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61.
Winter losses of nitrogen and phosphorus from Italian ryegrass, meadow fescue and white clover in a northern temperate climate 总被引:1,自引:0,他引:1
Ievina Sturite Trond Maukon Henriksen Tor Arvid Breland 《Agriculture, ecosystems & environment》2007,120(2-4):280-290
We have studied to what degree Italian ryegrass (Lolium multiflorum Lam.), white clover (Trifolium repens L.) and meadow fescue (Festuca pratensis L.) are able to preserve nitrogen (N) and phosphorous (P) in shoots and roots from one growing season to the next in a northern temperate climate. Field experiments were performed during four consecutive winters in central southeast Norway (60°42′N, 10°51′E), and N and P in plant biomass were measured in the autumn and in the spring. We also measured the contents of total N, total P and organic carbon (C) in seepage water that percolated through the aboveground plant material. Uptake of N and P in Italian ryegrass and white clover was substantially larger than in meadow fescue. The winter losses varied greatly from year to year, depending on the winter climate. On the average for all three of the plant species, the winter losses of N from aboveground biomass were 6, 35, 68 and 10% in the four experimental years, respectively. The corresponding P losses were 11, 36, 60 and 22%. On the average for all plant species and experimental years, 43 (±12)% (S.E., n = 12) of the N, 34 (±9)% of the P and 4 (±1)% of the C that was lost from the aboveground plant biomass during the winter, was recovered in seepage water, basically as a nutrient pulse in melt water in early spring. The very low C recovery rate in seepage water suggested a considerable microbial growth on lost plant C. Assuming that all un-recovered plant C was consumed by microorganisms not included in measurements of the seepage water, modelling showed that microbial immobilisation theoretically might explain the unexpectedly low recovery rates of N and P. The study was not designed to investigate the possible effects of psychrophilic microbes on N and P cycling. Therefore, it is inconclusive and underlines the need for more knowledge on this matter. 相似文献
62.
Genetic Origin and Success of Reintroduced White Storks 总被引:1,自引:0,他引:1
OLA OLSSON 《Conservation biology》2007,21(5):1196-1206
63.
Anniina Salmel Eero Kokkonen Ilpo Kulmal Anna-Maria Veijalainen Rob van Houdt Natalie Leys Audrey Berthier Ilyin Viacheslav Sergey Kharin Julia Morozov Alexander Tikhomirov Pertti Pasanen 《环境科学学报(英文版)》2018,30(7):227-238
This study aimed to evaluate the suitability of two bioaerosol generation systems(dry and wet generation) for the aerosolization of microorganisms isolated from the International Space Station, and to calibrate the produced bioaerosols to fulfill the requirements of computational fluid dynamics model(CFD) validation. Concentration, stability, size distribution, agglomeration of generated bioaerosol and deposition of bioaerosols were analyzed. In addition, the dispersion of non-viable particles in the air was studied.Experiments proved that wet generation from microbial suspensions could be used for the production of well-calibrated and stabile bioaerosols for model validation. For the simulation of the natural release of fungal spores, a dry generation method should be used. This study showed that the used CFD model simulated the spread of non-viable particles fairly well. The mathematical deposition model by Lai and Nazaroff could be used to estimate the deposition velocities of bioaerosols on surfaces, although it somewhat underestimated the measured deposition velocities. 相似文献
64.
Ana Martín-González Jacek Wierzchos Juan C. Gutiérrez Jesús Alonso Carmen Ascaso 《Die Naturwissenschaften》2009,96(5):551-564
Microorganisms are the most ancient cells on this planet and they include key phyla for understanding cell evolution and Earth
history, but, unfortunately, their microbial records are scarce. Here, we present a critical review of fossilized prokaryotic
and eukaryotic microorganisms entrapped in Cretaceous ambers (but not exclusively from this geological period) obtained from
deposits worldwide. Microbiota in ambers are rather diverse and include bacteria, fungi, and protists. We comment on the most
important microbial records from the last 25 years, although it is not an exhaustive bibliographic compilation. The most frequently
reported eukaryotic microfossils are shells of amoebae and protists with a cell wall or a complex cortex. Likewise, diverse
dormant stages (palmeloid forms, resting cysts, spores, etc.) are abundant in ambers. Besides, viral and protist pathogens
have been identified inside insects entrapped in amber. The situation regarding filamentous bacteria and fungi is quite confusing
because in some cases, the same record was identified consecutively as a member of these phylogenetically distant groups.
To avoid these identification errors in the future, we propose to apply a more resolute microscopic and analytical method
in amber studies. Also, we discuss the most recent findings about ancient DNA repair and bacterial survival in remote substrates,
which support the real possibility of ancient DNA amplification and bacterial resuscitation from Cretaceous resins. 相似文献
65.
Chen GQ Zou ZJ Zeng GM Yan M Fan JQ Chen AW Yang F Zhang WJ Wang L 《Chemosphere》2011,83(9):1201-1207
A novel coarsening route for extracellularly biosynthesized cadmium nanocrystals was investigated for the first time. In this process, the white rot fungus Coriolus versicolor was employed to take up cadmium ions and synthesize extracellular cadmium crystal particles. The coarsening of the particles was induced by thioacetamide under certain conditions. Scanning electron microscopy showed that the formed cadmium crystal particles were coarsened from about 100 nm to 2-3 μm. The corresponding energy-dispersive X-ray spectra confirmed the presence of proteins in the particles. The maximum removal efficiency of Cd(II) increased from 17% to 87%, and the corresponding sorption capacity of biomass increased from 4 to 24 mg g−1 with the completion of the coarsening process. The properties of the coarsened particles were also examined using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD analysis of fungal mycelial pellets embedded with the coarsened particles confirmed the formation of cubic crystalline cadmium sulfide particles. The TEM results suggest that the coarsened particles were composed of clusters of several smaller particles. The changes in the functional groups on the biomass surface were studied through Fourier transform infrared spectroscopy. Based on the results above, a possible mechanism for the formation and coarsening of cadmium crystal particle is also discussed. 相似文献
66.
林黎宇 《中国环境管理干部学院学报》1999,(2)
本文在综述白色污染形成原因、污染状况的基础上,介绍了我国目前解决白色污染的方法以及国外塑料废弃物的治理现状,同时探讨了白色污染防治中的问题,并提出了解决白色污染的对策。 相似文献
67.
沈阳市大气细菌与真菌粒子的关系 总被引:3,自引:1,他引:3
用ANDERSEN生物粒子采样器对沈阳市大气细菌和真菌粒子的密度、密度分布、粒度分布及两者关系进行了观察和。结果表明,沈阳市大气年平均密度细菌粒子为7228个/m^3,真菌粒子为1797个/m^3,细菌为真菌的4.1倍。细菌粒子密度和粒度均呈正偏态分布,真菌粒子密度和粒度均呈对数正态分布。〈8.2μm的可吸入粒子,细菌为4326个/m^3,占其总数的61.4%;真菌为1583个/m^3,占其总数的 相似文献
68.
69.
Sexual selection, feather breakage and parasites: the importance of white spots in the tail of the barn swallow (Hirundo rustica) 总被引:3,自引:0,他引:3
The long outermost tail feathers of barn swallows Hirundo rustica have white spots that are larger in males than in females and in adults than in juveniles. Spot size increases with age among
adults and is positively correlated with tail length. We tested the functional significance of these white spots by randomly
assigning males to either of three groups during spring: (1) subjected to a considerable reduction in the size of all spots
using a black permanent pen; (2) subjected to a small reduction in the size of all spots; or (3) a control group with no reduction.
Experimental treatment significantly affected the total number of offspring produced per season: breeding tended to be delayed
and second broods were less frequent after a considerable reduction in the size of the males' tail feather spots. White parts
of feathers lacking melanin were more often found to be the site of feather breakage than the melanised parts of similar width.
Furthermore, white tail spots were the preferred feeding site of feather-eating Mallophaga and, since long-tailed males have
fewer Mallophaga than short-tailed males, long-tailed males may pay a lower cost for their large white tail spots than short-tailed
males. Hence, the cost of increased risk of feather breakage at white tail spots and the non-random distribution of feather
lice among individuals will render tail spots a reliable signal of phenotypic quality.
Received: 25 May 1998 / Accepted after revision: 4 January 1998 相似文献
70.
Rosén K Vinichuk M Nikolova I Johanson K 《Journal of environmental radioactivity》2011,102(2):178-184
We examined the long-term effects of a single application of potassium (K) fertilizer (100 kg K ha−1) in 1992 on 137Cs uptake in a forest ecosystem in central Sweden. 137Cs activity concentrations were determined in three low-growing perennial shrubs, heather (Calluna vulgaris), lingonberry (Vaccinium vitis-idaea) and bilberry (Vaccinium myrtillus), and in four wild fungal species (Cortinarius semisanguineus, Lactarius rufus, Rozites caperata and Suillus variegatus). Uptake of 137Cs by plants and fungi growing on K-fertilized plots 17 years after application of the K fertilizer was significantly lower than in corresponding species growing in a non-fertilized control area. The 137Cs activity concentration was 21-58% lower in fungal sporocarps and 40-61% lower in plants in the K-fertilized area compared with the control. Over the study period, this decrease in 137Cs activity concentration was more consistent in plants than in fungi, although the effect was statistically significant and strongly pronounced in all species. The effect of K fertilization in reducing 137Cs activity concentration in fungi and plants decreased over time but was still significant in 2009, 17 years after fertilization. This suggests that application of K fertilizer to forests is an appropriate and effective long-term measure to decrease radiocaesium accumulation in plants and fungi. 相似文献