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1.
In a field experiment using microplots, a flooded Crowley silt loam (Typic Albaqualfs) rice soil was fertilized with 15N labelled (60–74 atom %) urea and KNO3. Emission of N2, N2O and CH4 and accumulation in soil were measured for 21 d after fertilizer application.Emission of 15N2-N measured from the urea and KNO3 treated plots ranged from <15 to 570 and from 330 to 3,420 g ha–1 d–1, respectively. Entrapped 15N2-N in the urea treated microplots was significantly lower (<15 g to 2.1 kg ha–1) on all sampling dates compared to the 15N2-N gas accumulation in the KNO3 treated plots (6.4 to 31.5 kg ha–1). Emissions of N2O-N were low and did not exceed 4 g ha–1 d–1. Fluxes of CH4 from the fertilizer and control plots were low and never exceeded 33 g ha–1 d–1. Maximum accumulation of CH4 in the flooded soil measured 460 and 195 g ha–1 for the urea and KNO3 treatments, respectively. 相似文献
2.
AbstractThe Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulation methods were used to investigate the adsorption and diffusion properties of CH4 and CO2 in montmorillonite slit-nanopores. It is found that, both CH4 and CO2 could adsorb closely onto the pore surface, while different adsorption states occur for CH4 and CO2, respectively, in montmorillonite slit-nanopores. Competitive adsorption of CO2 over CH4 exists in montmorillonite slit-nanopores, especially at the lower pressures, which is attributed to the different interaction intensity between the CH4–CO2 molecules and the pore surface. The diffusion coefficients of CH4 and CO2 both decrease with the enhanced pressures, while the CO2 has a relative weak diffusion coefficient comparing with CH4. A well displacement of the residual CH4 by CO2 in montmorillonite slit-nanopores was investigated, which is found that the displacement efficiency increases with the enhanced bulk pressures. It was determined that, the CO2 can be captured and reserved in the montmorillonite slit-nanopores during the displacement, and the sequestration amount of CO2 gets enhanced with the bulk pressure increasing. This study provides micro-behaviours of CH4 and CO2 in montmorillonite slit-nanopores, for the purpose to give out useful guidance for enhancing shale gas extraction by injecting CO2. 相似文献
3.
Heterotrophic soil microorganisms rely on carbon (C) allocated belowground in plant production, but belowground C allocation (BCA) by plants is a poorly quantified part of ecosystem C cycling, especially, in peat soil. We applied a C balance approach to quantify BCA in a mixed conifer-red maple (Acer rubrum) forest on deep peat soil. Direct measurements of CH4 and CO2 fluxes across the soil surface (soil respiration), production of fine and small plant roots, and aboveground litterfall were used to estimate respiration by roots, by mycorrhizae and by free-living soil microorganisms. Measurements occurred in two consecutive years. Soil respiration rates averaged 1.2 bm μmol m? 2 s? 1 for CO2 and 0.58 nmol m? 2 s? 1 for CH4 (371 to 403 g C m? 2 year? 1). Carbon in aboveground litter (144 g C m? 2 year? 1) was 84% greater than C in root production (78 g C m? 2 year? 1). Complementary in vitro assays located high rates of anaerobic microbial activity, including methanogenesis, in a dense layer of roots overlying the peat soil and in large-sized fragments within the peat matrix. Large-sized fragments were decomposing roots and aboveground leaf and twig litter, indicating that relatively fresh plant production supported most of the anaerobic microbial activity. Respiration by free-living soil microorganisms in deep peat accounted for, at most, 29 to 38 g C m? 2 year? 1. These data emphasize the close coupling between plant production, ecosystem-level C cycling and soil microbial ecology, which BCA can help reveal. 相似文献
4.
In order to gain information about seasonal and interannual variations of CH4-fluxes at a spruce control site, a limed spruce site and a beech site of the Höglwald Forest, Bavaria, Germany, complete annual cycles of CH4-exchange between the soil and the atmosphere with 2-hourly resolution were followed for 4 consecutive years. The ranges of CH4 fluxes observed for the different sites were: +12.4 to –69.4 g CH4 m–2 h–1 (spruce control site), +11.7 to –51.4 g CH4 m–2 h–1 (limed spruce site), and –4.4 to –167.3 g CH4 m–2 h–1 (beech site). Lowest rates of atmospheric CH4-uptake or even a weak net-emission of CH4 by the soils were observed during winter/spring times, whereas highest rates of CH4-uptake were always found in summer/spring. Over the entire observation period of 4 years, mean CH4-uptake rates were –1.82 kg CH4-C ha–1 yr–1 at the spruce control site, –1.31 kg CH4-C ha–1 yr–1 at the limed spruce site, and –4.84 kg CH4-C ha–1 yr–1 at the beech site. The results obtained in this study demonstrate that in view of the huge interannual variations in CH4-fluxes of approx. 1 kg CH4-C ha–1 yr–1, multiple year measurements of CH4-fluxes are necessary to accurately characterize the sink strength of temperate forest for atmospheric CH4. By comparison of CH4-fluxes measured at the spruce control site and the limed spruce site, a significant negative effect of forest floor liming on CH4-uptake could be demonstrated. Compared to the spruce stand, the beech stand showed on average approx. 3 times higher rates of atmospheric CH4-uptake, most likely due to pronounced differences between both sites with regard to the organic layer structure and bulk density of the mineral soil. Regression analysis between CH4-fluxes and environmental parameters revealed that at all sites the dominating factors regulating temporal variations of CH4 fluxes were soil moisture and soil temperature. Field measurements of CH4 concentrations in the soil profile and laboratory measurements of CH4-oxidation and CH4-production activity on soil samples taken from different soil depths showed that the CH4-flux at the Höglwald Forest sites is the net-result of simultaneous occurring production and consumption of CH4 within the soil. Highest CH4-oxidation activity was found in the uppermost centimeters of the mineral soil, whereas highest potential CH4-production activity was found in the organic layer. 相似文献
5.
Wei Cao Musen Zhou Garrett M. Tow Liangliang Huang Tingting Yang 《Molecular simulation》2017,43(7):502-509
AbstractMolecular simulation methods were applied to study the effect of hydrophilicity on CO2/CH4 separation using carbon nanotube (CNT) membranes. CNTs with a diameter of ~1 nm were functionalised by varying amounts of carbonyl groups, in order to achieve various hydrophilicity. The presence of –CO groups inside the CNT allow a significant gain in the diffusion selectivity of CO2, while in contrast the adsorption selectivity is hardly changed. The corresponding permeation selectivity increases as the hydrophilicity of the CNT-based membrane increases. However, the permeability of CO2 decreases due to a combination of the intermolecular interactions between the gas and functional groups and the steric effects of the added functional groups. Considering both the permeation selectivity and permeability, it was found that the maximum separation performance is achieved in a certain hydrophilic CNT membrane. Moreover, the separation performance of hydrophilic CNTs for CO2/CH4 mixtures breaks the Robeson upper bound. 相似文献
6.
OLEG V. MENYAILO BRUCE A. HUNGATE WOLF-RAINER ABRAHAM RALF CONRAD 《Global Change Biology》2008,14(10):2405-2419
Forest ecosystems assimilate more CO2 from the atmosphere and store more carbon in woody biomass than most nonforest ecosystems, indicating strong potential for afforestation to serve as a carbon management tool. However, converting grasslands to forests could affect ecosystem–atmosphere exchanges of other greenhouse gases, such as nitrous oxide and methane (CH4), effects that are rarely considered. Here, we show that afforestation on a well-aerated grassland in Siberia reduces soil CH4 uptake by a factor of 3 after 35 years of tree growth. The decline in CH4 oxidation was observed both in the field and in laboratory incubation studies under controlled environmental conditions, suggesting that not only physical but also biological factors are responsible for the observed effect. Using incubation experiments with 13CH4 and tracking 13C incorporation into bacterial phospholipid fatty acid (PLFA), we found that, at low CH4 concentrations, most of the 13C was incorporated into only two PLFAs, 18 : 1ω7 and 16 : 0. High CH4 concentration increased total 13C incorporation and the number of PLFA peaks that became labeled, suggesting that the microbial assemblage oxidizing CH4 shifts with ambient CH4 concentration. Forests and grasslands exhibited similar labeling profiles for the high-affinity methanotrophs, suggesting that largely the same general groups of methanotrophs were active in both ecosystems. Both PLFA concentration and labeling patterns indicate a threefold decline in the biomass of active methanotrophs due to afforestation, but little change in the methanotroph community. Because the grassland consumed CH4 at a rate five times higher than forest soils under laboratory conditions, we concluded that not only biomass but also cell-specific activity was higher in grassland than in afforested plots. While the decline in biomass of active methanotrophs can be explained by site preparation (plowing), inorganic N (especially NH4+) could be responsible for the change in cell-specific activity. Overall, the negative effect of afforestation of upland grassland on soil CH4 uptake can be largely explained by the reduction in biomass and to a lesser extent by reduced cell-specific activity of CH4-oxidizing bacteria. 相似文献
7.
We report a molecular simulation study to investigate the decomposition of CH4 hydrate. The decomposition is revealed to be stepwise from the outer to inner layers. Upon decomposition, the number of 51262 cages drops faster than that of 512 cages. CH4 molecules are released, dissolved in water, then enter gas phase; meanwhile, CH4 bubbles may form particularly at a high temperature. Based on the variations of potential energy, order parameter, cage number and density profile of CH4 at different temperatures (300, 330, 345 and 360 K) and NaCl concentrations (0, 0.6 and 1.8 M), the effects of temperature and salt are comprehensively examined. With increasing temperature, the decomposition in pure water is accelerated, whereas two opposite effects are observed in NaCl solution. At 330 K, the decomposition is retarded at a higher NaCl concentration, as attributed to the reduced CH4 solubility in NaCl solution and the participation of ions in cage formation; at 360 K, however, the decomposition is accelerated when NaCl concentration increases due to bubble formation. This simulation study provides microscopic insights into hydrate decomposition, which might be useful towards the optimisation of operating conditions for CH4 production from CH4 hydrate. 相似文献
8.
湿地是大气甲烷(CH_4)的主要排放源,而有关放牧对湿地CH_4排放的影响特征仍未得到足够的报道。因此,通过静态箱法,研究了放牧对四川省若尔盖高原湿地CH_4排放的影响,CH_4气体通过快速温室气体分析仪测量。结果表明:放牧样地和围栏内样地生长季CH_4排放量为(31.32±19.57)g/m~2和(30.31±23.46)g/m~2,它们之间无差异显著;但是集中放牧期间(7—9月),放牧样地(21.01±12.35)g/m~2较围栏内样地显著增加了CH_4排放量为54.3%。2014年生长季期间通过刈割植物模拟放牧表明两种刈割强度CH_4排放量为(5.01±5.37)g/m~2和(4.69±5.99)g/m~2,较未刈割样地(1.15±1.89)g/m~2增加了335.9%和308.0%,其原因可能是放牧或者刈割减少地表植物生物量,降低植物高度,缩短了CH_4排放的路径距离。该结果可为我国高原湿地保护与管理决策提供基础数据支撑。 相似文献
9.
Separation of important chemical feedstocks, such as C2H6 from natural gas, can greatly benefit the petrochemical industry. In this paper, the grand canonical Monte Carlo method has been used to study the adsorption and separation of CH4 and C2H6 in zeolites, isoreticular metal-organic framework-1 (IRMOF-1) and zeolitic imidazolate frameworks (ZIFs) with different topology, including soadlite, gmelinite and RHO topologies. Compared with mordenite zeolite and IRMOF-1, ZIFs and mordenite framework inverted (MFI) zeolite have better separation performance for C2H6/CH4 mixtures at different mole fractions of C2H6. From the study of equilibrium snapshots and density distribution profiles, adsorption sites could be grouped as (1) sites with strong interactions with adsorbent and (2) sites with strong interactions with surrounding adsorbates. The gas molecules occupied the first site and then went on to occupy the second site. In CH4/C2H6 mixture adsorption/separation, the adsorption of CH4 was confined by the existence of C2H6. Due to energetic effect, C2H6 selectivity was affected by temperature at a low-pressure range, but did not change as much in a high-pressure range because of packing effect in micropore. In binary adsorption, large C2H6 molecules favour sites with strong adsorbent interactions. At high pressures, packing effects played an important role and it became easy for small CH4 molecules to access the sites with strong adsorbate interactions. 相似文献
10.
Ruo He Matthew J Wooller John W Pohlman John Quensen James M Tiedje Mary Beth Leigh 《The ISME journal》2012,6(10):1937-1948
Methane (CH4) emitted from high-latitude lakes accounts for 2–6% of the global atmospheric CH4 budget. Methanotrophs in lake sediments and water columns mitigate the amount of CH4 that enters the atmosphere, yet their identity and activity in arctic and subarctic lakes are poorly understood. We used stable isotope probing (SIP), quantitative PCR (Q-PCR), pyrosequencing and enrichment cultures to determine the identity and diversity of active aerobic methanotrophs in the water columns and sediments (0–25 cm) from an arctic tundra lake (Lake Qalluuraq) on the north slope of Alaska and a subarctic taiga lake (Lake Killarney) in Alaska''s interior. The water column CH4 oxidation potential for these shallow (∼2 m deep) lakes was greatest in hypoxic bottom water from the subarctic lake. The type II methanotroph, Methylocystis, was prevalent in enrichment cultures of planktonic methanotrophs from the water columns. In the sediments, type I methanotrophs (Methylobacter, Methylosoma and Methylomonas) at the sediment-water interface (0–1 cm) were most active in assimilating CH4, whereas the type I methanotroph Methylobacter and/or type II methanotroph Methylocystis contributed substantially to carbon acquisition in the deeper (15–20 cm) sediments. In addition to methanotrophs, an unexpectedly high abundance of methylotrophs also actively utilized CH4-derived carbon. This study provides new insight into the identity and activity of methanotrophs in the sediments and water from high-latitude lakes. 相似文献
11.
于2012年7月—2014年6月对地处干旱区的张掖湿地甲烷(CH_4)通量进行观测,分析其CH_4通量的变化特征及其影响因子。结果表明:CH_4通量的日变化趋势总体表现为白天大于夜间;不同季节CH_4通量排放特征差异明显,夏季最大,春秋次之,冬季最小;CH_4通量日总量与空气温度、土壤温度之间指数相关关系显著,其中4 cm处土壤温度与之相关性最强;1—6月摩擦风速(U*)与CH_4通量显著正相关;结合CO_2通量观测数据,研究时段张掖湿地净碳吸收量为495.92 g C m~(-2)a~(-1),为明显碳汇。 相似文献
12.
Influence of elevated CO2 and nitrogen nutrition on rice plant growth,soil microbial biomass,dissolved organic carbon and dissolved CH4 总被引:1,自引:0,他引:1
Rice (Oryza sativa) was grown in six sunlit, semi-closed growth chambers for two seasons at 350 L L–1 (ambient) and 650 L L–1 (elevated) CO2 and different levels of nitrogen (N) supplement. The objective of this research was to study the influence of CO2 enrichment and N nutrition on rice plant growth, soil microbial biomass, dissolved organic carbon (DOC) and dissolved CH4. Elevated CO2 concentration ([CO2]) demonstrated a wide range of enhancement to both above- and below-ground plant biomass, in particular to stems and roots (for roots when N was not limiting) in the mid-season (80 days after transplanting) and stems/ears at the final harvest, depending on season and the level of N supplement. Elevated [CO2] significantly increased microbial biomass carbon in the surface 5 cm soil when N (90 kg ha–1) was in sufficient supply. Low N supplement (30 kg ha–1) limited the enhancement of root growth by elevated [CO2], leading consequently to diminished response of soil microbial biomass carbon to CO2 enrichment. The concentration of dissolved CH4 (as well as soil DOC, but to a lesser degree) was observed to be positively related to elevated [CO2], especially at high rate of N application (120 kg ha–1) or at 10 cm depth (versus 5 cm depth) in the later half of the growing season (at 80 kg N ha–1). Root senescence in the late season complicated the assessment of the effect of elevated [CO2] on root growth and soil organic carbon turnover and thus caution should be taken when interpreting respective high CO2 results. 相似文献
13.
长期施肥对双季稻田甲烷排放和关键功能微生物的影响 总被引:3,自引:0,他引:3
研究不同施肥措施对双季稻田甲烷(CH_4)排放特征的影响及其微生物学机理,对合理利用及评价不同施肥模式对水稻生长的影响具有重要意义。以长期施肥定位试验田为平台,采用静态箱-气相色谱法对施用化肥(MF:mineral fertilizer alone)、秸秆还田配施化肥(RF:rice residues plus mineral fertilizer)、30%有机肥配施70%化肥(LOM:30%organic matter plus 70%mineral fertilizer)、60%有机肥配施40%化肥(HOM:60%organic matter plus 40%mineral fertilizer)和无肥(CK:without fertilizer)条件下双季稻田CH_4排放及其微生物学机理进行了分析。结果表明,早稻和晚稻生长期,不同施肥处理稻田CH_4排放通量均显著高于CK,表现为HOMLOMRFMFCK。各处理间CH_4总排放量差异达显著水平,其大小顺序与排放通量趋势一致,以HOM处理为最高,比CK处理增加105.56%,其次是LOM和RF处理,分别比CK处理增加72.97%和54.17%。关键功能土壤微生物测定结果表明,早稻和晚稻各个主要生育时期,各处理稻田土壤产甲烷古菌的数量变化范围为(3.18—81.07)×10~3cfu/g,土壤甲烷氧化细菌的数量变化范围为(24.82—379.72)×10~3cfu/g。稻田土壤产甲烷古菌和甲烷氧化细菌数量大小顺序为HOMLOMRFMFCK,各施肥处理均显著高于CK;HOM、LOM、RF处理显著高于MF、CK处理。双季稻田CH_4排放与稻田土壤产甲烷古菌、甲烷氧化细菌数量变化关系密切。采用有机无机肥配施促进了双季稻田生态系统CH_4的排放和关键功能微生物的数量。 相似文献
14.
Effect of urea fertilizer and environmental factors on CH4 emissions from a Louisiana,USA rice field 总被引:1,自引:0,他引:1
C. W. Lindau P. K. Bollich R. D. Delaune W. H. Patrick Jr. V. J. Law 《Plant and Soil》1991,136(2):195-203
Methane emissions from a flooded Louisiana, USA, rice field were measured over the first cropgrowing season. Microplots contained the semidwarf Lemont rice cultivar drill seeded into a Crowley silt loam soil (Typic Albaqualfs). Urea fertilizer was applied preflood at rates of 0, 100, 200 and 300 kg N ha–1. Emissions of CH4 from the plots to the atmosphere were measured over a 86-d sampling period until harvest. Methane samples were collected in the morning hours (0730–0930) using a closed-chamber technique. Emissions of CH4 were highly variable over the first cropping season and a significant urea fertilizer effect was observed. Two peak CH4 emission periods were observed and occurred about 11 d after panicle differentiation and during the ripening stages. Maximum CH4 emmissions from the 0, 100, 200 and 300 urea-N treatments were 6.0, 8.9, 9.8 and 11.2 kg CH4 ha–1 d–1, respectively. These flux measurements corresponded to approximately 210, 300, 310 and 360 kg CH4 evolved ha–1 over the 86-d sampling period for the 4 treatments. 相似文献
15.
稻田土壤氧化态有机碳组分变化及其与甲烷排放的关联性 总被引:5,自引:0,他引:5
稻田土壤有机碳是甲烷排放的关键底物之一,不同研究者由于采取的有机碳研究方法不同而得出稻田甲烷排放与土壤有机碳关系的结论不一.为明确影响稻田甲烷排放的土壤有机碳组分,设计了稻田施用不同外源有机碳(稻草还田、鸡粪和猪粪)的田间试验,对稻田甲烷排放和土壤有机碳组分的动态变化及其关联性进行监测和分析.结果表明,猪粪处理的甲烷排放与化肥处理无显著差异,而鸡粪和稻草2个处理的甲烷排放分别比化肥增加1.67倍(P<0.05),2.69倍(P<0.05);甲烷排放量与土壤易氧化有机碳含量显示相同顺序:稻草>鸡粪>猪粪>化肥;通径分析表明,土壤易氧化有机碳组分1(被33 mmol/L KMnO4氧化的有机碳)与甲烷排放直接相关,其他有机碳组分仅通过组分1间接作用于水稻生育后期甲烷排放,且排放量较低.由此推断,易氧化有机碳组分1是甲烷排放的主要底物,通过有效措施降低肥源中易氧化态有机碳组分1是减排甲烷的关键技术之一. 相似文献
16.
免耕施肥对稻田甲烷与氧化亚氮排放及其温室效应的影响 总被引:12,自引:0,他引:12
2008年采用静态箱-气相色谱法对鄂东南免耕不施肥(NT0)、翻耕不施肥(CT0)、免耕施肥(NTC)和翻耕施肥(CTC) 4种处理下稻田CH4和N2O的排放进行测定.结果表明:各处理CH4排放均呈先升高后降低的季节性规律,而N2O排放的季节性规律不明显;施肥显著提高了稻田CH4和N2O的排放.与翻耕不施肥相比,免耕不施肥显著提高了CH4的排放量,并显著降低了N2O的排放量;与翻耕施肥相比,免耕施肥仅略降低了CH4的排放量和略提高了N2O的排放量.对稻田CH4和N2O两种气体的综合温室效应分析表明,与翻耕不施肥相比,免耕不施肥的综合温室效应提高了25.9%,与翻耕施肥相比,免耕施肥的综合温室效应降低了10.1%.因此,合理的肥料运筹和稻田免耕技术可降低两种气体的综合温室效应. 相似文献
17.
Summary Methane emission rates from rice-vegetated paddy fields followed a seasonal pattern different to that of weed-covered or unvegetated
fields. Presence of rice plants stimulated the emission of CH4 both in the laboratory and in the field. In unvegetated paddy fields CH4 was emitted almost exclusively by ebullition. By contrast, in rice-vegetated fields more than 90% of the CH4 emission was due to plant-mediated transport. Rice plants stimulated methanogenesis in the submerged soil, but also enhanced
the CH4 oxidation rates within the rhizosphere so that only 23% of the produced CH4 was emitted. Gas bubbles in vegetated paddy soils contained lower CH4 mixing ratios than in unvegetated fiels. Weed plants were also efficient in mediating gas exchnage between submerged soil
and atmosphere, but did not stimulate methanogenesis. Weed plants caused a relatively high redox potential in the submerged
soil so that 95% of the produced CH4 was oxidized and did not reach the atmosphere. The emission of CH4 was stimulated, however, when the cultures were incubated under gas atmospheres containing acetylene or consisting of O2-free nitrogen. 相似文献
18.
氮素是影响湿地甲烷代谢过程的重要因素之一。氮输入是否影响湿地甲烷排放,增加全球气候变暖的风险,一直受到科学界的高度关注。目前关于氮输入对湿地甲烷排放影响的几篇meta-analysis文章的主要结论均为氮输入促进湿地甲烷排放,但是多篇研究性论文的结果为氮输入抑制或不影响湿地甲烷排放,由此可见氮输入对湿地甲烷排放的影响十分复杂。湿地甲烷代谢包括湿地甲烷产生、氧化和传输过程以及最终的甲烷排放,综述不同形态氮输入对水稻田、内陆湿地和滨海湿地甲烷排放通量影响的复杂性;分析湿地甲烷产生速率和途径、甲烷好氧氧化和硝酸盐/亚硝酸盐型厌氧甲烷氧化对不同形态氮输入的响应及机制。硝态氮输入对湿地甲烷产生具有抑制作用已成共识,然而其它形态氮输入对湿地土壤甲烷产生的影响具有较大的不确定性,氮输入影响湿地甲烷产生的机制主要包括电子受体-底物竞争机制、离子毒性机制、促进植物生长-碳底物供给增加机制以及pH调控机制等。氮输入对湿地好氧甲烷氧化影响的研究多集中在水稻田和泥炭湿地,影响的结果包括促进、抑制或影响不显著;氮输入促进湿地土壤硝酸盐/亚硝酸盐型厌氧甲烷氧化。着重分析氮输入对湿地甲烷代谢影响不确定性的成因,指出... 相似文献
19.
Diversity and activity of methanotrophs in landfill cover soils with and without landfill gas recovery systems 总被引:1,自引:0,他引:1
Yao Su Xuan ZhangFang-Fang Xia Qi-Qi ZhangJiao-Yan Kong Jing WangRuo He 《Systematic and applied microbiology》2014
Aerobic CH4 oxidation plays an important role in mitigating CH4 release from landfills to the atmosphere. Therefore, in this study, oxidation activity and community of methanotrophs were investigated in a subtropical landfill. Among the three sites investigated, the highest CH4 concentration was detected in the landfill cover soil of the site (A) without a landfill gas (LFG) recovery system, although the refuse in the site had been deposited for a longer time (∼14–15 years) compared to the other two sites (∼6–11 years) where a LFG recovery system was applied. In April and September, the higher CH4 flux was detected in site A with 72.4 and 51.7 g m−2 d−1, respectively, compared to the other sites. The abundance of methanotrophs assessed by quantification of pmoA varied with location and season. A linear relationship was observed between the abundance of methanotrophs and CH4 concentrations in the landfill cover soils (R = 0.827, P < 0.001). The key factors influencing the methanotrophic diversity in the landfill cover soils were pH, the water content and the CH4 concentration in the soil, of which pH was the most important factor. Type I methanotrophs, including Methylococcus, Methylosarcina, Methylomicrobium and Methylobacter, and type II methanotrophs (Methylocystis) were all detected in the landfill cover soils, with Methylocystis and Methylosarcina being the dominant genera. Methylocystis was abundant in the slightly acidic landfill cover soil, especially in September, and represented more than 89% of the total terminal-restriction fragment abundance. These findings indicated that the LFG recovery system, as well as physical and chemical parameters, affected the diversity and activity of methanotrophs in landfill cover soils. 相似文献
20.
温带针阔混交林土壤碳氮气体通量的主控因子与耦合关系 总被引:3,自引:0,他引:3
中高纬度森林地区由于气候条件变化剧烈,土壤温室气体排放量的估算存在很大的不确定性,并且不同碳氮气体通量的主控因子与耦合关系尚不明确。以长白山温带针阔混交林为研究对象,采用静态箱-气相色谱法连续4a(2005—2009年)测定土壤二氧化碳(CO2)、甲烷(CH4)和氧化亚氮(N2O)净交换通量以及温度、水分等相关环境因子。研究结果表明:温带针阔混交林土壤整体上表现为CO2和N2O的排放源和CH4的吸收汇。土壤CH4、CO2和N2O通量的年均值分别为-1.3 kg CH4hm-2a-1、15102.2 kg CO2hm-2a-1和6.13 kg N2O hm-2a-1。土壤CO2通量呈现明显的季节性规律,主要受土壤温度的影响,水分次之;土壤CH4通量的季节变化不明显,与土壤水分显著正相关;土壤N2O通量季节变化与土壤CO2通量相似,与土壤水分、温度显著正相关。土壤CO2通量和CH4通量不存在任何类型的耦合关系,与N2O通量也不存在耦合关系;土壤CH4和N2O通量之间表现为消长型耦合关系。这项研究显示温带针阔混交林土壤碳氮气体通量主要受环境因子驱动,不同气体通量产生与消耗之间存在复杂的耦合关系,下一步研究需要深入探讨环境变化对其耦合关系的影响以及内在的生物驱动机制。 相似文献