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61.
Yasunori Mahara Tomoko Ohta Tomochika Tokunaga Hiroyuki Matsuzaki Eiji Nakata Yuki Miyamoto Yukihiro Mizuochi Toshiharu Tashiro Masahiro Ono Toshifumi Igarashi Keisuke Nagao 《Applied Geochemistry》2012
Fifty-three samples, including brines associated with oil and natural gas reservoirs and groundwater samples from deep boreholes, were collected from the Pacific and Japan Sea coastal regions in Japan. The 129I/127I and 36Cl/Cl ratios, and stable isotopes (δD and δ18O) are compared to investigate differences related to the geotectonic settings of the two regions. The δD and δ18O data indicate that brine and groundwater from the Pacific coastal region reflect mixing of meteoric water with connate seawater in the pores of sedimentary rocks. On the other hand, brine and groundwater from the Japan Sea coastal region have been hydrothermally altered. In particular, brines associated with petroleum accumulations at Niigata and Akita showed the same isotopic characteristics as fluids found in the Kuroko deposits of the Green Tuff region in northeastern Japan. There is little difference in the 36Cl/Cl ratios in brine and groundwater from the Pacific and Japan Sea coasts. Most brine and some deep groundwater, except those from the Pleistocene Kazusa Group, have already reached the average secular equilibrium ratio of 9.9 ± 2.7 × 10−15 for their mudstone and sandstone reservoirs. There was no correlation between the 36Cl/Cl ratios and differences in geotectonic setting between the Pacific and the Japan Sea coast. The molar I/Br ratio suggests that the I in all of water samples was of biogenic origin. The average 129I/127I ratio was 290 ± 130 × 10−15 to 294 ± 105 × 10−15 in both regions, showing no relationship to the different geotectonic settings. The uncontaminated brine and groundwater samples are likely to have retained the original 129I/127I ratios of marine I released from the old organic matter stored in sedimentary rock. 相似文献
62.
Ocean acidification results from an increase in the concentrations of atmospheric carbon dioxide (CO2) impacts on marine calcifying species, which is predicted to become more pronounced in the future. By the end of this century, atmospheric pCO2 levels will have doubled relative to the pre‐industrial levels of 280 ppm. However, the effects of pre‐industrial pCO2 levels on marine organisms remain largely unknown. In this study, we investigated the effects of pre‐industrial pCO2 conditions on the size of the pluteus larvae of sea urchins, which are known to be vulnerable to ocean acidification. The larval size of Hemicentrotus pulcherrimus significantly increased when reared at pre‐industrial pCO2 level relative to the present one, and the size of Anthocidaris crassispina larvae decreased as the pCO2 levels increased from the pre‐industrial level to the near future ones after 3 days' exposure. In this study, it is suggested that echinoid larvae responded to pre‐industrial pCO2 levels. Ocean acidification may be affecting some sensitive marine calcifiers even at the present pCO2 level. 相似文献
63.
Daisuke Nishio-Hamane Asa Shimizu Ritsuko Nakahira Ken Niwa Asami Sano-Furukawa Taku Okada Takehiko Yagi Takumi Kikegawa 《Physics and Chemistry of Minerals》2010,37(3):129-136
The stability and equation of state for the cotunnite phase in TiO2 were investigated up to a pressure of about 70 GPa by high-pressure in situ X-ray diffraction measurements using a laser-heated
diamond anvil cell. The transition sequence under high pressure was rutile → α-PbO2 phase → baddeleyite phase → OI phase → cotunnite phase with increasing pressure. The cotunnite phase was the most stable
phase at pressures from 40 GPa to at least 70 GPa. The equation of state parameters for the cotunnite phase were established
on the platinum scale using the volume data at pressures of 37–68 GPa after laser annealing, in which the St value, an indicator of the magnitude of the uniaxial stress component in the samples, indicates that these measurements were
performed under quasi-hydrostatic conditions. The third-order Birch-Murnaghan equation of state at K
0′ = 4.25 yields V
0 = 15.14(5) cm3/mol and K
0 = 294(9), and the second-order Birch-Murnaghan equation of state yields V
0 = 15.11(5) cm3/mol and K
0 = 306(9). Therefore, we conclude that the bulk modulus for the cotunnite phase is not comparable to that of diamond. 相似文献
64.
Manju Mohan Yukihiro Kikegawa B. R. Gurjar Shweta Bhati Narendra Reddy Kolli 《Theoretical and Applied Climatology》2013,112(3-4):647-658
Urban heat island intensities (UHI) have been assessed based on in situ measurements and satellite-derived observations for the megacity Delhi during a selected period in March 2010. A network of micrometeorological observational stations was set up across the city. Site selection for stations was based on dominant land use–land cover (LULC) classification. Observed UHI intensities could be classified into high, medium and low categories which overall correlated well with the LULC categories viz. dense built-up, medium dense built-up and green/open areas, respectively. Dense urban areas and highly commercial areas were observed to have highest UHI with maximum hourly magnitude peaking up to 10.7 °C and average daily maximum UHI reaching 8.3 °C. UHI obtained in the study was also compared with satellite-derived land surface temperatures (LST). UHI based on in situ ambient temperatures and satellite-derived land surface temperatures show reasonable comparison during nighttime in terms of UHI magnitude and hotspots. However, the relation was found to be poor during daytime. Further, MODIS-derived LSTs showed overestimation during daytime and underestimation during nighttime when compared with in situ skin temperature measurements. Impact of LULC was also reflected in the difference between ambient temperature and skin temperature at the observation stations as built-up canopies reported largest gradient between air and skin temperature. Also, a comparison of intra-city spatial temperature variations based UHI vis-à-vis a reference rural site temperature-based UHI indicated that UHI can be computed with respect to the station measuring lowest temperature within the urban area in the absence of a reference station in the rural area close to the study area. Comparison with maximum and average UHI of other cities of the world revealed that UHI in Delhi is comparable to other major cities of the world such as London, Tokyo and Beijing and calls for mitigation action plans. 相似文献