利用卫星光谱分析技术进行断层逸出气体监测

在不少震例中,临震前地壳出现气体异常,震前地下岩石受力产生裂隙,隐藏在地层中的CO2、CH4等温室气体逸出地表或水面。利用卫星光谱分析技术对断层逸出气体组分含量和总量进行监测,筛选出能够反应地震孕育过程中地下逸出气体异常演化特征的参数,建立地震短期预测的动态演化方法。对于认识震前地表气体异常机理,了解流体震兆的演变规律与这些气体异常的动态关系,改善卫星遥感地震预测,是很必要的。     

Impact of climate change on wetland ecosystems: A critical review of experimental wetlands

Climate change is identified as a major threat to wetlands. Altered hydrology and rising temperature can change the biogeochemistry and function of a wetland to the degree that some important services might be turned into disservices. This means that they will, for example, no longer provide a water purification service and adversely they may start to decompose and release nutrients to the surface water. Moreover, a higher rate of decomposition than primary production (photosynthesis) may lead to a shift of their function from being a sink of carbon to a source. This review paper assesses the potential response of natural wetlands (peatlands) and constructed wetlands to climate change in terms of gas emission and nutrients release. In addition, the impact of key climatic factors such as temperature and water availability on wetlands has been reviewed. The authors identified the methodological gaps and weaknesses in the literature and then introduced a new framework for conducting a comprehensive mesocosm experiment to address the existing gaps in literature to support future climate change research on wetland ecosystems. In the future, higher temperatures resulting in drought might shift the role of both constructed wetland and peatland from a sink to a source of carbon. However, higher temperatures accompanied by more precipitation can promote photosynthesis to a degree that might exceed the respiration and maintain the carbon sink role of the wetland. There might be a critical water level at which the wetland can preserve most of its services. In order to find that level, a study of the key factors of climate change and their interactions using an appropriate experimental method is necessary. Some contradictory results of past experiments can be associated with different methodologies, designs, time periods, climates, and natural variability. Hence a long-term simulation of climate change for wetlands according to the proposed framework is recommended. This framework provides relatively more accurate and realistic simulations, valid comparative results, comprehensive understanding and supports coordination between researchers. This can help to find a sustainable management strategy for wetlands to be resilient to climate change.     

It starts at home? Climate policies targeting household consumption and behavioral decisions are key to low-carbon futures

Through their consumption behavior, households are responsible for 72% of global greenhouse gas emissions. Thus, they are key actors in reaching the 1.5 °C goal under the Paris Agreement. However, the possible contribution and position of households in climate policies is neither well understood, nor do households receive sufficiently high priority in current climate policy strategies. This paper investigates how behavioral change can achieve a substantial reduction in greenhouse gas emissions in European high-income countries. It uses theoretical thinking and some core results from the HOPE research project, which investigated household preferences for reducing emissions in four European cities in France, Germany, Norway and Sweden. The paper makes five major points: First, car and plane mobility, meat and dairy consumption, as well as heating are the most dominant components of household footprints. Second, household living situations (demographics, size of home) greatly influence the household potential to reduce their footprint, even more than country or city location. Third, household decisions can be sequential and temporally dynamic, shifting through different phases such as childhood, adulthood, and illness. Fourth, short term voluntary efforts will not be sufficient by themselves to reach the drastic reductions needed to achieve the 1.5 °C goal; instead, households need a regulatory framework supporting their behavioral changes. Fifth, there is a mismatch between the roles and responsibilities conveyed by current climate policies and household perceptions of responsibility. We then conclude with further recommendations for research and policy.     

Fumarolic gases at Mombacho volcano (Nicaragua): presence of magmatic gas species and implications for volcanic surveillance

Mombacho is a deeply dissected volcano belonging to the Quaternary volcanic chain of Nicaragua. The southern, historic collapse crater (El Crater) currently hosts a fumarolic field with a maximum temperature of 121°C. Chemical and isotopic data from five gas-sampling field campaigns carried out in 2002, 2003 and 2005 highlight the presence of high-temperature gas components (e.g. SO₂, HCl and HF), which indicate a significant contribution of juvenile magmatic fluids to the hydrothermal system feeding the gas discharges. This is strongly supported by the mantle-derived helium and carbon isotopic signatures, although the latter is partly masked by either a sedimentary subduction-related or a shallow carbonate component. The observed chemical and isotopic composition of the Mombacho fluids seems to indicate that this volcanic system, although it has not experienced eruptive events during the last centuries, can be considered active and possibly dangerous, in agreement with the geophysical data recorded in the region. Systematic geochemical monitoring of the fumarolic gas discharges, coupled with a seismic and ground deformation network, is highly recommended in order to monitor a possible new eruptive phase.     

活动断裂带的壤中气汞量测量研究

在覆盖区应用壤中气汞量测量研究活动断裂是一种新方法,它不仅能较准确地确定活动断裂的位置,还可以确定其产状,规模,活动性及相对强度,甚至可以作为确定断裂力学性质的参考,本文简棕了断裂带壤中气汞量测量的基本原理,并以长江三峡,长春,吉林等地利用该种方法研究活动断裂的成果为例,说明该项研究的效果及应用前景。     

The Multiple Sources and Patterns of Methane inNorth Sea Waters

The methane concentration in the atmosphere andsurface water was surveyed along 58° N acrossthe North Sea. In addition, the vertical methanedistribution in the water column was determined at sixstations along the transect. The methane contents ofthe surface water as well as in the water column wereextremely inhomogeneous. Input by freshwater fromriver discharge and injection of methane from thesediment were both observed. The survey continued fromthe western side of the North Sea to the Elbe Riverestuary. The Elbe River appears to have low methaneconcentrations compared to other European rivers, itsaverage input into the North Sea is estimated to be70 nmol s-1 of methane. Near 58° N,1°40' E, an abandoned drill site releases about 25 % ofthe North Sea's emission of methane to the atmosphere.The advective methane transport induced by watercirculation was assessed for May 16, 1994, using a 3-DNorth Sea circulation model. For the period of thissurvey, the North Sea's source strength foratmospheric methane is estimated using in situwind velocities. In comparison to the advectivetransport by the water circulation, the gas flux tothe atmosphere appears to be the dominant sink ofNorth Sea methane. This flux is estimated to bebetween 1500 · 106 mol a-1 and 3100 ·106mol a-1, depending on the relationbetween wind speed and gas transfer velocity.     

Sources and sinks of atmospheric methane

In 1972 average mixing ratio of methane in the troposphere was 1.41 ppm and 1.3 ppmv for the northern and southern hemisphere, respectively, which corresponds to a total amount of 4×10¹⁵ g of CH₄ present in the atmosphere. Most is of recent biologic origin.¹⁴C analyses show that no more than 20 percent is released by fossil sources. The various ecosystems producing CH₄ are discussed and the total annual production is estimated to lie between 5.5×10¹⁴ g/yr and 11×10¹⁴ g/yr. The corresponding turnover times for atmospheric CH₄ range from 4 to 7 yrs. The destruction of CH₄ takes place mainly in the troposphere, most probably through the reaction of CH₄ + OH CH₃ + H₂O. About 10 percent of the CH₄ is destroyed in the stratosphere. The CH₄ cycle contributes on the order of 1 percent to the atmospheric carbon cycle.     

农业气象试验站温室土壤温度控制系统

采用８０３１,８２７９,８２５５,ＡＤＣ０８０９,２８６４,６２６４等芯片组成一实用的温室土壤温度控制系统。由键盘输入温室土壤的上,下限温度,通过ＡＤＣ０８０９对温室土壤温度进行采样,并实时显示土壤温度。当土壤温度超越上,下限时,系统报警,并进行自动处理。     

Atmospheric noble gases in volcanic glasses from the southern Lau Basin: origin from the subducting slab?

Noble gas concentrations and isotopic compositions have been determined for four submarine volcanic glasses from the Valu Fa Ridge (VFR) in the southern Lau Basin. The samples are the least differentiated ones from this area, and they display enrichments in fluid-mobile elements similar to the nearby island arc. ³He/⁴He ratios are slightly below average MORB (6.8–7.8 times atmospheric), whereas Ne, Ar, Kr, and Xe have isotopic compositions very similar to air. Together with previously published data from the Valu Fa Ridge and other spreading segments in the Lau Basin, our data show a systematic latitudinal variation of increasing Ne, Ar, Kr, and Xe abundances from north to south as well as Ne and Ar isotopic compositions changing from MORB-like to atmosphere-like in the same direction. Moreover, isotopic compositions and noble gas abundances of the lavas correlate strongly with Ba/Nb ratios and H₂O concentrations. Based on these observations and mass balance arguments, we propose that the atmospheric noble gases come from the subducting oceanic crust and are not due to shallow contamination with air dissolved in seawater or assimilation of old crust. Our data suggest that the noble gases released from the subducting slab are atmospheric and thus contain little or no solar He and Ne. In addition to the fact that ratios of He to heavy noble gases are small in aged ocean crust, He has possibly fractionated from the other noble gases due to its higher diffusivity, and thus He transport from the subducting slab into the mantle wedge is probably insignificant. We propose that the ³He/⁴He ratios lower than MORB observed in the VFR lavas result from radiogenic ingrowth of He in a highly depleted, and hence degassed, mantle wedge after the enrichment of U and Th released from the downgoing slab.     

The ocean as source or sink of reactive trace-gases

Summary After a brief review on recent experimental work on the uptake resp release of SO₂ and NH₃ by the ocean, new results on the distribution of these reactive trace-gases in the marine atmosphere are presented. In the case of SO₂ there is no doubt that the ocean acts as a sink. In the case of NH₃ new observations and calculations show that under certain conditions the ocean may be a NH₃ source.