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1.
本次研究选择中国东部一个生态和环境空间分异极大的浅水湖泊（太湖）以及周围河流,分别于2003年7月和9月两次采集湖水和河水样品,分析其中的N2O浓度,并利用扩散模型公式估算水-气界面N2O交换通量。结果显示N2O饱和度的空间变化从70％不饱和到2708％过饱和变化范围很大。N2O饱和度的空间分布,N2O与CH4、无机氮、TDS（总溶解固体物质）之间的相关性都表明： 太湖重度富营养区N2O的产生极大地受到人为N输入的影响。然而,初步的通量分析显示湖泊N2O的释放因子不超过0.63％,小于河流中的默认值,N2O产率也略低于水环境中的平均值,太湖以面积为权重的释放通量平均值并不高,在7月和9月分别为14.0μmol/m2·d和9.7μmol/m2·d。这些结果表明流域人为N输入对整个湖泊N2O的促进作用是有限的,预计未来湖泊N2O释放不会因为人为活动增加而出现大幅度增加的状况。流域内各生态景观N2O释放量的比较,也表明富营养湖泊总体上仍然是一个十分有限的大气N2O释放源。相反,太湖周围河流存在较大的N2O释放速率,在7月和9月估算的N2O释放通量分别为142.1μmol/m2·d和28.8μmol/m2·d。将这一释放速率推广到整个流域后,预计河网的N2O释放量将占到耕作土壤的10％～50％,显示了河流对区域N2O质量平衡具有较重要的影响。 相似文献
2.
结合含水量、TOC含量和TOC/TN比值变化曲线,18·5kaB·P·以来的四海龙湾玛珥湖沉积物全岩有机碳同位素组成（δ13CTOC）记录可划分为3个阶段:1)末次冰期晚期（18·5～14·7kaB·P·）,δ13CTOC值偏正,变化范围为-29·50‰～-26·18‰,平均值约为-28·10‰;2)末次冰消期（14·7～11·7kaB·P·）,δ13CTOC值显著偏负,变化范围为-33·92‰～-28·40‰,平均值约为-31·75‰,在δ13CTOC值变化曲线上表现为一个低谷,但在类似YoungerDryas的冷干事件期间（12·7～11·7kaB·P·）,δ13CTOC值再次显著偏正,最高可达-28·4‰;3)全新世以来（11·7kaB·P.至今）,δ13CTOC值变化幅度不大（-30·85‰～-27·37‰）,基本上都在平均值-29·1‰左右。研究表明,大气CO2浓度变化是影响18·5kaB·P·以来四海龙湾玛珥湖δ13CTOC值变化的主导因素。 相似文献
3.
根据《中华人民共和国气候变化初始国家信息通报》,1994年中国温室气体排放总量约为3650×106t的CO2当量,其中CO2,CH4和N2O分别占73.1 ％ ,19.7 ％ 和7.2 ％ 。CO2排放主要来自能源活动,CH4排放主要来自农业活动和能源活动,N2O排放主要来自农业活动。在过去的20余年里,中国为减缓全球温室气体排放的增长速度做出了重要的贡献。对文献资料和大量研究结果的分析表明,中国可通过采取相关措施和制订相应政策进一步减少温室气体的排放。减少CO2排放的主要措施和对策包括:调整能源结构(降低煤炭消费比例、适度提高天然气比例和发展核能);提高能源生产、转化、分配和使用过程中的效率;开发利用水能、风能、太阳能和生物能等可再生能源;通过植树造林,推广秸秆还田、平衡施肥和少(免)耕等增加陆地生态系统的碳吸收。减少CH4排放的主要措施和对策包括:回收利用煤层气;改造生活垃圾填埋场地和筛选环境适应性强的CH4氧化菌并接种于填埋场;改善反刍动物的营养成分;稻田合理灌溉、提高水稻的收获指数、选育和种植CH4排放低的水稻品种等。减少农田N2O排放的主要措施和对策包括:提高氮肥利用率;推广施用长效肥和控释肥;施用生物抑制剂和实施微生物工程等。 相似文献
4.
通过对北京东灵山草地和桦树林土壤气体CO2,N2O和CH4浓度及其排放通量的昼夜连续观测,探讨了生长季节草地和森林土壤温室气体昼夜变化及其环境影响因素。研究表明:1)土壤CO2排放通量昼高夜低,N2O排放通量有明显小时尺度波动,但昼夜变化不突出;土壤CO2和N2O浓度昼夜变化不明显,且与排放通量波动不一致;土壤是大气CH4的一个汇,相对厌氧的环境可能有利于土壤吸收CH4。2)无雨时气温昼夜变化通过影响土壤表层的气体扩散和CO2产生过程,来影响土壤CO2和N2O的地表排放通量,而对土壤10cm以下CO2和N2O的产生影响不大。小时尺度的土壤CO2和N2O浓度波动则可能还有其他影响因素或机制。3)降雨时土壤渗水引起的土壤空气对流取代气体浓度扩散成为土壤与大气空气交换的主要方式,导致土壤CO2和N2O排放通量的同步波动。降雨渗水较多时,较多的溶解氧随着雨水进入土壤内,会促进土壤CO2的生成和抑制N2O的产生。4)土壤CO2与N2O浓度存在显著的正相关关系,反映出土壤CO2和N2O有相对稳定的产率比。土壤有效碳可能是造成土壤CO2与N2O浓度正相关的主要原因,土壤空气的氧分压则可能是造成土壤CO2和N2O浓度波动不一致的重要因素。 相似文献
5.
6.
东天山造山带的图拉尔根镁铁-超镁铁杂岩体为一个早古生代长期活动的幔源岩浆通道,大型铜镍钴硫化物矿体赋存于Ⅰ号超镁铁质岩体的顶部,不同类型岩石中辉石矿物的流体挥发份化学组成以H2O为主（平均91%,5400.4mm3/g）,其次为H2（2.0%）、H2S（2.3%）和CO2（2.1%）;赋矿角闪橄榄岩中CO2和H2S含量最高,辉长岩中流体挥发份含量低于辉石橄榄岩和橄榄辉石岩等岩浆早期结晶的岩石。CO2和CH4的δ13C值位于地壳与甲烷氧化的范围内,甲烷同系物的碳同位素组成具有正序分布模式,部分样品（TLG512）释出的CH4和C2H6具有较重的δ13C值和反序分布特征。表明I号岩体不同类型岩石可能是不同期次岩浆活动的产物,成矿岩浆具有富H2O和H2S的特征,可能起源于被流体交代的亏损地幔源区,混染壳源组分可能为俯冲板片来源蚀变沉积有机质组分。 相似文献
7.
腾冲新生代火山区温泉CO2气体排放通量研究 总被引：6，自引：6，他引：0
近期研究表明,不仅火山喷发期会向当时的大气圈输送大量的温室气体,火山间歇期同样会释放大量的温室气体。在火山活动间歇期,火山区主要以喷气孔、温(热)泉以及土壤微渗漏等形式向大气圈释放温室气体。腾冲是我国重要的新生代火山区,同时也是重要的水热活动区,那里出露大量的温泉,然而目前未见腾冲火山区温泉气体排放通量的研究报道。本文利用数字皂膜通量仪测量了腾冲新生代火山区温泉中CO2的排放通量。研究结果表明,腾冲新生代火山区温泉向当今大气圈输送的CO2通量达3.58×103 t·a-1,相当于意大利锡耶纳Bassoleto地热区温泉中CO2的排放规模。腾冲火山区温泉的CO2释放通量主要受深部岩浆囊、断裂分布、地下水循环、围岩成分等多方面因素的影响。本文根据温泉中CO2的排放特征,将腾冲温泉分为南北两区,南区温泉CO2通量远高于北区的温泉,热海地热区的通量为腾冲CO2通量的最大值。在北温泉区,CO2通量主要受控于断裂的分布;而在南温泉区,除受到断裂控制外,热海地热区底部的岩浆囊及其与围岩的相互作用成为CO2气体的重要物质来源,同时高温的岩浆囊为温泉及CO2的形成提供了重要热源。 相似文献
8.
营厂岩体分布于辽北西丰县和隆镇境内，研究结果表明，该岩体主要为似斑状二长花岗岩，锆石206Pb/238U年龄加权平均值为156.1 Ma±1.5 Ma，形成时代为晚侏罗世。营厂岩体w（Na2O）/w（K2O）平均值为1.07，属高钾钙碱性系列；里特曼指数σ平均值为2.15，属钙碱系列；铝饱和指数A/CNK平均值为1.16，A/CN平均值为1.99，属过铝型；Rb、Sr、Ba、Th、Hf含量偏高，Cr、Ni、Co、V、Rb、Zr、Nb等元素含量低，为"S"型花岗岩特征。稀土元素总量平均值为w（ΣREE）＝82.80×10-6，w（LREE）/w（HREE）=15.76，w（La）N/w（Yb）N=24.32，表明其轻稀土相对富集，重稀土相对亏损，稀土配分曲线右倾。δEu=0.80，铕弱负异常，说明成因与板块运动有关，w（Sm）/w（Nd）=0.20，w（Ba）/w（Sr）=1.60，w（K）/w（Rb）=249.15，表明具有壳源性质。营厂岩体具有埃达克岩的特点，其属于受太平洋板块向欧亚板块俯冲作用的影响，在挤压环境下加厚下地壳部分熔融，从而形成活动陆缘型花岗岩。 相似文献
9.
河北省青龙满族自治县四拨子-六拨子钼铜矿位于燕辽成矿带东部,是近年来发现的中型钼铜矿床。辉钼矿呈细脉状、网脉状、浸染状、薄膜状赋存于长城系石英砂岩及白云岩中的矽卡岩带,钼矿化与硅化关系密切。矿体呈似层状、脉状和透镜状。矿床的形成经历了矽卡岩期和石英-硫化物期,铜和钼矿化主要形成于石英-硫化物期。研究表明,矽卡岩期矿物以发育液体包裹体为特征,石英-硫化物期石英中主要发育液体包裹体、含CO2两相和三相包裹体。矽卡岩期成矿流体为高-中温(192~497℃)、中-低盐度(5.41%~16.53% NaCleqv)、中-低密度(0.59~0.92g/cm3)的NaCl-H2O体系。石英-硫化物期成矿流体为中-低温(主要变化于160~330℃)、低盐度(2.07%~15.17% NaCleqv)和中低密度(0.69~1.01g/cm3)的NaCl-H2O-CO2 (±CH4/N2)型流体。石英的δDSMOW为-128‰~-80‰,δ18OSMOW值为9.6‰~14‰,δ18OH2O值为-3.61%~5.30‰,表明成矿流体具有岩浆水混合大气降水的特征。硫化物的δ34S变化于-0.9‰~5.7‰,平均值为2.9‰,表明成矿物质中硫来自深部岩浆。成矿时代为早侏罗世早期,成矿作用与花岗斑岩岩浆期后热液活动有关。 相似文献
10.
通过福建省寿宁县多目标区域地球化学调查,查明了土壤硒分布和富集特征,研究了土壤硒与pH值及其他元素的相关关系。结果表明,表层土壤硒含量为0.13~0.92 mg/kg,平均值为0.35 mg/kg,深层土壤硒含量为0.14~0.54mg/kg,平均值为0.29 mg/kg,燕山晚期正常花岗岩（ξγK1）发育的土壤中硒含量最高,平均值为0.39mg/kg,其次为南园组四段（J3n4）和小溪组上段（K1x2）发育的土壤,不同土壤类型硒平均含量呈现出黄壤 > 红壤 > 水稻土的特点。表层土壤总体上属于富硒、足硒土壤,富硒土壤面积为405.04 km2,占28.24%,表层土壤硒含量相对于深层土壤表现出明显的富集特征,强烈富集区域与富硒土壤区域基本吻合,具有开发富硒农产品的潜力。相关分析表明,土壤硒含量与TOC、Al2O3、TFe2O3、Mn等呈显著正相关,与pH呈显著负相关,说明土壤理化性质、铁锰氧化物等对硒的表生地球化学行为有重要影响。 相似文献
11.
Methane and carbon dioxide flux from a macrotidal salt marsh,Bay of Fundy,New Brunswick 总被引：1，自引：0，他引：1
Fluxes of methane (CH4) and carbon dioxide (CO2) to the atmosphere at 52 sites within a salt marsh were measured by a dark static chamber technique from mid July to mid September. Mean CH4 fluxes ranged from 0.2 mg m?2 d?1 to 11.0 mg m?2 d?1, with an overall average of 1.6 mg m?2 d?1. Flux of CH4 was inversely correlated (r2=0.23, p = 0.001) with salinity of the upper porewater at the site, suggesting the dominant role of SO4 2? in inhibiting methanogenesis in salt-marsh sediments. The combination of salinity and water table position was able to explain only 29% of the variance in CH4 emission. Mean soil flux of CO2 ranged from 0.3 g m?2 d?1 to 3.7 g m?2 d?1, with an overall average of 2.5 g m?2 d?1; it was correlated with aboveground biomass (positive, r2=0.38, p = 0.001) and position of the water table (negative, r2 = 0.55, p = 0.001). The combination of biomass and water table position accounted for 63% of the variance in CO2 flux. There were high variations in gas flux within the six plant communities. The sequences were CH4: upland edge > panne > pool > middle marsh > low marsh > high marsh, and CO2: middle marsh > low marsh > upland edge > high marsh > panne > pool. Compared to other salt-marsh systems, this Bay of Fundy marsh emits small amounts of CH4 and CO2. 相似文献
12.
Eddy covariance based methane flux in Sundarbans mangroves,India 总被引：1，自引：0，他引：1
Chandra Shekhar Jha Suraj Reddy Rodda Kiran Chand Thumaty A K Raha V K Dadhwal 《Journal of Earth System Science》2014,123(5):1089-1096
We report the initial results of the methane flux measured using eddy covariance method during summer months from the world’s largest mangrove ecosystem, Sundarbans of India. Mangrove ecosystems are known sources for methane (CH4) having very high global warming potential. In order to quantify the methane flux in mangroves, an eddy covariance flux tower was recently erected in the largest unpolluted and undisturbed mangrove ecosystem in Sundarbans (India). The tower is equipped with eddy covariance flux tower instruments to continuously measure methane fluxes besides the mass and energy fluxes. This paper presents the preliminary results of methane flux variations during summer months (i.e., April and May 2012) in Sundarbans mangrove ecosystem. The mean concentrations of CH4 emission over the study period was 1682 ± 956 ppb. The measured CH4 fluxes computed from eddy covariance technique showed that the study area acts as a net source for CH4 with daily mean flux of 150.22 ± 248.87 mg m?2 day?1. The methane emission as well as its flux showed very high variability diurnally. Though the environmental conditions controlling methane emission is not yet fully understood, an attempt has been made in the present study to analyse the relationships of methane efflux with tidal activity. This present study is part of Indian Space Research Organisation–Geosphere Biosphere Program (ISRO–GBP) initiative under ‘National Carbon Project’. 相似文献
13.
Although the sediments of coastal marine mangrove forests have been considered a minor source of atmospheric methane, these estimates have been based on sparse data from similar areas. We have gathered evidence that shows that external nutrient and freshwater loading in mangrove sediments may have a significant effect on methane flux. Experiments were performed to examine methane fluxes from anaerobic sediments in a mangrove forest subjected to secondary sewage effluents on the southwestern coast of Puerto Rico. Emission rates were measured in situ using a static chamber technique, and subsequent laboratory analysis of samples was by gas chromatography using a flame ionization detector. Results indicate that methane flux rates were lowest at the landward fringe nearest to the effluent discharge, higher in the seaward fringe occupied by red mangroves, and highest in the transition zone between black and red mangrove communities, with average values of 4 mg CH4 m?2 d?1, 42 mg CH4 m?2 d?1, and 82 mg CH4 m?2 d?1, respectively. Overall mean values show these sediments may emit as much as 40 times more methane than unimpacted pristine areas. Pneumatophores ofAviciennia germinans have been found to serve as conduits to the atmosphere for this gas. Fluctuating water level overlying the mangrove sediment is an important environmental factor controlling seasonal and interannual CH4 flux variations. Environmental controls such as freshwater inputs and increased nutrient loading influence in situ methane emissions from these environments. 相似文献
14.
Lihua Zhang Changchun Song Xunhua Zheng Dexuan Wang Yiyong Wang 《Environmental Geology》2007,52(3):529-539
Freshwater marshes could be a source of greenhouse gases emission because they contain large amounts of soil carbon and nitrogen.
These emissions are strongly influenced by exogenous nitrogen. We investigate the effects of exogenous nitrogen on ecosystem
respiration (CO2), CH4 and N2O emissions from freshwater marshes in situ in the Sanjiang Plain Northeast of China during the growing seasons of 2004 and
2005, using a field fertilizer experiment and the static opaque chamber/GC techniques. The results show that there were no
significant differences in patterns of seasonal variations of CO2 and CH4 among the fertilizer and non-fertilizer treatments, but the seasonal patterns of N2O emission were significantly influenced by the exogenous nitrogen. Seasonal averages of the CO2 flux from non-fertilizer and fertilizer were 987.74 and 1,344.35 mg m
−2 h
−1, respectively, in 2004, and 898.59 and 2,154.17 mg m
−2 h
−1, respectively, in 2005. And the CH4 from the control and fertilizer treatments were 6.05 and 13.56 mg m
−2 h
−1 and 0.72 and 1.88 mg m
−2 h
−1, respectively, in 2004 and 2005. The difference of N2O flux between the fertilizer and non-fertilizer treatments is also significant either in 2004 and 2005. On the time scale
of 20-, 100-, and 500-year periods, the integrated global warming potential (GWP) of CO2 + CH4 + N2O released during the two growing seasons for the treatment of fertilizer was 97, 94 and 89%, respectively, higher than that
for the control, which suggested that the nitrogen fertilizer can enhance the GWP of the CH4 and N2O either in long time or short time scale. 相似文献
15.
Gas flux measurements have for the first time been taken from vents and soil of eastern Romania mud volcanoes, the largest geological structures in Europe releasing methane into the atmosphere. In the quiescent phase, the methane emission from single vents is up to 28 t yr?1. Diffuse soil microseepage is of the order of 102?105 mg m?2 day?1. A total output of at least 1200 tonnes of CH4 per year can be conservatively estimated over the area investigated alone (～ 2.3 km2). Helium fluxes are up to five orders of magnitude higher than the average flux in a stable continental area, pointing to a close link between mud volcanoes and crustal degassing through faults crossing the deep hydrocarbon reservoirs. These data represent a key contribution towards refining global CH4‐emission estimates, which indicate mud volcanoes as a significant and unavoidable source of greenhouse gases for the atmosphere. 相似文献
16.
Derrick Y. F. Lai 《Environmental Geology》2009,58(6):1197-1206
Peatlands are a large potential source of methane (CH4) to the atmosphere. In order to investigate the effects of climate change on CH4 emission from northern ombrotrophic peatlands, a simulation model coupling water table dynamics with methane emission was
developed for the Mer Bleue Bog in Ontario, Canada. The model was validated against reported values of CH4 flux from field measurements and the model outputs exhibited high sensitivity to acrotelm thickness, leaf area index, transmissivity
and slope of water table. With a 2–4°C temperature rise over the 4-year simulation period, the rate of CH4 release dropped significantly to under 0.1 mg m−2 day−1. On the other hand, mean CH4 emission increased by >26-fold when the increase in precipitation was >15%. When looking at the combined effects, the highest
CH4 release (13.3 mg m−2 day−1) was attained under the scenario of 2°C temperature rise and 25% precipitation increase. Results obtained in this study highlight
the importance of avoiding more extreme climate change, which would otherwise lead to enhanced methane release from peatlands
and further atmospheric warming through positive feedback. 相似文献
17.
Methane release from soils of a Georgia salt marsh 总被引：1，自引：0，他引：1
A seasonal study of methane release from marsh soils to the atmosphere indicates that ebullition is a significant process varying both seasonally and spatially. Release rates are higher during summer months than winter months and ebullition is greatest in the short Spartina alterniflora marshes and least in the tall S. alterniflora marshes. The annual amounts of methane released in the short and tall marshes are 53.1 and 0.4 gm?3 which represents a loss of 8.8 and 0.002% of the net carbon fixation in the two respective marsh types.In vitro experimentation shows that methane production is sensitive to changes in temperature and addition of H2 and CO2. 相似文献
18.
Yan-hua Wang Chun Ye Hao Yang Ji-xiang Zhang Chang-chun Huang Biao Xie 《Environmental Earth Sciences》2013,70(4):1647-1652
The present study evaluated the effect of plant species on methane (CH4) emission and microbial populations in three types of soil–plant systems. Results showed large variation of CH4 flux rate ranging from 1.35 to 212.61 mg CH4 m?2 h?1. Emission peak of CH4 occurred in July. No significant difference was found in the non-vegetation system spanning 2 years. Compared with non-vegetation, vegetation systems had much higher flux of CH4, and obvious seasonal variation was observed. The polyculture system planted with Zizania latifolia (Z. latifolia) and Phragmites australis (P. australis) released higher CH4 fluxes than the mono system (P. australis), reflecting that Z. latifolia growth could simulate CH4 emission. The fluorescence in situ hybridization (FISH) results support the characteristics of CH4 fluxes. Much higher methanotrophs amount and lower methanogens amount from the mono system than those from the polyculture system was observed indicating that Z. latifolia growth may limit the oxygen transportation resulting in higher CH4 emission. The polyculture system has the highest potential of CH4 emission. 相似文献
19.
Fredric Lipschultz 《Estuaries and Coasts》1981,4(2):143-145
Gaseous methane loss from a brackish, intertidal salt marsh sediment was measured in April, June, August, and October 1977. Twenty-four sediment cores were taken on each date. Annual loss of methane carbon from the mud flats was 10.7 g CH4?C per m2 per year, a value closer to freshwater values than marine systems. Loss of methane fromSpartina peat was low. 相似文献
20.
冻土区甲烷排放研究进展 总被引：6，自引：0，他引：6
冻土区土牡表面和活动层土的ＣＨ４排放和吸收表现出强烈的时空变化性。根据多年冻土中ＣＨ４含量的模拟结果表明，全球尺度上，平均每米厚度多年冻土含有ＣＨ４６５Ｔｇ。在未来的２００年间，多年冻土融化所导致的大气ＣＨ４附加年源强变化于２～２５Ｔｇ。 相似文献