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411.
412.
The transfer 137Cs, 238Pu, 239/240Pu and 241Am to sheep which graze a saltmarsh in the Esk estuary, 7 km south of the sellafield reprocessing plant in west Cumbria (UK), has been estimated.The concentrations of gamma-emitting radionuclides and of 238Pu, 239/240Pu and 241Am were measured in liver, lung, muscle, kidney and bone from saltmarsh ewes and lambs. 137Cs concentrations in the soft tissues were similar in liver, lung and muscle but were consistently higher in kidney and much lower in bone. The highest concentration of the transuranics was found in liver.Transfer coefficients and concentration factors were calculated for both ewes and lambs. The concentration of 137Cs in the tissues of 5-month old lambs was higher than in those of their mothers. Therefore, a higher transfer coefficient was obtained for lamb muscle (1·8 × 10?1 d kg?1) than for ewe muscle (6·4 × 10?2 d kg?1). Concentration factors were consistently higher for 137Cs than for the transuranics. 相似文献
413.
Ronald E. Hoeppel Howard E. Westerdahl 《Journal of the American Water Resources Association》1983,19(2):197-204
ABSTRACT: Four 10-ha plots in dense watermilfoil beds of Lake Seminole, Georgia, were each treated with either 2,4-D DMA or 2,4-D BEE at rates of 22.5 and 45 kg a.e./ha. Both formulations were shown to be rapidly converted to the 2,4-D acid form, with no detection of 2,4-D DMA or 2,4-D BEE in the water within less than 24 hours after treatment. The maximum detected 2,4-D concentrations in the high rate 2,4-D DMA and 2,4-D BEE plots were 3.6 and 0.68 mg/, respectively. However, all but seven samples at a 2,4-D BEE plot showed nondetectable herbicide levels by day 7, with all water samples showing nondetectable levels by day 13. Dimethylnitrosamine and 2,4-dichlorophenol, potentially toxic transformation products of the herbicide formulations, were at nondetectable levels in all water samples. Sediment samples showed no significant net accumulation of 2,4-D, 2,4-D BEE, or 2,4-dichlorophenol during the summer monitoring; dimethylnitrosamine remained at nondetectable levels. There was no accumulation of 2,4-D in fish collected from the two plots treated with 2,4-D DMA. Four of 24 game fish from the 2,4-D BEE treatment plots contained low levels of 2,4-D in muscle tissue, with a maximum value of 0.29 μg/g. In contrast, 18 of 20 gizzard shad collected from these plots through day 13 contained detectable 2,4-D in the muscle, with a maximum concentration of 6.9 μg/g. All fish collected after day 13 contained nondetectable levels of 2,4-D. Small decreases in dissolved oxygen and pH, associated with the complete watermilfoil control in all plots, had returned to normal summer values by day 28. 相似文献
414.
415.
Mating behaviors of ants fall into two categories: female calling, in which a female alate releases pheromones that attract
males, and male swarming, in which large male aggregations attract females. Female calling is common in species with queens
that return to their natal nest to found colonies dependently after mating, while male swarming is common in species with
queens that disperse to found independently. In some species that display both founding strategies, a queen-size polymorphism
has evolved in which dependent-founding queens are smaller than independent-founding queens. Dependent founding is likely
difficult if gynes (virgin queens) are mating in distant swarms. Therefore, a queen may adopt one or the other mating strategy
based on its size and founding behavior. We investigated mating behaviors in the queen-polymorphic ant, Temnothorax longispinosus. Observations in laboratory mating arenas indicated that small gynes exhibited significantly lower flight activity than large
gynes. Both forms mated in male swarms, and neither form exhibited female calling. The reduced flight activity of the small
morph may facilitate returning to the natal nest after mating, provided the mating swarm is located nearby. Therefore, alternative
colony-founding behaviors may be possible without the evolution of female-calling behavior; however, the reduced flight activity
of small morphs may require that mating swarms are not distant from the natal nest. 相似文献
416.
Review of Russian language studies on radionuclide behaviour in agricultural animals: part 1. Gut absorption 总被引:2,自引:2,他引:0
Fesenko S Isamov N Howard BJ Voigt G Beresford NA Sanzharova N 《Journal of environmental radioactivity》2007,98(1-2):85-103
An extensive programme of experiments was conducted in the former USSR on transfer of radionuclides to a wide range of different agricultural animals. Only a few of these studies were made available in the English language literature or taken into account in international reviews of gastrointestinal uptake. The paper gives extended information on Russian research on radionuclide absorption in the gut of farm animals performed in controlled field and laboratory experiments from the 1960s to the current time. The data presented in the paper, together with English language values, will be used to provide recommended values of absorption specifically for farm animals within the revision of the IAEA Handbook of Parameter Values IAEA [International Atomic Energy Agency, 1994. Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Temperate Environments, IAEA technical reports series No. 364. International Atomic Energy Agency, Vienna]. 相似文献