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2.
Relationship between atmospheric deposition fluxes and concentrations of Si and210Po in the surface air were examined through daily basis simultaneous observation at the coast of the Japan Sea. Both the Si and210Po, the atmospheric fluxes were highly variable from day to day. According to correlation analysis, there was no significant correlation between flux and atmospheric concentration of these terrigenous materials in the surface air. On the other hand, flux of Si and210Po significantly correlated to precipitation rate. These results indicate that the atmospheric flux of terrigenous material is not constantly proportional to atmospheric concentration in the surface air. This may be due to the deposition flux represents an integrated value throughout the air column of in-and below-cloud, while the air concentration represents only the environment of earth's surface. 相似文献
3.
A hydrochemical study of the Hammam Righa geothermal waters in north-central Algeria 总被引:1,自引:0,他引:1
Mohamed Belhai Yasuhiro Fujimitsu Fatima Zohra Bouchareb-Haouchine Abdelhamid Haouchine Jun Nishijima 《中国地球化学学报》2016,35(3):271-287
This study focuses on the hydrochemical characteristics of 47 water samples collected from thermal and cold springs that emerge from the Hammam Righa geothermal field, located in north-central Algeria. The aquifer that feeds these springs is mainly situated in the deeply fractured Jurassic limestone and dolomite of the Zaccar Mount. Measured discharge temperatures of the cold waters range from 16.0 to 26.5 °C and the hot waters from 32.1 to 68.2 °C. All waters exhibited a near-neutral pH of 6.0–7.6. The thermal waters had a high total dissolved solids (TDS) content of up to 2527 mg/l, while the TDS for cold waters was 659.0–852.0 mg/l. Chemical analyses suggest that two main types of water exist: hot waters in the upflow area of the Ca–Na–SO4 type (Hammam Righa) and cold waters in the recharge zone of the Ca–Na–HCO3 type (Zaccar Mount). Reservoir temperatures were estimated using silica geothermometers and fluid/mineral equilibria at 78, 92, and 95 °C for HR4, HR2, and HR1, respectively. Stable isotopic analyses of the δ18O and δD composition of the waters suggest that the thermal waters of Hammam Righa are of meteoric origin. We conclude that meteoric recharge infiltrates through the fractured dolomitic limestones of the Zaccar Mount and is conductively heated at a depth of 2.1–2.2 km. The hot waters then interact at depth with Triassic evaporites located in the hydrothermal conduit (fault), giving rise to the Ca–Na–SO4 water type. As they ascend to the surface, the thermal waters mix with shallower Mg-rich groundwater, resulting in waters that plot in the immature water field in the Na–K–Mg diagram. The mixing trend between cold groundwaters from the recharge zone area (Zaccar Mount) and hot waters in the upflow area (Hammam Righa) is apparent via a chloride-enthalpy diagram that shows a mixing ratio of 22.6 < R < 29.2 %. We summarize these results with a geothermal conceptual model of the Hammam Righa geothermal field. 相似文献
4.
Dissolved and particulate concentrations of silver in Tokyo Bay estuarine waters and Japanese rivers were determined in this
study. The dissolved silver concentrations in the surface water of Tokyo Bay range from 5.9 to 15.1 pmol kg−1, which is comparable to those in the surface water of the Japan Sea, but two or three times higher than those in the surface
water of the open ocean. However, elevated concentrations of dissolved silver are not found in Tokyo Bay compared with those
in other highly urbanized estuaries, such as San Francisco Bay (20∼243 pmol kg−1). In the Tokyo Bay estuary, silver typically exhibits non-conservative mixing behavior, which is a common feature in the
other estuaries reported previously. Dissolved silver concentrations decrease with salinity from the rivers to the mouth of
Tokyo Bay. Silver is efficiently scavenged by suspended particulates, as evidenced by the high conditional distribution coefficients
for silver throughout the estuary (log Kd > 5.0 ± 0.6). The silver fluxes into Tokyo Bay via inflowing rivers and atmospheric deposition were estimated as 83 kg y−1 and 15 kg y−1, respectively. A simple budget calculation shows that the silver supplied from rivers and atmosphere must be rapidly scavenged
within the Tokyo Bay estuary. 相似文献
5.
Takashi Doi Michiaki Takano Kei Okamura Tamaki Ura Toshitaka Gamo 《Journal of Oceanography》2008,64(3):471-477
We present the results of a chemical survey at a submarine volcano, Teishi Knoll, obtained using a submersible in-situ Mn
analyzer (GAMOS) mounted on an autonomous underwater vehicle (AUV) platform. During this survey, high-resolution data of dissolved
Mn were obtained in three dimensions in nearly real time. The AUV enabled continuous detailed observations along a preprogrammed
pathway, which could not have been performed with conventional CTD hydrocasts. During this observation, anomalously high dissolved
Mn concentrations were obtained within the crater, corresponding to high water temperatures. The anomalies might be a hydrothermal
signature due to volcanic activity from the crater. 相似文献
6.
Hirokazu Ozaki Hajime Obata Mikio Naganobu Toshitaka Gamo 《Journal of Oceanography》2009,65(2):235-244
We measured potential temperature, salinity, and dissolved oxygen profiles from the surface to the bottom at two locations
in the north Ross Sea (65.2°S, 174.2°E and 67.2°S, 172.7°W) in December 2004. Comparison of our data with previous results
from the same region reveals an increase in potential temperature and decreases in salinity and dissolved oxygen concentration
in the bottom layer (deeper than 3000 m) over the past four decades. The changes were significantly different from the analytical
precisions. Detailed investigation of the temperature, salinity, dissolved oxygen and σ
3 value distributions and the bottom water flow in the north Ross Sea suggests a long-term change in water mass mixing balance.
That is to say, it is speculated that the influence of cool, saline, high-oxygen bottom water (high-salinity Ross Sea Bottom
Water) formed in the southwestern Ross Sea has possibly been decreased, while the influences of relatively warmer and fresher
bottom water (low-salinity Ross Sea Bottom Water) and the Adélie Land Bottom Water coming from the Australia-Antarctic Basin
have increased. The possible impact of global warming on ocean circulation needs much more investigation. 相似文献
7.
Y. Mizumura J. Kushida K. Nishijima G.V. BicknellR.W. Clay P.G. EdwardsS. Gunji S. HaraS. Hayashi S. KabukiF. Kajino A. KawachiT. Kifune R. KiuchiK. Kodani Y. MatsubaraT. Mizukami Y. MizumotoM. Mori H. MuraishiT. Naito M. OhishiV. Stamatescu D.L. SwabyT. Tanimori G. ThorntonF. Tokanai T. ToyamaS. Yanagita T. YoshidaT. Yoshikoshi 《Astroparticle Physics》2012,35(9):563-572
We have searched for very high energy (VHE) gamma rays from four blazars using the CANGAROO-III imaging atmospheric Cherenkov telescope. We report the results of the observations of H 2356-309, PKS 2155-304, PKS 0537-441, and 3C 279, performed from 2005 to 2009, applying a new analysis to suppress the effects of the position dependence of Cherenkov images in the field of view. No significant VHE gamma ray emission was detected from any of the four blazars. The GeV gamma-ray spectra of these objects were obtained by analyzing Fermi/LAT archival data. Wide range (radio to VHE gamma-ray bands) spectral energy distributions (SEDs) including CANGAROO-III upper limits, GeV gamma-ray spectra, and archival data, even though they are non-simultaneous, are discussed using a one-zone synchrotron self-Compton (SSC) model in combination with a external Compton (EC) radiation. The HBLs (H 2356-309 and PKS 2155-304) can be explained by a simple SSC model, and PKS 0537-441 and 3C 279 are well modeled by a combination of SSC and EC model. We find a consistency with the blazar sequence in terms of strength of magnetic field and component size. 相似文献
8.
Toshifumi Komatsu Ryota Urakawa Toshitaka Inada Kazuki Yamauchi Takumi Maekawa Reishi Takashima Mark Williams Phong D. Nguyen Hung D. Doan Minh T. Nguyen Shuji Niko Gengo Tanaka Tatsuhiko Yamaguchi 《Island Arc》2019,28(1)
Upper Devonian carbonates of the Toc Tat Formation in the Si Phai Pass area of Dong Van District, northern Vietnam were deposited in carbonate platform, slope, and basin environments. These carbonates yield abundant conodonts indicative of the Palmatolepis nasuta, Pa. linguiformis and Pa. triangularis zones, the Frasnian–Famennian stage boundary being identified by the first occurrence of Pa. triangularis. Two positive carbon isotope excursions are recognized, the lower excursion peaking in the interval of the lower to middle Pa. nasuta Zone, whilst the upper excursion peaks just above the local Frasnian–Famennian boundary. Based on the biostratigraphy, these excursions equate to the Lower and Upper Kellwasser events. Locally, tentaculitoid taxa (Nowakia, Styliolina, Homoctenus, and Metastyliolina?) are abundant in the interval of the Pa. nasuta Zone, but show a drastic decline in abundance before the Lower Kellwasser Event, and only two taxa survived into the Famennian. 相似文献
9.
10.
Wataru Nishijima Yoichi Nakano Satoshi Nakai Tetsuji Okuda Tsuyoshi Imai Mitsumasa Okada 《Marine pollution bulletin》2013
We investigated the effects of river floods on the macrobenthic community of the intertidal flat in the Ohta River Estuary, Japan, from 2005 to 2010. Sediment erosion by flood events ranged from about 2–3 cm to 12 cm, and the salinity dropped to 0‰ even during low-intensity flood events. Cluster analysis of the macrobenthic population showed that the community structure was controlled by the physical disturbance, decreased salinity, or both. The opportunistic polychaete Capitella sp. was the most dominant species in all clusters, and populations of the long-lived polychaete Ceratonereis erythraeensis increased in years with stable flow and almost disappeared in years with intense flooding. The bivalve Musculista senhousia was also an important opportunistic species that formed mats in summer of the stable years and influenced the structure of the macrobenthic community. Our results demonstrate the substantial effects of flood events on the macrobenthic community structure. 相似文献