Effects of elevated pCO₂ on reproductive properties of the benthic copepod Tigriopus japonicus and gastropod Babylonia japonica     

Jun Kita  Takashi Kikkawa  Takamasa Asai  Atsushi Ishimatsu 《Marine pollution bulletin》2013

We investigated the effects of elevated pCO₂ in seawater both on the acute mortality and the reproductive properties of the benthic copepod Tigriopus japonicus and gastropod Babylonia japonica with the purpose of accumulating basic data for assessing potential environmental impacts of sub-sea geological storage of anthropogenic CO₂ in Japan. Acute tests showed that nauplii of T. japonicus have a high tolerance to elevated pCO₂ environments. Full life cycle tests on T. japonicus indicated NOEC = 5800 μatm and LOEC = 37,000 μatm. Adult B. japonica showed remarkable resistance to elevated pCO₂ in the acute tests. Embryonic development of B. japonica showed a NOEC = 1500 μatm and LOEC = 5400 μatm. T. japonicus showed high resistance to elevated pCO₂ throughout the life cycle and B. japonica are rather sensitive during the veliger stage when they started to form their shells.  相似文献   

Morphological changes in branchial mitochondria-rich cells of the teleost Paralichthys olivaceus as a potential indicator of CO₂ impacts     

Masahiro Hayashi  Takashi Kikkawa  Atsushi Ishimatsu 《Marine pollution bulletin》2013

We studied the morphological and biochemical changes of mitochondria-rich cells (MRCs) of a demersal teleost, Paralichthys olivaceus, during exposure to 0.98, 2.97 and 4.95 kPa pCO₂. The apical opening area of MRCs increased 2.2 and 4.1 times by 24 h exposure to 2.97 and 4.95 kPa pCO₂, respectively, while the cross-sectional area or density of MRCs did not change. Gill Na⁺/K⁺-ATPase activity more than doubled at 72 h and then returned to the pre-exposure level at 168 h in 0.98 kPa pCO₂, while it increased 1.7 times at 24 h at 4.95 kPa. These results indicate that the apical opening area of MRCs and the gill Na⁺/K⁺-ATPase activity may be used as an indicator of acute (up to 72 h), but not chronic, impacts of high (>1 kPa) seawater CO₂ conditions in P. olivacues. Limitations of those parameters as indices of CO₂ impacts are discussed.  相似文献   

Analysis of dust events in 2008 and 2009 using the lidar network, surface observations and the CFORS model     

Nobuo Sugimoto  Yukari Hara  Atsushi Shimizu  Tomoaki Nishizawa  Ichiro Matsui  Masataka Nishikawa 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(1):27-39

The Asian dust events in 2008 (May 24–June 4 in 2008) and in 2009 (March 12–25, October 13–26, and December 15–28 in 2009) were analyzed with the lidar network observations, surface observations in China, Korea, Japan, and Mongolia, and with the chemical transport model CFORS. Transport of Asian dust and mixing of dust with air pollution aerosols were studied. The event of May 24 to June 4 in 2008 was a significant event unusually late in the spring dust season. The dust event of March 12–25, 2009 was an interesting example of elevated dust layer, and transport of dust from the elevated dust layer to the ground by the boundary layer activity was observed with the lidars and surface observations in Japan. The concentration of air pollution aerosols was relatively high during the dust event, and the results suggest that vertical structure as well as transport path is important for the mixing of dust and air pollution aerosols. The dust events in October and December 2009 were examples of dust events in autumn and winter. The online mode CFORS reproduced the observation data generally well, except for the event of May 24 to June 4 in 2008. The results of the fourdimensional variational assimilation of the lidar network data reproduced the dust concentration in Korea and Japan reasonably in that event.  相似文献   

Rapid Alkalization in Lake Inawashiro, Fukushima, Japan: Implications for Future Changes in the Carbonate System of Terrestrial Waters     

Takuya Manaka  Hiroyuki Ushie  Daisuke Araoka  Akihiko Inamura  Atsushi Suzuki  Hodaka Kawahata 《Aquatic Geochemistry》2013,19(4):281-302

The global carbon cycle, one of the important biogeochemical cycles controlling the surface environment of the Earth, has been greatly affected by human activity. Anthropogenic nutrient loading from urban sewage and agricultural runoff has caused eutrophication of aquatic systems. The impact of this eutrophication and consequent photosynthetic activity on CO₂ exchange between freshwater systems and the atmosphere is unclear. In this study, we focused on how nutrient loading to lakes affects their carbonate system. Here, we report results of surveys of lakes in Japan at different stages of eutrophication. Alkalization due to photosynthetic activity and decreases in PCO₂ had occurred in eutrophic lakes (e.g., Lake Kasumigaura), whereas in an acidotrophic lake (Lake Inawashiro) that was impacted by volcanic hot springs, nutrient loading was changing the pH and carbon cycling. When the influence of volcanic activity was stronger in the past in Lake Inawashiro, precipitation of volcanic-derived iron and aluminum had removed nutrients by co-precipitation. During the last three decades, volcanic activity has weakened and the lake water has become alkalized. We inferred that this rapid alkalization did not result just from the reduction in acid inputs but was also strongly affected by increased photosynthetic activity during this period. Human activities affect many lakes in the world. These lakes may play an important part in the global carbon cycle through their influence on CO₂ exchange between freshwater and the atmosphere. Biogeochemical changes and processes in these systems have important implications for future changes in aquatic carbonate systems on land.  相似文献   

Crustal strain observation for nine years with a laser strainmeter in Kobe, Japan     

Shuzo Takemoto  Takeyasu Yamamoto  Atsushi Mukai  Shigeaki Otsuka  Kunio Fujimori 《Journal of Geodynamics》2003,35(4-5):483-498

We carried out precise crustal strain observation using a laser strainmeter system at the Rokko-Takao station in Kobe, Japan from 1989 to 1997. The long-term strain record is characterized by remarkable annual changes of the order of 2–3×10⁻⁶ and linear strain accumulation of −4.4×10⁻⁷/year (in contraction). The annual strain changes are inversely proportional to temperature changes that precede the strain changes by about 1 month. The apparent annual strain changes were mainly caused by refractive-index changes in the light path due to the ambient temperature changes. After eliminating the annual temperature effect, linear strain accumulation is corrected to be −6.3−6.7×10⁻⁷/year. Residual strains show the oscillating behavior, in which the oscillating cycle seems to become shorter and shorter as time goes by. During the period, a destructive earthquake of M=7.2 occurred near the Kobe City on 17 January 1995. We investigated the oscillating behavior in secular variations of ground-strains by introducing the deterministic approach of earthquake prediction to search for the “critical point” of the occurrence of an earthquake in the extended power law equation. However, we could not obtain a unique solution to determine eight unknown parameters including the “critical point”. This may be mainly due to lack of data for 4 months from August to November in 1994 by the failure of the laser source before the occurrence of earthquake on 17 January 1995. After removing environmental effects and tidal components, we carefully re-examined strain changes in 7 days and 1 day before the occurrence of the earthquake, but we could not detect anomalous strain changes exceeding 1×10⁻⁸ before the earthquake.  相似文献   

Styles of mesoscale brittle deformations associated with the Miocene folding of the Taishu Group,Tsushima, between the Japan Sea and East China Sea backarc basins     

Atsushi Yamaji  Tatsuhiko Yanagisawa  Katsushi Sato 《Island Arc》2021,30(1):e12392

The Taishu Group is a folded, Eocene–Lower Miocene, thick sedimentary package exposed widely on Tsushima Island between the Japan Sea and East China Sea. This location makes the strata important to understand tectonics and paleo-environments in the Far East, but the timing of the folding is controversial. We studied the styles of brittle deformations of the strata. It was found that flextural-slip folds were dominant. Mesoscale faults were classified into two groups: NE–SW trending reverse faults and NW–SE trending strike-slip faults. Members of both the groups showed movements largely perpendicular to the fold axes. The latter group consisted of sinistral and dextral faults. Accordingly, we interpreted that they were transfer faults activated during the folding. Consequently, mesoscale faults and flexural-slip faults evidence the map-scale plane strain of the Taishu Group in the plane perpendicular to the NE-trending fold axes. There were few transpressional deformations in the group. This is inconsistent with the transpression hypothesis for explaining the simultaneous folding and Japan Sea opening. Another hypothesis in which the folds in Tsushima are regarded as an onshore part of the Taiwan-Shinji fold belt is inconsistent with the timing of folding suggested by mining geologists to be consistent with and contemporaneous with this deformation. On the other hand, we found that dolerite dikes and sills were involved in the folding. Therefore, we conclude that the folding began during the late Early Miocene time and climaxed during the ore mineralization at around 15 Ma. We suggest that the folding in Tsushima was the easternmost manifestation of the compressional regime around the Yellow Sea and East China Sea in the Early to early Middle Miocene, and that the compression was brought about by the arrival of the Philippine Sea plate to initiate buoyant subduction under Kyushu.  相似文献   

Age and associated stress field of middle Miocene back-arc basalt magmatism in Northeast Japan     

Jun Hosoi  Atsushi Yamaji  Hideki Iwano  Tohru Danhara  Takafumi Hirata 《Island Arc》2021,30(1):e12379

A large volume of middle Miocene basaltic rocks is widely distributed across the back-arc region of Northeast Japan, including around the Dewa Mountains. Petrological research has shown that basaltic rocks of the Aosawa Formation around the Dewa Mountains were generated as a result of the opening of the Sea of Japan. To determine the precise ages of the middle Miocene basaltic magmatism, we conducted U–Pb and fission-track (FT) dating of a rhyolite lava that constitutes the uppermost part of the Aosawa Formation. In addition, we estimated the paleostress field of the volcanism using data from a basaltic dike swarm in the same formation. The rhyolite lava yields a U–Pb age of 10.73 ±0.22 Ma (2σ) and a FT age of 10.6 ±1.6 Ma (2σ), and the paleostress analysis suggests a normal-faulting stress regime with a NW–SE-trending σ₃-axis, a relatively high stress ratio, and a relatively high magma pressure. Our results show that the late Aosawa magmatism occurred under NW–SE extensional stress and ended at ~ 11 Ma.  相似文献   

2021年日本福岛县冲地震的震源破裂过程分析基于采用经验格林函数方法的波形反演          下载免费PDF全文

吴双兰  野津厚  長坂陽介 《世界地震工程》2021,(2):001-12

利用中小震作为经验格林函数,选取0.2~2.0 Hz频段的强震数据进行波形反演,获得了2021年福岛县冲地震的破裂过程。结果表明:该地震的破裂主要集中在断层面距离震源约25 km的区域内,沿震源向东北延伸约5 km,向西南延伸约20 km;在该区域内,识别出两个滑动量集中的区域,均分布在距离震源约15 km西南侧,主要滑动量集中区域最大滑动量约3.2 m,深度基本与震源一致;次要滑动量集中区域略比主要滑动量集中区域浅约18 km。该震源模型对应矩震级M_w7.3,破裂速度为2.4 km/s。通过选择不同的中小震组合进行波形反演,结果对该震源模型特性无显著影响,揭示了该震源模型的稳健性;基于该震源模型合成反演分析中未使用的强震观测台站强震动,获得的合成波形与观测波形有很好的相关性,充分证明了该震源模型时空特征的可靠性。  相似文献   

The layered structure of lunar maria: Identification of the HF-radar reflector in Mare Serenitatis using multiband optical images     

Shoko Oshigami  Shinya Okuno  Yasushi Yamaguchi  Makiko Ohtake  Junichi Haruyama  Takao Kobayashi  Atsushi Kumamoto  Takayuki Ono 《Icarus》2012,218(1):506-512

Comparison of the Lunar Radar Sounder (LRS) data to the Multiband Imager (MI) data is performed to identify the subsurface reflectors in Mare Serenitatis. The LRS is FM-CW radar (4–6 MHz) and the 2 MHz bandwidth leads to the range resolution of 75 m in a vacuum, whereas the sampling interval in the flight direction is about 75 m when an altitude of the spacecraft with polar orbit is nominal (100 km). Horizontally continuous reflectors were clearly detected by LRS in limited areas that consist of about 9% of the whole maria. The typical depth of the reflectors is estimated to be a few hundred meters. Layered structures of mare basalts are also discernible on some crater walls in the MI data of the visible bands (VIS). The VIS range has nine wavelengths of 415, 750, 900, 950, and 1000 nm, and their spatial resolution is 20 m/pixel at a nominal altitude. The stratigraphies around Bessel and Bessel-H craters in Mare Serenitatis are examined in this paper. It was revealed that the subsurface reflectors lie on the boundaries between basalt units with different chemical compositions. In addition, model calculations using the simplified radar equation indicate that the subsurface reflectors are not compositional interfaces but layer boundaries with a high-porosity contrast. These results suggest that the detected reflectors in Mare Serenitatis are regolith accumulated during so long hiatus of mare volcanisms enough for chemical composition of magma to change, not instantaneously. Therefore combination of the LRS and MI data has a potential to reveal characteristics of a series of magmatism forming each lithostratigraphic unit in Mare Serenitatis and other maria.  相似文献   

An empirical test of household identification risk in geomasked maps     

Dara E. Seidl  Piotr Jankowski  Atsushi Nara 《制图学和地理信息科学》2013,40(6):475-488

ABSTRACT

Geomasking techniques displace point data to new locations in order to protect privacy while maintaining overall spatial distributions. If the end users of geomasked data are unaware that the data are masked, there is a risk that they will incorrectly associate individuals at the new locations with the masked data attributes. The probability of correct and false household identification depends on human understanding of whether maps contain masked coordinates and the spatial relationships of the points to contextual geographic data. Using a map-based experiment, this study finds that confidence in performing a household identification is substantially lowered when masked points are situated equidistantly between residential parcels. Despite initial notifications that data are masked, map users often report confidence in assigning masked points to specific households. Only map users who receive frequent notifications that the points are masked have reduced confidence in associating them with particular households, thereby lowering identification risk.  相似文献