Analysis of the Trend and Seasonal Cycle of Carbon Monoxide Concentrations in an Urban Area (4 pp)

Background, Aim and Scope Air quality is an field of major concern in large cities. This problem has led administrations to introduce plans and regulations to reduce pollutant emissions. The analysis of variations in the concentration of pollutants is useful when evaluating the effectiveness of these plans. However, such an analysis cannot be undertaken using standard statistical techniques, due to the fact that concentrations of atmospheric pollutants often exhibit a lack of normality and are autocorrelated. On the other hand, if long-term trends of any pollutant’s emissions are to be detected, meteorological effects must be removed from the time series analysed, due to their strong masking effects. Materials and Methods The application of statistical methods to analyse temporal variations is illustrated using monthly carbon monoxide (CO) concentrations observed at an urban site. The sampling site is located at a street intersection in central Valencia (Spain) with a high traffic density. Valencia is the third largest city in Spain. It is a typical Mediterranean city in terms of its urban structure and climatology. The sampling site started operation in January 1994 and monitored CO ground level concentrations until February 2002. Its geographic coordinates are W0°22′52″ N39°28′05″ and its altitude is 11 m. Two nonparametric trend tests are applied. One of these is robust against serial correlation with regards to the false rejection rate, when observations have a strong persistence or when the sample size per month is small. A nonparametric analysis of the homogeneity of trends between seasons is also discussed. A multiple linear regression model is used with the transformed data, including the effect of meteorological variables. The method of generalized least squares is applied to estimate the model parameters to take into account the serial dependence of the residuals of this model. This study also assesses temporal changes using the Kolmogorov-Zurbenko (KZ) filter. The KZ filter has been shown to be an effective way to remove the influence of meteorological conditions on O₃ and PM to examine underlying trends. Results The nonparametric tests indicate a decreasing, significant trend in the sampled site. The application of the linear model yields a significant decrease every twelve months of 15.8% for the average monthly CO concentration. The 95% confidence interval for the trend ranges from 13.9% to 17.7%. The seasonal cycle also provides significant results. There are no differences in trends throughout the months. The percentage of CO variance explained by the linear model is 90.3%. The KZ filter separates out long, short-term and seasonal variations in the CO series. The estimated, significant, long-term trend every year results in 10.3% with this method. The 95% confidence interval ranges from 8.8% to 11.9%. This approach explains 89.9% of the CO temporal variations. Discussion The differences between the linear model and KZ filter trend estimations are due to the fact that the KZ filter performs the analysis on the smoothed data rather than the original data. In the KZ filter trend estimation, the effect of meteorological conditions has been removed. The CO short-term componentis attributable to weather and short-term fluctuations in emissions. There is a significant seasonal cycle. This component is a result of changes in the traffic, the yearly meteorological cycle and the interactions between these two factors. There are peaks during the autumn and winter months, which have more traffic density in the sampled site. There is a minimum during the month of August, reflecting the very low level of vehicle emissions which is a direct consequence of the holiday period. Conclusions The significant, decreasing trend implies to a certain extent that the urban environment in the area is improving. This trend results from changes in overall emissions, pollutant transport, climate, policy and economics. It is also due to the effect of introducing reformulated gasoline. The additives enable vehicles to burn fuel with a higher air/fuel ratio, thereby lowering the emission of CO. The KZ filter has been the most effective method to separate the CO series components and to obtain an estimate of the long-term trend due to changes in emissions, removing the effect of meteorological conditions. Recommendations and Perspectives Air quality managers and policy-makers must understand the link between climate and pollutants to select optimal pollutant reduction strategies and avoid exceeding emission directives. This paper analyses eight years of ambient CO data at a site with a high traffic density, and provides results that are useful for decision-making. The assessment of long-term changes in air pollutants to evaluate reduction strategies has to be done while taking into account meteorological variability     

The application of life cycle assessment to design

This paper explores the practical application of life cycle assessment (LCA) to product system development. While life cycle assessment methods have been studied and demonstrated extensively over the last two decades, their application to product design and development has not been critically addressed. Many organizational and operational factors limit the integration of the three LCA components (inventory analysis, impact assessment and improvement assessment) with product development. Design of the product system can be considered a synthesis of individual decisions and choices made by the design team, which ultimately shape the system's environmental profile. The environmental goal of life cycle design is to minimize the aggregate environmental impacts associated with the product system. Appropriate environmental information must be supplied to decision makers throughout each stage of the development process to achieve this goal. LCA can serve as a source of this information, but informational requirements can vary as the design moves from its conceptual phase, where many design choices are possible, to its detailed design and implementation. Streamlined approaches and other tools, such as design checklists, are essential. The practical use of this tool in product development also depends on the nature and complexity of the product system (e.g. new vs. established), the product development cycle (time-to-market constraints), availability of technical and financial resources, and the design approach (integrated vs. serial). These factors will influence the role and scope of LCA in product development. Effective communication and evaluation of environmental information and the integration of this information with cost, performance, cultural and legal criteria will also be critical to the success of design initiatives based on the life cycle framework. An overview of several of these design initiatives will be presented.     

发展循环经济的实践和思考

发展循环经济是国内走新型工业化道路的具体表现。介绍了葫芦岛市抓好项目链接，发展循环经济的实践，并提出了进一步发展循环经济工作的几点建议。     

Life cycle analysis and choice of natural gas-based automotive alternative fuels in Chongqing Municipality,China

Road transport produces significant amounts of emissions by using crude oil as the primary energy source. A reduction of emissions can be achieved by implementing alternative fuel chains. The objective of this study is to carry out an economic, environmental and energy (EEE) life cycle study on natural gas-based automotive fuels with conventional gasoline in an abundant region of China. A set of indices of four fuels/vehicle systems on the basis of life cycle are assessed in terms of impact of EEE, in which natural gas produces compressed natural gas (CNG), methanol, dimethylether (DME) and Fischer Tropsch diesel (FTD). The study included fuel production, vehicle production, vehicle operation, infrastructure and vehicle end of life as a system for each fuel/vehicle system. A generic gasoline fueled car is used as a baseline. Data have been reviewed and modified based on the best knowledge available to Chongqing local sources. Results indicated that when we could not change electric and hydrogen fuel cell vehicles into commercial vehicles on a large scale, direct use of CNG in a dedicated or bi-fuel vehicle is an economical choice for the region which is most energy efficient and more environmental friendly. The study can be used to support decisions on how natural gas resources can best be utilized as a fuel/energy resource for automobiles, and what issues need to be resolved in Chongqing. The models and approaches for this study can be applied to other regions of China as long as all the assumptions are well defined and modified to find a substitute automotive energy source and establish an energy policy in a specific region.     

加压活性炭生物膜法处理DSD有机废水

采用加压活性炭生物膜法处理以对硝基甲苯磺酸盐为主的难降解的有机废水的研究,是在活性炭生物膜法处理有机废水基础上发展起来的新技术。本实验结果表明,在加压9.8×10~4Pa(1kgt/cm~2)的条件下,COD_(Cr)去除率为62％～70％,比常压活性炭生物膜法高20％～25％;其容积负荷Nv=1.7～2.9kgCOD/m~3·d,比一般活性污泥法高3～6倍。     

Life cycle energy impacts of automotive liftgate inner

This paper compares the life cycle energy use of a cast-aluminum, rear liftgate inner and a conventional, stamped steel liftgate inner used in a minivan. Using the best available aggregate life cycle inventory data and a simple spreadsheet-level analysis, energy comparisons were made at both the single-vehicle and vehicle-fleet levels. Since the product manufacture and use are distributed over long periods of time that, in a fleet, are not simple linear combinations of single product life cycles. Thus, it is all the products in use over a period of time, rather than a single product, that are more appropriate for the life cycle analysis. Using a set of consistent data, analyses also examine sensitivity to the level of analysis and the assumptions to determine the most favorable materials with respect to life cycle energy benefits.As expected, life cycle energy impacts of aluminum are lower than steel at a single-vehicle level – energy savings are determined to be 1.8 GJ/vehicle. Most energy savings occur at the vehicle operation phase due to improved fuel economy from lightweighting. The energy benefits are realized only very close to the average vehicle life of 14 years. With the incremental growth of the vehicle fleet, it takes longer – about 21 years – for aluminum to achieve life cycle equivalence with steel. The number of years aluminum needs to achieve equivalence with steel was found to be quite sensitive to aluminum manufacturing energy and fuel economy. As the steel industry races to compete with other materials for automotive lightweighting, a systems approach, instead of part-to-part comparison, is more appropriate in the determination of viability of aluminum substitution from an energy perspective.     

丹江口水库浮游细菌和氮磷循环基因垂直分布特征及其驱动因素

丹江口水库作为南水北调中线工程水源地,不同深度浮游细菌群落组成、 氮磷循环功能及其驱动因素尚未清晰. 选取丹江口水库5个生态点位,采用宏基因组学研究表层、 中层和底层垂直分布浮游细菌群落组成,分析预测氮磷循环功能及其驱动因素. 结果表明,丹江口水库主要由变形菌门、 放线菌门和浮霉菌门等优势种群组成,不同深度来源的浮游细菌群落结构具有显著差异,水温（T）、 氧化还原电位（ORP）、 溶解氧（DO）和Chla是影响浮游细菌群落组成的主要因素. 氮循环功能基因分析表明,主要涉及生物固氮过程、 硝化作用、 反硝化作用和异化硝酸盐还原作用等7个主要途径的gltB、 glnA、 gltD、 gdhA和NRT等39个氮循环功能基因. 磷循环功能基因分析表明,主要涉及有机磷矿化、 无机磷溶解、 调节等6个主要途径的pstS、 ppx-gppA、 glpQ和ppk1等54个磷循环功能基因. 聚类分析表明不同深度是影响氮磷循环功能基因组成和丰度的主要因素,表层和底层氮磷循环功能基因丰度高于中层样品. 奇异球菌属、 嗜氢菌属、 Limnohabitans和棍状杆菌属等是氮磷循环的关键物种. DO、 pH、 T、 总溶解性固体（TDS）、 电导率（EC）和Chla与氮磷循环功能基因显著相关,以上环境因子随丹江口水库深度增加浓度降低或升高,导致浮游细菌氮磷循环功能基因呈明显的垂直分布特征. 通过揭示丹江口水库不同深度浮游细菌群落组成、 氮磷循环功能及其影响因素,可为丹江口浮游细菌生态功能和多样性保护发挥潜在的作用.     

农业生态系统的氮素循环研究进展

在自然和人为作用的双重驱动下,地球表面氮素的生物地球化学过程及其环境效应成为当前全球变化中区域研究的重要内容。探讨了氮素循环各个过程及其数量特征,对氮素循环模型进行了介绍,并对当前生态系统中氮素循环的研究热点进行了简要的论述。     

森林新近凋落叶溶出DOM的性质及其对菲增溶作用的影响

凋落叶作为森林凋落物的主要组成部分,其溶出的大量有机质也是森林土壤可溶性有机质（DOM）的主要来源之一。研究森林凋落叶溶出DOM对PAHs增溶作用的影响有利于合理预测及评价森林土壤中PAHs的环境行为和生态风险。本研究采集了南亚热带常绿阔叶人工林的4种常见树种--尾叶桉（Eucalyptus urophylla）、木荷（Schima superba）、大叶相思（Acacia auriculiformis）和湿地松（Pinus elliottii）的新近凋落叶为试验材料,研究其DOM含量、组成与性质,对比分析了不同凋落叶DOM对菲的増溶作用及其与DOM性质的相关关系。结果表明,4种凋落叶的可溶性有机碳（DOC）质量分数在C 11.61~36.25 mg·g-1之间,其中尾叶桉的含量最大,湿地松最小。尾叶桉和木荷DOM的主要组分是可溶性糖（SS）和可溶性酚（SP）,两者总C量占DOC的比例超过47%,而大叶相思和湿地松中SS和SP两者总量所占比例均低于30%。另外,4种凋落叶DOM的质量分数（以C计）与其电导率的线性关系图中有明显转折点,说明它们均具有表面活性剂的性质。凋落叶DOM在临界胶束浓度（CMC）之上对菲具有不同程度的増溶作用,其与菲的结合系数（logKDOC）的大小顺序为尾叶桉（3.05 L·kg-1）＞木荷（3.02 L·kg-1）＞大叶相思（2.79 L·kg-1）＞湿地松（2.54 L·kg-1）,这表明尾叶桉和木荷DOM的增溶作用明显高于大叶相思和湿地松DOM。经分析表明,logKDOC与各DOM在254、280 nm处的特征紫外吸光度值（SUV-A254、SUV-A280）及其SS、SP的相对含量均呈显著正相关（p＜0.01）,与A240/A420、A254/A400比值呈显著负相关（p＜0.01）,说明DOM的芳香化程度越高,分子量越大, SS与SP所占比例越高,其对菲的増溶效果越明显。     

Effects of salinity on soil bacterial and archaeal community in estuarine wetlands and its implications for carbon sequestration: verification in the Yellow River Delta

Soils from two typical tidal salt marshes with varied salinity in the Yellow River Delta wetland were analysed to determine possible effects of salinity on soil carbon sequestration through changes in soil microbiology. The mean soil respiration (SR) of the salt water–fresh water mixing zone (MZ) was 2.89 times higher than that of the coastal zone (CZ) (4.73 and 1.63?μmol?m^?2?s^?1, respectively, p?Pseudomonas sp. and Limnobacter sp. that might have led to its higher dehydrogenase activity and respiratory rates. Additionally, the CZ possessed more Halobacteria and Thaumarchaeota with the ability to fix CO₂ than the MZ. Significantly lower soil salinity in MZ (4.25?g?kg^?1) was suitable for β-Proteobacteria, but detrimental for Halobacteria compared with CZ (7.09?g?kg^?1, p?相似文献