribution at an operation level of two different injected parts made of acrylonitrile-butadiene-styrene and produced in a hybrid injection moulding machine. The methodology followed by the authors incorporates an experiment carried out in an industrial facility. A large sample size, and data-acquisition and data post-processing processes to obtain an accurate PUP and SEC are used. A breakdown of the energy consumed by the injection moulding process of the parts studied at an operation level using Sankey diagrams is discussed. The study results are used to identify strategies to reduce the energy consumed by the processes. The methodology employed, and the strategies reported could be used with other plastic parts regardless of the material and machine used. The results reported are new experimental data useful input for theoretical models.  相似文献   

18.
1 INTRODUCTIONStrategic Environmental Assessment (SEA) is the application of EIA(Environment Impact Assessment) to strategic actions such as policies, plans or programs (PPPs). More specially, SEA is: 'The formalized, systematic and comprehensive process of evaluating the environmental impacts of a policy, plan or program and its alternatives, including the preparation of a written report on the findings of that evaluation, and using the findings in publicly accountable decision-ma…  相似文献   

19.
Mexico was the main vanilla producer worldwide many years ago. However, it currently provides just around 5 % of the global production. The issues that have led to the current stagnation of the vanilla production in Mexico have been addressed from various perspectives, but few studies have included the opinion of smallholder farmers. For this reason, the aim of this study was to conduct a participatory diagnostic to identify the challenges and constraints that affect the vanilla productive sector in Mexico from the smallholder farmers perspective. This study was conducted under the of Participatory Rural Appraisal (PRA) approach; consequently, we used PRA techniques for data collection. The qualitative data obtained were transcribed and analyzed using the Content Analysis Method (CAM) and Constant Comparative Method (CCM). The results showed that most of the challenges and limitations referred to by smallholder farmers result from the lack of training to improve production, processing, and marketing. Likewise, various restrictive aspects were identified in the production process that affect crop productivity, such as cultivation in small parcels, high incidence of diseases, premature abortion of fruits, and low tolerance of plants to stress. An aspect common to all processes is the need to promote organization and training schemes, since under the conditions described for the vanilla production chain in Mexico, relationships have been built in highly competitive communities and, in general, the targets seek have been mutually exclusive. For the above, we consider that achieving more profitable and sustainable production schemes require placing smallholder farmers at the base of an inclusive production system supported by fair trade, with organization, institutions, technology transfer, level of trust, and cooperation as core elements.  相似文献   

20.
地处青藏高原腹地的长江源区是长江流域的水源涵养地和生态系统的天然屏障,同时也是自然生态系统最敏感、生态环境十分脆弱的地区,浮游植物作为水体生态系统中的初级生产者,其群落结构对反映水体质量具有重要的指示作用。为探究长江源区水环境特性和浮游植物群落特征,于2018年3月份与10月份对长江源区10个典型河段的水环境因子与浮游植物群落组成进行了系统调查。结果显示:10月份各调查河段流速、浊度、水温及电导率等水环境参数均比3月份高;同一月份中,楚玛尔河的浊度、盐度、电导率等水环境参数均显著高于其余河段;两个月份各调查河段的pH、溶解氧以及亚硝酸盐氮等指标差异不显著。采样调查共鉴定出浮游植物4门28属58种,其中以硅藻、绿藻和蓝藻物种数占优,分别占总数的79.3%、10.4%和8.6%。调查期间,长江源区浮游植物密度在6.06×10~4~39.90×10~4 cells·L~(-1)之间,平均生物量为0.59 mg·L~(-1)。浮游植物优势种有美丽颤藻(Oscillatoria formosa)、普通等片藻(Diatoma vulgare)、脆杆藻(Fragilaria sp.)、针杆藻(Synedra sp.)、舟形藻(Navicula sp.)、桥弯藻(Cymbella sp.)、小球藻(Chlorella sp.)等。两个月份Shannon-Wiener多样性指数(H’)均值分别为3.06和3.12,Margalef丰富度指数(D)均值为1.17和1.52,Pielou均匀度指数(J)均值为0.90和0.82。结合水体营养盐指标、浮游植物密度及多样性指数等指标对水质评价,长江源区水质总体呈无污染或轻度污染状态。  相似文献   

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