Standing stock and production rate of phytoplankton and a red tide outbreak in a heavily eutrophic embayment, Dokai Bay, Japan.   总被引：4，自引：0，他引：4  

K Tada  M Morishita  K Hamada  S Montani  M Yamada 《Marine pollution bulletin》2001,42(11):1177-1186

The seasonal variation of phytoplankton biomass and primary productivity in a heavily eutrophic embayment, Dokai Bay, Japan, was determined. Dokai Bay was characterized by high phytoplankton biomass and productivity during summer and low phytoplankton biomass and productivity during other seasons. The results suggested that phytoplankton growth was limited by only irradiance and water temperature under the high nutrient concentrations available for phytoplankton growth in the entire year. Moreover, in spite of sufficient nutrient for phytoplankton growth in the entire year, a red tide occurred only in the summer period in this bay. Our results suggested that a red tide occurred by the high phytoplankton growth rate in the summer season, but in other periods surface phytoplankton was flushed out of the bay before forming the red tide, because phytoplankton growth rate was low and could not form the red tide due to low irradiance and low water temperature.  相似文献   

Characteristic Features of Tin–iron–copper Mineralization in the Anle-Huanggangliang Mining Area, Inner Mongolia, China     

Daizo ISHIYAMA  Ryoji SATO  Toshio MIZUTA  Yohei ISHIKAWA  Jingbin WANG 《Resource Geology》2001,51(4):377-392

Abstract: The Anle Sn‐Cu and Huanggangliang Fe‐Sn deposits have been exploited in the Linxi district, which is located 165 km northwest of Chifeng City in northern China. In this study the formation mechanisms of the tin deposits in the Anle and Huanggangliang mining area were investigated to understand the mechanisms of tin mineralization in northern China. The veins of the Anle deposit are divided into cassiterite–quartz–chlorite veins, chalcopyrite‐bearing quartz veins, cassi–terite–chalcopyrite–bearing quartz veins and sphalerite‐quartz veins. The sequence of mineralization is tin mineralization (stage I), copper mineralization (stage II), and lead‐zinc mineralization (stage III). The Huanggangliang tin deposit consists of magnetite skarn orebodies and many cassiterite‐bearing feldspar–fluorite veins and veinlets cutting the magnetite orebodies. The fluid inclusions in quartz and fluorite in ores from the Anle and Huanggangliang tin deposits are divided into two‐phase fluid inclusions, vapor‐rich fluid inclusions and poly‐phase fluid inclusions. The final homogenization temperatures of fluid inclusions of quartz in the ores of the Anle deposit and fluorite of tin‐bearing feldspar veins in the Huanggangliang tin deposit range from 195 to 425C and from 215 to 450C, respectively. The fluids responsible for the Anle and Huanggangliang tin deposits were of very high temperature and NaCl‐rich ones containing K, Ca, Al, Si, Ti, Fe and Cl in addition to ore metals such as Sn and Cu. The temperature and chemical composition of fluid in fluid inclusions of igneous rocks in the mining area are very similar to those of fluid in fluid inclusions in the ores of these deposits. The fluid for these ore deposits had a close relation with the fluid coexisting with melt of Late Jurassic granitic rocks in this mining area. Salinities of fluid inclusions from these ore deposits and granitic rocks in the mining area were estimated to range from 35 to 50 wt % NaCl equivalent. Based on arsenopy‐rite geothermometry and fluid inclusion studies, a fluid containing 40 wt% NaCl (eq.) could be formed by phase separation of fluid having 6 wt% NaCl (eq.) at a temperature of 420 to 500C and a pressure of 0.3 to 0.4 kb. The temperatures and pressures presented above indicate an NaCl‐rich magmatic fluid derived from granitic melt that had intruded into a shallow level of crust caused the Sn–Fe–Cu mineralization of the mining area. The geological relationship between these ore deposits and granitic bodies around the ore deposits, and the similarity of fluids forming these ore deposits and coexisting with granitic melt, suggest that these ore deposits were formed by the activity of fluid derived from granitic melt in Late Jurassic age.  相似文献   

Defining hydrochemical evolution of streamflow through flowpath dynamics in Kawakami headwater catchment,Central Japan     

Kasdi Subagyono  Tadashi Tanaka  Yohei Hamada  Maki Tsujimura 《水文研究》2005,19(10):1939-1965

The hydrochemical behaviour of catchments is often investigated by inferring stream chemistry through identification of source areas involved in hydrograph separation analysis, yet its dynamic evolution of hydrologic pathways has received little attention. Intensive hydrometric and hydrochemical measurements were performed during two different storms on March 29, 2001 and August 21–22, 2001 to define hydrochemical evolution under the dynamic of flow pathways in a 5·2 ha first‐order drainage of the Kawakami experimental basin (KEB), Central Japan, a forested headwater catchment with various soil depths (1·8 to 5 m) overlying late Neogene of volcanic bedrocks. The hydraulic potential distribution and flow lines data showed that the change in flow direction, which was controlled by rainfall amount and antecedent wetness of the soil profile, agreed well with the hydrochemical change across the slope segment during the storm. Hydrograph separation predicted by end‐member mixing analysis (EMMA) using Ca²⁺ and SiO₂ showed that near surface riparian, hillslope soil water and deep riparian groundwater were important in stream flow generation. The evidence of decrease in solutes concentration at a depth of 1 m in the hillslope and 0·6 m in the near surface riparian during peak storm suggested a flushing of high solutes concentration. Most of the solutes accumulated in the deep riparian groundwater zone, which was due to prominent downward flow and agreed well with the residence time. The distinct flow pathways and chemistry between the near surface riparian and deep riparian groundwater zones and the linkage hillslope aquifer and near surface riparian reservoir, which controls rapid flow and solutes flushing during the storm event, are in conflict with the typical assumption that the whole riparian zone resets flow pathways and chemical signature of hillslope soil water, as has been reported in a previous study. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Alteration of gene expression profiles in the brain of Japanese medaka (Oryzias latipes) exposed to KC-400 or PCB126     

Kei Nakayama  Naomi Sei  Yuji Oshima  Kosuke Tashiro  Yohei Shimasaki  Tsuneo Honjo 《Marine pollution bulletin》2008,57(6-12):460

Polychlorinated biphenyls (PCBs) are known as neurotoxic chemicals and possibly alter animal behavior. We previously reported that PCB-exposure induced abnormal schooling behavior in Japanese medaka (Oryzias latipes). This abnormal behavior might be caused by the functional alteration of central or terminal nervous system. To understand the mechanism(s) of behavioral change by PCB-exposure, we analyzed the gene expression profiles in the brain of medaka exposed to 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) or a PCB mixture (Kanechlor-400: KC-400) using a cDNA microarray that we constructed. Twelve FLF-II strain medaka (six individuals per treatment) were dietary exposed to PCB126 (0.01 μg/g b.w./day) or KC-400 (1 μg/g b.w./day) for three weeks. For the control, six fish were fed a control diet. After the exposure period, fish were dissected, and the brain samples were collected. The samples from control fish were pooled and used as a common reference in the microarray experiment. Microarray data were normalized by the LOWESS method, and we screened the genes whose expression levels were altered more than 1.5-fold. Gene expression profiling showed 97 down-regulated and 379 up-regulated genes in the brain of medaka exposed to PCB126. KC-400 exposure suppressed 15 genes and induced 266 genes in medaka brain. Among these genes, the expression levels of 7 and 188 genes were commonly down- or up-regulated, respectively in both treatment groups. On the other hand, 31 gene expressions were significantly different between PCB126 and KC-400 treatment groups, and three out of 31 genes were received opposite effects. In addition, the microarray data showed that thyroid hormone-responsive genes were up-regulated by PCB-exposure, which may imply that PCBs or their metabolites mimic thyroid hormone effects in the brain of PCB-exposed medaka.  相似文献   

Alteration of gene expression profiles in the brain of Japanese medaka (Oryzias latipes) exposed to KC-400 or PCB126     

Nakayama K  Sei N  Oshima Y  Tashiro K  Shimasaki Y  Honjo T 《Marine pollution bulletin》2008,57(6-12):460-466

Polychlorinated biphenyls (PCBs) are known as neurotoxic chemicals and possibly alter animal behavior. We previously reported that PCB-exposure induced abnormal schooling behavior in Japanese medaka (Oryzias latipes). This abnormal behavior might be caused by the functional alteration of central or terminal nervous system. To understand the mechanism(s) of behavioral change by PCB-exposure, we analyzed the gene expression profiles in the brain of medaka exposed to 3,3',4,4',5-pentachlorobiphenyl (PCB126) or a PCB mixture (Kanechlor-400: KC-400) using a cDNA microarray that we constructed. Twelve FLF-II strain medaka (six individuals per treatment) were dietary exposed to PCB126 (0.01 microg/g b.w./day) or KC-400 (1 microg/g b.w./day) for three weeks. For the control, six fish were fed a control diet. After the exposure period, fish were dissected, and the brain samples were collected. The samples from control fish were pooled and used as a common reference in the microarray experiment. Microarray data were normalized by the LOWESS method, and we screened the genes whose expression levels were altered more than 1.5-fold. Gene expression profiling showed 97 down-regulated and 379 up-regulated genes in the brain of medaka exposed to PCB126. KC-400 exposure suppressed 15 genes and induced 266 genes in medaka brain. Among these genes, the expression levels of 7 and 188 genes were commonly down- or up-regulated, respectively in both treatment groups. On the other hand, 31 gene expressions were significantly different between PCB126 and KC-400 treatment groups, and three out of 31 genes were received opposite effects. In addition, the microarray data showed that thyroid hormone-responsive genes were up-regulated by PCB-exposure, which may imply that PCBs or their metabolites mimic thyroid hormone effects in the brain of PCB-exposed medaka.  相似文献   

Comparison of seismic analysis methods applied to a historical church struck by 2009 L’Aquila earthquake     

Yohei Endo  Luca Pelà  Pere Roca  Francesca da Porto  Claudio Modena 《Bulletin of Earthquake Engineering》2015,13(12):3749-3778

  相似文献   

Estimation of particulate organic carbon flux in relation to photosynthetic production in a shallow coastal area in the Seto Inland Sea   总被引：3，自引：0，他引：3  

Yamaguchi H  Montani S  Tsutsumi H  Hamada Ki  Ueda N 《Marine pollution bulletin》2003,47(1-6):18-24

Sediment trap experiments were carried out three times from 1999 to 2000, in the western part of the Seto Inland Sea (Suo-Sound), Japan. We investigated both the particulate flux and the composition of chemical substances in the sediment trap samples. Based on the results, we discuss the origin of particulate organic carbon (POC) collected by the sediment traps in a coastal area. Moreover, we purposed to estimate the flux of the portion of the POC that is derived from phytoplankton photosynthesis. The fluxes of POC varied between 677 and 3424 mgC m(-2) d(-1). Significant positive correlations between POC and aluminum (Al) fluxes suggested that these components show almost the same behaviour. The mean value of the Al flux was about eight times higher than that of Al burial rates on the sediment surface. Therefore, it seems that the POC flux observed with the sediment traps was considerably overestimated. Moreover, judging from the fact that Al is a typical terriginous element, it seems that most of the POC collected in the sediment traps derived from the re-suspended surface sediment or sediment transported laterally from shallow flanks such as intertidal mudflats. The fluxes of chlorophyll a (Chl a) were independent of the POC fluxes, and a relatively consistent correlation was found between Chl a abundance in the water column and the Chl a flux. Moreover, surface sediment Chl a content was approximately 100 times lower than that of suspended matter. Therefore, resuspension and terriginous contributions to Chl a collected in sediment traps are likely to be negligible. The POC content in the trap samples varied between 22.4 and 70.7 mg g(-1) dry weight. The variations of POC contents were positively correlated with the Chl a contents: POC(mg g(-1))=76.5 x Chl a(mg g(-1)) + 26.0 (r=0.95, p<0.01, n=9). This result shows that POC contents strongly corresponded with phytoplankton and their debris. It was also considered that the fraction of POC derived from phytoplankton primary production could be estimated as Chl a content times a certain factor. In this study, we estimated the flux of the portion of the POC originating from phytoplankton production by multiplying the Chl a fluxes by 76.5 (the mean POC:Chl a ratio in the trap samples). These values varied between 308 and 758 mgC m(-2) d(-1), and accounted for 35.1+/-21.2% of total POC flux. Although the amount of POC that originates from phytoplankton photosynthesis was a small portion of total POC flux, it seems to be a large portion of potential primary production in the water column.  相似文献   

A GRASS GIS parallel module for radio-propagation predictions     

Lucas Benedičič  Felipe A. Cruz  Tsuyoshi Hamada  Peter Korošec 《International journal of geographical information science》2014,28(4):799-823

Geographical information systems are ideal candidates for the application of parallel programming techniques, mainly because they usually handle large data sets. To help us deal with complex calculations over such data sets, we investigated the performance constraints of a classic master–worker parallel paradigm over a message-passing communication model. To this end, we present a new approach that employs an external database in order to improve the calculation–communication overlap, thus reducing the idle times for the worker processes. The presented approach is implemented as part of a parallel radio-coverage prediction tool for the Geographic Resources Analysis Support System (GRASS) environment. The prediction calculation employs digital elevation models and land-usage data in order to analyze the radio coverage of a geographical area. We provide an extended analysis of the experimental results, which are based on real data from an Long Term Evolution (LTE) network currently deployed in Slovenia. Based on the results of the experiments, which were performed on a computer cluster, the new approach exhibits better scalability than the traditional master–worker approach. We successfully tackled real-world-sized data sets, while greatly reducing the processing time and saturating the hardware utilization.  相似文献   

Small-scale landfills: impacts on groundwater and soil     

Rodrigo Augusto Bellezoni  Cristiano Kenji Iwai  Vagner Roberto Elis  Wanderley da Silva Paganini  Jorge Hamada 《Environmental Earth Sciences》2014,71(5):2429-2439

In Brazil, the large quantities of solid waste produced are out of step with public policies, technological developments, and government budgets for the division. In small municipalities, the common lack of technological knowledge and financial conditions for suitable waste disposal has resulted in a large number of illegal dumps. Therefore, small sanitary landfill facilities are working with simplified operations focusing on cost reduction and meeting the economic and technological standards of the city without endangering the environment or public health. Currently, this activity is regulated at a federal level although there is some uncertainty regarding the risk of soil and aquifer contamination as theses facilities do not employ liners. Thus, this work evaluates a small landfill to identify changes in soil and groundwater using geotechnical parameters, monitoring wells, and geophysical tests performed by electrical profiling. It is verified that based on current conditions, no contaminants have migrated via underground water aquifers, and overall no significant changes have occurred in the soil. It is concluded that, despite its simplicity, the method investigated is a viable alternative for the final disposal of municipal solid waste from small cities, especially in developing countries.  相似文献   

Three‐dimensional texture of natural pseudotachylyte: Pseudotachylyte formation mechanism in hydrous accretionary complex          下载免费PDF全文

Yohei Hamada  Gaku Kimura  Jun Kameda  Asuka Yamaguchi  Mari Hamahashi  Rina Fukuchi  Yujin Kitamura  Shin'ya Okamoto 《Island Arc》2018,27(2)

Melt‐origin pseudotachylyte is the most reliable seismogenic fault rock. It is commonly believed that pseudotachylyte generation is rare in the plate subduction zone where interstitial fluids are abundant and can trigger dynamic fault‐weakening mechanisms such as thermal pressurization. Some recent studies, however, have discovered pseudotachylyte‐bearing faults in exhumed ancient accretionary complexes, indicating that frictional melting also occurrs during earthquakes in subduction zones. To clarify the pseudotachylyte generation mechanism and the variation of slip behavior in the plate subduction zone, a pseudotachylyte found in the exhumed fossil accretionary complex (the Shimanto Belt, Nobeoka, Japan) was re‐focused and microscopic and three‐dimensional observations of the pseudotachylyte‐bearing fault were performed based on optical, electron, and X‐ray microscope images. Based on the patterns contained in the fragment, the pseudotachylyte is divided into four domains, although no clear domain boundaries or layering structures are not found. Three‐dimensional observation also suggests that the pseudotachylyte were fragmented or isolated by cataclasite or carbonate breccia. The pseudotachylyte was rather injected into the surrounding carbonate breccia, which is composed of angular fragments of the host rock and a matrix of tiny crystalline carbonate. The pseudotachylyte volume was extracted from the X‐ray microscope image and the heat abundance consumed by the pseudotachylyte generation was estimated at 2.18 MJ/m², which can be supplied during a slip of approximately 0.5 m. These observations and calculations, together with the results of the previous investigations, suggest hydrofracturing and rapid carbonate precipitation that preceded or accompanied the frictional melting. Dynamic hydrofracturing during a slip can be caused by rapid fluid pressurization, and can induce abrupt decrease in fluid pressure while drastically enhancing the shear strength of the shear zone. Consequently, frictional heating would be reactivated and generate the pseudotachylyte. These deformation processes can explain pseudotachylyte generation in hydrous faults with the impermeable wall rock.  相似文献