The use of physiological characteristics for comparison of organic compounds phytotoxicity

The influence of intact (FLT) and photomodified (phFLT) fluoranthene (0.05, 0.5 and 5 μmol l⁻¹) and herbicide Basagran (5, 20, 35 and 50 nmol l⁻¹) on the germination, growth of seedlings and photosynthetic processes in pea plants (Pisum sativum L., cv. Garde) was investigated. The germination was significantly inhibited already by the lowest concentration (0.05 μmol l⁻¹) of FLT and phFLT, while Basagran caused inhibition only in higher concentrations (35 and 50 nmol l⁻¹). The growth of roots was significantly inhibited by higher concentration 5 μmol l⁻¹ of both FLT and phFLT and the shoot of seedlings was significantly influenced only by photomodified form. The length of root and shoot was inhibited already by concentration 5 nmol l⁻¹ of Basagran. Organic compounds applied on chloroplasts suspension influenced primary photochemical processes of photosynthesis. In chlorophyll fluorescence parameters, the significant increase of F₀ values and the decrease of F_V/F_M and Φ_II values by application of FLT (0.5 and 5 μmol l⁻¹) and phFLT (0.05, 0.5 and 5 μmol l⁻¹) was recorded. The maximum capacity of PSII (F_V/F_M) was influenced by the highest (50 nmol l⁻¹) and the effective quantum yield of PSII (Φ_II) already by the lowest (5 nmol l⁻¹) concentration of Basagran. Hill reaction activity decreased and was significantly inhibited by higher concentration (0.5 and 5 μmol l⁻¹) of FLT and phFLT and already by the lowest concentration (5 nmol l⁻¹) of Basagran.     

京津冀典型城市采暖季颗粒物浓度与元素分布特征

选择京津冀地区3个典型城市和从南至北的4个国家大气背景站作为研究对象,收集采暖季空气颗粒物PM2.5、PM10样品,微波消解-ICP-MS法分析了样品中的68种元素。结果表明,北京、天津、石家庄PM2.5和PM10日均质量浓度均高于国家二级标准限值和背景点,一元线性回归分析结果表明,PM10与PM2.5质量浓度呈线性相关,Na、Mg、Al、S、K、Ca、Fe质量浓度为0.1~10μg/m3,Si、P、Ti、Mn、Ni、Cu、Zn、Ba、Pb质量浓度为10~100 ng/m3,其他元素质量浓度为0.01~10 ng/m3或未检出。在元素构成上,S、Na、Al、K、Fe、Mg、Ca、P、Si等是主要元素,元素含量均大于1%。其他微量元素每种元素含量为0.1%~1%。14种重点防控重金属在PM2.5中的吸附显著高于PM10,主要来源于燃煤、燃油、工业排放、机动车尾气等。     

Development and Parameterization of a Rain- and Fire-driven Model for Exploring Elephant Effects in African Savannas

We describe the development and parameterization of a grid-based model of African savanna vegetation processes. The model was developed with the objective of exploring elephant effects on the diversity of savanna species and structure, and in this formulation concentrates on the relative cover of grass and woody plants, the vertical structure of the woody plant community, and the distribution of these over space. Grid cells are linked by seed dispersal and fire, and environmental variability is included in the form of stochastic rainfall and fire events. The model was parameterized from an extensive review of the African savanna literature; when available, parameter values varied widely. The most plausible set of parameters produced long-term coexistence between woody plants and grass, with the tree–grass balance being more sensitive to changes in parameters influencing demographic processes and drought incidence and response, while less sensitive to fire regime. There was considerable diversity in the woody structure of savanna systems within the range of uncertainty in tree growth rate parameters. Thus, given the paucity of height growth data regarding woody plant species in southern African savannas, managers of natural areas should be cognizant of different tree species growth and damage response attributes when considering whether to act on perceived elephant threats to vegetation.     

挺水植物化感作用抑制藻类生长的机理与应用

根据国内外挺水植物化感作用抑制藻类的研究,对菖蒲等15科20种挺水植物化感抑制水华鱼腥藻等18种水华藻类的作用予以评述;归纳了挺水植物化感作用在影响藻细胞亚显微结构、酶体系活性、呼吸作用、光合作用、细胞膜和细胞内小分子物质的含量等6方面的抑制藻类生长的机理;对移植栽种植物共培养、从植物中提取化感物质和直接施加化感物质等3种类型抑制藻类的应用方式进行概述;结合当前中国水华频发、抑藻和除藻任务繁重的现状,指出存在的主要问题并提出今后研究和应用化感作用抑制藻类的展望。     

污泥掺烧对燃煤电厂痕量元素排放特性影响

采用EPAMethod29方法、冷原子吸收光谱法和电感耦合等离子体质谱法采集和分析一台超低排放燃煤机组污泥掺烧前后的原燃料、烟气和副产物样品中各痕量元素浓度,研究污泥掺烧对燃煤电厂痕量元素排放特性的影响.结果表明:污泥中富含Zn、Cu元素,浓度分别是煤样中的18.81倍和17.64倍.污泥掺烧使掺配后入炉煤中痕量元素含量普遍升高.污泥掺烧前后整个系统、锅炉系统和全流程大气污染控制设施的痕量元素质量平衡率均在可接受范围内.污泥掺烧对痕量元素的分布特征无明显影响,随粉煤灰排放是痕量元素的主要排放去向.通过烟囱排放到大气环境的痕量元素排放量占比很小,不超过0.43%.污泥掺烧前后SCR入口烟气中痕量元素除Hg外主要以颗粒态形式存在.污泥掺烧后各痕量元素在粉煤灰和底渣中的相对富集系数未显著改变.经过全流程大气污染控制设施协同控制后,污泥掺烧前后烟囱总排口痕量元素排放浓度分别为0～12.76,0～14.97μg/m³.污泥掺烧后痕量元素排放浓度均满足美国燃煤发电机组有害大气污染物排放标准、上海市燃煤耦合污泥电厂大气污染排放标准和生态环境部生活垃圾焚烧污染控制标准的限值要求....     

Woody plant roots fail to penetrate a clay-lined landfill: Managment implications

In many locations, regulatory agencies do not permit tree planting above landfills that are sealed with a capping clay, because roots might penetrate the clay barrier and expose landfill contents to leaching. We find, however, no empirical or theoretical basis for this restriction, and instead hypothesize that plant roots of any kind are incapable of penetrating the dense clays used to seal landfills. As a test, we excavated 30 trees and shrubs, of 12 species, growing over a clay-lined municipal sanitary landfill on Staten Island, New York. The landfill had been closed for seven years, and featured a very shallow (10 to 30-cm) soil layer over a 45-cm layer of compacted grey marl (Woodbury series) clay. The test plants had invaded naturally from nearby forests. All plants examined—including trees as tall as 6 m—had extremely shallow root plates, with deformed tap roots that grew entirely above and parallel to the clay layer. Only occasional stubby feeder roots were found in the top 1 cm of clay, and in clay cracks at depths to 6 cm, indicating that the primary impediment to root growth was physical, although both clay and the overlying soil were highly acidic. These results, if confirmed by experimental research should lead to increased options for the end use of many closed sanitary landfills.     

Developing of a pricing model for Turkish lignite used in thermal plants

The objective of this paper is to develop a general pricing model for Turkish Lignite, which is mainly sold to thermal plants. This model will contribute to the development of coal mining within the scope of privatization efforts of the Turkish energy market. The paper consists of two stages. First, data of 10 thermal plants have been evaluated by using hedonic pricing analysis to determine influential price parameters. The results of hedonic regression analysis indicate the effect and importance of calorific value and electricity price on lignite prices. Second, a general coal-pricing model has been developed by taking into account the results of hedonic analysis. Comparison of the coal prices estimated by the developed pricing model and the coal prices obtained from thermal plants indicates an acceptable relation.     

POTENTIALS FOR REUSE OF WASTEWATER IN NORTH CENTRAL TEXAS1

ABSTRACT There are several possible ways in which wastewater from municipalities may be reclaimed and reused so as to minimize the need for imported water in North Central Texas. The rationale for reuse is enhanced by the fact that new water quality requirements in the Trinity River system will necessitate a very high degree of treatment at municipal sewage plants, just for discharge to surface streams. The largest potential market for municipal effluent is the steam-electric power industry. Within the next decade the generating capacity for electric power in North Central Texas will have to be more than doubled to meet increasing demand. Adequate supplies of condenser cooling water for such expansion will be difficult to obtain and assure. New large power stations might advantageously be located adjacent to municipal wastewater treatment plants, to utilize effluent as make-up water for cooling towers. Experience elsewhere has shown that well-treated wastewater can be used for cooling tower make-up with a minimum of trouble, with a considerable saving in overall cost, and with conservation of pristine water for other uses.     

DESIGN OF DESALTING PLANTS FOR CONJUNCTIVE OPERATION1

ABSTRACT The selection of an evaporator design must reflect the balancing of captial cost (primarily in heat exchanger surface and vessels) against operating cost (primarily steam cost) to achieve minimum cost. In a conjunctive plant the tendency is to select a low-capital cost, high-operating cost plant. In addition, it is advantageous to use a high-capacity plant which needs to be operated much less of the time than a plant which is sized just at the needed rate. For example, in the study of a possible system to satisfy a future increase of 450 MGD in water supply to New York Qty, a plant of 750 MGD capacity was selected as optimum. This plant, of the advanced VTE-MSF process type, would have a performance ratio of 9 lb product/1000 Btu as compared to 10-13 normally used for base-loaded plants. Steam would be supplied by a multi-unit dual-purpose nuclear power plant. The most economical type of energy supply would be “interruptible”; the steam would be used by a low pressure turbine to generate electricity during periods of peak electrical demand but would be available to the desalting plant at other times. The low pressure turbine would be available as spinning reserve during desalting plant operation. It is estimated that the desalting plant would have a load factor of 27 per cent over its life.