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941.
Eremosparton songoricum (Fabaceae) is a rare, native, clonal small shrub of the deserts of central Asia. Although human activities have greatly fragmented the distribution of E. songoricum, it occurs in areas where artificial sand fixing (AS) has been implemented. We sought to explore whether AS promotes survival and growth of E. songoricum. In the Gurbantunggut Desert of northwestern China in June 2010, we established 10 plots in an area where sand fixing occurred (5–10 years previously) and 11 plots on original sand substrate on which some plants had settled without fixing sand. Sand fixing changed soil properties and biological characteristics in sand‐fixed plots. The soil surface where sand fixing occurred was covered by algal crusts and some lichen, but not bare sand (BS). Soil nutrients; water content of deep soil (30–150 cm); overall plant and herbaceous species richness, diversity, abundance, and cover; above‐ and belowground biomass; and cover, biomass, and height of E. songoricum in the sand‐fixed plots were significantly greater than in plots of BS. However, distribution of E. songoricum individuals in the 2 types of plots did not differ. Our results indicate AS may enhance survival of E. songoricum and increase the overall diversity and stability of the desert plant community. We suggest AS as a way to protect this rare desert plant in situ. Efectos de la Fijación Artificial de Arena sobre las Características de la Comunidad de un Arbusto Desértico Raro  相似文献   
942.
The International Union for Conservation of Nature (IUCN) Red List Index (RLI) is recognized as one of the key indicators of trends in the status of species. The red‐list assessment done by Finnish authorities of species in Finland is taxonomically one of the most extensive national assessments. We used the Finnish Red Lists from 2000 and 2010 to calculate for the first time the national RLIs for 11 taxonomic groups at different trophic levels and with different life cycles. The red‐list index is calculated on the basis of changes in red‐list categories and indicates trends in the status of biological diversity of sets of species. The RLI value ranges from 0 to 1. The lower the value the faster the set of species is heading toward extinction. If the value is 1, all species in the set are least concern and if the value is 0, all species are (regionally) extinct. The overall RLI of Finnish species decreased. This means that, in Finland, these taxonomic groups were heading toward extinction faster in 2010 than in 2000. Of the analyzed groups of organisms, RLIs of 5 decreased and RLIs of 6 increased. At the national level, the RLIs and status trends varied markedly between species groups. Thus, we concluded that generalizations on the basis of RLIs of a few taxa only may yield a biased view of ongoing trends in the status of biological diversity at the species level. In addition, one overall RLI that includes many different species groups may also be misleading if variation in RLI among species groups is not considered and if RLI values are not presented separately for each group. Aplicación del Índice de la Lista Roja a Nivel Nacional para Grupos de Especies Múltiples  相似文献   
943.
In recent years, the ability of microorganisms to decolorize textile wastewater has received great attention due to the environmental persistence and toxicity of these pollutants. In this paper biological decolorization of triphenylmethane dye, C.I. Basic Green 4 (BG 4), by Chlorella species was investigated. The effect of operational parameters (temperature, pH, initial dye concentration and algal concentration) on decolorization efficiency was examined. Results indicated that the desired initial pH was 9. The stability and efficiency of the algae in long-term repetitive operations were also examined. Michaelis-Menten kinetics was employed to describe the apparent correlation between the decolorization rate and dye concentration. The optimal kinetic parameters, Vmax (specific decolorization rate) and Km (maximum specific decolorization rate) were 4.6 mg dye g cell-1 h-1and 151.0 mg L-1, respectively. Fig 10, Tab 2, Ref24  相似文献   
944.
This paper aims to evaluate the environmental burdens associated with spray dried soluble coffee over its entire life cycle and compare it with drip filter coffee and capsule espresso coffee. It particularly aims to identify critical environmental issues and responsibilities along the whole life cycle chain of spray dried coffee. This life cycle assessment (LCA) specifically uses foreground data obtained directly from coffee manufacturers and suppliers. Aside from energy consumption and greenhouse gases emissions, water footprint is also studied in detail, including regionalization of water impacts based on the ecological scarcity method 2006. Other impact categories are screened using the IMPACT 2002+ impact assessment method.The overall LCA results for a 1 dl cup of spray dried soluble coffee amounts approximately to 1 MJ of primary non-renewable energy consumption, to emissions of 0.07 kg of CO2-eq, and between 3 and 10 l of non-turbined water use, depending on whether or not the coffee cultivation is irrigated and wet treated. When considering turbined water, use can be up to 400 l of water per cup. Pouch – and to a lesser extent metal can packaging alternatives – show lower environmental burdens than glass or sticks.On average, about one half of the environmental footprint occurs at a life cycle stage under the control of the coffee producer or its suppliers (i.e., during cultivation, treatment, processing, packaging up to distribution, along with advertising) and the other half at a stage controlled by the user (shopping, appliances manufacturing, use and waste disposal). Key environmental parameters of spray dried soluble coffee are the amount of extra water boiled and the efficiency of cup cleaning during use phase, whether the coffee is irrigated or not, as well as the type and amount of fertilizer used in the coffee field. The packaging contributes to 10% of the overall life cycle impacts.Compared to other coffee alternatives, spray dried soluble coffee uses less energy and has a lower environmental footprint than capsule espresso coffee or drip filter coffee, the latter having the highest environmental impacts on a per cup basis. This study shows that a broad LCA approach is needed to help industry to minimize the environmental burdens directly related to their products. Including all processes of the entire system is necessary i) to get a comprehensive environmental footprint of the product system with respect to sustainable production and consumption, ii) to share stakeholders responsibility along the entire product life cycle, and iii) to avoid problem shifting between different life cycle stages.  相似文献   
945.
Engineering projects involving hydrogeology are faced with uncertainties because the earth is heterogeneous, and typical data sets are fragmented and disparate. In theory, predictions provided by computer simulations using calibrated models constrained by geological boundaries provide answers to support management decisions, and geostatistical methods quantify safety margins. In practice, current methods are limited by the data types and models that can be included, computational demands, or simplifying assumptions. Data Fusion Modeling (DFM) removes many of the limitations and is capable of providing data integration and model calibration with quantified uncertainty for a variety of hydrological, geological, and geophysical data types and models. The benefits of DFM for waste management, water supply, and geotechnical applications are savings in time and cost through the ability to produce visual models that fill in missing data and predictive numerical models to aid management optimization. DFM has the ability to update field-scale models in real time using PC or workstation systems and is ideally suited for parallel processing implementation. DFM is a spatial state estimation and system identification methodology that uses three sources of information: measured data, physical laws, and statistical models for uncertainty in spatial heterogeneities. What is new in DFM is the solution of the causality problem in the data assimilation Kalman filter methods to achieve computational practicality. The Kalman filter is generalized by introducing information filter methods due to Bierman coupled with a Markov random field representation for spatial variation. A Bayesian penalty function is implemented with Gauss–Newton methods. This leads to a computational problem similar to numerical simulation of the partial differential equations (PDEs) of groundwater. In fact, extensions of PDE solver ideas to break down computations over space form the computational heart of DFM. State estimates and uncertainties can be computed for heterogeneous hydraulic conductivity fields in multiple geological layers from the usually sparse hydraulic conductivity data and the often more plentiful head data. Further, a system identification theory has been derived based on statistical likelihood principles. A maximum likelihood theory is provided to estimate statistical parameters such as Markov model parameters that determine the geostatistical variogram. Field-scale application of DFM at the DOE Savannah River Site is presented and compared with manual calibration. DFM calibration runs converge in less than 1 h on a Pentium Pro PC for a 3D model with more than 15,000 nodes. Run time is approximately linear with the number of nodes. Furthermore, conditional simulation is used to quantify the statistical variability in model predictions such as contaminant breakthrough curves.  相似文献   
946.
Simultaneous anammox and denitrification(SAD) is an efficient approach to treat wastewater having a low C/N ratio; however, few studies have investigated a combination of SAD and partial nitritation(PN). In this study, a lab-scale up-flow blanket filter(UBF) and zeolite sequence batch reactor(ZSBR) were continuously operated to implement SAD and PN advantages, respectively. The UBF achieved a high total nitrogen(TN) removal efficiency of over 70% during the start-up stage(days 1–50), and reached...  相似文献   
947.
Abstract

Inundatively used mycoherbicides have been uneconomical and ineffectual, mainly because a large inoculum is required to overcome weeds’ innate defenses, as well as the need for long dew periods to become established. Weed defenses can be suppressed by specific chemical agents, or overcome biologically (using mixed organisms and/or engineering enhanced pathogenicity), and better formulants replace the long dew periods.  相似文献   
948.
反硝化除磷脱氮系统中DPB的驯化富集培养   总被引:2,自引:2,他引:0  
黄荣新  张杰  谌建宇 《环境科学》2010,31(5):1252-1256
反硝化同时脱氮除磷系统中反硝化除磷菌(DPB)的培养驯化状况,将直接影响污水中氮磷等营养元素的同时去除效率以及系统的高效稳定运行,为此本实验研究设计了一套以实际生活污水为处理对象的双污泥反硝化脱氮除磷工艺流程,采用逐渐过渡的培养方式,为DPB创造良好的厌氧/缺氧交替环境,即创造特定的适合DPB生存的环境条件让其进行自然选择,以筛选出来需要的DPB菌.结果表明,通过15d的间歇曝气的厌氧/好氧(A/O)运行方式可以对PAOs进行快速诱导;第二阶段,通过好氧曝气时间的逐渐减少,缺氧段投加硝酸氮的厌氧/好氧/缺氧(A/O/A)运行模式,25d左右可达到强化诱导反应器里面的DPB占PAOs的比例;最后让DPB在严格的厌氧/缺氧交替环境下进行富集培养19d,通过这种逐渐过渡培养的方式获得了对所需要的DPB菌的成功诱导富集,该菌的成功驯化培养为市政生活污水中的氮磷同时高效稳定去除提供了一种新方法.  相似文献   
949.
同时贮存与生长理论认为,活性污泥吸收有机碳基质同时用于储存和生长.向SBR反应器投加不同浓度乙酸基质,监测活性污泥氧利用速率(OUR)、聚羟基烷酸盐(PHA)和出水COD的变化,运用活性污泥同时贮存与生长理论分析有机碳储存与消耗过程的特征.结果表明,饱食期结束与COD消耗至最低水平、PHA浓度出现最大值和OUR由最大值急速下降相对应;在饱食阶段,基质贮存OUR是利用外部基质直接生长OUR的2倍.随基质投加历时延长,饱食期平均OUR和最大OUR均下降,PHA产率降低,甚至出现PHA净消耗.因此,基质投加方式对有机碳基质储存与消耗有重要影响.  相似文献   
950.
生活垃圾生物预处理后筛分及分选特性试验研究   总被引:1,自引:0,他引:1  
杨列  陈朱蕾  张俊 《环境科学学报》2015,35(12):3943-3946
堆肥化技术作为垃圾预处理方式在国内外已得到了广泛认可.本文通过现场试验,研究了生物预处理对垃圾筛分和分选特性的影响.结果表明,预处理后垃圾含水率降低了7.69%,堆体的体积从275 m~3减少到183 m~3,垃圾的容重从最初的356 kg·m~(-3)增加到470 kg·m~(-3).经过生物预处理,有机物不断被降解.预处理可以提高筛分后筛下物比例,预处理后的筛下物百分比提高了17%.预处理对可回收成分(金属、塑料、纸张、玻璃和布匹等)分选效率都较新鲜垃圾有不同程度的提高,对金属分选效果提高最显著,达到22.01%.本研究表明,生物预处理对垃圾筛分和分选均具有积极的作用,可以提高后期资源回收利用率.  相似文献   
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