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1.
对中国贵州省不同类型的民用燃煤的ＣＨ４释放量进行了实际监测,得出了各自的ＣＨ４释放因子,并借此探讨了民用燃煤过程的ＣＨ４释放规律。根据民用燃煤情况,估算出１９９０年一年内中国和贵州省民用燃煤的ＣＨ４释放量分别为１．４３Ｔｇ和０．０６Ｔｇ。 相似文献
2.
作者对渭南黄土剖面连续采取的样品进行了系统的１４Ｃ和ＴＬ年龄测定，测得的１４Ｃ年龄做了δ１３Ｃ校正和日历年龄校正，并与ＳＰＥＣＭＡＰ比较，取得了很好的结果。根据测得的年龄，Ｓ０底部１４３ｃｍ处的１４Ｃ年龄为１０３００ａＢ．Ｐ，即全新世起始于１０３００ａＢ．Ｐ．；Ｌ１可划分五层，其中Ｌ(１－２)和Ｌ(１－４)为古土壤层，Ｌ(１－２)顶部１４Ｃ年龄为２２０００ａＢ．Ｐ．，深度为３６１ｃｍ，Ｌ(１－４)．底部有一层明显的碳酸盐结核，其ＴＬ年龄为５１９１０ａＢ．Ｐ．，深度为６４０Ｃｍ；Ｌ１底部的ＴＬ年龄为７３０００ａＢ．Ｐ．，深度为８５５ｃｍ，这便是马兰黄土的起始年龄；Ｓ１底部为１３４５００ａＢ．Ｐ．，深度为１２１６ｃｍ。与深海沉积物氧同位素阶段对比，马兰黄土相当于１—４阶段，Ｓ１相当于５阶段。 相似文献
3.
若尔盖高原沼泽湿地CH4排放研究 总被引：26，自引：0，他引：26
若尔盖高原沼泽湿地海拔 3400 m，面积 4038km2，是我国面积最大的高原沼泽湿地分布区。2001年 5～9月的非冰冻期，其主要沼泽类型木里苔草沼泽的CH4排放通量范围是 0.51～ 8.20 m g/（m 2· h），平均值为 2.87 m g/（m 2· h）；乌拉苔草沼泽CH4排放通量范围是 0.36～10.04 m g/（m 2· h），平均值为 4.51 m g/（m 2· h）。在空间分布上，不同沼泽类型之间CH4排放通量具有一定的差异。在季节变化上，没有明显的排放高峰。根据代表性观测点的CH4平均排放量、日数和沼泽总面积推算，非冰冻期若尔盖高原沼泽湿地CH4的排放量为 0.052Tg/a。 相似文献
4.
作者通过对陕西洛川黄土剖面中碳酸盐总量、氧化物比值和元素演化周期性的分析，讨论了黄土高原地区２．４Ｍａ以来古气候的演化模式。对渭南黄土剖面高密度连续采集的样品，着重分析了ＣａＣＯ３、Ｆｅ2Ｏ３／ＦｅＯ值和有机碳的高分辨记录。指出它们的变化彼此同步(但趋势不尽相同)，与黄土一古土壤系列变化一致，井与深海沉积物氧同位素可进行良好的对比。它们综合反映了该区１３４５００年来有五次万年级的暖湿(或凉湿)一冷干的气候波动，其中各期又有若干次级的小颤动。它们的变化与季风影响强弱程度明显有关。 相似文献
5.
青藏高原五道梁冻土活动层表面二氧化碳和甲烷的排放 总被引：9，自引：3，他引：9
通过静态箱取样方法，首次获得青藏高原冻土活动层排放气体。分析测定结果表明，ＣＨ４含量为０．６３～１．５４μｇ／ｇ，平均为１．１９μｇ／ｇ，大多数样品ＣＨ４含量低于当地大气ＣＨ４含量（１．３２μｇ／ｇ）；ＣＯ２含量为０．１５％～０．２７％，平均为０．２１％，明显高于大气ＣＯ２的浓度（０．０６９％）。ＣＨ４、ＣＯ２含量具有一定的日变化特征。ＣＨ４排放率为－０．０３２～０．０４８ｍｇｍ－２ｈ－１，平均为０．００１ｍｇｍ－２ｈ－１；ＣＯ２排放率为－５６．５０３～６１．４２５ｍｇｍ－２ｈ－１，平均为０．０９５ｍｇｍ－２ｈ１。从所获得的冻土排放气体中ＣＨ４和ＣＯ２的浓度来看，这种干燥寒冷的高原冻土活动层表面ＣＨ４排放较少，ＣＯ２的排放较高 相似文献
6.
青藏高原花石峡冻土站高寒湿地CH4排放研究 总被引：10，自引：3，他引：7
利用静态箱技术对青藏高原花石峡冻土站附近湿地生态系统ＣＨ４排放的初步调查表明,各个植物群落内部和不同群落之间的ＣＨ４排放量变化都很大．花石峡地区高寒湿地基本可分为潮湿高寒草甸、沼泽化草甸、杉叶藻沼泽和毛柄水毛茛沼泽,其群落夏季ＣＨ４平均排放量分别为４４３１,１００５,４５９４和－０２８ｍｇ·ｍ－２ｄ－１．花石峡融化季节ＣＨ４排放量为４０８ｇ·ｍ－２ａ－１．简单外推表明,青藏高原高寒湿地ＣＨ４年排放量约为１Ｔｇ·ａ－１． 相似文献
7.
极地冰盖气泡研究表明,工业革命前大气圈天然ＣＯ2浓度约为２８０×１０－６,天然ＣＯ2浓度变化反映了冰期－间冰期循环这一长期气候变化固有特征。工业革命后,大量人为ＣＯ2进人大气圈,人为ＣＯ2收支明显不平衡,一个大于２．６ＧＴＣ／ａ的未知陆地生态汇很可能存在于北半球中纬度地带。土壤、岩溶作用、河流作用、地球化学作用、干旱－半干旱环境等系统以及海洋内部ＣＯ2循环的同位素示踪研究,可为人为ＣＯ2未知汇即“ＭｉｓｓｉｎｇＳｉｎｋ”的探求提供线索。 相似文献
8.
利用Ｂ／Ｍ地磁极性倒转层位０．７３ＭａＢ．Ｐ．时间参考点，通过黄土剖面１０Ｂｅ变化曲线与深海ＳＰＥＣＭＡＰδ１８Ｏ变化曲线匹配拟合，求得洛川黄土剖面０．７５Ｍａ以来的相对连续时标。时标精度约５０００—１００００ａ。由于０．１５Ｍａ以来洛川剖面加密取样以及１０Ｂｅ、δ１８Ｏ两曲线之间更好的相关性，１０Ｂｅ相对时标精度与ＳＰＥＣＭＡＰδ１０Ｏ时标精度大体相同，即３０００—５０００ａ。各时期１０Ｂｅ通量与黄土堆积速率之间存在十分好的线性相关关系，展示了一条崭新的地层定年途径。黄土１０Ｂｅ记录３５０００ａＢ．Ｐ．处的Ｒａｉｓｂｅｃｋ峰可被用作地层时间参考点。黄土１０Ｂｅ／(２６)Ａｌ值、黄土石英中“就地”成因１０Ｂｅ／(２６)Ａｌ值以及“就地”成因１０Ｂｅ浓度等均可望应用于黄土地层精确定年。 相似文献
9.
甲烷水合物是由天然气（主要是ＣＨ４）和水组成的象冰一样的化合物，其晶体结构有效地凝缩着ＣＨ４（每立方米的水合物可以产生超过１５０立方米的ＣＨ４）。水合物“粘结”沉积并给予相当的机械强度；它们填满孔隙并限制了渗透率。生物成因和热成因的两种ＣＨ４都已从水合物中回采。 相似文献
10.
脉型金矿流体包裹体的研究表明，含金的成矿流体多为低盐度，含较多的ＣＯ２和一定量的ＣＨ４。在金大量沉淀阶段的石英中往往有不混溶包裹体发育，因此一般认为流体的不混溶导致了金的沉淀。前人的高温高压实验资料表明在ＣＯ２－Ｈ２Ｏ－ＮａＣｌ体系中有少量ＣＨ４的加主，可以扩大该体系的不混溶区。三个实例一方面说明了ＣＨ４与金的成矿有着密切的关系；另一方面，ＣＨ４的存在反映了成矿流体的还原性，这正是金迁移沉淀折必需 相似文献
11.
《China Geology》2022,5(3):475-509
Global warming and the response to it have become a topic of concern in today’s society and are also a research focus in the global scientific community. As the world’s third pole, the global warming amplifier, and the starting region of China’s climate change, the Qinghai-Tibet Plateau is extremely sensitive to climate change. The permafrost on the Qinghai-Tibet Plateau is rich in natural gas hydrates (NGHs) resources. Under the background of global warming, whether the NGHs will be disassociated and enter the atmosphere as the air temperature rises has become a major concern of both the public and the scientific community. Given this, this study reviewed the trend of global warming and accordingly summarized the characteristics of the temperature increase in the Qinghai-Tibet Plateau. Based on this as well as the distribution characteristics of the NGHs in the permafrost on the Qinghai-Tibet Plateau, this study investigated the changes in the response of the NGHs to global warming, aiming to clarify the impacts of global warming on the NGHs in the permafrost of the plateau. A noticeable response to global warming has been observed in the Qinghai-Tibet Plateau. Over the past decades, the increase in the mean annual air temperature of the plateau was increasingly high and more recently. Specifically, the mean annual air temperature of the plateau changed at a rate of approximately 0.308–0.420°C/10a and increased by approximately 1.54–2.10°C in the past decades. Moreover, the annual mean ground temperature of the shallow permafrost on the plateau increased by approximately 1.155–1.575°C and the permafrost area decreased by approximately 0.34×106 km2 from about 1.4×106 km2 to 1.06×106 km2 in the past decades. As indicated by simulated calculation results, the thickness of the NGH-bearing permafrost on the Qinghai-Tibet Plateau has decreased by 29–39 m in the past 50 years, with the equivalent of (1.69 – 2.27)×1010–(1.12–1.51)×1012 m3 of methane (CH4) being released due to NGHs dissociation. It is predicted that the thickness of the NGH-bearing permafrost will decrease by 23 m and 27 m, and dissociated and released NGHs will be the equivalent of (1.34–88.8)×1010 m3 and (1.57–104)×1010 m3 of CH4, respectively by 2030 and 2050. Considering the positive feedback mechanism of NGHs on global warming and the fact that CH4 has a higher greenhouse effect than carbon dioxide, the NGHs in the permafrost on the Qinghai-Tibet Plateau will emit more CH4 into the atmosphere, which is an important trend of NGHs under the background of global warming. Therefore, the NGHs are destructive as a time bomb and may lead to a waste of efforts that mankind has made in carbon emission reduction and carbon neutrality. Accordingly, this study suggests that human beings should make more efforts to conduct the exploration and exploitation of the NGHs in the permafrost of the Qinghai-Tibet Plateau, accelerate research on the techniques and equipment for NGHs extraction, storage, and transportation, and exploit the permafrost-associated NGHs while thawing them. The purpose is to reduce carbon emissions into the atmosphere and mitigate the atmospheric greenhouse effect, thus contributing to the global goal of peak carbon dioxide emissions and carbon neutrality.©2022 China Geology Editorial Office. 相似文献
12.
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
13.
Natural seabed gas seeps as sources of atmospheric methane 总被引：5，自引：0，他引：5
Microbial and thermogenic methane migrates towards the seabed where some is utilised during microbially-mediated anaerobic oxidation. Excess methane escapes as gas seeps, which occur in a variety of geological contexts in every sea and ocean, from inter-tidal zones to deep ocean trenches. Some seeps are localised, gentle emanations; others are vigorous covering areas of >1 km2; the most prolific seeps reported (offshore Georgia) produce ~40 t CH4 per year. Gas bubbles lose methane to the water as they rise, so deep water seeps are unlikely to contribute to the atmosphere. However, bubbles break the surface above some shallow water seeps. Estimates of the total methane contribution to the atmosphere are poorly constrained, largely because the data set is so small. 20 Tg yr–1 is considered a realistic first approximation. This is a significant contribution to the global budget, particularly as methane from seeps is 14C-depleted. A seep measurement programme is urgently required.GEM 相似文献
14.
《Atmósfera》2014,27(2):185-191
Anaerobic fermentation of structural carbohydrates in the rumen of bovines produces waste products such as volatile fatty acids, fermentation heat, carbon dioxide and methane gas. Methane is a greenhouse gas having several times the global warming potential of CO2. The purpose of the present paper is to provide a realistic estimate of the national inventory of methane produced by the enteric fermentation of cattle, based on a simulation model and to provide estimates of CH4 produced by cattle fed typical diets from the tropical and temperate climates of Mexico. Predicted total emission of methane produced by the 23.3 million heads of cattle in Mexico is approximately 2.02 Tg/yr. It was concluded that the modeling approach was suitable in producing a better estimate of the national methane inventory for cattle. It is flexible enough to incorporate more cattle groups or classification schemes, productivity levels and a variety feed ingredients for cattle. The model could also be used to evaluate different mitigation strategies and serve as a tool to design mitigation policies. 相似文献
15.
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
16.
Hydraulic fracturing of shale deposits has greatly increased the productivity of the natural gas industry by allowing it to exploit previously inaccessible reservoirs. Previous research has demonstrated that this practice has the potential to contaminate shallow aquifers with methane (CH4) from deeper formations. This study compares concentrations and isotopic compositions of CH4 sampled from domestic groundwater wells in Letcher County, Eastern Kentucky in order to characterize its occurrence and origins in relation to both neighboring hydraulically fractured natural gas wells and surface coal mines. The studied groundwater showed concentrations of CH4 ranging from 0.05 mg/L to 10 mg/L, thus, no immediate remediation is required. The δ13C values of CH4 ranged from −66‰ to −16‰, and δ2H values ranged from −286‰ to −86‰, suggesting an immature thermogenic and mixed biogenic/thermogenic origin. The occurrence of CH4 was not correlated with proximity to hydraulically fractured natural gas wells. Generally, CH4 occurrence corresponded with groundwater abundant in Na+, Cl−, and HCO3−, and with low concentrations of SO42−. The CH4 and SO42−concentrations were best predicted by the oxidation/reduction potential of the studied groundwater. CH4 was abundant in more reducing waters, and SO42− was abundant in more oxidizing waters. Additionally, groundwater in greater proximity to surface mining was more likely to be oxidized. This, in turn, might have increased the likelihood of CH4 oxidation in shallow groundwater. 相似文献
17.
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
18.
中国农田的温室气体排放 总被引：70，自引：2，他引：70
李长生 肖向明 S.Frolking B·Moore Ⅲ W.Salas 邱建军 张宇 庄亚辉 王效科 戴昭华 刘纪远 秦小光 廖柏寒 R.Sass 《第四纪研究》2003,23(5):493-503
中国是一个农业大国,拥有约1.33百万平方公里的农田。这些田地的种植、翻耕、施肥、灌溉等管理措施不仅长期改变着农田生态系统中的化学元素循环,而且给全球气候变化带来影响。农业生态系统对全球变化的影响主要是通过改变3种温室气体,即二氧化碳(CO2)、甲烷(CH4)和氧化亚氮(N2O)在土壤-大气界面的交换而实现的。为了分析多种因素(如气候、土壤质地、农作物品种及各种农田经营管理措施等)对农业土壤释放CO22222222 相似文献
19.
Permian Khuff reservoirs along the east coast of Saudi Arabia and in the Arabian Gulf produce dry sour gas with highly variable nitrogen concentrations. Rough correlations between N2/CH4, CO2/CH4 and H2S/CH4 suggest that non-hydrocarbon gas abundances are controlled by thermochemical sulfate reduction (TSR). In Khuff gases judged to be unaltered by TSR, methane δ13C generally falls between −40‰ and −35‰ VPDB and carbon dioxide δ13C between −3‰ and 0‰ VPDB. As H2S/CH4 increases, methane δ13C increases to as much as −3‰ and carbon dioxide δ13C decreases to as little as −28‰. These changes are interpreted to reflect the oxidation of methane to carbon dioxide.Khuff reservoir temperatures, which locally exceed 150 °C, appear high enough to drive the reduction of sulfate by methane. Anhydrite is abundant in the Khuff and fine grained nodules are commonly rimmed with secondary calcite cement. Some cores contain abundant pyrite, sphalerite and galena. Assuming that nitrogen is inert, loss of methane by TSR should increase N2/CH4 of the residual gas and leave δ15N unaltered. δ15N of Paleozoic gases in Saudi Arabia varies from −7‰ to 1‰ vs. air and supports the TSR hypothesis. N2/CH4 in gases from stacked Khuff reservoirs varies by a factor of 19 yet the variation in δ15N (0.3–0.5‰) is trivial.Because the relative abundance of hydrogen sulfide is not a fully reliable extent of reaction parameter, we have attempted to assess the extent of TSR using plots of methane δ13C versus log(N2/CH4). Observed variations in these parameters can be fitted using simple Rayleigh models with kinetic carbon isotope fractionation factors between 0.98 and 0.99. We calculate that TSR may have destroyed more than 90% of the original methane charge in the most extreme instance. The possibility that methane may be completely destroyed by TSR has important implications for deep gas exploration and the origin of gases rich in nitrogen as well as hydrogen sulfide. 相似文献