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461.
Footprint secretions deposited at the nest entrance or on food sources are used for chemical communication by honey bees, bumble bees, and stingless bees. The question of the glandular origin of the substances involved, however, has not been unequivocally answered yet. We investigated the morphology and structure of tarsal glands within the fifth tarsomeres of the legs of workers of Melipona seminigra in order to clarify their possible role in the secretion of footprints. The tarsal gland is a sac-like fold forming a reservoir. Its glandular tissue is composed of a unicellular layer of specialized epidermal cells, which cover the thin cuticular intima forming the reservoir. We found that the tarsal glands lack any openings to the outside and therefore conclude that they are not involved in the secretion of footprint substances. The secretion produced accumulates within the glands reservoir and reaches as far as into the arolium. Thus it is likely that it serves to fill and unfold the arolium during walking to increase adhesion on smooth surfaces, as is known for honey bees and weaver ants. 相似文献
462.
Martin Plath Rüdiger Riesch Alexandra Oranth Justina Dzienko Nora Karau Angela Schießl Stefan Stadler Adriana Wigh Claudia Zimmer Lenin Arias-Rodriguez Ingo Schlupp Michael Tobler 《Die Naturwissenschaften》2010,97(8):769-774
Adaptation to ecologically heterogeneous environments can drive speciation. But what mechanisms maintain reproductive isolation among locally adapted populations? Using poeciliid fishes in a system with naturally occurring toxic hydrogen sulfide, we show that (a) fish from non-sulfidic sites (Poecilia mexicana) show high mortality (95 %) after 24 h when exposed to the toxicant, while locally adapted fish from sulfidic sites (Poecilia sulphuraria) experience low mortality (13 %) when transferred to non-sulfidic water. (b) Mate choice tests revealed that P. mexicana females exhibit a preference for conspecific males in non-sulfidic water, but not in sulfidic water, whereas P. sulphuraria females never showed a preference. Increased costs of mate choice in sulfidic, hypoxic water, and the lack of selection for reinforcement due to the low survival of P. mexicana may explain the absence of a preference in P. sulphuraria females. Taken together, our study may be the first to demonstrate independent—but complementary—effects of natural and sexual selection against immigrants maintaining differentiation between locally adapted fish populations. 相似文献
463.
The dissolved organic matter in aquatic systems consists of a heterogeneous mixture of compounds with wide ranging chemical properties and diverse origins. the presence of organic matter (OM) in surface and ground waters has important implications with regard to the mobility and therefore fate of many potential organic and inorganic pollutants. the majority of the analytical approaches in current use require exhaustive pre-treatment steps which may lead to the formation of artefacts within the sample. an analytical technique based upon gel permeation chromatography is proposed as a more reliable procedure for the characterisation of naturally occurring dissolved organic matter. 相似文献
464.
The design floods of several reservoirs were recently re-evaluated and the revised spillway outflow could result in dam overtopping with catastrophic consequences for some embankment structures. Herein a physical study was performed on flat and pooled stepped spillways with a slope typical of embankments $(\uptheta = 26.6^{\circ })$ and four stepped configurations were tested: a stepped spillway with flat horizontal steps, a pooled stepped spillway, and two stepped spillways with in-line and staggered configurations of flat and pooled steps. The focus of the study was on the flow aeration, air–water flow properties, cavity flow processes, and energy dissipation performances. The results demonstrated the strong aeration of the flow for all configurations. On the in-line and staggered configurations of flat and pooled steps, the flow was highly three-dimensional. The residual head and energy dissipation rates at the stepped chute downstream end were calculated based upon the detailed air–water flow properties. The results showed that the residual energy was the lowest for the flat stepped weir. The data for the stepped spillway configuration with in-line and staggered configurations of flat and pooled steps showed large differences in terms of residual head in the transverse direction. Altogether the present results showed that, on a $26.6^{\circ }$ slope stepped chute, the designs with in-line and staggered configurations of flat and pooled steps did not provide any advantageous performances in terms of energy dissipation and flow aeration, but they were affected by three-dimensional patterns leading to some flow concentration. 相似文献
465.
Gerrit Holighaus Bernhard Weißbecker Maximilian von Fragstein Stefan Schütz 《Chemoecology》2014,24(2):57-66
An enormous variety of volatile substances are released in distinctive blends by fungal substrates that should be recognisable for fungivores. Certain compounds dominate in most of the fungal species. Fungal oxylipins as the eight-carbon volatiles are the most prominent. This raises the question whether such are specific enough to qualify as appropriate host cues for a fungivore. We could demonstrate differentiated responses of the fungivorous beetle Bolitophagus reticulatus to eight-carbon volatiles: Nine eight-carbon volatiles were identified with GC–MS from its host fungus Fomes fomentarius. 1-Octen-3-ol, 3-octanone and 3-octanol induced contrasting behaviour of beetles in olfactometer bioassays. Electroantennographic experiments investigating the beetle olfactory sense revealed distinguishable antennal responses. Moreover, their individual release from F. fomentarius fruiting bodies changes not only considerably, but also independently over successive stages of beetle colonisation. Concentrations of attractive and repellent eight-carbon volatiles correlate to frequency of beetles in the field and further substantiate their relevance as host cues. Our results show that a specialist fungivore is able to differentiate the most common eight-carbon volatiles of fungi to assess host quality. Key roles and marked similarities of fungal to plant oxylipins suggest a comparable importance of eight-carbon volatiles to fungivores as green leaf volatiles have to herbivores. 相似文献
466.
Volker Berding Stefan Schwartz Michael Matthies 《Environmental science and pollution research international》2000,7(3):147-158
Regional PECs (Potential Environmental Concentrations) calculated with the software EUSES were compared with measured values
using different emission and environmental distribution scenarios. The environmental data set recommended in EUSES (default
data set) represents a generic standard region. In different scenarios the parameters of the generic region are replaced by
concrete values, and estimated parameters (emissions, degradation rates and partition coefficients) are substituted by measured
or investigated values. Deviations with regard to the measured values can be up to three orders of magnitude. Despite the
basically conservative approximations, underestimations can occur. However, these are usually due to poor monitoring data
or inappropriate input values. The use of regional data instead of default parameters only slightly ameliorates the results.
The use of real emission and degradation rates alone can improve the results significantly. 相似文献
467.
Gartiser S Hafner C Kronenberger-Schäfer K Happel O Trautwein C Kümmerer K 《Environmental science and pollution research international》2012,19(8):3597-3609
Many pharmaceuticals and related metabolites are not efficiently removed in sewage treatment plants and enter into surface water. There, they might be subject of drinking water abstraction and treatment by ozonation. In this study, a systematic approach for producing and effect-based testing of transformation products (TPs) during the drinking water ozonation process is proposed. For this, two pharmaceutical parent substances, three metabolites and one environmental degradation product were investigated with respect to their biodegradability and fate during drinking water ozonation. The Ames test (TA98, TA100) was used for the identification of mutagenic activity present in the solutions after testing inherent biodegradability and/or after ozonation of the samples. Suspicious results were complemented with the umu test. Due to the low substrate concentration required for ozonation, all ozonated samples were concentrated via solid phase extraction (SPE) before performing the Ames test. With the exception of piracetam, all substances were only incompletely biodegradable, suggesting the formation of stable TPs. Metformin, piracetam and guanylurea could not be removed completely by the ozonation process. We received some evidence that technical TPs are formed by ozonation of metformin and piracetam, whereas all tested metabolites were not detectable by analytical means after ozonation. In the case of guanylurea, one ozonation TP was identified by LC/MS. None of the experiments showed an increase of mutagenic effects in the Ames test. However, the SPE concentration procedure might lead to false-positive results due to the generation of mutagenic artefacts or might lead to false-negative results by missing adequate recovery efficiency. Thus, these investigations should always be accompanied by process blank controls that are carried out along the whole ozonation and SPE procedure. The study presented here is a first attempt to investigate the significance of transformation products by a systematic approach. However, the adequacy and sensitivity of the methodology need to be further investigated. The approach of combining biodegradation and ozonation with effect-based assays is a promising tool for the early detection of potential hazards from TPs as drinking water contaminants. It can support the strategy for the evaluation of substances and metabolites in drinking water. A multitude of possible factors which influence the results have to be carefully considered, among them the selectivity and sensibility of the mutagenicity test applied, the extraction method for concentrating the relevant compounds and the biocompatibility of the solvent. Therefore, the results have to be carefully interpreted, and possible false-negative and false-positive results should be considered. 相似文献
468.
Markert B Wuenschmann S Fraenzle S Graciana Figueiredo AM Ribeiro AP Wang M 《Environmental pollution (Barking, Essex : 1987)》2011,159(8-9):1991-1995
After considering the particular problems of atmospheric pollution in megacities, i.e. agglomerations larger than 5 mio. inhabitants, with urbanization of World's population going on steadily, possibilities of active biomonitoring by means of green plants are discussed. Based on specific definitions of active and passive bioindication the chances of monitoring heavy metals in Sao Paulo megacity were demonstrated (first results published before). This is to show that there is need for increased use of bioindication to tackle the particular problems of megacities concerning environmental "health", the data to be processed according to the Multi-Markered-Bioindication-Concept (MMBC). Comparison to other work shows this approach to be reasonable. 相似文献
469.
Potentials for the prevention of municipal solid waste 总被引:1,自引:0,他引:1
Salhofer S Obersteiner G Schneider F Lebersorger S 《Waste management (New York, N.Y.)》2008,28(2):245-259
Waste prevention has been assigned the highest priority under European waste management law. However, the initiatives which have been taken so far have not reduced the regular annual increase in total waste arising across Europe. The purpose of this paper is to quantify and analyze in depth the prevention potential for selected case studies (advertising material, beverage packaging, diapers, food waste, waste from events). Only such measures are considered, which do not require a reduction of consumption. The prevention potentials for household waste in theory are exemplified for the city of Vienna, also with a view to barriers that may reduce the achievable prevention potential. The results show that the prevention potentials for the analyzed individual measures can reach an order of magnitude of some 10% of the relevant waste stream (e.g., advertising material, beverage packaging), or rather 1-3% of municipal solid waste. The prevention potentials appear to be relatively small in relation to the total municipal waste quantities. Methodological shortcomings, such as the missing availability of basic data, make it difficult to exactly estimate the impact of waste prevention measures on waste quantities, which is only one of the effects of waste prevention among other ecological, social and economic aspects. 相似文献
470.
Animal husbandry and manure treatment have been specifically documented as significant sources of methane, ammonia, nitrous oxide, and particulate matter. Although volatile organic compounds (VOCs) are also produced, much less information exists concerning their impact. We report on chemical ionization mass spectrometry and photo-acoustic spectroscopy measurements of mixing ratios of VOCs over a 2-wk measurement period in a large cowshed at the Federal Agricultural Research Centre (FAL) in Mariensee, Germany. The high time resolution of these measurements enables insight into the sources of the emissions in a typical livestock management setting. During feeding hours and solid manure removal, large mixing ratio spikes of several VOCs were observed and correlated with simultaneous methane, carbon dioxide, and ammonia level enhancements. The subsequent decay of cowshed concentration due to passive cowshed ventilation was used to model emission rates, which were dominated by ethanol and acetic acid, followed by methanol. Correlations of VOC mixing ratios with methane or ammonia were also used to calculate cowshed emission factors and to estimate potential nationwide VOC emissions from dairy cows. The results ranged from around 0.1 Gg carbon per year (1 Gg = 10(9) g) for nonanal and dimethylsulfide, several Gg carbon per year for volatile fatty acids and methanol, to over 10 Gg carbon per year of emitted ethanol. While some estimates were not consistent between the two extrapolation methods, the results indicate that animal husbandry VOC emissions are dominated by oxygenated compounds and may be a nationally but not globally significant emission to the atmosphere. 相似文献