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51.
Kirkfeldt Trine Skovgaard Hansen Anne Merrild Olesen Pernille Mortensen Lucia Hristova Kameliya Welsch Alexander 《Regional Environmental Change》2017,17(3):725-737
Regional Environmental Change - The Arctic Region is characterised by vulnerable ecosystems and residing indigenous people, dependent on nature for subsistence fishing and hunting. The Arctic also... 相似文献
52.
Plants control the seasonal dynamics of microbial N cycling in a beech forest soil by belowground C allocation 总被引:1,自引:0,他引:1
Kaiser C Fuchslueger L Koranda M Gorfer M Stange CF Kitzler B Rasche F Strauss J Sessitsch A Zechmeister-Boltenstern S Richter A 《Ecology》2011,92(5):1036-1051
Soil microbes in temperate forest ecosystems are able to cycle several hundreds of kilograms of N per hectare per year and are therefore of paramount importance for N retention. Belowground C allocation by trees is an important driver of seasonal microbial dynamics and may thus directly affect N transformation processes over the course of the year. Our study aimed at unraveling plant controls on soil N cycling in a temperate beech forest at a high temporal resolution over a time period of two years, by investigating the effects of tree girdling on microbial N turnover. In both years of the experiment, we discovered (1) a summer N mineralization phase (between July and August) and (2) a winter N immobilization phase (November-February). The summer mineralization phase was characterized by a high N mineralization activity, low microbial N uptake, and a subsequent high N availability in the soil. During the autumn/winter N immobilization phase, gross N mineralization rates were low, and microbial N uptake exceeded microbial N mineralization, which led to high levels of N in the microbial biomass and low N availability in the soil. The observed immobilization phase during the winter may play a crucial role for ecosystem functioning, since it could protect dissolved N that is produced by autumn litter degradation from being lost from the ecosystem during the phase when plants are mostly inactive. The difference between microbial biomass N levels in winter and spring equals 38 kg N/ha and may thus account for almost one-third of the annual plant N demand. Tree girdling strongly affected annual N cycling: the winter N immobilization phase disappeared in girdled plots (microbial N uptake and microbial biomass N were significantly reduced, while the amount of available N in the soil solution was enhanced). This was correlated to a reduced fungal abundance in autumn in girdled plots. By releasing recently fixed photosynthates to the soil, plants may thus actively control the annual microbial N cycle. Tree belowground C allocation increases N accumulation in microorganisms during the winter which may ultimately feed back on plant N availability in the following growing season. 相似文献
53.
Isaac Schifter Luis D��az Rene Rodr��guez Lucia Salazar 《Environmental monitoring and assessment》2011,173(1-4):343-360
Recently, the Mexican government launched a national program encouraging the blending of renewable fuels in engine fuel. To aid the assessment of the environmental consequences of this move, the effect of gasoline fuel additives, ethanol and methyl tert-butyl ether, on the tailpipe and the evaporative emissions of Mexico sold cars was investigated. Regulated exhaust and evaporative emissions, such as carbon monoxide, non-methane hydrocarbons, and nitrogen oxides, and 15 unregulated emissions were measured under various conditions on a set of 2005?C2008 model light-duty vehicles selected based on sales statistics for the Mexico City metropolitan area provided by car manufacturers. The selected car brands are also frequent in Canada, the USA, and other parts of the world. This paper provides details and results of the experiment that are essential for evaluation of changes in the emission inventory, originating in the low-blend ethanol addition in light vehicle fuel. 相似文献
54.
55.
Mohd Reza Esa Anthony Halog Lucia Rigamonti 《Journal of Material Cycles and Waste Management》2017,19(3):1144-1154
Construction and demolition (C&D) waste is a pressing issue not only in Malaysia, but it is also a worldwide concern including the developed countries as well. C&D waste should be managed throughout the construction cycle. The concept of circular economy (CE) is an emerging notion that has the potential to be utilized as waste minimization approach. This paper aims to assess the potentials of incorporating the CE concept as an approach to minimizing C&D wastes, by developing a CE-based theoretical framework for C&D waste management in Malaysia. In line with this objective, a systematic review has been conducted to determine how CE can be operationalised as a strategy to minimize wastes, while considering it as a key factor for mitigating the environmental impacts. Based on the literature review, a CE-based theoretical framework has been proposed using Malaysia as a case study. The framework has been developed following a three-layer approach namely micro-, meso-, and macro-levels. Waste minimization strategies have been identified for each level taking into account the main stages in the construction industry, i.e., planning, designing, procurement, construction, and demolition. The different stakeholders involved at each stage and their interactions in the stages have also been identified. 相似文献
56.
57.
Bruno Brambati Lucia Tului Alessandro Lanzani Giuseppe Simoni Maurizio Travi 《黑龙江环境通报》1991,11(10):767-774
Both the principles of first-trimester genetic diagnosis in multiple pregnancy and the special considerations required to avoid potential diagnostic pitfalls are presented. The experience consisted of 65 cases of twins and one case of quadruplets. Dichorionic twins were recognized by sonography in 54 cases. Transabdominal aspiration was generally preferred to trans-cervical for obtaining chorionic tissue, although in two cases both approaches were used. Diagnostic error following erroneous sampling was reported in 3 out of 54 sets of dichorionic twins (5.5 per cent). When like-sex dichorionic twins cannot be differentiated by cytogenetic or DNA polymorphism studies, amniocentesis should be recommended to confirm the reliability of the result on chorionic tissue. 相似文献
58.
Algal bioassays and pesticide analysis were joined in Tuscany regional monitoring of surface and ground waters. Results were compared. Waters affected algal growth in any of the following ways: stimulation, inhibition, stimulation at low concentrations and inhibition at higher concentrations. Most of ground waters inhibited algal growth whereas only a little percentage were contaminated with pesticide. Most of surface waters stimulated algal growth and a higher percentage were contaminated with pesticides. In waters with inhibitory effect toxicological parameters (EC50, EC25, EC10 and NOEC) were measured and compared; EC25 values were very close to NOEC values. Hazard to aquatic primary productivity for each pesticide found during chemical monitoring was evaluated; for this aim the margin of safety (MOS) was calculated by using algal toxicity and the pesticide concentration measured. 相似文献
59.
Ana M. M. Viana Anne Frézard Christian Malosse Terezinha M. C. Della Lucia Christine Errard Alain Lenoir 《Chemoecology》2001,11(1):29-36
Summary. Leaf cutting ants live in symbiosis with a basidiomycete fungus that is exploited as a source of nutrients for the ant larvae.
Tests of fungus transport demonstrated that Acromyrmex subterraneus subterraneus workers discriminate concolonial fungus from alien fungus, and rejected the latter. Larvae and pupae of the ant were used
as controls. Chemical analysis of the fungus revealed a great similarity between its hydrocarbon profile and that found on
the ant brood. Experiments with lures showed that chemical extracts from the fungus are responsible for this discrimination
process. Moreover, the presence of brood inside the fungus seemed to be important for discrimination of the fungus by workers.
Resident workers accepted concolonial broodless fungus less than concolonial fungus inoculated with brood odor. Fungus seems
to acquire colonial odor passively, simply by contact with the brood. The impact of fungus volume present in the nest on closure
of the colony is discussed. We show here for the first time the importance of a symbiotic vegetal organism in colonial recognition
in social insects.
Received 14 April 2000; accepted 29 September 2000 相似文献
60.
Borras-Guevara Martha Lucia Batres Carlota Perrett David I. 《Behavioral ecology and sociobiology》2017,71(12):1-11
Behavioral Ecology and Sociobiology - Honey bee colonies require adequate pollen for maintenance and growth. Pollens vary in nutritional value, and a balanced diet is achieved by mixing pollens... 相似文献