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501.
Effects of trifluralin on soil microbial populations and the nitrogen fixation activities 总被引:6,自引:0,他引:6
Hang M Zhongyun C Yuhua Z Meichi C 《Journal of environmental science and health. Part. B》2001,36(5):569-579
Effects of trifluralin on soil microbial populations and the nitrogen fixation activity of nitrogen-fixing bacteria Azotobacter chroococcum and Bradyrhizobium japonicum and the decomposition of trifluralin by soil microorganisms were studied. Trifluralin at lower concentrations from 0.5 mg microg(-1) dry soil to lower than 10.0 mg microg(-1) dry soil appeared to stimulate the growth of soil bacteria, actinomycetes, mould, and the pure cultures of Br. japonicum and A. chroococcum. Not only the colony amounts of these two species of nitrogen-fixing bacteria increased, grown on agar medium containing lower concentrations of trifluralin, but also these colonies also enlarged in size and appeared obviously in shorter formation time. However, trifluralin at higher concentrations would inhibit the development of microbial colonies both in amount and size. Trifluralin inhibited the activity of acetylene reduction of A. chroococcum when it was added at the same time of inoculation with A. chroococcum, but it showed a noteworthy stimulation to nitrogen fixation of A.chroococcum when it was put into culture after the cells of the nitrogen-fixing bacterium had grown well. The observation that soil microorganisms could use trifluralin as sole carbon and nitrogen resources for their growth, indicated that microorganisms could decompose trifluralin well. 相似文献
502.
One of the roles of the BIOMASS Theme 3 Fruit Working Group was to identify significant radionuclides to support its work programme. This paper provides a short review of radionuclide emissions to atmosphere together with comments on their relative dosimetric impacts to identify those radionuclides most relevant to the Fruit Working Group. Speciation of the identified radionuclides is also discussed to identify the most likely chemical forms to which fruits might be exposed. It is noted that no information currently exists on radionuclide speciation in regard to the uptake and retention of radionuclides in fruit crops. 相似文献
503.
An encapsulation system designed to give long-lasting effectiveness of the insect growth regulator (IGR) cyromazine (Neporex) against Culex pipiens (Culicidae) mosquito larvae was developed. The main thrust of the research was to develop a simple method for preparing controlled-release formulations by means of an extrusion technique in combination with a supplementary coating and to study the release characteristics and effectiveness of the formulations. A series of formulations were prepared with low-density polyethylene (LDPE 600) for the matrix and with polyurea or one of four types of polyurethane for the coating. The rate of release of the active material from the controlled-release formulations was determined in an in vitro dissolution system. The biological activity of the controlled-release formulations was tested in vivo against C. pipiens larvae. 相似文献
504.
Z Samaras T Zachariadis R Joumard D Hassel F J Weber R Rijkeboer 《Journal of the Air & Waste Management Association (1995)》2001,51(6):913-938
This paper provides an overview and the main results of a study aiming to evaluate current and alternative inspection and maintenance (I/M) programs to control emissions from in-use cars in Europe. For this purpose, a large number of passenger cars from five countries (France, Germany, Greece, the Netherlands, and the United Kingdom) were tested according to a common test protocol that included a variety of driving cycles and short tests, both legislative and specifically developed for this exercise. Evaluation of all test results was conducted with the objective of defining effective I/M test procedures and examining the potential of periodic I/M programs to reduce pollutant emissions and improve fuel economy of in-use cars. The results indicate that the current idle test used for catalyst-equipped cars in Europe is probably ineffective, while short transient loaded testing was found to offer higher potential in environmental terms. Regarding conventional gasoline cars, it is concluded that the idle test is sufficient, provided that the CO cut point is reduced and an HC test is added at high idle. Finally, the effectiveness of the free acceleration smoke test for diesels is questioned, while a transient cycle with continuous opacity measurement was found to be very promising. A companion paper further uses these results to analyze the likely cost-effectiveness on a per-country basis and discusses the possible effect of maintenance on emissions. 相似文献
505.
Penguins may exhibit plasticity in their diving and foraging behaviors in response to changes in prey availability. Chinstrap
penguins are dependent predators of Antarctic krill in the Scotia Sea region, but krill populations have fluctuated in recent
years. We examined the diet of chinstrap penguins at Livingston Island, South Shetland Islands, in relation to their diving
and foraging behavior using time-depth recorders over six breeding seasons: 2002–2007. When krill were smaller, more chinstrap
penguins consumed fish. In these years, chinstrap penguins often exhibited a shift to deep dives after sundown, and then resumed
a shallower pattern at sunrise. These night dives were unexpectedly deep (up to 110 m) and mean night dive depths sometimes
exceeded those from the daytime. The average size of krill in each year was negatively correlated to mean night dive depths
and the proportion of foraging trips taken overnight. Based on these patterns, we suggest that when krill were small, penguins
increasingly targeted myctophid fish. The average krill size was negatively correlated to the time chinstrap penguins spent
foraging which suggests that foraging on smaller krill and fish incurred a cost: more time was spent at sea foraging. 相似文献
506.
We used radio telemetry and observations to study the activity patterns and behavior of gentoo penguin chicks at Admiralty
Bay, King George Island, South Shetland Islands in 2005 during their “fledging period”; defined as the time between a chick’s
first trip to sea and its final dispersal from the breeding colony. Gentoo penguins exhibited delayed dispersal of young and
extended parental provisioning, behaviors not observed in other Pygoscelis species. Chicks took their first trip to sea at a mean age of 70 days of age, before finally departing the colony at a mean
age of 82 days. During this fledging period, individual chicks made an average of five trips to sea. Trip duration increased
significantly as chicks aged, with trips to sea becoming similar to literature values of adult foraging trips in both timing
and duration. Behavioral observations and mass dynamics confirmed that many chicks were still being fed during this fledging
period, with parental feeding behaviors most often observed in the late afternoon to evening hours. We hypothesize that these
behaviors provide an opportunity for chicks to gain experience at sea prior to dispersal and might allow them to develop foraging
skills before they are completely independent. 相似文献
507.
Csaba Moskát Jesús M. Avilés Miklós Bán Rita Hargitai Anikó Zölei 《Behavioral ecology and sociobiology》2008,62(12):1885-1890
Common cuckoo (Cuculus canorus) parasitism drastically reduces the reproductive success of their hosts and selects for host discrimination of cuckoo eggs.
In a second stage of anti-parasite adaptation, once cuckoos can lay eggs that mimic those of their hosts, a high uniformity
of host egg appearance within a clutch may favour cuckoo egg discrimination. Comparative evidence provides indirect support
for this hypothesis although experimental support is currently lacking. Here, we studied the effect of experimentally decreased
uniformity of host egg appearance on cuckoo egg discrimination by great reed warbler (Acrocephalus arundinaceus) hosts in a population in which long-term cuckoo parasitism has led to high levels of cuckoo–host egg mimesis. We manipulated
host clutch uniformity by adding extra spots to fresh host eggs just after they were laid. Rejection of non-mimetic experimental
eggs added to these nests was compared with those in control nests in which uniformity was not altered. Previously, by over-painting
real spots in a control group of nests, we showed a negligible effect of our paints on hosts’ perception of their eggs. We
show that for the great reed warbler, non-mimetic experimental eggs were relatively more tolerated in experimental nests,
i.e. with lower uniformity (40%) than in control nests (5%). This is the first experimental study, to our knowledge, which
demonstrates a reduced discrimination of foreign eggs as a consequence of an increase of egg phenotypes variation perception
in a cuckoo host. 相似文献
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