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491.
Although cannibalism is ubiquitous in food webs and frequent in systems where a predator and its prey also share a common resource (intraguild predation, IGP), its impacts on species interactions and the dynamics and structure of communities are still poorly understood. In addition, the few existing studies on cannibalism have generally focused on cannibalism in the top-predator, ignoring that it is frequent at intermediate trophic levels. A set of structured models shows that cannibalism can completely alter the dynamics and structure of three-species IGP systems depending on the trophic position where cannibalism occurs. Contrary to the expectations of simple models, the IG predator can exploit the resources more efficiently when it is cannibalistic, enabling the predator to persist at lower resource densities than the IG prey. Cannibalism in the IG predator can also alter the effect of enrichment, preventing predator-mediated extinction of the IG prey at high productivities predicted by simple models. Cannibalism in the IG prey can reverse the effect of top-down cascades, leading to an increase in the resource with decreasing IG predator density. These predictions are consistent with current data. Overall, cannibalism promotes the coexistence of the IG predator and IG prey. These results indicate that including cannibalism in current models can overcome the discrepancy between theory and empirical data. Thus, we need to measure and account for cannibalistic interactions to reliably predict the structure and dynamics of communities. 相似文献
492.
Maximilian Berthold Ulf Karsten Mario von Weber Alexander Bachor Rhena Schumann 《Ambio》2018,47(1):146-158
The EU-water framework directive aims at nutrient reductions, since anthropogenically induced eutrophication is a major threat for coastal waters. However, phytoplankton biomass in southern Baltic Sea coastal water bodies (CWB) remains high and the underlying mechanisms are not well understood. Therefore, a CWB data set was analysed regarding changes in phytoplankton biomass and nutrient concentration of nitrogen (N) and phosphorus (P) from 2000 to 2014. It was expected to find imbalances between produced phytoplankton biomass and total nutrient concentrations. Inner CWB were cyanobacteria-dominated and showed up to five times higher chlorophyll a-concentrations compared to outer CWB with similar total phosphorus-concentrations. Phytoplankton tended to be P-limited during spring and N-limited during summer. Phytoplankton biomass and nutrient concentrations were even higher during very humid years, which indicated a close coupling of the CWB with their catchment areas. This study suggests that re-mesotrophication efforts need to consider the importance of changed phytoplankton composition and nutrient availabilities. 相似文献
493.
Denise Margaret S. Matias Julia Leventon Anna-Lena Rau Christian Borgemeister Henrik von Wehrden 《Ambio》2017,46(4):456-467
In order to understand the role of wild bees in both social and ecological systems, we conducted a quantitative and qualitative review of publications dealing with wild bees and the benefits they provide in social contexts. We classified publications according to several attributes such as services and benefits derived from wild bees, types of bee–human interactions, recipients of direct benefits, social contexts where wild bees are found, and sources of changes to the bee–human system. We found that most of the services and benefits from wild bees are related to food, medicine, and pollination. We also found that wild bees directly provide benefits to communities to a greater extent than individuals. In the social contexts where they are found, wild bees occupy a central role. Several drivers of change affect bee–human systems, ranging from environmental to political drivers. These are the areas where we recommend making interventions for conserving the bee-human system. 相似文献
494.
Erica von Essen Michael P. Allen 《Environmental Communication: A Journal of Nature and Culture》2017,11(5):654-666
Two obstructionist ways of doing politics on contentious wildlife management issues currently reflect a legitimacy deficit in official channels for public engagement. The first is that of a pernicious “direct-action” politics, in the form of resort by hunters in rural Sweden to illegal killings of protected wolves over whose policy they contest. The second obstruction is when environmental non-governmental organizations routinely file appeals in higher-level courtrooms contesting democratically mandated wolf cull decisions. Although markedly different when it comes to their categorically deliberative values as well as fidelity to the law, we argue both extra-legal and the litigative phenomena reflect disenfranchisement with the participation channels in which such controversies may be resolved through a public dialogue. We also argue that both possess negative systemic deliberative value inasmuch as they frustrate goals of reaching deliberative consensus, by contributing to a stalled public communication on wolf management. We address this deficit by appeal to recent developments in the theory and practice of mini-publics that promote both the categorical and systemic deliberative value of channeling contestation. In particular, we appeal to a novel conception of hunter-initiated, but citizen controlled, mini-publics as a vehicle for re-starting stalled public communication on wolf conservation. 相似文献
495.
Peitzsch M Sulyok M Täubel M Vishwanath V Krop E Borràs-Santos A Hyvärinen A Nevalainen A Krska R Larsson L 《Journal of environmental monitoring : JEM》2012,14(8):2044-2053
Secondary metabolites produced by fungi and bacteria are among the potential agents that contribute to adverse health effects observed in occupants of buildings affected by moisture damage, dampness and associated microbial growth. However, few attempts have been made to assess the occurrence of these compounds in relation to moisture damage and dampness in buildings. This study conducted in the context of the HITEA project (Health Effects of Indoor Pollutants: Integrating microbial, toxicological and epidemiological approaches) aimed at providing systematic information on the prevalence of microbial secondary metabolites in a large number of school buildings in three European countries, considering both buildings with and without moisture damage and/or dampness observations. In order to address the multitude and diversity of secondary metabolites a large number of more than 180 analytes was targeted in settled dust and surface swab samples using liquid chromatography/mass spectrometry (LC/MS) based methodology. While 42%, 58% and 44% of all samples collected in Spanish, Dutch and Finnish schools, respectively, were positive for at least one of the metabolites analyzed, frequency of detection for the individual microbial secondary metabolites - with the exceptions of emodin, certain enniatins and physcion - was low, typically in the range of and below 10% of positive samples. In total, 30 different fungal and bacterial secondary metabolites were found in the samples. Some differences in the metabolite profiles were observed between countries and between index and reference school buildings. A major finding in this study was that settled dust derived from moisture damaged, damp schools contained larger numbers of microbial secondary metabolites at higher levels compared to respective dust samples from schools not affected by moisture damage and dampness. This observation was true for schools in each of the three countries, but became statistically significant only when combining schools from all countries and thus increasing the sample number in the statistical analyses. 相似文献
496.
497.
498.
P.S. Monks C. Granier S. Fuzzi A. Stohl M.L. Williams H. Akimoto M. Amann A. Baklanov U. Baltensperger I. Bey N. Blake R.S. Blake K. Carslaw O.R. Cooper F. Dentener D. Fowler E. Fragkou G.J. Frost S. Generoso P. Ginoux R. von Glasow 《Atmospheric environment (Oxford, England : 1994)》2009,43(33):5268-5350
Air quality transcends all scales with in the atmosphere from the local to the global with handovers and feedbacks at each scale interaction. Air quality has manifold effects on health, ecosystems, heritage and climate. In this review the state of scientific understanding in relation to global and regional air quality is outlined. The review discusses air quality, in terms of emissions, processing and transport of trace gases and aerosols. New insights into the characterization of both natural and anthropogenic emissions are reviewed looking at both natural (e.g. dust and lightning) as well as plant emissions. Trends in anthropogenic emissions both by region and globally are discussed as well as biomass burning emissions. In terms of chemical processing the major air quality elements of ozone, non-methane hydrocarbons, nitrogen oxides and aerosols are covered. A number of topics are presented as a way of integrating the process view into the atmospheric context; these include the atmospheric oxidation efficiency, halogen and HOx chemistry, nighttime chemistry, tropical chemistry, heat waves, megacities, biomass burning and the regional hot spot of the Mediterranean. New findings with respect to the transport of pollutants across the scales are discussed, in particular the move to quantify the impact of long-range transport on regional air quality. Gaps and research questions that remain intractable are identified. The review concludes with a focus of research and policy questions for the coming decade. In particular, the policy challenges for concerted air quality and climate change policy (co-benefit) are discussed. 相似文献
499.
Dietmar Reinert Oliver Schwaneberg Norbert Jung Sven Ullmann Wilfried Olbert Dieter Kamin Rudolf Kohler 《Safety Science》2009,47(8):1175-1184
Several hundred accidents involving the use of circular saws and resulting in injury, to hands or fingers occur each year in Germany.In the presented project, new approaches for the prevention of hand injuries and for the contactless detection of fingers are being investigated for comprehensive protection on circular saws. The basic principles can be applied to other machines with manual loading and/or unloading. This paper describes several principles to distinct human skin and wood and a safety guard that prevents touching the rotating blade. In a first approach a reliable protective device with functional diversity has been developed using a passive infrared sensor in combination with a capacitive field sensor. Second the distinction between skin and wood or other material is done by dedicated kind of spectral analysis in the near infrared region. With a kind of light curtain the intrusion into the dangerous zone near the blade can be prevented.The safety guard protects the operator’s hand within 50 ms. The forces of the protective system peak at no more than 120 N. We are presenting a complete strategy for such different tasks as cutting wedges, stopped cutting and hidden cutting, which have a very high odds ratio. 相似文献
500.
Metabolism of acetaminophen (paracetamol) in plants—two independent pathways result in the formation of a glutathione and a glucose conjugate 总被引:1,自引:0,他引:1
Christian Huber Bernadett Bartha Rudolf Harpaintner Peter Schröder 《Environmental science and pollution research international》2009,16(2):206-213
Background, aim, and scope Pharmaceuticals and their metabolites are detected in the aquatic environment and our drinking water supplies. The need for
high quality drinking water is one of the most challenging problems of our times, but still only little knowledge exists on
the impact of these compounds on ecosystems, animals, and man. Biological waste water treatment in constructed wetlands is
an effective and low-cost alternative, especially for the treatment of non-industrial, municipal waste water. In this situation,
plants get in contact with pharmaceutical compounds and have to tackle their detoxification. The mechanisms for the detoxification
of xenobiotics in plants are closely related to the mammalian system. An activation reaction (phase I) is followed by a conjugation
(phase II) with hydrophilic molecules like glutathione or glucose. Phase III reactions can be summarized as storage, degradation,
and transport of the xenobiotic conjugate. Until now, there is no information available on the fate of pharmaceuticals in
plants. In this study, we want to investigate the fate and metabolism of N-acetyl-4-aminophenol (paracetamol) in plant tissues using the cell culture of Armoracia rusticana L. as a model system.
Materials and methods A hairy root culture of A. rusticana was treated with acetaminophen in a liquid culture. The formation and identification of metabolites over time were analyzed
using HPLC-DAD and LC–MSn techniques.
Results With LC–MS technique, we were able to detect paracetamol and identify three of its metabolites in root cells of A. rusticana. Six hours after incubation with 1 mM of acetaminophen, the distribution of acetaminophen and related metabolites in the
cells resulted in 18% paracetamol, 64% paracetamol–glucoside, 17% paracetamol glutathione, and 1% of the corresponding cysteine
conjugate.
Discussion The formation of two independently formed metabolites in plant root cells again revealed strong similarities between plant
and mammalian detoxification systems. The detoxification mechanism of glucuronization in mammals is mirrored by glucosidation
of xenobiotics in plants. Furthermore, in both systems, a glutathione conjugate is formed. Due to the existence of P450 enzymes
in plants, the formation of the highly reactive NAPQI intermediate is possible.
Conclusions In this study, we introduce the hairy root cell culture of A. rusticana L. as a suitable model system to study the fate of acetaminophen in plant tissues. Our first results point to the direction
of plants being able to take up and detoxify the model substrate paracetamol. These first findings underline the great potential
of using plants for waste water treatments in constructed wetlands.
Recommendations and perspectives This very first study on the detoxification of a widely used antipyretic agent in plant tissues again shows the flexibility
of plant detoxification systems and their potential in waste water treatment facilities. This study covers only the very first
steps of acetaminophen detoxification in plants; still, there is no data on long-term exposure as well as the possible impact
of pharmaceuticals on the plant health and stress defense. Long-term experiments need to be performed to follow the fate of
acetaminophen in root and leaf cells in a whole plant system, and to evaluate possible usage of plants for the remediation
of acetaminophen from waste water. 相似文献