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41.
Journal of Material Cycles and Waste Management - This paper describes the effect of torrefaction on the characteristics of empty fruit bunches (EFB) and palm kernel shell (PKS). The torrefaction...  相似文献   
42.
A new challenge—development of test systems for the infochemical effect   总被引:1,自引:1,他引:0  

Background, aim, and scope

Many—if not all—organisms depend on so-called infochemicals, chemical substances in their surroundings which inform the receivers about their biotic and abiotic environment and which allow them to react adequately to these signals. Anthropogenic substances can interfere with this complex chemical communication system. This finding is called infochemical effect. So far, it is not known to what extent anthropogenic discharges act as infochemicals and influence life and reproduction of organisms in the environment because adequate testing methods to identify chemicals which show the infochemical effect and to quantify their effects have not been developed yet. The purpose of this article is to help and find suitable test designs.

Main features

Test systems used in basic research to elucidate the olfactory cascade and the communication of environmental organisms by infochemicals are plentiful. Some of them might be the basis for a quantified ecotoxicological analysis of the infochemical effect. In principle, test systems for the infochemical effect could be developed at each step of the chemosensory signal transduction and processing cascade.

Results

Experimental set-ups were compiled systematically under the aspect whether they might be usable for testing the infochemical effect of single chemicals in standardized quantifying laboratory experiments. For an appropriate ecotoxicological assessment of the infochemical effect, experimental studies of many disciplines, such as molecular biology, neurobiology, physiology, chemical ecology, and population dynamics, should be evaluated in detail before a decision can be made which test system, respectively which test battery, might be suited best. The test systems presented here are based on the knowledge of the genetic sequences for olfactory receptors, binding studies of odorants, signal transmission, and reactions of the receivers on the level of the organisms or the populations. The following basic approaches are conceivable to identify the role of an infochemical: binding studies to the odorant-binding protein or to the odorant receptor binding protein (e.g., by in situ hybridization and immunohistochemical studies), measurement of electrical signals of the receptor cells in the tissue (e.g., electroolfactograms, electroantennograms), registration of phenotypic changes (e.g., observation under the microscope), behavioral tests (e.g., in situ online biomonitoring, use of T-shaped olfactometers, tests of avoidance responses), measurement of population changes (e.g., cell density or turbidity measurements), and multispecies tests with observation of community structure and community function. The main focus of this study is on aquatic organisms.

Discussion

It is evident that the infochemical effect is a very complex sublethal endpoint, and it needs further studies with standardized quantitative methods to elucidate whether and to what extent the ecosystem is affected. The collection of approaches presented here is far from being complete but should serve as a point of depart for further experimental research.

Conclusions

This article is the first to compare various approaches for testing the infochemical effect. The development of a suitable test system will not be easy as there are a multitude of relevant chemicals, a multitude of relevant receptors, and a multitude of relevant reactions, and it must be expected that the effective concentrations are very low. The chemical communication is of utmost importance for the ecosystem and justifies great endeavors to find solutions to these technical problems.

Recommendations and perspectives

The infochemical effect is a new chapter in ecotoxicology. Will a new endpoint, the so-called infochemical effect, be required in addition to the actual standard test battery of Annex 5 to Commission Directive 92/69/EEC (EC 1992)? Finding the answer to this question is a big challenge that could be met by a comprehensive research project.  相似文献   
43.
Cumulative human impacts across the world's oceans are considerable. We therefore examined a single model taxonomic group, the penguins (Spheniscidae), to explore how marine species and communities might be at risk of decline or extinction in the southern hemisphere. We sought to determine the most important threats to penguins and to suggest means to mitigate these threats. Our review has relevance to other taxonomic groups in the southern hemisphere and in northern latitudes, where human impacts are greater. Our review was based on an expert assessment and literature review of all 18 penguin species; 49 scientists contributed to the process. For each penguin species, we considered their range and distribution, population trends, and main anthropogenic threats over the past approximately 250 years. These threats were harvesting adults for oil, skin, and feathers and as bait for crab and rock lobster fisheries; harvesting of eggs; terrestrial habitat degradation; marine pollution; fisheries bycatch and resource competition; environmental variability and climate change; and toxic algal poisoning and disease. Habitat loss, pollution, and fishing, all factors humans can readily mitigate, remain the primary threats for penguin species. Their future resilience to further climate change impacts will almost certainly depend on addressing current threats to existing habitat degradation on land and at sea. We suggest protection of breeding habitat, linked to the designation of appropriately scaled marine reserves, including in the High Seas, will be critical for the future conservation of penguins. However, large‐scale conservation zones are not always practical or politically feasible and other ecosystem‐based management methods that include spatial zoning, bycatch mitigation, and robust harvest control must be developed to maintain marine biodiversity and ensure that ecosystem functioning is maintained across a variety of scales. Contaminación, Pérdida de Hábitat, Pesca y Cambio Climático como Amenazas Críticas para los Pingüinos  相似文献   
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The purpose of the present statistical analysis was the assessment of the relation between time series of environmental factors and of frequencies of diseases of the respiratory system in pre-school children. During about one year, daily measurements of air pollutants and climatic variables were taken. During the same period of time two series of medical data were collected: (i) The daily relative number of pre-school children, exhibiting diseases of the respiratory tracts who either came to the outpatients' clinic of the children's hospital or were reported by paediatricians in Basle (ENTRIES). (ii) The daily relative frequency of symptoms of the respiratory tracts observed in a group of randomly selected pre-school children (SYMPTOMS).By means of transfer function models the relation between the two target variables and the explaining variables was analysed. Several practical problems did arise: Choice of the appropriate transformation of the different series, interpretation of the crosscorrelation function using different methods of prewhitening, time splitting and nonstationarity of the crosscorrelation structure. In particular, it was found that after prewhitening the crosscorrelation function between the explanatory series SO2 and the response series SYMPTOMS changes with time. While during the winter period an instantaneous relation between these two series (and to a lesser extent between NO2 and SYMPTOMS) was identified, no such relation was found for the other seasons.  相似文献   
48.
Stable carbon and nitrogen isotopes (delta13C and delta15N) and trace metals (Cd, Zn, Cu, Fe, Se, and Hg) were analysed in the tissues of 46 harbour porpoises (Phocoena phocoena relicta) caught in fishing nets along the Ukrainian coasts between 1997 and 1998. Mean delta13C values differed significantly between male and female harbour porpoises suggesting a trophic segregation between sexes with a more coastal distribution for females at least during their gestation and nursing periods. Hepatic Hg was correlated to delta13C measurements, reflecting a different exposure linked to coastal vs offshore feeding habitats. A geographical comparison with existing data from other regions showed general low levels of Hg, Cd, Cu and Zn in the tissues of harbour porpoises from the Black Sea compared to other Atlantic and North Sea areas.  相似文献   
49.
Swine excreta were dried by boiling via immersion in hot oil. In this method, moisture in the excreta is replaced with oil or evaporated by turbulent heat transfer in high-temperature oil. The dried excreta can be used in an incinerator like low-rank coal or solid fuel. Refined waste oil and B–C heavy oil were used for drying. Drying for 8 min at 150 °C reduced the water content of raw excreta from 78.90 wt.% to 1.56 wt.% (refined waste oil) or 1.62 wt.% (B–C heavy oil) and that of digested excreta from 79.58 wt.% to 3.40 wt.% (refined waste oil) or 3.48 wt.% (B–C heavy oil). The low heating values of the raw and digested excreta were 422 kJ/kg and ?2,713 kJ/kg, respectively, before drying and 27,842–28,169 kJ/kg and 14,394–14,905 kJ/kg, respectively, after drying. A heavy metal analysis did not detect Hg, Pb, Cd, As, and Cr in the dried excreta, but Al, Cu, and Zn, which occur in the feed formula, were detected. Thermogravimetric analysis before and after drying revealed that emission of volatiles and combustion of volatiles and fixed carbon occurred at temperatures of 250–500 °C when air was used as the transfer gas.  相似文献   
50.
In-air hearing in birds has been thoroughly investigated. Sound provides birds with auditory information for species and individual recognition from their complex vocalizations, as well as cues while foraging and for avoiding predators. Some 10% of existing species of birds obtain their food under the water surface. Whether some of these birds make use of acoustic cues while underwater is unknown. An interesting species in this respect is the great cormorant (Phalacrocorax carbo), being one of the most effective marine predators and relying on the aquatic environment for food year round. Here, its underwater hearing abilities were investigated using psychophysics, where the bird learned to detect the presence or absence of a tone while submerged. The greatest sensitivity was found at 2 kHz, with an underwater hearing threshold of 71 dB re 1 μPa rms. The great cormorant is better at hearing underwater than expected, and the hearing thresholds are comparable to seals and toothed whales in the frequency band 1–4 kHz. This opens up the possibility of cormorants and other aquatic birds having special adaptations for underwater hearing and making use of underwater acoustic cues from, e.g., conspecifics, their surroundings, as well as prey and predators.  相似文献   
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