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261.
262.
Pheromones produce dramatic behavioral and physiological responses in a wide variety of species. Releaser pheromones elicit
rapid responses within seconds or minutes, while primer pheromones produce long-term changes which may take days to manifest.
Honeybee queen mandibular pheromone (QMP) elicits multiple distinct behavioral and physiological responses in worker bees,
as both a releaser and primer, and thus produces responses on vastly different time scales. In this study, we demonstrate
that releaser and primer responses to QMP can be uncoupled. First, treatment with the juvenile hormone analog methoprene leaves
a releaser response (attraction to QMP) intact, but modulates QMP’s primer effects on sucrose responsiveness. Secondly, two
components of QMP (9-ODA and 9-HDA) do not elicit a releaser response (attraction) but are as effective as QMP at modulating
a primer response, downregulation of foraging-related brain gene expression. These results suggest that different responses
to a single pheromone may be produced via distinct pathways. 相似文献
263.
Plant-soil microorganism interactions: heritable relationship between plant genotype and associated soil microorganisms 总被引:3,自引:0,他引:3
Schweitzer JA Bailey JK Fischer DG LeRoy CJ Lonsdorf EV Whitham TG Hart SC 《Ecology》2008,89(3):773-781
Although soil microbial communities are known to play crucial roles in the cycling of nutrients in forest ecosystems and can vary by plant species, how microorganisms respond to the subtle gradients of plant genetic variation is just beginning to be appreciated. Using a model Populus system in a common garden with replicated clones of known genotypes, we evaluated microbial biomass and community composition as quantitative traits. Two main patterns emerged. (1) Plant genotype influenced microbial biomass nitrogen in soils under replicated genotypes of Populus angustifolia, F1, and backcross hybrids, but not P. fremontii. Genotype explained up to 78% of the variation in microbial biomass as indicated by broad-sense heritability estimates (i.e., clonal repeatability). A second estimate of microbial biomass (total phospholipid fatty acid) was more conservative and showed significant genotype effects in P. angustifolia and backcross hybrids. (2) Plant genotype significantly influenced microbial community composition, explaining up to 70% of the variation in community composition within P. angustifolia genotypes alone. These findings suggest that variation in above- and belowground traits of individual plant genotypes can alter soil microbial dynamics, and suggests that further investigations of the evolutionary implications of genetic feedbacks are warranted. 相似文献
264.
265.
Helmut W. Fischer Susanne Ulbrich Daniela Pittauerov Bernd Hettwig 《Journal of environmental radioactivity》2009,100(12):1079-1085
Motivated by the detection of 131I in river sediment in routine long-term surveillance samples, a systematic short-term study of the wastewater treatment chain was planned and conducted. Inflow, effluent and primary sludge were collected on a daily basis during two weeks at a regional wastewater treatment plant. Samples were investigated by gamma spectroscopy. Four medically used isotopes could be identified (131I and 99mTc regularly, 153Sm and 123I sporadically). The concentration levels coincide well with literature data for 131I, and with our own long-term data for 131I and 99mTc for the same plant. Cosmogenic 7Be activity in primary sludge correlated well with rainfall intensity. Surface sediment was sampled at low tide at both shores of the river, up- and downstream of the plant. 131I was identified in all samples, with a sharp maximum (about 100 Bq kg−1 d.m.) at the discharge point of the plant and lower levels elsewhere, decreasing monotonically in downstream direction. 7Be and 137Cs showed the same behaviour, but no peak at the discharge point. Predictions from simple equilibrium models for the transport and sedimentation of 131I show good agreement with the experimental data and suggest that the wastewater treatment plant is the main source for this isotope. 相似文献
266.
Schlummer M Mäurer A van Eldik R Quicker P Fischer W Faulstich M 《Environmental science and pollution research international》2007,14(6):414-420
GOAL, SCOPE AND BACKGROUND: Changes in German and European legislation shifted processing of polymer-rich shredding residues (SR) from landfill to thermal treatment. However, when waste of electric and electronic equipment (WEEE) is the source of SR, thermal treatment is complicated by halogens as well as the presence of polybrominated dioxins and furans (PBDD/F) and brominated flame retardants (BFR). Hence, WEEE requires high temperature incineration with sufficient residence times. Post-combustion synthesis of polyhalogenated dioxins and furans (PXDD/F) is dominant in the temperature range between 250-450 degrees C. Thus, a very rapid gas cooling from 450 degrees to 250 degrees C is important for proper raw gas treatment. The pebble heater technology developed by ATZ Entwicklungszentrum (Sulzbach-Rosenberg, Germany) might serve as an alternative to the state-of-the-art quench cooling. It is based on the application of a pebble bed of natural bulk material, which the exhaust gases flows through radially. It provides an excellent heat transfer and a temperature gradient in the range of 1,500-2,000 K/m. The paper presents data of a pilot application of the pebble heater technology for the treatment of raw gas derived from the incineration of polymeric materials from WEEE. METHODS: A liquid fuel was chosen in order to minimise technical modifications of the plant. It was analysed for halogens by x-ray fluorescence, for brominated flame retardants by HPLC-UV/MS and for PXDD/F by GC-HRMS. Combustion gases were rapidly cooled down to temperatures below 200 degrees C and emissions of PBDD/F and PCDD/ F were estimated without further off-gas treatment. PBDD/F emissions were computed as PCDD/F toxicity equivalents applying two different calculation approaches. RESULTS AND DISCUSSION: PCDD/F emissions accounted for 0.04 ng I-TEQ/Nm3 and are in compliance with European emission limits. Calculated PBDD/F toxicity equivalents exceeded the emission limit of 0.1 ng I-TEQ/Nm3 by factors of 75 and 208 depending on the calculation approach. A mass balance of PBDD/F and PCDD/F congeners revealed an efficient elimination of more than 95% in most cases. Lower reduction rates (76% for 2,3,7,8-TeBDF and 82% for 1,2,3,7,8-PeBDF) were attributed to incomplete combustion. An intended recovery of halogens by one-stage scrubbing downstream of the pebble heater was ineffective, recovering 28% of the applied chlorine and 9% of the bromine, only. CONCLUSIONS: Our pilot incineration test indicates that the pebble heater technology can effectively suppress a post-combustion synthesis of PCDD/F and PBDD/F, resulting in low PCDD/F emission levels without further off-gas treatment. The presented data state that WEEE is sensible to incomplete combustion, which will lead to increased PBDD/F emissions without increasing PCDD/F emission limits. This finding is especially relevant for small and low-technical incineration appliances, which have been reported to treat WEEE in developing countries and are considered to serve as a significant source of PXDD/F these days. RECOMMENDATIONS AND PERSPECTIVES: Monitoring of PCDD/F emissions only might considerably underestimate the total emission of dioxins and dioxin-like compounds. It is therefore an ineffective means for assessing resulting health risks, at least for those waste treatment plants which are considered to handle the increasing amounts of PBDD/ F-containing polymers from WEEE in future. Consequently, it is recommended to initiate a screening programme for PXDD/F emissions in large scale incineration facilities which are capable of treating WEEE shredder residues. 相似文献
267.
The current lack of a working resource management plan Magdalena Bay (southern Baja California, Mexico) has weakened attempts
to set priorities among resource users and has contributed to: reduced fish stocks, land and marine contamination, and declines
in the ecological integrity of the bay of 170 000 ha and its vast mangrove lagoon systems. The government agencies responsible
for maintaining ecological integrity and managing marine resource use have not been successful in addressing these problems
due to jurisdictional ambiguities, lack of community support, and lack of manpower for monitoring and enforcing policies.
A framework was designed by the authors to work toward an approach for balancing between community development and conserving
ecological integrity at the local level in the peripheral and central zones of the Magdalena Bay system. The goal of this
framework was to suggest a basis for setting management priorities that included the perceptions and preferences of stakeholder
groups with regard to direct threats to the environmental health of the study areas. To achieve this goal a crossdisciplinary
study of the central and peripheral zones was used to examine factors that influence current resource use and the environmental
state in these two regions of the bay system. Insights into the preferences and perceptions of stakeholder groups with regard
to management priorities were acquired using the key informant technique. The results revealed potential conflicts with regard
to preferred management priorities between stakeholder groups, as well as polarities within stakeholder groups themselves. 相似文献
268.
F. Stuart Chapin III Elke U. Weber Elena M. Bennett Reinette Biggs Jeroen van den Bergh W. Neil Adger Anne-Sophie Crpin Stephen Polasky Carl Folke Marten Scheffer Kathleen Segerson John M. Anderies Scott Barrett Juan-Camilo Cardenas Stephen R. Carpenter Joern Fischer Nils Kautsky Simon A. Levin Jason F. Shogren Brian Walker James Wilen Aart de Zeeuw 《Ambio》2022,51(9):1907
Transformation toward a sustainable future requires an earth stewardship approach to shift society from its current goal of increasing material wealth to a vision of sustaining built, natural, human, and social capital—equitably distributed across society, within and among nations. Widespread concern about earth’s current trajectory and support for actions that would foster more sustainable pathways suggests potential social tipping points in public demand for an earth stewardship vision. Here, we draw on empirical studies and theory to show that movement toward a stewardship vision can be facilitated by changes in either policy incentives or social norms. Our novel contribution is to point out that both norms and incentives must change and can do so interactively. This can be facilitated through leverage points and complementarities across policy areas, based on values, system design, and agency. Potential catalysts include novel democratic institutions and engagement of non-governmental actors, such as businesses, civic leaders, and social movements as agents for redistribution of power. Because no single intervention will transform the world, a key challenge is to align actions to be synergistic, persistent, and scalable. 相似文献
269.
Richard N. Koustas David Fischer 《Journal of the Air & Waste Management Association (1995)》2013,63(5):434-440
ABSTRACT Pesticide contamination results from manufacturing, improper storage, handling, or disposal of pesticides, and from agricultural processes. Since most pesticides are mixtures of different compounds, selecting a remedy for pesticide-contaminated soils can be a complicated process. The various available treatment options for remediation fall into three broad categories: containment-immobilization, separation-concentration, and destruction. This paper categorizes pesticides into waste groups based on available treatment options and provides a review of separation treatment options that have been demonstrated to—or show potential to— treat pesticide-contaminated soil. Technologies include radio frequency heating, soil washing, thermal desorp-tion, and solvent extraction. 相似文献
270.
It is frequently assumed that males have an almost unlimited reproductive capacity, while access to receptive females is typically
limiting. Consequently, sexual selection is expected to favor vigorous courtship behavior in males. If such behavior is associated
with non-trivial costs, ample current mating opportunities should be accompanied by a reduction in future mating vigor. To
test this hypothesis, three treatments differing in sex ratio were established using the tropical butterfly Bicyclus anynana: 50 males each were housed either with 0, 25, or 50 females. Mating trials involving the competition among males from each
treatment for a single virgin female were carried out on days 3, 9, and 15 after allocation to treatments. While there was
no difference on day 3, prior mating opportunity clearly reduced mating success on days 9 and 15, being lowest if identical
numbers of males and females were housed together. This finding suggests accumulating costs associated with high courtship
and/or mating activity. Further, older males were more active and initiated copulation earlier than the younger ones, consistent
with the residual reproductive value hypothesis. We found no evidence for a survival or fertility cost of mating. 相似文献