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111.
High genetic variability may increase metabolic efficiency and thus allows responding to environmental challenges as limits
to adaptation are approached. Therefore, it has been suggested that high genetic variability contributes strongly to the fitness
of an individual. Survival to high age may thus depend on high genetic variability, and genetically variable individuals may
have a higher survival rate to high ages in comparison to less variable sympatric conspecifics. Such a heterozygosity × age
relationship might be more readily detectable in stressful as compared to benign environments. For testing the relationship
between age and heterozygosity, we genetically analyzed 71 individuals of the frog species Rana perezi from a total of seven populations at 13 allozyme loci. The age of the individuals was determined by skeletochronology. We
found effects on age of both environment and allozyme heterozygosity, especially in populations with high stress regimes.
A significant heterozygosity × age relationship has so far rarely been shown in natural populations. The result of our analysis
suggests that more heterozygous individuals have a higher longevity and may be an important source of genetic variability
of a population, likely contributing to a stabilization of the effective population size. 相似文献
112.
Fourier-transform infrared(FT-IR) spectroscopic experiments were carried out during phosphate adsorption on highly crystalline gibbsite, poorly crystalline 2-line-ferrihydrite and amorphous iron–aluminum–hydroxide mixtures in the molar ratio 1:0, 10:1, 5:1, 1:1, 1:5, 1:10 and 0:1. The OH stretching vibrational bands were utilized to analyze changes in structural and surface OH groups during adsorption, because the position of characteristic P\O vibrational bands can shift depending on reaction conditions, pH or adsorbed phosphate content.Adsorption and desorption kinetics were studied at pH6 and different initial phosphate concentrations to achieve varying phosphate coverage on the mineral surfaces. For gibbsite the formation of AlHPO_4 and Al_2HPO_4 can be assumed, while for ferrihydrite, a FeHPO_4 or Fe_2PO_4 complex and the precipitation of FePO_4 with longer equilibration time were proposed.Fe_2HPO_4 or a Fe_2PO_4 surface complex was deduced for Fe-hydroxides, an AlH_2PO_4 surface complex was identified for Al-hydroxide, and both displayed either hydrogen bonds to neighboring hydroxyl groups or hydrogen bonds to outer-sphere complexes. Fe:Al-hydroxide mixtures with high Al ratios showed a low phosphate desorption rate, while ferrihydrite and the Fe:Al-hydroxide mixtures with high Fe ratios had almost negligible desorption rates. It was concluded that within the weakly associated amorphous FeO(OH) materials, FePO_4 precipitated, which was bound by outer-sphere hydrogen bonds. With high Al ratios, desorption increased, which indicated weaker phosphate binding of both inner-sphere and outer-sphere complexes and hence, either no or minor quantities of precipitate. Ferrihydrite showed a more rigid structure and a lower extent of precipitation compared to amorphous Fe-hydroxide. 相似文献
113.
Johannes Stökl Robert Twele Dirk H. Erdmann Wittko Francke Manfred Ayasse 《Chemoecology》2007,17(4):231-233
Summary.
Ophrys flowers mimic the female produced sex pheromone of their pollinator species to attract males for pollination. The males try
to copulate with the putative female and thereby pollinate the flower. Using electrophysiological and chemical analyses, floral
volatiles released by O. iricolor as well as the female sex pheromone of its pollinator species, Andrena morio are investigated. Overall, 38 peaks comprising 41 chemical compounds, were found to release reactions in the antennae of
male A. morio bees. Analyses using coupled gas chromatography-mass spectrometry revealed the presence of alkanes and alkenes with 20 to
29 carbon atoms, aldehydes (C9 to C24) and two esters. Almost all of those compounds were found in similar proportions in
both, the floral extracts of O. iricolor and cuticle surface extracts of A. morio females. The pattern of biologically active volatiles described here is very similar to that used by other Ophrys species pollinated by Andrena males. 相似文献
114.
Andreas Ahrens Frank Claus Kerstin Heitmann Dirk Jepsen Lothar Kistenbrügger 《Environmental Sciences Europe》2006,18(2):123-128
In October 2003, the EU Commission presented the proposal for a new Chemicals Regulation. In late autumn 2005, Parliament and Council were working on finding their position on the Commission’s proposal. From November 2004 to April 2005, a simulation was carried out at EU level aiming to test the workability of registration under REACh. Based on a strategic partnership, the European Chemical Industry Council together with other industry associations, the EU Commission and a number of Member States had launched this project. 53 manufacturers or users of chemicals and competent authorities of 13 EU Member States took part in the simulation: eight registration cases were dealt with in parallel. The participants had to conduct the registration of a substance (including preparatory work) and the dossier evaluation by the authorities. The simulation was performed in a ’free-flow mode’, which means, that the participants worked without any guidance on how to practically implement the duties and tasks as laid down in the draft regulation. In the final phase of the project, the three strategic parners worked towards a common understanding on potential workability problems and suitable options for solutions. This process resulted in a report including a set of agreed recommendations on 12 identified workability issues The recommendations are mostly related to the co-operation between registrants, the sharing of responsibilities and communication between manufactures and down-stream users as well as technical and scientific aspects of dossier compilation., In addition, the recommendations address the need to develop a common understanding across Europe regarding the role of authorities in evaluating the registration dossiers and developing suitable tools for the evaluation. In addition to the set of practical recommendations, SPORT has demonstrated that useful insights in the workability of a new piece of legislation can be gained from simulating the key processes in practise already during the legislative process. Such pilot trials could be seen as a contribution toBetter Regulation, one of the strategic goals of the EU Commission. 相似文献
115.
Background Different types of indicators have been developed to describe the impact of chemicals on society and environment. Due to
the high number of substances and their different types of use, most of these indicators are directed to specific areas of
interest – regarding workplace safety, environmental health or consumer health. They address a specific subset of chemicals
and can be used for monitoring enterprise-specific, national or international management measures.
Main Features A survey of existing indicators for chemicals has shown that indicators already exist for a remarkable number of problem
fields. As soon as the release and the environmental fate of chemicals are taken into account, the complexity of the approaches
increases considerably. The distinction between indicators for drivers, pressures, state, impacts and responses, as proposed
by the European Environmental Agency, supports the identification of proper indicators for a specific type of problem.
Discussion and Conclusions. No single indicator exists which is able to cover the whole range of chemicals and their applications. Several
indicator approaches cover at least a subset of the most relevant substances. If they are intended to be used for European
monitoring, robust data must be provided by EU Member States.
Chemicals in enterprises (ancillary inputs as well as process chemicals) are an important element of in-plant material flow
management – in terms of occupational safety and health as well as environmental protection. Existing indicators for hazardous
chemicals can be a valuable tool for process and product refinement regarding hazardous chemicals, especially for enterprises.
Outlook Indicators for production and impact of chemicals, as well as policy performance indicators, are essential elements in order
to monitor the management of chemicals. They have to be established for the national and for the EU level. 相似文献
116.
Asymmetric flow-field flow fractionation-inductively-coupled plasma-mass spectrometry was used to determine whether colloidal arsenic(As) exists in soil pore water and soil extract samples at two arsenic-contaminated abandoned gold mines(Montague and Goldenville, Nova Scotia). Colloidal arsenic was found in 12 out of the 80 collected samples(= 15%), and was primarily associated with iron(Fe) in the encountered colloids. The molar Fe/As ratios indicate that the colloids in some samples appeared to be discrete iron–arsenic minerals, whereas in other samples, they were more consistent with As-rich iron(oxy)hydroxides. Up to three discrete size fractions of colloidal As were encountered in the samples, with mean colloid diameters between 6 and 14 nm. The pore water samples only contained one size fraction of As-bearing colloids(around 6 nm diameter), while larger As-bearing colloids were only encountered in soil extracts. 相似文献
117.
Friederike Hoffmann Hans Røy Kristina Bayer Ute Hentschel Martin Pfannkuchen Franz Brümmer Dirk de Beer 《Marine Biology》2008,153(6):1257-1264
The Mediterranean sponge Aplysina aerophoba kept in aquaria or cultivation tanks can stop pumping for several hours or even days. To investigate changes in the chemical
microenvironments, we measured oxygen profiles over the surface and into the tissue of pumping and non-pumping A. aerophoba specimens with Clark-type oxygen microelectrodes (tip diameters 18–30 μm). Total oxygen consumption rates of whole sponges
were measured in closed chambers. These rates were used to back-calculate the oxygen distribution in a finite-element model.
Combining direct measurements with calculations of diffusive flux and modeling revealed that the tissue of non-pumping sponges
turns anoxic within 15 min, with the exception of a 1 mm surface layer where oxygen intrudes due to molecular diffusion over
the sponge surface. Molecular diffusion is the only transport mechanism for oxygen into non-pumping sponges, which allows
total oxygen consumption rates of 6–12 μmol cm−3 sponge day−1. Sponges of different sizes had similar diffusional uptake rates, which is explained by their similar surface/volume ratios.
In pumping sponges, oxygen consumption rates were between 22 and 37 μmol cm−3 sponge day−1, and the entire tissue was oxygenated. Combining different approaches of direct oxygen measurement in living sponges with
a dynamic model, we can show that tissue anoxia is a direct function of the pumping behavior. The sponge-microbe system of
A. aerophoba thus has the possibility to switch actively between aerobic and anaerobic metabolism by stopping the water flow for more
than 15 min. These periods of anoxia will greatly influence physiological variety and activity of the sponge microbes. Detailed
knowledge about the varying chemical microenvironments in sponges will help to develop protocols to cultivate sponge-associated
microbial lineages and improve our understanding of the sponge-microbe-system. 相似文献
118.
Dirk Bruns-Nagel Torsten C. Schmidt Oliver Drzyzga Eberhard v. Löw Klaus Steinbach 《Environmental science and pollution research international》1999,6(1):7-10
Water extracts of soil samples of the former ammunition plant “Tanne” near Clausthal-Zellerfeld, Lower Saxony, Germany, were investigated for highly polar oxidized 2,4,6-trinitrotoluene (TNT) metabolites. 0.4 to 9.0 mg/kg dry soil 2,4,6-trinitrobenzoic acid (TNBA) and 5.8 to 544 mg/kg dry soil 2-amino-4,6-dinitrobenzoic acid (2-ADNBA) were found. In addition to the oxidized metabolites, TNT, 4- and 2-aminodinitrotoluene (4- and 2-ADNT), and 2,4-dinitrotoluene (2,4-DNT) were extractable with water. Most interestingly, in one sample, 2-ADNBA represented the main contaminant. The origin of the oxidized nitroaromatics is unknown at this time. They might be generated chemically or photochemically. Furthermore, a biological synthesis seems possible. 相似文献
119.
Speier Christopher J. Mondal Moni M. Weichgrebe Dirk 《Journal of Material Cycles and Waste Management》2018,20(4):2150-2162
Journal of Material Cycles and Waste Management - India currently has the second largest urban population worldwide, while facing an increasing burden on its urban solid waste infrastructure. To... 相似文献
120.
Dirk J. Roux Richard T. Kingsford Carly N. Cook Jane Carruthers Katrina Dickson Marc Hockings 《Conservation biology》2019,33(6):1266-1274
Although protected areas represent a pivotal response to escalating anthropogenic threats, they face many pressures, inside and outside their boundaries. Amid these challenges, effective conservation is guided by evidence-based decision making supported by dynamic processes of learning and knowledge exchange. Although different models promote knowledge exchange, embedding research scientists within conservation agencies is best suited to supporting evidence-based conservation. Based on available literature and our experiences on several continents, we considered the benefits, challenges, and opportunities associated with embedding research scientists within conservation agencies and the research required to better understand the effectiveness of the embedding model for evidence-based conservation. Embedded researchers provide long-term commitment to building social capital among academic and nonacademic stakeholders; act as skilled gatekeepers who increase 2-way flow of knowledge between scientists and managers; attract, coordinate, and support management-relevant external research projects; drive the design and maintenance of long-term monitoring; and align their research with information needs. Notwithstanding the many benefits, research capacity of conservation agencies is declining worldwide. A significant challenge is that the values, structures, functions, and effectiveness of the embedding model of knowledge exchange remain poorly evaluated and documented. Also, embedded researchers have to balance their desire for creativity and flexibility with the standardization and quality control required by their public sector agencies; may be perceived as not credible because they are not truly independent of their agency; and have to couple scientific productivity with skills for transdisciplinary research, social facilitation, and stakeholder engagement. Systematic research on embedding and other models of knowledge exchange, across different world contexts, is required to better understand the benefits, costs, and institutional arrangements associated with different models. 相似文献