Precise Positioning of Ocean Bottom Seismometer by Using Acoustic Transponder and CTD

We have obtained precise estimates of the position of Ocean Bottom Seismometers (OBS) on the sea bottom. Such estimates are usually uncertain due to their free falling deployment. This uncertainty is small enough, or is correctable, with OBS spacing of more than 10 km usually employed in crustal studies. But, for example, if the spacing is only 200 m for OBS reflection studies, estimates of the position with an accuracy of the order of 10 m or more is required.The determination was carried out with the slant range data, ship position data and a 1D acoustic velocity structure calculated from Conductivity–Temperature–Depth (CTD) data, if they are available. The slant range data were obtained by an acoustic transponder system designed for the sinker releasing of the OBS or travel time data of direct water wave arrivals by airgun shooting. The ship position data was obtained by a single GPS or DGPS. The method of calculation was similar to those used for earthquake hypocenter determination.The results indicate that the accuracy of determined OBS positions is enough for present OBS experiments, which becomes order of 1 m by using the DGPS and of less than 10 m by using the single GPS, if we measure the distance from several positions at the sea surface by using a transponder system which is not designed for the precise ranging. The geometry of calling positions is most important to determine the OBS position, even if we use the data with larger error, such as the direct water wave arrival data. The 1D acoustic velocity structure should be required for the correct depth of the OBS. Although it is rare that we use a CTD, even an empirical velocity structure works well.     

The idea of nature in the east in comparison with the west

Conclusion — Contemporary Implications According to Buddhist philosophy, men constitute just one class of living beings. As such, they have no right to unlimited use of natural resources. Also men have no right to unlimited exploitation of animal and plant life, which forms part of Nature. Until recently, Westerners or moderns tended to think that men were quite separate and different from the natural world. This assumption is ungrounded and unreasonable. It has brought about devastation. Men incur retaliation by nature.In order to deal with the difficult situation that has come about, we must seek a solution that is both objective and subjective. On the objective side, we must discard the arrogance of supposing that men are entitled to exploit the natural world at their own will, without limit and regardless of the consequences. It is not appropriate to maintain the idea of conquering nature. Nature should be met with affection. In this connection, we emphasize that the world of nature should not be monopolized by a few countries. The whole natural world should be shared by all mankind. We cannot but feel angry at the small, limited number of countries which totally control the reserves of a limited energy supply, and which are extravagantly wasting what nature has entrusted to them. Just as individual egoism must be curtailed and placed under control, so national and ethnic egoism also should be restrained in the name of justice and respect for nature.On the subjective side, there is need for correction of the opinion of moderns that the progress of mankind consists in the unlimited satisfaction of human desire for material objects. Buddhism taught satisfaction with what is given to men. To know being satisfied was thought to be the way to spiritual happiness. The key to the relationship between man and the environment may very well lie in the control of our desires according to this concept of satisfaction. For that purpose our desire should be scaled to the possibilities of nature conceived as supporting human existence. Nature is not an entity to confront us as if it were quite different from us; it is something to embrace, as we might think it as that from which we cannot separate ourselves. Admitting the disinction between man and nature, we have to think how to live with the knowledge that nature is necessary to us.     

Characterization of water quality variation in the Mekong River at Vientiane by frequent observations

To better understand the variation of water quality in the Mekong River, sampling and measurement were scheduled twice a week for about 3 years at Vientiane, followed by basic statistical analysis of the observed data. The frequent measurement revealed detailed characteristics of the water quality variation, which had not been detected by monthly observation in the previous studies. The variation in total ionic content was considered to be governed by dilution of the amount of water. Increases in turbidity could be attributed to physical effects including surface soil erosion and bed material resuspension at the time of discharge increase. Nitrogen concentrations were stably low during the low flow period and abruptly increased in May. After the annual maximum in late May, the nitrate concentration steadily decreased regardless of the remarkable rise in the discharge from mid‐July, whereas the ammonium concentration remained at a similar level until October. It was considered that the first small discernable runoff after the long dry season flushed the accumulated nitrogen in the surface soil and mobilized the nitrogen in the riverbed. The variation in phosphorus concentrations was different from that in nitrogen concentrations. During the high flow period, continual dilutions at discharge peaks and occasional large additions of phosphorus by surface runoff were suggested. Copyright © 2011 John Wiley & Sons, Ltd.     

The role of crabs (Macrophthalmus japonicus) burrows on organic carbon cycle in estuarine tidal flat,Japan

The objective of this study is to elucidate the burrow structure and to clarify the role of burrows in material cycle in the tidal flat. In our work, we focused on the dominant species in muddy tidal flat, crab Macrophthalmus japonicus.Burrow structure of Macrophthalmus japonicus was investigated on a Katsuura river tidal flat in Tokushima prefecture, Japan, using in situ resin casting. Sampling was conducted in August 2006, and a total of 48 burrow casts were obtained. Burrows consisted mainly of J-shaped structures (98%) while the rest belonged to U-shaped structures (2%). The maximum measured burrow volume was 120 cm³ and wall surface area was 224 cm², while maximum burrow length and depth were 23.2 cm and 16.5 cm, respectively. Burrow volume and surface area were strongly correlated with carapace width of M. japonicus. Investigation of the individual number of M. japonicus in 13 quadrats (50 × 50 × 20 cm) was conducted using 2 mm sieve. The number of M. japonicus was 15–31 ind./m². Using cohort analysis we estimated that surface area of burrows was 0.07–0.15 m²/m².CO₂ emission rate was measured at the surface sediment during the period from June to December 2008. Results varied from 13.8 ± 2.2 to 49.4 ± 3.2 mg CO₂/m²/h, and organic carbon decomposition was 3.8 ± 0.6–13.5 ± 0.9 mg C/m²/h. This leads the increase of organic carbon decomposition by 1.1 times, because of the expansion of the tidal flat surface area by burrowing activity. Organic carbon decomposition in burrow walls therefore contributed to organic matter decomposition in the tidal flat. These results indicated that in situ activities of Macrophthalmus japonicus significantly influence the material cycle and it is important to consider the existence of burrow in order to understand the fluxes of materials and to evaluate the purification function of the tidal flat.     

Harmonization of international risk assessment protocol

For over centuries developments in food production and new food safety management systems in most developed countries have been perceived by many to be efficient in the prevention of food-borne disease. Nevertheless a number of problems remain dominant, one of these being the high level of food-borne microbiological disease which seems, for some pathogens, to have increased over the last decades. The development of an interdisciplinary approach with direct interaction between surveillance and risk analysis systems is described as a potential basis for improved prevention of food-borne disease. Quantitative microbiological risk assessment is a relatively new scientific approach, able to link data from food within the entire food chain and the various data on human disease to provide a clear estimation of risk. Today food safety is one of the WHOs top eleven priorities; the Organization calls for more systematic and aggressive steps to be taken to reduce significantly the risk of microbiological food-borne diseases. Dealing with this challenge is one of the major challenges for the 21st century in regard to food safety, implying a significant re-direction of food microbiology efforts in many parts of the world.     

Alfvén polar oscillations of relativistic stars

We study polar Alfvén oscillations of relativistic stars endowed with a strong global poloidal dipole magnetic field. Here, we focus only on the axisymmetric oscillations which are studied by numerically evolving the two-dimensional perturbation equations. Our study shows that the spectrum of the polar Alfvén oscillations is discrete in contrast to the spectrum of axial Alfvén oscillations which is continuous. We also show that the typical fluid modes, such as the f and p modes, are not significantly affected by the presence of the strong magnetic field.     

Relationship between species diversity and reef growth in the Holocene at Ishigaki Island,Pacific Ocean

Coral reefs are influenced by global and local factors, and living corals are currently faced with a potential loss of species diversity. Knowledge of the relationship between species diversity and reef growth during the Holocene is important in terms of accurately reconstructing natural conditions prior to recent disturbances (e.g., human impact, pollution, and over-harvesting) and in predicting future scenarios (e.g., abrupt sea-level rise, coastal change, and economic services). This study seeks to characterize the Holocene and present-day reef at Ishigaki Island in the Ryukyu Islands, focusing on spatial and temporal variations in the relationship between species diversity and reef growth. The analysis is based on a drilling core obtained for the Holocene reefs and quantitative species-diversity data (Shannon and Weaver's diversity index, H′) obtained for the present-day reef. H′ was calculated for four coral communities surveyed at the Ibaruma and Fukido reefs. The Holocene sequence was dominated by the corymbose coral community (e.g., Acropora digitifera, A. hyacinthus, Goniastrea retiformis, and Platygyra ryukyuensis), yielding an H′ value of 1.6. The encrusting coral community (e.g., Echinopora lamellose and Pachyseris rugosa) showed the highest diversity at the reef (H′ = 2.2); however, this community was not one of the main reef builders during the Holocene. The massive coral community (e.g., Porites lutea and Favites chinensis) showed the lowest diversity (H′ = 0.6). It also made a minor contribution to reef building; this community appeared in a shallow lagoon once sea level had stabilized. The arborescent coral community (e.g., A. formosa and A. nobilis) was one of the main reef builders, although yielding an H′ value of much less than 1.0. Species diversity is not a prerequisite in terms of Holocene reef growth. Thus, a few species (e.g., A. digitifera, A. hyacinthus, A. formosa, A. nobilis, G. retiformis, and P. ryukyuensis) from two main reef-building communities are important for reef growth. These corals that act as reefs are characterized by high growth rates, having an upward reef growth rate of 2–12 m kyr^? 1 in the Indo-Pacific during the Holocene.     

36Cl, 26Al,and O isotopes in an Allende type B2 CAI: Implications for multiple secondary alteration events in the early solar system

Abstract— We measured ³⁶Cl‐³⁶S and ²⁶Al‐²⁶Mg systematics and O isotopes of secondary phases in a moderately altered type B2 CAI (CAI#2) from the Allende CV3 chondrite. CAI#2 has two distinct alteration domains: the anorthite‐grossular (An‐Grs) domain that mostly consists of anorthite and grossular, and the Na‐rich domain that mostly consists of sodalite, anorthite, and Fe‐bearing phases. Large ³⁶S excesses (up to ～400‰) corresponding to an initial ³⁶Cl/³⁵Cl ratio of (1.4 ± 0.3) × 10^?6 were observed in sodalite of the Na‐rich domain, but no resolvable 26Mg excesses were observed in anorthite and sodalite of the Na‐rich domain (the initial ²⁶Al/²⁷Al ratio < 4.4 × 10^?7). If we assume that the ³⁶Cl‐³⁶S and the ²⁶Al‐²⁶Mg systematics were closed simultaneously, the ³⁶Cl/³⁵Cl ratio would have to be on the order of ～10^?2 when CAIs were formed. In contrast to sodalite in Na‐rich domain, significant ²⁶Mg excesses (up to ～35‰) corresponding to an initial ²⁶Al/²⁷Al ratio of (1.2 ± 0.2) × 10^?5 were identified in anorthite of the An‐Grs domain. The ²⁶Al‐²⁶Mg systematics of secondary phases in CAI#2 suggest that CAIs experienced multiple alteration events. Some of the alteration processes occurred while ³⁶Cl (half‐life is 0.3 Myr) and ²⁶Al (half‐life is 0.72 Myr) were still alive, whereas others took place much later. Assuming that ²⁶Al was homogeneously distributed in the solar nebula, our study implies that alteration of CAIs occurred as early as within 1.5 Myr of CAI formation and as late as 5.7 Myr after.     

Determination of Total Sulfur in Thirty One Geochemical Reference Materials Using an Inductively Coupled Plasma-Atomic Emission Spectrometer Fitted with a Semiconductor Photodiode Detector

The total sulfur contents of thirty one geochemical reference materials were determined using an inductively coupled plasma-atomic emission spectrometer fitted with a semiconductor photodiode detector. Most samples were decomposed using an HF-aqua regia digestion. However, a few were incompletely decomposed by simple acid digestion, and these were decomposed by a fusion method. The agreement between the analytical results from this work and published data is generally good.