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811.
森林生态系统在碳循环中的作用 总被引:9,自引:0,他引:9
描述了森林生态系统的碳循环及其在全球碳循环中的作用,说明了森林生态系统在碳循环中的作用主要取决于森林生态系统的生物量、林产品、植物枯枝落叶和根系碎屑以及森林土壤。最后,阐明了中国森林生态系统碳循环的研究现状和趋势。 相似文献
812.
In underground coal mining, methane explosions often can cause tremendous disasters. In the meantime, carbon monoxide (CO), generated during the process of coal oxidation, may appear in the air. Therefore, the explosion characteristics of the mixture of CH4 and CO must be investigated to prevent gas explosion accidents in coal mines. We conducted experiments by using a 20-L nearly spherical gas explosion testing device. The software FLACS was used to simulate the explosion of the mixture of CH4 and CO at various mixing concentrations, and the simulation results corresponded to experimental results. With the increase of CO concentration, both upper and lower explosive limits of CH4 decreased. On the whole, the explosion characteristic parameters of CH4 and the mixture are similar. When CH4 concentration was below the stoichiometric concentration, the addition of CO could promote the intensity of gas explosion; oppositely, excessive CO would inhibit the gas explosion reaction. The inhibitory effects become more significant as the concentration of CH4 increases. 相似文献
813.
China will set up a national carbon emissions trading market by the end of 2017, which is initially open to individual investors from the initial market for business and institutional investors. In this article, the main influencing factors and mechanism of individual participation in carbon trading market are studied by establishing multiple linear regression model. The study found that age, education level, length of account opening time, and risk attitude are the main factors influencing the participation of individual investors. Environmental awareness and environmental impact are less affected; information transparency and transaction risk also have an impact on the degree of individual investor participation; investment experience does not affect the participation of individual investors in the carbon trading market. 相似文献
814.
We introduce ten papers on sustainable resource dynamics. In addition, we provide analytical results on the effect of stochastic damages on optimal economic growth, the effects of habits and loss aversion on the cost-benefit discount rate, and the effect of a carbon budget and carbon capture and storage (CCS) on optimal investment in technical change. 相似文献
815.
816.
Quantification of natural and engineered carbon nanotubes (CNT) in the environment is urgently needed to study their occurrence and fate and to enable a proper risk assessment. Currently, such methods are lacking. Here, we tested the resistance of 15 structurally different CNTs to chemothermal oxidation at 375 °C (CTO-375), a method used to isolate soots from environmental samples. Depending on their structure, CNTs survived CTO-375 in proportions ranging from 26 to 93%. Standard addition of CNTs to soil and sediment yielded recoveries between 66 and 171%, demonstrating the capability of CTO-375 to isolate CNTs from complex environmental matrices. These data of pure and added CNTs correspond to recoveries obtained with “ordinary” soots under similar experimental conditions. Hence, soot fractions commonly isolated with CTO-375 from environmental matrices most probably encompass CNTs. Future work should attempt to enhance the method's selectivity, i.e., its capability to separate CNTs from other forms of soot. 相似文献
817.
Richon P Perrier F Koirala BP Girault F Bhattarai M Sapkota SN 《Journal of environmental radioactivity》2011,102(2):88-102
Temporal variation of radon-222 concentration was studied at the Syabru-Bensi hot springs, located on the Main Central Thrust zone in Central Nepal. This site is characterized by several carbon dioxide discharges having maximum fluxes larger than 10 kg m−2 d−1. Radon concentration was monitored with autonomous Barasol™ probes between January 2008 and November 2009 in two small natural cavities with high CO2 concentration and at six locations in the soil: four points having a high flux, and two background reference points. At the reference points, dominated by radon diffusion, radon concentration was stable from January to May, with mean values of 22 ± 6.9 and 37 ± 5.5 kBq m−3, but was affected by a large increase, of about a factor of 2 and 1.6, respectively, during the monsoon season from June to September. At the points dominated by CO2 advection, by contrast, radon concentration showed higher mean values 39.0 ± 2.6 to 78 ± 1.4 kBq m−3, remarkably stable throughout the year with small long-term variation, including a possible modulation of period around 6 months. A significant difference between the diffusion dominated reference points and the advection-dominated points also emerged when studying the diurnal S1 and semi-diurnal S2 periodic components. At the advection-dominated points, radon concentration did not exhibit S1 or S2 components. At the reference points, however, the S2 component, associated with barometric tide, could be identified during the dry season, but only when the probe was installed at shallow depth. The S1 component, associated with thermal and possibly barometric diurnal forcing, was systematically observed, especially during monsoon season. The remarkable short-term and long-term temporal stability of the radon concentration at the advection-dominated points, which suggests a strong pressure source at depth, may be an important asset to detect possible temporal variations associated with the seismic cycle. 相似文献
818.
López Bellido J Peltomaa E Ojala A 《Environmental pollution (Barking, Essex : 1987)》2011,159(6):1649-1659
Up to now, carbon gas fluxes from urban lakes in the boreal zone have seldom been studied. In summer 2005 we investigated fluxes from an urban boreal lake basin in southern Finland with long history of eutrophication and anoxia. Hypolimnetic CO2 and CH4 concentrations were high compared to other boreal lakes. During the open-water period, the lake basin acted as a source of CO2 and CH4 with fluxes of 2.10 mol m−2 and 0.04 mol m−2, respectively. Despite the high oxidation rate (83%), CH4 flux was higher than in other lakes and CH4 contributed 60% to Global Warming Potential. The ratio of carbon emission to accumulation was 4, i.e. emissions were an important route for carbon departure but less so than in rural lakes. Since the lake oxygen conditions affected nutrient availability, there was a positive feedback from hypolimnion to carbon uptake, which was reflected in gas concentrations. 相似文献
819.
Wyness K Mills G Jones L Barnes JD Jones DL 《Environmental pollution (Barking, Essex : 1987)》2011,159(10):2493-2499
The combined impacts of simulated increased nitrogen (N) deposition (75 kg N ha−1 yr−1) and increasing background ozone (O3) were studied using two mesotrophic grassland species (Dactylis glomerata and Ranunculus acris) in solardomes, by means of eight O3 treatments ranging from 15.5 ppb to 92.7 ppb (24 h average mean). A-Ci curves were constructed for each species to gauge effects on photosynthetic efficiency and capacity, and effects on biomass partitioning were determined after 14 weeks. Increasing the background concentration of O3 reduced the healthy above ground and root biomass of both species, and increased senesced biomass. N fertilisation increased biomass production in D. glomerata, and a significantly greater than additive effect of O3 and N on root biomass was evident. In contrast, R. acris biomass was not affected by high N. The study shows the combined effects of these pollutants have differential implications for carbon allocation patterns in common grassland species. 相似文献
820.
Pakarinen K Petersen EJ Leppänen MT Akkanen J Kukkonen JV 《Environmental pollution (Barking, Essex : 1987)》2011,159(12):3750-3756
Effects of fullerene-spiked sediment on a benthic organism, Lumbriculus variegatus (Oligochaeta), were investigated. Survival, growth, reproduction, and feeding rates were measured to assess possible adverse effects of fullerene agglomerates produced by water stirring and then spiked to a natural sediment. L. variegatus were exposed to 10 and 50 mg fullerenes/kg sediment dry mass for 28 d. These concentrations did not impact worm survival or reproduction compared to the control. Feeding activities were slightly decreased for both concentrations indicating fullerenes’ disruptive effect on feeding. Depuration efficiency decreased in the high concentration only. Electron and light microscopy and extraction of the worm fecal pellets revealed fullerene agglomerates in the gut tract but not absorption into gut epithelial cells. Micrographs also indicated that 16% of the epidermal cuticle fibers of the worms were not present in the 50 mg/kg exposures, which may make worms susceptible to other contaminants. 相似文献