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931.
M. D. Yevdokimenko 《Russian Journal of Ecology》2011,42(3):205-210
Consideration is given to the results of studies on the postfire dynamics of Transbaikal forests, which are formed under conditions
of highly arid climate and extreme pyrological regime. Data are presented on tree die-off and recruitment in naturally burned
forests and in test stands affected by creeping fires differing in intensity. The hydrothermal regime of soils, precipitation
runoff, and its multifactor models are discussed. It is shown that fires aggravate moisture deficiency on mountain slopes,
impair the productivity of tree stands, and cause their digression. The statistics of forest fires and the risk of lightning
fires are analyzed. 相似文献
932.
A. B. Savinov 《Russian Journal of Ecology》2011,42(3):179-185
According to the basic concept of the theory dealt with in this study, autocenosis, i.e., a self-regulatory host-symbiont system, rather than an individual, is the individual-level unit. Then, democenosis, which is a system of autocenoses, corresponds to the population level. Therefore, natural selection of autocenoses rather
than individuals occurs in a democenosis, and auto- and democenoses, rather than “individuals” and “populations,” are components
of food chains and webs. However, the symbiotic approach does not exclude the population paradigm and will be developed in
parallel with it. 相似文献
933.
934.
The results of studies on the radial increment of larch and pine in central Yakutia are presented. The application of dendroclimatological
methods to the study of tree-ring chronologies has made it possible to evaluate tree growth response to the dynamics of climatic
factors over the past 120 years. The results of analysis of radial tree increment show that the onset of the growing season
has shifted to earlier dates by the end of the 20th century. 相似文献
935.
Behavioral adaptations of ant species were studied in associations of different biotopes in the Crimean Mountains. The pattern
of an association was found to depend on the mode of the territorial behavior of dominant species, irrespective of their number.
The dominance hierarchy was more strict in monodominant than in bidominant associations. Ant species demonstrated different
behavioral strategies, plasticity of foraging, and avoidance of aggressive encounters. A method for formalizing interspecies
relationships and a model describing stochastic properties of the biological system are proposed, which can be useful in solving
various ethological and ecological problems. 相似文献
936.
937.
The dynamics of arsenic in four paddy fields in the Bengal delta 总被引:4,自引:0,他引:4
Stroud JL Norton GJ Islam MR Dasgupta T White RP Price AH Meharg AA McGrath SP Zhao FJ 《Environmental pollution (Barking, Essex : 1987)》2011,159(4):947-953
Irrigation with arsenic contaminated groundwater in the Bengal Delta may lead to As accumulation in the soil and rice grain. The dynamics of As concentration and speciation in paddy fields during dry season (boro) rice cultivation were investigated at 4 sites in Bangladesh and West Bengal, India. Three sites which were irrigated with high As groundwater had elevated As concentrations in the soils, showing a significant gradient from the irrigation inlet across the field. Arsenic concentration and speciation in soil pore water varied temporally and spatially; higher As concentrations were associated with an increasing percentage of arsenite, indicating a reductive mobilization. Concentrations of As in rice grain varied by 2-7 fold within individual fields and were poorly related with the soil As concentration. A field site employing alternating flooded-dry irrigation produced the lowest range of grain As concentration, suggesting a lower soil As availability caused by periodic aerobic conditions. 相似文献
938.
Impact of carbon nanomaterials on the behaviour of 14C-phenanthrene and 14C-benzo-[a] pyrene in soil
Towell MG Browne LA Paton GI Semple KT 《Environmental pollution (Barking, Essex : 1987)》2011,159(3):706-715
The impact of fullerene soot (FS), single-walled (SWCNTs) and multi-walled (MWCNTs) carbon nanotubes on the behaviour of two 14C-PAHs in sterile soil was investigated. Different concentrations of carbon nanomaterials (0, 0.05, 0.1 and 0.5%) were added to soil, and 14C-phenanthrene and 14C-benzo[a]pyrene extractability assessed over 80 d through dichloromethane (DCM) and hydroxypropyl-β-cyclodextrin (HPCD) shake extractions. Total 14C-PAH activity in soils was determined by combustion, and mineralisation of 14C-phenanthrene was monitored over 14 d, using a catabolically active pseudomonad inoculum. No significant loss of 14C-PAH-associated activity from CNM-amended soils was observed over the ‘aging’ period. CNMs had a significant impact on HPCD-extractability of 14C-PAHS; extractability decreased with increasing CNM concentration. Additionally, 14C-phenanthrene mineralisation was inhibited by the presence of CNMs at concentrations of ≥0.05%. Differences in overall extents of 14C-mineralisation were also apparent between CNM types. It is suggested the addition of CNMs to soil can reduce PAH extractability and bioaccessibility, with PAH sorption to CNMs influenced by CNM type and concentration. 相似文献
939.
Chemical recycling of polyamide waste in water was studied using 0.5 L high pressure autoclave at temperatures of 150, 200,
210, 220,230 and 240 °C and at various pressures of 100, 200, 300, 400, 500, 600 and 700 psi (pound per square inch). Viscosity
average molecular weight of the polyamide waste sample was determined by Ostwald method and recorded as 1.928 × 103. The reaction was found to be first order with velocity constant in order of 10−2 min−1. The velocity constant and percent conversion of depolymerization reaction at 240 °C and 700 psi pressure were recorded as
2.936 × 10−2 min−1 and 99.99% respectively. The velocity constant was obtained on the basis of measurement of amine value. Kinetic and thermodynamic
parameters such as energy of activation, frequency factor, enthalpy of activation were found to be 10.6 kJ mole−1, 0.3719 min−1 and 6.3 kJ mole−1 respectively, at the optimum conditions for maximum depolymerization of polyamide waste. 相似文献
940.
M. Jawaid H. P. S. Abdul Khalil P. Noorunnisa Khanam A. Abu Bakar 《Journal of Polymers and the Environment》2011,19(1):106-109
In this research, hybrid composite materials were prepared from combination of oil palm Empty fruit bunches (EFB) fibre and
jute fibre as reinforcement, epoxy as polymer matrix. This study intended to investigate the effect of jute fiber hybridization
and different layering pattern on the physical properties of oil palm EFB-Epoxy composites. Water absorption and thickness
swelling test reveal that hybrid composite shows a moderate water absorption which is 11.20% for hybrid EFB/Jute/EFB composite
and 6.08% for hybrid Jute/EFB/Jute composite. The thickness swelling and water absorption of the hybrid composites slightly
increased as the layering pattern of hybrid composites changed. Hybrid composites are more water resistance and dimensional
stable compare to the pure EFB composites. This is attributed to the more hydrophilic nature of EFB composites. Hybridization
of oil palm EFB composites with jute fibres can improve the dimensional stability and density of pure EFB and Jute fibre reinforced
composites has higher density of 1.2 g/cm3 compared to all other composites. 相似文献