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51.
Preface to the special issue on electromagnetic phenomena related to seismic and volcanic activities from EMSEV in 2016 下载免费PDF全文
<正>EMSEV,Electromagnetic Studies of Earthquake and Volcanoes,set up in 2002,is a joint academic organization by multi-associations in IUGG(International Union of Geodesy and Geophysics),including IAGA(International Association of Geomagnetism and Aeronomy),IASPEI(International Association of Seismology and Physics of the Earth’s Interior),IAVCEI(International Association of Volcanology and Chemistry of the Earth’s Interior).On 相似文献
52.
Beryllium-7 Deposition and Its Relation to Sulfate Deposition 总被引:2,自引:0,他引:2
Yasuhito Igarashi Katsumi Hirose Makiko Otsuji-Hatori 《Journal of Atmospheric Chemistry》1998,29(3):217-231
Deposition of 7Be, a cosmogenic radionuclide, was observed at the Meteorological Research Institute in Tsukuba, Japan from 1986 to 1993 and compared with those of several chemical species observed in Tsukuba over the same period. We found a correlation between the monthly depositions of 7 Be and SO 4 2 -, a major acidic species. The correlation was especially strong for late spring and fall, when both species had high depositional fluxes. This correlation was also observed in precipitation samples collected daily in 1992 at the same site. The cause of this correlation is discussed in connection with the fact that the stratospheric aerosol is composed largely of SO 4 2 -. 7 Be is produced in the upper atmosphere, and detection of 7Be, especially in spring and fall in Japan, can be regarded as detection of stratospheric aerosol. However, we conclude that the bulk of the SO 4 2 - observed did not have a stratospheric or an upper tropospheric origin. The correlation, therefore, may present a new question regarding acidic deposition: Why does the deposition of stratospheric aerosol in Japan coincide with that of nss-SO 4 2 - originally from anthropogenic sources on the Earth's surface? 相似文献
53.
The responses of atmospheric pCO2 and sediment calcite content to changes in the export rain ratio of calcium carbonate to organic carbon are examined using
a diffusion-advection ocean biogeochemical model coupled to a one-dimensional sediment geochemistry model. Our model shows
that a 25% reduction in rain ratio decreases atmospheric pCO2 by 59 ppm. This is caused by alkalinity redistribution by a weakened carbonate pump and an alkalinity increase in the whole
ocean via carbonate compensation with decreasing calcite burial. The steady state responses of sedimentary calcite content
and calcite preservation efficiency are rather insensitive to the deepening of the saturation horizon of 1.9 km. This insensitivity
is a result of the reduced deposition flux that decreases calcite burial, counteracting the saturation horizon deepening that
increases calcite burial. However, in the first 10,000 years the effect of reduced calcite deposition on the burial change
is more prominent; while after 10,000 years, the effect of saturation horizon deepening is more dominant. The lowering of
sediment calcite content for the first 10,000 years is effectively decoupled from the 1.9 km downward shift of the saturation
horizon. Our results are in part a consequence of the more dominant role that respiration CO2 plays in sediment calcite dissolution over bottom water chemistry in our control run and support the decoupling of calcite
lysocline depth and saturation horizon shifts, as suggested originally by Archer and Maier-Reimer (1994) and Archer et al. (2000). 相似文献
54.
L. Alappat M. Frechen S. Tsukamoto A. Vink 《Proceedings of the Geologists' Association. Geologists' Association》2012,123(4):666-668
The major concerns in the correspondence of Mauz (2012) was the correction applied for the calculation of cosmic dose in response of changing sea level in the past and statistical parameters used as well as the selection of MAM. A better approach is discussed in this note for the calculation of cosmic dose over a variable time span of rising sea level with the help of established sea level curves in the area. The selection of MAM-3 for the estimation of final De's are discussed in the article. The comments by Mauz (2012) have been helpful in rectifying some confusions that might have arisen in the original article of Alappat et al. (2010). However, some comments were merely speculative in nature and made by ignoring the statements that have been clearly mentioned in the article. After addressing various concerns of Mauz (2012), the results show that the variation in the final age due to this is small and within the uncertainty for all the samples. 相似文献
55.
Yusuke Tsukamoto 《Icarus》2011,212(2):911-919
56.
Tobias Lauer Manfred Frechen Sumiko Tsukamoto 《Proceedings of the Geologists' Association. Geologists' Association》2010,121(2):154-161
The Upper Rhine Graben (URG) is characterized by a thickness of up to 500 m of unconsolidated Quaternary sediments, providing excellent records of the Rhine river system and its responses to tectonic and climatic changes. The most complete Quaternary sequence of fluvial and limnic-fluvial deposits is found in the Heidelberg Basin, due to its long-term subsidence since the mid-Eocene. The aim of this study is to provide a chronological framework using optically stimulated luminescence (OSL) dating of aeolian and fluvial sands derived from the upper 33 m of a sediment core, which was drilled into the Heidelberg Basin infill close to the village of Viernheim, Germany. The OSL ages demonstrate that the dated fluvial sediments were deposited during the last glacial period (Weichselian) and that there were at least three aggradation periods during this episode. The coversands that cap the sequence were emplaced during the early Holocene. 相似文献
57.
58.
59.
Luminescence chronology of the upper part of the Stari Slankamen loess sequence (Vojvodina,Serbia) 总被引:1,自引:0,他引:1
E.D. Schmidt B. Machalett S.B. Marković S. Tsukamoto M. Frechen 《Quaternary Geochronology》2010,5(2-3):137-142
A thick Middle and Late Pleistocene loess-palaeosol sequence is exposed at the Stari Slankamen section in the Vojvodina region situated in the south-eastern part of the Pannonian basin, Serbia. The profile exposes an about 45 m thick series of loess intercalated by at least eight pedocomplexes. Ten samples were dated by luminescence methods using a modified single aliquot regenerative dose (SAR) protocol for polymineral fine grains and for quartz extracts from the upper part of the Stari Slankamen loess sequence. The infrared stimulated luminescence (IRSL) and post-IR optically stimulated luminescence (OSL) signals from all polymineral samples showed anomalous fading, suggesting that the post-IR OSL signal is still dominated by feldspar OSL. The ages ranging from 4.6 to 193 ka were obtained after fading correction. These ages indicate that the loess unit V-L1L1, the weakly developed soil complex V-L1S1 and the loess unit V-L1L2 were deposited during marine isotope stage (MIS) 2, 3, and 4, respectively, and also indicate that the loess unit V-L2 is of the penultimate glacial age. 相似文献
60.
The “overshoot scenario” is an emissions scenario in which CO2 concentration in the atmosphere temporarily exceeds some pre-defined, “dangerous” threshold (before being reduced to non-dangerous levels). Support for this idea comes from its potential to achieve a balance between the burdens of current and future generations in dealing with global warming. Before it can be considered a viable policy, the overshoot scenario needs to be examined in terms of its impacts on the global climate and the environment. In, particular, it must be determined if climate change cause by the overshoot scenario is reversible or not, since crossing that “dangerous” CO2 threshold could result in climate change from which we might not be able to recover. In this study, we quantify the change in several climatic and environmental variables under the overshoot scenario using a global climate model of intermediate complexity. Compared to earlier studies on the overshoot scenario, we have an explicit carbon cycle model that allows us to represent carbon-climate feedbacks and force the climate model more realistically with CO2 emissions rates rather than with prescribed atmospheric pCO2. Our standard CO2 emissions rate is calculated on the basis of historical atmospheric pCO2 data and the WRE S650 non-overshoot stabilization profile. It starts from the preindustrial year 1760, peaks in the year 2056, and ends in the year 2300. A variety of overshoot scenarios were constructed by increasing the amplitude of the control emissions peak but decreasing the peak duration so that the cumulative emissions remain essentially constant. Sensitivity simulations of various overshoot scenarios in our model show that many aspects of the global climate are largely reversible by year 2300. The significance of the reversibility, which takes roughly 200 years in our experiments, depends on the time horizon with which it is viewed or the number of future generations for whom equity is sought. At times when the overshoot scenario has emissions rates higher then the control scenario, the transient changes in atmospheric and oceanic temperatures and surface ocean pH can be significant, even for moderate overshoot scenarios that remain within IPCC SRES emissions scenarios. The large transient changes and the centennial timescale of climate reversibility suggest that the overshoot might not be the best mitigation approach, even if it technically follows the optimal economic path. 相似文献