Effect of arsenic and mercury speciation on inhibition of respiration rate in activated sludge systems

The inhibition effect of arsenite, As(III), arsenate, As(V), inorganic mercury, Hg(II) and methylmercury, MeHg, on the respiration rate of activated heterotrophic sludge microorganisms was evaluated. As(III) and MeHg were much more toxic to activated sludge than As(V) and Hg(II) respectively. The effect of various experimental parameters on the toxicity, such as sludge age, concentration of suspended solids and exposure time, was investigated. An increase of sludge age or the concentration of suspended solids reduces the observed inhibition. Longer exposure seems to dramatically increase the inhibition of As(III), MeHg and Hg(II) during the first hours of exposure, while the later inhibition increases at a slower rate. On the contrary, in the presence of As(V), 24 hours after exposure, the respiration rate was similar to that of the control biomass.     

Das neue Chemikalienprogramm von UNEP Chemicals

Zusammenfassung  UNEP International Register of Potentially Toxic Chemicals (IRPTC) wurde von der ersten VN-Umweltkonferenz 1972 geschaffen. Sein Einfu? und Zusammenwirken in den 80ziger Jahren mit anderen internationalen Programmen der WHO, FAO, OECD und EG in der Chemikalienkontrolle wird beschrieben. Nach dem Erdgipfel von Rio 1992 werden im VN-Rahmen drei neue Gremien gebildet, die das Fachprogramm des Kapitels 19 der Agenda 21 (umweltfreundliches Chemikalienmanagement) umsetzen sollen: die United nations Commission of Sustainable Development, das Intergovernmental Forum on Chemical Safety und das Interorganization Programme for the Sound Management of Chemicals. Der Erdgipfel brachte auch für IRPTC eine Neuorientierung. Seit 1996 hat UNEP Chemicals, wie sich IRPTC nunmehr nennt, drei Aufgaben in sein Arbeitsprogramm aufgenommen, die beschrieben werden: das internationale übereinkommen zum Prior Informed Consent, das internationale übereinkommen zur Kontrolle der Persistent Organic Pollutants, und schlie?lich sein traditionelles Arbeitsgebiet des Informations-austausches über Stoffe wird weitergeführt.

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Die Aussagen dieses Beitrages sind die Meinung des Autors. Sie müssen nicht mit der Auffassung des Umweitbundesamtes oder von UNEP Chemicals übereinstimmen.     

套种模式对水土保持效应的影响

在东江中上游低效水土保持林的改造中,营建了不同套种模式的水保林,效益监测结果表明,乔灌草模式、乔灌模式和马尾松纯林模式中,以乔灌草模式的水土保持效果为最佳.乔、灌、草层分别对降水的截留和吸附,以及大量的地上枯落物具有强大的持水能力,有效地减少了雨滴直接冲刷地表,使得乔灌草模式的土壤侵蚀明显减少,套种4 a后土壤侵蚀模数降为960 t/(km2(a),约为乔灌模式的1/3和马尾松纯林的1/5;同时使土壤蓄水能力提高,土壤肥力状况得到改善.     

The poison gland of the antMyrmicaria eumenoides and its role in recruitment communication

Summary The antMyrmicaria eumenoides is a significant arthropod predator. For rapid attraction of large numbers of nestmates to newly discovered food sources the ants use an efficient recruitment communication system based on the poison gland secretion. Workers exhibit age-based division of labour. Young workers perform brood-care; their poison gland reservoir develops and reaches its final size of 0.5 µl at an age of 6 weeks, when they become foragers. The secretion deposited during combat with enemies or prey is composed of equal amounts of both a high volatile and a low volatile fraction. Within the high volatile fraction (+)—limonene is the main component (97%) and is the only olfactory trigger to alert ants in the vicinity and to recruit them to places of combat, where they assemble. Ants respond to synthetic (+)—limonene in exactly the same way as to the poison gland secretion when applied at the same airborne concentrations. Further components of the high volatile fraction are four additional monoterpene hydrocarbons and hexanoic nitrile. The high volatile and the low volatile fraction of the poison gland secretion each have dual functions: The low volatiles, of which the main component is an alkaloid, serve as a fixative and extend the effective period of the limonene signal by modifying its evaporation kinetics. On the other hand the high volatile recruitment signal (+)—limonene is also the solvent for the alkaloid and enhances its spreading on the surface of the cuticle of arthropod enemies or prey.     

应用蝶啶荧光分析法推断巨尾阿丽蝇成虫日龄

为探明蝶啶荧光分析法在尸食性蝇类成虫日龄推断中的应用潜力,采用荧光分光光度计对4种恒温和自然变温下巨尾阿丽蝇(Aldrichina grahami)雌雄成虫头壳蝶啶含量与日龄的关系进行了研究.结果表明,性别、温度和日龄对成虫蝶啶含量均有显著影响,其中日龄为最主要的影响因子.在16℃、20℃、24℃和28℃下,雌雄成虫头壳蝶啶含量与日龄均呈显著的线性关系(P<0.01,R2>0.90).蝶啶积累速率与温度也呈显著的线性关系.应用蝶啶荧光分析法对自然变温下巨尾阿丽蝇雌雄成虫日龄的估计表明,估计日龄与实际日龄呈显著的线性关系,其中雌成虫日龄估计误差平均为2.68d,雄成虫为±1.56d.以上研究结果表明,蝶啶荧光分析法在巨尾阿丽蝇成虫尤其是雄成虫日龄的推断中具有较大的应用价值.图4表2参19     

中小企业财务管理存在的问题与战略对策

中小企业是国民经济中一支重要的经济力量，在我国发展社会主义市场经济中发挥着重要的作用．财务问题是所有企业成败的关键，对中小企业尤其如此．本文从简述我国现阶段中小企业财务管理现状人手，揭示当前中小企业财务管理存在的问题．结合实际，分析其发生、存在的原因，并为解决这些问题，提出了相应的战略对策．     

坝上地区生态资源综合评估

以生态资源承载力的理论和方法为指导,对坝上地区进行生态资源综合评估。考虑坝上生态条件特点,有重点地选择相应指标,以客观准确反映该区域的特点;同时参考国际及国内的有关标准,构筑了表现生态资源综合评估的指标及分值标准,确定表达式及评价分值,并结合具体区域进行试用和检验。为深入综合探讨坝上生态资源特点奠定基础。     

反倾销:出口贸易的障碍及对策

改革开放以来，中国成了全球最大的反倾销受害国．频遭反倾销指控，对我国的出口贸易和国民经济造成了极大的损失．对此，我国一方面要尽力扭转国际上对我国的一系列歧视性做法，一方面深化国内外贸管理体制改革，提高出口企业的产品质量和应诉能力等，以更快适应WTO的贸易规则，在国际反倾销战中赢得主动．     

Genetic Effects of Habitat Fragmentation on Common Species of Swiss Fen Meadows

Abstract:  The area of Caricion davallianae alliance in Switzerland has been considerably reduced and fragmented during the last 150 years. We assessed the genetic variability, inbreeding level, and among-population differentiation of two common habitat-specific plant species, Carex davalliana SM. and Succisa pratensis Moench, in 18 Caricion davallianae fen meadows subjected to fragmentation. We used a spatial field design of fen systems (six systems total), each consisting of one large habitat island and two small habitat islands. We used allozyme electrophoresis to derive standard genetic parameters ( A, P, H_O, H_E, F_IS, F_ST ). In Carex we identified a consistently lower A in isolated habitat islands; furthermore, H_E was lower in small habitat islands than in large habitat islands. In Succisa we identified a lower H_O in small habitat islands than in larger ones. Small habitat islands were marginally significantly differentiated (  F_ST ) from large islands for Succisa . For both species, no effects were evident for F_IS ; therefore, we argue that genetic drift rather than inbreeding is the main cause of the observed differences. The genetic structure of Carex and Succisa in small habitat islands differed from that in large habitat islands, but differences were small. It appears that the observed differences in genetic variability among fen meadows correspond to observed differences in fitness and demographic traits. We show that habitat fragmentation affects not only the rare species in an ecosystem but also reduces the survival probabilities of common species. One of the main goals of conservation should be to mitigate fragmentation of natural habitats in order to increase population sizes and connectivity.     

大气甲醛卫生检验方法的分析条件

对《居住区大气中甲醛卫生检验标准方法分光光度法》(GB／T16129-1995)中实验条件进行了实验研究，研究表明进口和天津显色剂的灵敏度有差别，但对测定结果无影响；最佳显色时间为2-8min；样品在0℃～4℃条件下保存4d对测定无影响。