Microbial responses using denaturing gradient gel electrophoresis to oil and chemical dispersant in enclosed ecosystems     

Yoshida A  Nomura H  Toyoda K  Nishino T  Seo Y  Yamada M  Nishimura M  Wada M  Okamoto K  Shibata A  Takada H  Kogure K  Ohwada K 《Marine pollution bulletin》2006,52(1):89-95

Microbial responses to the addition of oil with or without a chemical dispersant were examined in mesocosm and microcosm experiments by using denaturing gradient gel electrophoresis of bacterial ribosomal DNA and direct cell counting. When a water-soluble fraction of oil was added to seawater, increases in cell density were observed in the first 24h, followed by a decrease in abundance and a change in bacterial species composition. After addition of an oil-dispersant mixture, increases in cell density and changes in community structure coincided, and the amount of bacteria remained high. These phenomena also occurred in response to addition of only dispersant. Our results suggest that the chemical dispersant may be used as a nutrient source by some bacterial groups and may directly or indirectly prevent the growth of other bacterial groups.  相似文献   

Three-dimensional distributions of sewage markers in Tokyo Bay water--fluorescent whitening agents (FWAs)     

Managaki S  Takada H  Kim DM  Horiguchi T  Shiraishi H 《Marine pollution bulletin》2006,52(3):281-292

Three-dimensional distributions of fluorescent whitening agents (FWAs: more specifically, DSBP and DAS1), which are sewage-derived water-soluble markers, were observed in Tokyo Bay water through multi-layer sampling of water at 20 locations. In summer, FWAs predominated in the surface layers, with trace but significant concentration of FWAs in bottom water due to stratification of seawater. In winter, on the other hand, FWAs were extensively mixed into the bottom layers because of the vertical mixing of seawater. In the surface layer, FWA concentrations and the DSBP/DAS1 ratio (the concentration ratio of DSBP to DAS1) were lower in summer than in winter, suggesting more efficient photodegradation of FWAs in euphotic zones during the summer due to stronger solar radiation. Horizontally, FWAs were widely distributed over the surface layer of Tokyo Bay. Surface water with DSBP concentrations above 50ng/L, corresponding to <200 times dilution of sewage effluent, was found to have spread up to 10km from the coastline. In addition, an offshore decline in FWA concentrations was observed, showing a half-distance of 10-20km. The decrease was caused by dilution by seawater of fresh water containing FWAs. The eastern part of the bay was different with respect to surface layers, with higher concentrations seen in northeastern parts. Furthermore, dispersion of combined sewer overflow (CSO)-derived water mass was observed in Tokyo Bay after heavy rain.  相似文献   

Retardation capacity of altered granitic rock distributed along fractured and faulted zones in the orogenic belt of Japan     

H. Yoshida  R. Metcalfe  Y. Seida  H. Takahashi  T. Kikuchi 《Engineering Geology》2009,106(3-4):116-122

There are wide areas of granitic rocks in the Japanese orogenic belt. These granitic bodies inevitably contain fracture and fault systems associated with alteration zones. However, relatively little attention has been given to the possible influence of such widely distributed alteration zones on the migration of radionuclides from any radioactive waste repository that might in future be sited within granitic rock. In particular, the influences of alteration products and micro-fractures, due to chemical sorption and/or physical retardation require further consideration. In order to understand the retardation capacity of the altered deep granitic rocks, detailed geometrical characterization of pores, geochemical analysis, and batch sorption and flow-through experiments have been carried out. Those results show that the altered granite has a large volume of accessible pores, particularly in potassium-feldspar grains, which would influence nuclide retardation more than the accessible porosity in other minerals present, such as biotite. The distribution coefficients, Kd estimated from batch sorption tests and flow-through experiments suggest that altered granite has a high capability to retard the migration of nuclides. The retardation would probably be due to sorption on altered minerals such as sericite and iron hydroxides formed along grain boundaries and in pores created by dissolution, in addition to sorption on primary sorptive minerals. These results provide confidence that even altered and fractured parts of any granitic rock that might be encountered in a site for the disposal of high level radioactive waste may still retard radionuclide migration and thereby help the geosphere to function as a barrier.  相似文献   

Biogeochemistry of nitrous oxide in groundwater in a forested ecosystem elucidated by nitrous oxide isotopomer measurements   总被引：3，自引：0，他引：3  

K. Koba  K. Osaka  Y. Tobari  S. Toyoda  N. Ohte  M. Katsuyama  N. Suzuki  M. Itoh  H. Yamagishi  M. Kawasaki  S.J. Kim  N. Yoshida  T. Nakajima 《Geochimica et cosmochimica acta》2009,73(11):3115-1037

The biological and physical controls on microbial processes that produce and consume N₂O in soils are highly complex. Isotopomer ratios of N₂O, with abundance of ¹⁴N¹⁵N¹⁶O, ¹⁵N¹⁴N¹⁶O, and ¹⁴N¹⁴N¹⁸O relative to ¹⁴N¹⁴N¹⁶O, are promising for elucidation of N₂O biogeochemistry in an intact ecosystem. Site preference, the nitrogen isotope ratio of the central nitrogen atom minus that of the terminal nitrogen atom, is useful to distinguish between N₂O via hydroxylamine oxidation and N₂O via nitrite reduction.We applied this isotopomer analysis to a groundwater system in a temperate coniferous-forested ecosystem. Results of a previous study at this location showed that the N₂O concentration in groundwater varied greatly according to groundwater chemistry, i.e. NO₃⁻, DOC, and DO, although apportionment of N₂O production to nitrification or denitrification was ambiguous. Our isotopic analysis (δ¹⁵N and δ¹⁸O) of NO₃⁻ and N₂O implies that denitrification is the dominant production process of N₂O, but definitive information is not derived from δ¹⁵N and δ¹⁸O analysis because of large variations in isotopic fractionations during production and consumption of N₂O. However, the N₂O site preference and the difference in δ¹⁵N between NO₃⁻ and N₂O indicate that nitrification contributes to total N₂O production and that most measured N₂O has been subjected to further N₂O reduction to N₂. The implications of N₂O biogeochemistry derived from isotope and isotopomer data differ entirely from those derived from conventional concentration data of DO, NO₃⁻, and N₂O. That difference underscores the need to reconsider our understanding of the N cycle in the oxic-anoxic interface.  相似文献   

Multiple sulfur isotope chemostratigraphy across the Permian–Triassic boundary at Chaotian,China: Implications for a shoaling model of toxic deep-waters     

Masafumi Saitoh  Yuichiro Ueno  Yukio Isozaki  Naohiro Yoshida 《Island Arc》2021,30(1):e12398

Previous studies on multiple sulfur isotopes (³²S, ³³S, and ³⁴S) in sedimentary pyrite at the end-Permian suggested a shoaling of anoxic/sulfidic deep-water contributing to the extinction. This scenario is based on an assumption that the sedimentary sulfur cycle was largely controlled by benthos activity, though a stratigraphic correlation between the sulfur records and ichnofabrics of the sediments at the end-Permian has not yet been examined. We report the multiple sulfur isotopic composition of pyrite in the Permian–Triassic boundary interval at Chaotian, South China. Our data can be generally explained by a mixing of sulfur in sulfide from two different sources: one produced via sulfate reduction in an open system with respect to sulfate and the other produced in a closed system. In particular, the former with the substantially low δ³⁴S (<−40 ‰) and high ∆³³S (up to +0.100 ‰) values was likely produced via water-mass sulfate reduction or via sulfate reduction in oxic sediments with common burrows. The frequent occurrence of small pyrite framboids (mostly <5 μm in diameter) in the Lopingian (Late Permian) Dalong Formation of deep-water facies supports the enhanced water-mass sulfate reduction in an anoxic deep-water mass. The negative ∆³³S values are observed only in the oxic limestones, and no substantial ∆³³S change is observed across the extinction horizon despite of the disappearance of bioturbation. Our results are apparently inconsistent with the previous shoaling model. We expand the model and infer that, when the deep-water was sulfidic and its shoaling rate was high, a substantial amount of hydrogen sulfide (H₂S) was supplied onto the shelf via the shoaling; that resulted in the positive ∆³³S value of the bulk sediments. The observed ∆³³S variation on a global scale suggests a substantial variation in H₂S concentration and/or in upwelling rate of shoaling deep-waters during the Permian–Triassic transition.  相似文献   

基于TOPEX/Poseidon卫星数据的江河流量测算     

张继群  徐开钦  龟山哲  渡边正孝  陈秀万  孙春鹏 《地理学报》2004,59(1):95-100

TOPEX／Poseidon卫星的原始目的是测量海面高度变化信息,为海洋监测服务。作者通过假设基准面的方法,将由TOPEX／Poseidon卫星数据估算的下垫面水位相对变化信息转化为”水位”系列并建立了由TOPEX／Poseidon得出的“水位”与相邻水文站实测流量间的相关关系,进而实现了由TOPEX／Poseidon卫星数据估算河道流量的目的。利用1998～1999年TOPEX／Poseidon在长江下游大通附近的过境数据和对应年份大通水文站实测流量数据,验证了本方法的可行性。研究结果表明：在长江下游河道地区,由TOPEX／Poseidon卫星数据可定量估算出山河流流量信息。  相似文献   

Nutrients,light and phytoplankton production in the shallow,tropical coastal waters of Bandon Bay,Southern Thailand          下载免费PDF全文

Takashi Yoshikawa  Kosuke Tomizawa  Yuki Okamoto  Kazuya Watanabe  Jintana Salaenoi  Kenichi Hayashizaki  Hisashi Kurokura  Satoshi Ishikawa 《Marine Ecology》2017,38(6)

Phytoplankton primary production and its regulation by light and nutrient availability were investigated in the shallow, tropical coastal waters of Bandon Bay, Southern Thailand. The bay was meso‐eutrophicated and highly turbid, receiving river water discharge. Water column stratification was consistently weak during both rainy and dry seasons. Dissolved inorganic nitrogen (DIN) was higher off the river mouth than in the other regions, suggesting that river water discharge was a main source of DIN. By contrast, dissolved inorganic phosphorus (DIP) showed a significant negative correlation with total water depth, implying that regeneration around the sea floor was an important source of DIP. Surface DIN and DIP showed positive correlations with surface primary production (PP) and water column primary productivity (ΣPP*), respectively. The combined correlation and model analyses indicate that total water depth had an ambivalent influence on water column primary production (ΣPP); shallower water depth induced more active regeneration of nutrients, but it also caused higher turbidity and lower light availability as a result of enhanced resuspension of sediments. Furthermore, there was a vertical constraint for phytoplankton during the rainy season: total water depth tended to be shallower than euphotic zone depth. In conclusion, light limitation and vertical constraint owing to shallow water depth appear to be more important than nutrient limitation for water column primary production in Bandon Bay.  相似文献   

Experimental study on the bidirectional inelastic deformation capacity of U‐shaped steel dampers for seismic isolated buildings          下载免费PDF全文

Diana Ene  Shoichi Kishiki  Satoshi Yamada  Yu Jiao  Yoshinao Konishi  Masao Terashima  Norihisa Kawamura 《地震工程与结构动力学》2016,45(2):173-192

Hysteretic dampers are used to dissipate earthquake‐induced energy in base‐isolated structures by acquiring inelastic deformations, rendering their hysteretic behavior of vital importance. The present paper focuses on investigating the behavior of U‐shaped steel dampers under bidirectional loading; this is significantly different from their corresponding uniaxial behavior. Two main sets of loading tests on full‐scale specimens are conducted in this regard: (i) quasi‐static tests with simple histories and (ii) dynamic tests with realistic loading histories. Based on the results obtained in the quasi‐static tests, an interaction curve that accounts for the reduction of the cyclic deformation capacity is proposed. However, the fidelity of this relation must be assessed under loading conditions similar to those of a seismically isolated structure subjected to an earthquake, which represents the goal of the second set of tests. The results of the dynamic tests validate the proposed interaction curve for estimating the deformation capacity of U‐shaped steel dampers under bidirectional loading. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Disturbance of recruitment success of mantis shrimp in Tokyo Bay associated with effects of hypoxia on the early life history     

Keita Kodama  Yoshihiro Tajima  Takamichi Shimizu  Satoshi Ohata  Hiroaki Shiraishi  Toshihiro Horiguchi 《Marine pollution bulletin》2014

We investigated effects of severe hypoxia (dissolved oxygen <1 ml l⁻¹) on recruitment of mantis shrimp Oratosquilla oratoria in Tokyo Bay. Ten-year field surveys were conducted to examine quantitative relationships in annual mean densities of larvae and juveniles, and spatial distribution of juveniles and severe hypoxia. There was no significant correlation between annual mean densities of larvae and juveniles, suggesting that mortality during larval or juvenile stages varies among years, which might have regulated abundance of young-of-the-year juveniles. Juvenile density was low in the severely hypoxic area, implying that hypoxia could affect survivals and spatial distribution of juveniles. Meanwhile, there are yearly fluctuations in juvenile density in normoxic areas of both northern and southern part of the bay. This evidence suggests that abundance of post-settled juveniles might have been determined by not only effects of hypoxia, but also other factors influencing mortality during the early life stages.  相似文献   

Long-term variability of the Kuroshio path south of Japan     

Norihisa Usui  Hiroyuki Tsujino  Hideyuki Nakano  Satoshi Matsumoto 《Journal of Oceanography》2013,69(6):647-670

This study investigates the long-term variability of the Kuroshio path south of Japan. Sensitivity experiments using a data-assimilative model suggest that the duration of the large meander (LM) strongly depends on the Kuroshio transport; specifically, low transport leads to a long duration of the LM. Actually, we find a good correlation between the duration of the past LMs and the Sverdrup transport estimated by a wind-driven linear baroclinic vorticity model. Then we explore favorable conditions for the LM and find a close relationship between the Kuroshio Extension (KE) state and the LM. That is, a precondition for the LM that the Kuroshio path on the Izu Ridge is fixed at a deep channel located around 34°N is achieved during a stable KE state. In addition, westward propagating signals with negative anomalies in the Kuroshio region and high sea-surface height (SSH) state east of Taiwan are key for generation of a small meander southeast of Kyushu that triggers a subsequent LM. The signals related to the above conditions change the upstream Kuroshio transport and velocity, which are consistent with features indicated by the former observational studies. Using reanalysis data, we construct long-time series of indices for the three conditions, which explain well the past LMs. The indices suggest that long-term non-LM states around 1970 and in the 1990s were attributed to a low-SSH state east of Taiwan and an unstable KE state, respectively.  相似文献