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排序方式: 共有49条查询结果,搜索用时 15 毫秒
1.
A. A. Krylov O. M. Khlystov T. I. Zemskaya H. Minami A. Hachikubo H. Shoji M. Kida T. P. Pogodaeva L. Naudts J. Poort 《Geochemistry International》2008,46(10):985-995
This paper presents data on authigenic siderite first found in surface sediments from mud volcanoes in the Central (K-2) and Southern (Malen’kii) basins of Lake Baikal. Ca is the predominant cation, which substitutes Fe in the crystalline lattice of siderite. The enrichment of the carbonates in the 13C isotope (from +3.3 to +6.8‰ for the Malen’kii volcano and from +17.7 to +21.9‰ for K-2) results from the crystallization of the carbonates during methane generation via the bacterial destruction of organic matter (acetate). The overall depletion of the carbonates in 18O is mainly inherited from the isotopic composition of Baikal water. 相似文献
2.
Rice paddies as a methane source 总被引:8,自引:0,他引:8
Rice fields are considered to be among the highest sources of atmospheric methane, an important source of global warming. In order to meet the projected rice needs of the increasing world population, it is estimated that the annual world's rough rice production must increase to 760 million tons (a 65% increase) in the next 30 years. This will increase methane emissions from ricefields if current technologies are kept. Methane emissions from ricefields are affected by climate, water regime, soil properties, and various cultural practices like irrigation and drainage, organic amendments, fertilization, and rice cultivars. Irrigated rice comprises 50% of the world-harvested rice area and contributes 70% to total rice production. Because of assured flooding during the growing period it is the primary source of methane. Rainfed rice emits less methane due to periods of droughts. Upland rice, being never flooded for a significant period of time, is not a significant source of methane. There is great potential to develop no regret mitigation options that are in accordance with increasing rice production. 相似文献
3.
Shouji Kihara Kenichi Hoshino Makoto Watanabe Hirotsugu Nishido Shunso Ishihara 《Resource Geology》2005,55(2):123-129
Abstract. The Umanotani-Shiroyama pegmatite deposits, the largest producer of K-feldspar and quartz in Japan, are of typical granitic pegmatite. Ilmenite-series biotite granite and granite porphyry, hosting the ore deposits, and biotites separated from these rocks yielded K-Ar ages ranging from 89.0 to 81.4 Ma and 95.2 to 93.7 Ma, respectively. Muscovite and K-feldspar separated from the ore zone yielded K-Ar ages with the range of 96.2 to 93.1 Ma and 87.3 to 80.7 Ma, respectively. Muscovites from quartz-muscovite veins in the ore zone and in the granite porphyry yielded K-Ar ages of 90.4 and 76.3 Ma, respectively. K-feldspar is much younger in age than coexisting muscovite. It is noted that the K-Ar ages of biotite separates and the whole-rock ages are identical to those of muscovite and K-feldspar in the ore zone, respectively. These time relations, as well as field occurrence, indicate that the formation of the pegmatite deposits at the Umanotani-Shiroyama mine is closely related in space and time to a series of granitic magmatism of ilmenite-series nature. Using closure temperatures of the K-Ar system for biotite and K-feldspar (microcline), cooling rate of the pegmatite deposits is estimated to be about 82C/m.y. at the beginning, but slowed down to about 15C/m.y. in the later period. 相似文献
4.
Krylov Alexey A. Hachikubo Akihiro Minami Hirotsugu Pogodaeva Tatyana V. Zemskaya Tamara I. Krzhizhanovskaya Mariya G. Poort Jeffrey Khlystov Oleg M. 《International Journal of Earth Sciences》2018,107(6):2011-2022
International Journal of Earth Sciences - Early diagenetic carbonates are rare in Lake Baikal. Siderite (Fe carbonate) concretions in the sediments were discovered only recently. Here, we discuss... 相似文献
5.
Tadao Minami 《地震工程与结构动力学》1987,15(6):697-709
Earthquake observations and microtremor measurements were conducted on a 12-storey steel-reinforced concrete building just after its completion. Marked stiffness deterioration was observed over the following five-year period, during which time several earthquakes were recorded and two additional series of microtremor measurements were made. The large contribution made by non-structural elements (especially the curtain walls that cover all sides of the building) to the apparent stiffness of the entire building was lost during this period. Both ageing effects and stiffness reductions depend greatly on the amplitude of the structural response of this building. 相似文献
6.
Mitigating Agricultural Emissions of Methane 总被引:7,自引:0,他引:7
A.R. Mosier J.M. Duxbury J.R. Freney O. Heinemeyer K. Minami D.E. Johnson 《Climatic change》1998,40(1):39-80
Agricultural crop and animal production systems are important sources and sinks for atmospheric methane (CH4). The major CH4 sources from this sector are ruminant animals, flooded rice fields, animal waste and biomass burning which total about one third of all global emissions. This paper discusses the factors that influence CH4 production and emission from these sources and the aerobic soil sink for atmospheric CH4 and assesses the magnitude of each source. Potential methods of mitigating CH4 emissions from the major sources could lead to improved crop and animal productivity. The global impact of using the mitigation options suggested could potentially decrease agricultural CH4 emissions by about 30%. 相似文献
7.
Long-Term Variations of Potential Temperature and Dissolved Oxygen of the Japan Sea Proper Water 总被引:4,自引:0,他引:4
Observed potential temperatures and concentrations of dissolved oxygen are analyzed to elucidate their variations during the
period from 1958 to 1996 at Stn. P (37°43′ N, 134°43′ E) and from 1965 to 1996 at Stn. H (40°30′ N, 137°40′ E) in the Japan
Sea. At Stn. P, increases of the potential temperature for the period are found below 800 m depth with the largest value of
0.16 ± 0.09°C per century at 800 m depth. At Stn. H, the potential temperature increased below 500 m depth. The increase rate
has the largest value of 0.50 ± 0.18°C per century at 500 m depth and it is 0.30 ± 0.09°C per century at 800 m depth. The
concentrations of dissolved oxygen increased around 800 m depth at Stn. P. At Stn. H, they increased above 800 m depth. On
the other hand, they decreased below 1200 m depth at both stations. The layer of the dissolved oxygen minimum has deepened
in these decades. These features appearing in the distributions of temperature and dissolved oxygen are successively simulated
by a vertical one-dimensional advection-diffusion model including consumption of dissolved oxygen and termination of the deep
water supply. These results suggest that the supply of the Japan Sea Proper Water into the deep layer, which is cold and rich
in dissolved oxygen, has been decreasing for the last four decades.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
8.
Masao SAKAMOTO Arnold GUCSIK Hirotsugu NISHIDO Kiyotaka NINAGAWA Tasuku OKUMURA Shin TOYODA 《Meteoritics & planetary science》2010,45(1):32-42
Abstract– Planar deformation features (PDFs) and planar fractures (PFs) have been found and confirmed by optical microscope observations and microRaman spectroscopy in quartz grains from Mt. Oikeyama (Akaishi Mountains, Central Japan), for which the semicircular topographic feature of the ridge suggests a crater formed by an impact event. According to the optical microscope observations, a low shock pressure (8–10 GPa) is estimated by the occurrence of basal or ω PDFs leading to lack of multiple sets of PDFs. In addition, a new type of planar microstructure was found in several quartz grains. The microRaman characteristics of PDFs in quartz from Mt. Oikeyama show the amorphous state indicating the presence of weak broad bands at 400 and 800 cm?1 peak positions. These characteristics are indicative of PDFs that are limited to shocked quartz. This indicates an impact origin for distinct planar microstructures in quartz from Mt. Oikeyama. 相似文献
9.
Akihiro Hachikubo Oleg Khlystov Masato Kida Hirotoshi Sakagami Hirotsugu Minami Satoshi Yamashita Nobuo Takahashi Hitoshi Shoji Gennadiy Kalmychkov Jeffrey Poort 《Geo-Marine Letters》2012,32(5-6):419-426
This study reports measurements of the Raman spectra of Lake Baikal gas hydrates and estimations of the hydration number of methane-rich samples. The hydration number of gas hydrates retrieved from the southern Baikal Basin (crystallographic structure I) was approx. 6.1. Consistent with previous results, the Raman spectra of gas hydrates retrieved from the Kukuy K-2 mud volcano in the central Baikal Basin indicated the existence of crystallographic structures I and II. Measurements of the dissociation heat of Lake Baikal gas hydrates by calorimetry (from the decomposition of gas hydrates to gas and water), employing the hydration number, revealed values of 53.7–55.5?kJ?mol–1 for the southern basin samples (structure I), and of 54.3–55.5?kJ?mol–1 for the structure I hydrates and 62.8–64.2?kJ?mol–1 for the structure II hydrates from the Kukuy K-2 mud volcano. 相似文献
10.
Jeffrey Poort Oleg M. Khlystov Lieven Naudts Albert D. Duchkov Hitoshi Shoji Shin’ya Nishio Marc De Batist Akihiro Hachikubo Masato Kida Hirotsugu Minami Andrey Y. Manakov Marina V. Kulikova Alexey A. Krylov 《Geo-Marine Letters》2012,32(5-6):407-417
Thermal measurements and hydrate mapping in the vicinity of the K-2 mud volcano in Lake Baikal have revealed a particular type of association of thermal anomalies (29–121?mW?m–2) near hydrate-forming layers. Detailed coring within K-2 showed that hydrates are restricted to two distinct zones at sub-bottom depths exceeding 70–300?cm. Temperature data from stations with hydrate recovery and degassing features all display low thermal gradients. Otherwise, the thermal gradients within the mud volcano are generally increased. These findings imply a more complicated thermal regime than often assumed for mud volcanoes, with important roles for both fluids and hydrates. The coexistence of neighbouring low and high thermal anomalies is interpreted to result from discharging and recharging fluid activity, rather than hydrate thermodynamics. It is suggested that hydrates play a key role in controlling the fluid circulation pattern at an early stage. At a later stage, the inflow of undersaturated lake water would favour the dissolution of structure I hydrates and the formation of structure II hydrates, the latter having been observed on top of structure I hydrates in the K-2 mud volcano. 相似文献