Bacterial pretreatment enhances removal of heavy metals during treatment of post-methanated distillery effluent by Typha angustata L

A combination of bacterial pretreatment followed by free water surface flow through wetland plants was investigated to determine its effect on removal of heavy metals in bioremediation of post-methanated distillery effluent (PMDE). The bacterial pretreatment was intended to transform the metal complexes and organic pollutants into simpler, biologically assimilable molecules. The 10% and 30% v/v concentrations of PMDE favored luxuriant bacterial growth; the 50% concentration supported less growth, whereas the undiluted effluent (i.e., 100%) supported very little bacterial growth. The use of bacterial pretreatment combined with the constructed wetland system greatly increase the overall bioaccumulation of all heavy metals by the plants compared with the control treatment. However, the integration of bacterial pretreatment of PMDE with the Typha angustata resulted in enhanced removal of Cd (34.02–61.50% increase), Cr (35.90–57.60% increase), Cu (32.88–54.22% increase), Fe (32.50–51.26% increase), Mn (35.99–82.85% increase), Ni (35.85–59.24% increase), Pb (33.45–59.51% increase) and Zn (31.95–53.70% increase) compared with a control that lacked this pretreatment. In addition to the bioaccumulation of these heavy metals, several physico-chemical parameters also improved at the 30% effluent concentration: color, BOD, COD, phenol and total nitrogen decreased by 98.33%, 98.89%, 98.50%, 93.75% and 82.39%, respectively, after 7 days of free water surface flow treatment. The results suggest that bacterial pretreatment of PMDE, integrated with phytoremediation will improve the treatment process of PMDE and promote safer disposal of this waste.     

Horizontal mergers in the iron ore industry—An application of PCAIDS

The purpose of this paper is to estimate and analyse the price effects of the iron ore mergers between Rio Tinto and North Ltd in 2000, and CVRD and Caemi in 2001. The analyses are conducted using a merger simulation model that, based on the pre-merger situation, estimates the post-merger outcome. This paper applies the so-called proportionality-calibrated almost ideal demand system (PCAIDS) model, which assumes that the product is differentiated and that the strategic variable is price. The results from the merger simulations show that in the case of the merger between Rio Tinto and North Ltd, the merged firm has a combined market share of almost 20%. However, the estimated market weighted average price effect is only 2.6%. Regarding the merger between CVRD and Caemi, the merged firm's market share is about 29%, and the estimated market weighted average price effect is 4.6%. When removing Caemi's Canadian asset, which was the Commission decision in order to allow the merger, the market price effect decreases to 3.1%. Overall the results in this study support the Commission's decisions regarding both merger cases, and shows that merger simulations of price effects can be valuable tools in merger assessments.     

Plant and Soil System Responses to Ozone After 3 Years in a Lysimeter Study with Juvenile Beech (Fagus sylvatica L.)

A lysimeter study was performed to monitor effects of elevated ozone on juvenile trees of Fagus sylvatica L. as well as on the plant–soil system. During a fumigation period over almost three growing seasons, parameters related to plant growth, phenological development and physiology as well as soil functions were studied. The data analyses identified elevated ozone to delay leaf phenology at early and to accelerate it at late developmental stages, to reduce growth, some leaf nutrients (Ca, K) as well as some soluble phenolics (hydroxycinnamic acid derivatives, total flavonol glycosides). No or very weak ozone effects were found in mobile carbon pools of leaves (starch, sucrose), and other phenolic compounds (flavans). Altered gene expression related to stress and carbon cycling corresponded well with findings from leaf phenology and chemical composition analyses indicating earlier senescence and oxidative stress in leaves under elevated ozone. Conversely in the soil system, no effects of ozone were detected on soil enzyme activities, rates of litter degradation and lysimeter water balances. Despite the fact that the three reported years 2003–2005 were climatically very contrasting including a hot and dry as well as an extremely wet summer, and also mild as well as cold winters, the influence of ozone on a number of plant parameters is remarkably consistent, further underlining the phytotoxic potential of elevated tropospheric ozone levels.     

家蚕斑纹限性品种SC_1的RAPD差异DNA片段的克隆及其酶切图谱分析

利用RAPD技术对家蚕限性普斑品种SC1的雌雄体分别进行PCR扩增通过120种引物的筛选,得到1个雌体特异的RAPDDNA片段将该片段克隆到pUC19质粒,井进行了限制性内切酶图谱分析.     

Accumulation of Fluoride and Aluminium Related to Different Varieties of Tea Plant

Samples of young shoot, mature leaf, twig, root, and litter were taken from four recently bred varieties Zhe-nong 113, Zhe-nong 121, Zi-sun, and Bi-feng grown at two tea plantations located at Zhejiang and Jiangsu Provinces. The results showed that the concentrations of F and Al in tea plants were significantly different among the four varieties. It is therefore possible that F and Al concentrations in tea products can be reduced through variety selection. The results also revealed that old leaves would be the major contribution to the high levels of F and Al in brick tea since it is produced mainly for old leaves. Therefore, in order to eliminate the hazard of over-exposure to F and Al derived from tea, younger shoot should be used for making tea products while mature leaves should be avoided.     

非离子型表面活性剂AE对大薸损伤程度的酶学诊断

以超氧化物歧化酶 (SOD)、过氧化氢酶 (CAT)和过氧化物酶 (POD)的比活力变化作为观测指标 ,进行了脂肪醇聚氧乙烯醚 (AE)对大薸 (PistiastratiotesL .)损伤程度的酶学诊断 .结果表明 :在 17℃下 ,ρ(AE) 0 .1mg L的AE对大薸的伤害程度极微 ;ρ(AE)为 1.0、10 .0mg L时 ,大薸受到较大的伤害 ,但能逐渐恢复正常生理活动 ;ρ(AE)为 2 0 .0、5 0 .0mg L时 ,由于伤害程度大 ,超出了酶的修复能力 ,组织逐渐坏死 .同时推测 :在AE污染下 ,大薸的POD是起保护作用的主导酶 .图 3表 1参 12     

金鱼藻与环棱螺对铜绿微囊藻生长及光合活性的抑制作用

沉水植物和螺类是生物防治有害水华的重要手段,然而目前关于这两者对有害蓝藻的协同抑制效率和作用机制尚不清楚.本研究利用沉水植物金鱼藻与铜锈环棱螺在实验室内探究草-螺组合系统对铜绿微囊藻（Microcystis aeruginosa）生长的抑制效果.结果表明,金鱼藻组、环棱螺组及草-螺组合系统均显著降低了体系内蓝藻Chl-a浓度、总Chl-a浓度和铜绿微囊藻密度,与初始相比,蓝藻活体Chl-a浓度分别减少99.24%、100.00%和98.61%,铜绿微囊藻密度分别减少98.64%、86.44%和97.71%.草-螺共培养和金鱼藻单独培养均可以显著抑制铜绿微囊藻生长,效果相似,而环棱螺单独培养可以使蓝藻Chl-a浓度和光曲线参数值降为零,同时使得微囊藻细胞全部失活.金鱼藻与环棱螺都可以降低铜绿微囊藻光合活性,草-螺共培养系统可以最大程度降低藻类整体的生长潜能.研究发现,草-螺耦合系统对铜绿微囊藻的总体抑制效率略低于两者单独抑制效率,表明金鱼藻和环棱螺在此过程中存在微弱的拮抗作用,但由于草-螺耦合系统的抑制成效同样显著,且抑制途径更多样,同时能更好地维持水体营养盐平衡.在实践过程中建议加强沉...     

三叶鬼针草生物量分配与化感作用对大气温度升高的响应

全球气候变暖已经成为不容置疑的事实,同时外来入侵植物对入侵地的生态环境造成严重的危害,外来入侵植物可能对温度升高做出积极地响应。文章研究了不同温度(22、26和30℃)处理对入侵植物三叶鬼针草(Bidens pilosa L.)种子萌发、幼苗生物量分配及化感作用的影响,探讨三叶鬼针草对全球气候变暖的响应策略。结果表明;温度为22和26℃比30℃有利于三叶鬼针草种子的萌发。温度升高显著增加三叶鬼针草的株高、生物量和叶面积,三叶鬼针草幼苗增加对茎和叶的生物量投资。同时相同浓度的三叶鬼针草水浸提液对马唐(Digitaria sanguinalis(L.)Scop)和牛筋草(Eleusine indica(L.)Gaertn)的化感作用随着温度升高而增强。研究表明:温度升高促进了三叶鬼针草的生长,改变生物量分配模式同时增强了对受体植物的化感作用。温度升高可能是促进三叶鬼针草入侵的生态环境因子之一,未来全球气温变暖可能使其入侵加剧。     

Effect of the temperature and the exclusion of UVB radiation on the phenolics and iridoids in Menyanthes trifoliata L. leaves in the subarctic

The long-term effects of UVB exclusion and temperature on the methanol extractable (ME) phenolics (flavonoids, phenolic acids) and iridoids of Menyanthes trifoliata L. (Mt) leaves were studied in northern Finland (68°N) using wooden frames covered with filters for UVB exclusion (polyester filter), control (cellulose acetate filter) and ambient (no filter) conditions. Analysis of ambient plots showed no effect of the daily mean temperature (2σ = 1.58 °C) on the leaf ME compound content and composition, but minimum temperatures decreased the flavonol content. UVB exclusion did not affect the total ME compound content but significantly decreased the proportion of flavonols concomitantly with an increase in iridoids. Due to its high iridoid content, Mt appears as an interesting model plant for studying the iridoid biosynthesis and its regulation under stress conditions.     

Evaluating mine plans under uncertainty: Can the real options make a difference?

Over the last few years, many studies have presented the real options valuation (ROV) as a promising technique of valuing natural resource investments under conditions of uncertainty. Apart from the common conclusion that the ROV is better than the conventional net present value (NPV) method in integrating the value of management flexibility and proper handling of cash flows risk, there is a lack of procedures for testing the usefulness and advantages of the ROV over the static NPV method in practice. Arguably, it is not yet clear whether the ROV can deal with the complexity of mining projects and whether it can really be applied to make decisions that improve project value.