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131.
132.
Summary. Research on insect migration has justifiably emphasized females – the so-called “oogenesis-flight syndrome”– since it is
the females that place the eggs into new habitats. The large and small milkweed bugs, Oncopeltus fasciatus and Lygaeus kalmii, respectively, have featured prominently in studies of insect migration and sequestration of host plant toxins for chemical
defense. Here we report that males of these species, and males of another well-studied lygaeine (Neacoryphus bicrucis), produce pheromones in glands usually considered to serve only a defensive role in Heteroptera (the metathoracic scent glands),
and that these pheromones are exploited by a tachinid parasitoid as a host-finding kairomone. The pheromones are mixtures
of C6 and C8 saturated and unsaturated esters reminiscent of lepidopteran pheromones, and the key compound of the O. fasciatus pheromone has now been correctly identified as (E)-2,7-octadienyl acetate. It is proposed that the concept of the oogenesis-flight syndrome for these kinds of insects should
accommodate the role of males in the migration process. The hypothesis is presented that male-produced pheromones play a significant
role in guiding colonization of new habitats in many heteropteran species. In addition, data are presented suggesting that
there is a trade-off between the amount of pheromone produced by colonizing males and the host breadth of the species.
Received 21 December 1998; accepted 15 February 1999. 相似文献
133.
134.
Oliver Bomsel 《Natural resources forum》1989,13(4):285-293
Since the 1960s the Kédia mines have been the main source of iron ore for Mauritania. In the 1970s SN1M, the Mauritanian state enterprise responsible for the mining of the country's iron ore, concerned about the eventual depletion of its reserves at Kédia, and at the urging of its European customers, undertook to develop new iron-ore deposits at the Guelbs. The deposits at the Guelbs, however, were low-grade magnetite ore as opposed to the high-grade hematite ore at Kedia, and were much more costly to mine and process. The cost of the Guelbs project and its failure to meet production targets have strained the resources of SNIM to a financial and technical breaking point. The paper suggests that one solution to SNIM's difficulty may be to mothball the Guelbs project and to develop instead other deposits in the vicinity of the Guelbs. 相似文献
135.
Barry G. Oliver 《Chemosphere》1985,14(8):1087-1106
The desorption of 20 chlorinated organics from sediments has been studied using a nitrogen purge/Tenax trap system for separating the “dissolved” and “sorbed” fractions in sediment/water slurries. The desorption partition coefficient, KD, was found to decrease with increasing temperature and suspended sediment concentration. While some differences in KD and desorption rates were observed for the study chemicals, considering their wide range of physical/chemical properties such as KOW, these changes were small. Desorption half-lives averaged about 60d at 4°C, 40d at 20°C and 10d at 40°C under continuous gaseous purging. Estimates of the loadings of chemicals via desorption from bottom sediments in Lake Ontario are compared to loadings of these chemicals to the lake from the Niagara River. 相似文献
136.
Derek M. Oliver 《The Environmentalist》1985,5(3):171-178
Summary The private enterprise development of a series of disused gravel pits, situated just 20 miles from the centre of London, into an attractive and commercially viable theme park for leisure and recreation is described.
相似文献
137.
Wei Shiqiang College of Environment Resources Southwest Agricultural University Chongqing China Oliver Lindqvist Jonas Sommar Department of Inorganic Chemistry Chalmers University of Technology University of Gteborg Sweden 《环境科学学报(英文版)》1997,(2)
ApplicationofKCldenuderformeasuringgasphasemercuricspecies(Hg2+)inatmosphereWeiShiqiangColegeofEnvironmentandResources,Sout... 相似文献
138.
The stability of historically polycyclic aromatic hydrocarbon (PAH)-contaminated soils during cold storage was investigated. Samples from two former manufactured gas plants exhibited quantitative recoveries of PAHs over the whole period of sample holding at 4 °C in the dark (8–10 months), whereas significant losses of PAHs were observed for soils received from a former railroad sleeper preservation plant with low molecular weight compounds being notably more affected compared to heavier PAHs. Already after 2 weeks of holding time, 3-ring PAHs in one of theses samples were down to 29–73% of the initial concentration and significant losses were observed for up to 5-ring compounds. Dissipation of PAHs was found to be predominantly due to aerobic microbial metabolism since sodium azide poisoned samples showed quantitative recoveries for all PAHs over the entire storage time of 3 months. A similar stabilizing effect was observed for freezing at −20 °C as means of preservation. Except for acenaphthene, no significant loss for any of the PAHs was observed over 6 weeks of holding time. Eventually, selected chemical, physical, and biological parameters of two soils were investigated and identified as potential indicators for the stability of PAH-contaminated soil samples. 相似文献
139.
Oliver Drzyzga 《Umweltwissenschaften und Schadstoff-Forschung》1999,11(6):365-373
Zusammenfassung Diphenylamin (DPA), das einfachste, rein aromatische sekund?re Amin, ist ein Stoff der dritten Altstoffpriorit?tenliste priorit?tenliste
der Europ?ischen Union (EU). Es wurde der Bundesrepublik Deutschland zugewiesen, die von diesem Stoff ausgehenden Umweltrisiken
zu erfassen und zu bewerten. DPA wird als Stabilisator in Nitrocellulose-haltigen Explosivstoffen und Treibladungspulvern
eingeserzt, au?erdem als Stabilisator in der Parfümerie und als Antioxidationsmittel in der Gummi- und Elastomer-Industrie.
DPA wird auch vielfach genutzt, um ?pfel und Birnen nach der Ernte vor vorzeitigem Altern bzw. Verfall zu bewahren. Ferner
ist es Ausgangsverbindung zahlreicher Derivate, welche u.a. in der Produktion von Farben, Pharmazeutika und Fotografiechemikalien
Anwendung finden. Anfang der 80er Jahre wurden weltweit sch?tzungsweise ca. 40.000 t DPA pro Jahr produziert (in Deutschland
ca. 10% davon). Die Chemikalie wird noch heute weltweit von der chemischen Industrie hergestellt. Neuere Publikationen zeigen,
da? DPA bereits im Boden und im Grundwasser (in ppb- bis ppm-Konzentrationen) nachgewiesen werden konnte. Einige ?kotoxikologische
Ver?ffentlichungen demonstrierten die Gef?hrlichkeit verschiedener DPA-Derivate gegenüber der aquatischen Umwelt und auch
gegenüber Bakterien und Tieren. Studien bezüglich der biologischen Abbaubarkeit von DPA und Derivaten sind sehr sp?rlich vorhanden.
Aus diesem Grund sind weiterführende Forschungsarbeiten notwendig, um das volle Ausma\ der Umweltgef?hrdung für mit DPA und
DPA-Derivaten kontaminierte Bereiche zu bestimmen, und um entsprechende (biologische) Sanierungsverfahren einzuleiten. Dieser
übersichtsbeitrag fa\t die zug?ngliche Literatur zusammen, welche die Umweltrelevanz von DPA aufzeigt. Er kann m?glicherweise
die deutschen Beh?rden bzw. Gutachter bei der Bewertung von Risiken dieses Altstoffes der EU-Priorit?tenliste unterstützen.
相似文献
140.
Species Lists in Ecology and Conservation: Abundances Matter 总被引:2,自引:0,他引:2
Oliver Balmer 《Conservation biology》2002,16(4):1160-1161