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181.
Methane emission characteristics and its relations with plant and soil parameters under irrigated rice ecosystem of northeast India 总被引:1,自引:0,他引:1
Methane flux from rice varieties grown under two identical soils of Assam were monitored. In the first experiment, variety Jaya and GRT was grown in sandy loam soil of Lower Brahmaputra Valley Zone of Assam and the second experiment was conducted with variety Jyotiprasad and Bishnuprasad in sandy to sandy loam soils of Upper Brahmaputra Valley Zones of Assam. Methane flux recorded from variety Jyotiprasad and GRT was higher compared to variety Bishnuprasad and Jaya. The seasonal integrated flux recorded was 10.76 g m−2, 9.98 g m−2, 9.74 g m−2 and 11.31 g m−2 for variety GRT, Jaya, Bishnuprasad and Jyotiprasad, respectively. All the varieties exhibited two methane peaks one at maximum tillering stage and other at panicle initiation stage of the crop. Crop growth parameters such as leaf number, number of tillers and leaf area index (LAI) showed strong positive relationship with total methane flux. In both the experiments it was calculated that CH4 emission was substantially influenced by crop phenology and growth. This study emphasise the relationship of different growth parameters with methane emission. 相似文献
182.
Methanotrophic–heterotrophic communities were selectively enriched from sewage sludge to obtain a mixed culture with high levels of poly-β-hydroxybutyrate(PHB)accumulation capacity from methane.Methane was used as the carbon source,N_2as sole nitrogen source,and oxygen and Cu content were varied.Copper proved essential for PHB synthesis.All cultures enriched with Cu could accumulate high content of PHB(43.2%–45.9%),while only small amounts of PHB were accumulated by cultures enriched without Cu(11.9%–17.5%).Batch assays revealed that communities grown with Cu and a higher O_2content synthesized more PHB,which had a wider optimal CH_4:O_2range and produced a high PHB content(48.7%)even though in the presence of N_2.In all methanotrophic–heterotrophic communities,both methanotrophic and heterotrophic populations showed the ability to accumulate PHB.Although methane was added as the sole carbon source,heterotrophs dominated with abundances between 77.2%and 85.6%.All methanotrophs detected belonged to type II genera,which formed stable communities with heterotrophs of different PHB production capacities. 相似文献
183.
Stimulation of reductive dechlorination of hexachlorobenzene in soil by inducing the native microbial activity 总被引:16,自引:0,他引:16
The reductive dechlorination and behaviour of 14C-hexachlorobenzene (HCB) was investigated in an arable soil. The activity of the native anaerobic microbial communities could be induced by saturating the soil with water. Under these conditions high rates of dechlorination were observed. After 20 weeks of incubation only 1% of the applied 14C-HCB could be detected in the fraction of extractable residues. Additional organic substances, like wheat straw and lucerne straw, however considerably delayed and reduced the dechlorination process in the soil. The decline of HCB was not only caused by dechlorination but also by the formation of non-extractable residues, whereby their amounts varied with time depending on the experimental conditions. Several dechlorination products were detected, indicating the following main HCB transformation pathway: HCB → PCB → 1,2,3,5-TeCB → 1,3,5-TCB → 1,3-DCB, with 1,3,5-TCB as main intermediate dechlorination product. The other TeCB-, TCB- and DCB-isomers were also detected in low amounts, showing the presence of more than one dechlorination pathway. Since the methane production rates were lowest when the dechlorination rates were highest, it can be assumed that methanogenic bacteria were not involved in the dechlorination process of HCB. The established 14C-mass balances show, that with increasing dechlorination and incubation times, the 14C-recoveries decreased. 相似文献
184.
随着工业生产和人类活动的加强,大气中痕量气体含量明显增加。这种增加有可能破坏臭气层、导致全球温室效应。阐述这些气体导致温室效应的机理,总结这些痕量气体近年来在大气中的浓度变化趋势,分析引起这些变化的机理。 相似文献
185.
《环境科学学报(英文版)》2023,35(4):333-347
Pd/Al2O3 catalysts supported on Al2O3 of different particle sizes were synthesized and applied in methane combustion. These catalysts were systematically characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), high resolution-transmission electron microscopy (HR-TEM), high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), H2-temperature-programmed reduction (H2-TPR), O2-temperature-programmed oxidation (O2-TPO), X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine structure (XAFS). The characterization results indicated that nano-sized Al2O3 enabled the uniform dispersion of palladium nanoparticles, thus contributing to the excellent catalytic performance of these nano-sized Pd/Al2O3 catalysts. Among them, Pd/Al2O3-nano-10 (Pd/Al2O3 supported by alumina with an average particle size of 10 nm) showed superior catalytic activity and stability for methane oxidation under harsh practical conditions. It maintained excellent catalytic performance for methane oxidation for 50 hr and remained stable even after harsh hydrothermal aging in 10 vol.% steam at 800°C for 16 hr. Characterization results revealed that the strong metal-support interactions and physical barriers provided by Al2O3-nano-10 suppressed the coalescence ripening of palladium species, and thus contributed to the superior sintering resistance of the Pd/Al2O3-nano-10 catalyst. 相似文献
186.
大气中甲磺酸粒子的来源及其对环境的影响 总被引:2,自引:0,他引:2
讨论了大气中甲磺酸粒子的来源,分析了甲磺酸粒子的自然循环及其对酸雨形成和气候变化的影响。 相似文献
187.
188.
温室气体引起全球变暖,是当今全球环境以及国际政治和经济发展中的一个热点问题,尽管其中不确定的因素很多,但近年来有关的研究进展相当快。本文介绍了一种重要的温室气体—甲烷排放问题在国内外的研究进展和趋势,并对今后国内有关研究的发展提出了建议。 相似文献
189.
The greenhouse gas (GHG) emissions from MSW landfill, and control methods to eliminate or minimize these impacts including energy recovery from landfill gas (LFG) of MSW landfill in Thailand have been evaluated. Life Cycle Assessment (LCA) is used as the analytical tool to evaluate the environmental consequences of landfilling holistically. The economic implications of the control methods are also briefly assessed. The results show that in terms of GHG emissions as well as in terms of economics, it is more advantageous to have a large centralized landfill and produce electricity from the LFG rather than having several small, localized landfills despite significantly lower transportation requirement for the latter case. Sensitivity analysis revealed that the global warming potential was sensitive to gas collection efficiency as well as methane oxidation rate in the landfill. This study shows the utility of a life cycle approach for evaluating LFG-to-energy (LFGTE) projects. 相似文献
190.
水田中甲烷的发生,释放机制及其削减对策 总被引:1,自引:0,他引:1
CH4是温度效应气体之一,人类的生活和生产活动导致大气中CH4浓度的增加,通过水田中CH4的发展,释放机制的研究方法,以及近期研究成果的介绍,提出了控制CH4发生量的有关技术问题及应采取的有效措施。 相似文献