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131.
Bacon JR Farmer JG Dunn SM Graham MC Vinogradoff SI 《Environmental pollution (Barking, Essex : 1987)》2006,141(3):469-481
Sequential extraction (modified BCR procedure) combined with isotope analysis has been investigated as a tool for assessing mobilisation of lead into streams at an upland catchment in NE Scotland. The maximum lead concentrations (up to 110 mg kg(-1) in air-dried soil) occurred not at the surface but at about 10 cm depth. The lowest (206)Pb/(207)Pb ratios in any profile occurred, with one exception, at 2.5-5 cm depth. In the one exception, closest to the only road in the area, significantly lower (206)Pb/(207)Pb ratios in the surface soil together with much increased chloride concentrations (in comparison to other surface waters) indicated the possible mobilisation of roadside lead and transfer to the stream. The (206)Pb/(207)Pb ratios in extractable fractions tended at depth towards the ratio measured in the residual phase but the ratios in the oxidizable fraction increased to a value higher than that of the residual phase. 相似文献
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Nick J. Royle Margaret E. Hall Jonathan D. Blount Scott Forbes 《Behavioral ecology and sociobiology》2011,65(2):313-323
Despite their importance to offspring fitness outcomes, there has been little previous work on egg-mediated maternal effects
in avian brood parasites which lay their eggs in the nests of other species. Here, we examine patterns of egg yolk antioxidant
deposition in an avian host (red-winged blackbird, Agelaius phoeniceus) and their brood parasite (brown-headed cowbird, Molothrus ater). Cowbird nestlings compete directly for food with host blackbird chicks and succeed, despite hatching from a smaller egg,
by begging more intensely and growing as or more rapidly than their hosts. Dietary-derived antioxidants, such as carotenoids
and vitamins E and A, deposited in egg yolk, may enhance growth rate and reduce oxidative stress, and therefore provide a
potential mechanism by which female cowbirds could enhance the competitiveness of their young in host nests. However, provision
of antioxidants to eggs is costly so we predicted that female cowbirds should adjust the amount of antioxidants in response
to variation in host quality. We found that whilst red-winged blackbird clutches parasitised by cowbirds did not differ in
the pattern of antioxidant deposition compared to non-parasitised clutches, levels of vitamin E deposited in cowbird eggs
were closely matched to that of the individual host clutch in which cowbirds laid their egg. This supports the prediction
that female cowbirds adjust the antioxidant concentration of their eggs to increase the likely competitiveness of their offspring
in the host nest into which they are laid and may help explain the success of cowbirds in competing with larger host young. 相似文献
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Troy Goodnough Arne Kildegaard Margaret Kuchenreuther Lowell Rasmussen Pete Wyckoff 《Journal of Cleaner Production》2009,17(12):1138-1142
This article presents an overview of the sustainability initiative at the University of Minnesota, Morris, key components of which include a realistic goal of energy self-sufficiency by 2010, a new environmental studies curriculum, and various research and outreach projects. Many non-obvious institutional assets – such as lobbying networks in the state legislature, and geographic/demographic features that are more commonly thought of as liabilities – turned out to play critical roles in setting the initiative in motion. The initial physical assets have been leveraged into complementary opportunities for research, teaching, and institutional development in this direction. 相似文献
137.
Host-plant-mediated competition via induced resistance: interactions between pest herbivores on potatoes. 总被引:1,自引:0,他引:1
Margaret E Lynch Ian Kaplan Galen P Dively Robert F Denno 《Ecological applications》2006,16(3):855-864
Plant-mediated competition among insect herbivores occurs when one species induces changes in plant chemistry, nutrition, or morphology that render plants resistant to attack by others. We explored plant-mediated interspecific interactions between the potato leafhopper (Empoasca fabae) and the Colorado potato beetle (Leptinotarsa decemlineata), two important pests on potatoes. Leafhoppers colonize fields in advance of beetles, and thus the possibility exists that previous feeding by leafhoppers induces changes in potato plants that have adverse consequences for beetles. The consequences of leafhopper-induced resistance for beetle performance were studied in the greenhouse, field cages, and in large open-field plots. Potato plants were exposed to four densities of leafhoppers (none, low, moderate, and high), and visible feeding symptoms were measured as percentage leaf curling, chlorosis, and necrosis. The oviposition preference, performance, and survivorship of Colorado potato beetles were then measured on the four categories of induced plants in field-cage and greenhouse settings. In open field plots, survival on the four categories of induced plants was determined by placing cohorts of beetle adults onto plants and measuring the densities of resulting eggs, larvae, and emerging Fl adults. Leafhopper-induced symptoms on potato plants were density dependent, with the percentage of curled, chlorotic, and necrotic leaves increasing with leafhopper density. Previous feeding by leafhoppers adversely affected oviposition and larval performance of beetles. Fewer egg masses were deposited on plants that incurred high levels of leafhopper feeding. Similarly, larval development was delayed and emerging adult beetles weighed less when fed induced foliage from the high leafhopper-density treatment. Beetles survived less well in the field on plants experiencing moderate and high levels of leafhopper feeding as evidenced by lower densities of eggs, larvae, and emerging F1 adults. Overall, leafhoppers and beetles competed through feeding-induced changes in plant quality. Notably, the asymmetric interaction took place at a large spatial scale in open field plots and had negative consequences that persisted to the next beetle generation. Ultimately, to establish an effective management strategy for crop pests such as leafhoppers, it is essential to consider the positive indirect effects of induced resistance along with the negative direct effects on crop yield. 相似文献
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Theresa M. Marteau Irma Nippert Sue Hall Caroline Limbert Margaret Reid Martin Bobrow Alan Cameron Martina Cornel Mariet van Diem Bernd Eiben Sixto García-Miñaur Janine Goujard Donna Kirwan Karen McIntosh Peter Soothill Corien Verschuuren-Bemelmans Catherine de Vigan Stephen Walkinshaw Lenore Abramsky Frank Louwen Peter Miny Jürgen Horst 《黑龙江环境通报》2002,22(7):562-566
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