Photographic monitoring system for observing heavy free-falling objects: Multi-stage design packages of radioactive waste

In the consideration of safety it is required that packages containing radioactive wastes when dumped at sea should keep their integrity and retain their contents until they reach the seabed. Packages containing simulated radioactive wastes (non-radioactive) were tested by a free-fall method at depthsca. 4,300 m in an area for dumping industrial waste off Shikoku Island. Since the weight of the largest package was 4,300 kg, special attention was paid to the connection of a buoyancy system with mooring rope. Descent and ascent velocities of the free-fall system were calculated prior to the experiment. A free-fall experiment with an extremely heavy object, heavier than ever previously reported, was accomplished without trouble by using the free-fall system. Recovery of a camera, flash-light, and other components was successful in each of the three experiments. Successive photographing of the package during descent was made and its integrity was observed using the photographs taken by the recovered camera. The packages remained intact during descent and at least for a short time after arrival on the seabed.     

Holocene millennial-scale climate variations documented by multiple lake-level proxies in sediment cores from Hurleg Lake,Northwest China

Millennial-scale climate variability has not been well documented in arid northwest China due to the scarcity of high-resolution, well-dated paleoclimate records. Here we present multi-proxy records from sediment cores taken in freshwater Hurleg Lake on the northeastern Tibetan Plateau, which reveal millennial-scale lake-level and climate variations over the past 8,000 years. This high-elevation region is very sensitive to large-scale climate change, thus allowing us to better understand Holocene climate variations in East Asia. The lake-level record, derived from lithology, magnetic mineralogy, carbonate isotopes, ostracode shell isotopes and trace elements, X-ray fluorescence (XRF), and gray scale data, indicates a highly variable and generally dry climate from 7.8 to 1 ka (1 ka = 1,000 cal year BP), and a relatively stable and wet climate after 1 ka. Superimposed on this general trend, six dry intervals at 7.6–7.2 ka, 6.2–5.9 ka, 5.3–4.9 ka, 4.4–3.8 ka, 2.7–2.4 ka, and 1.7–1.1 ka were detected from the high-resolution carbonate content and XRF data. The generally dry climate between 7.8 and 1 ka was almost synchronous with the decrease of East Asian and Indian monsoon intensities shortly after 8 ka. The six dry intervals can be correlated with weak monsoon events recorded in the East Asia and Indian monsoon regions, as well as the North Atlantic cold events. Our data suggest that millennial-scale monsoon variations could cause highly variable climate conditions in arid northwest China during the Holocene. These millennial-scale climate variations may reflect changes in solar variation and/or changes in oceanic and atmospheric circulation.     

A Test of Mining Simulations for Phosphorus Adjustment in a Limestone Quarry - Dynamic Programming Compared with a Genetic Algorithm

Limestone quarries where slaked lime is produced for steel makers have been urged to reduce the concentration of phosphorus in their products. In a few quarries in Japan, limestone blocks with low concentrations are blended with limestone blocks with high concentrations to stay below the limit of permitted phosphorus quality. The life of the quarry is extended as long as possible by this blending. Some quarries have a geological database with accurate records of the operations for phosphorus adjustment.However, the combination problem of these blocks typically is addressed by Dynamic Programming; that is, all combinations of possible limestone blocks are examined in the solving process; the combination numbers are so huge that the optimum combination cannot be solved in practical process times. Although it took 8 hours to solve for 600 blocks with a 2GHz high performance personal computer, it would take more than 36 days to approximately solve for 1200 blocks, and 3,378 days are estimated to solve 2,400 blocks. Therefore, a Genetic Algorithm was used to try and work out the optimum combination. First, blocks that can be removed are selected in the quarry and their removal sequence makes the genotype. The Order-base or the Grefenstette method was applied to avoid generating lethal genes in crossover. The fitness value was estimated by the number of products that included less than the permitted concentration of phosphorus.The GA process took less than 3 hours to solve for 1,200 blocks. Because the processing time is almost proportional to the block numbers, this GA method is practical in large quarries. Moreover, this method is easy to apply to other conditions in mining plans, such as environmental protection, noise prevention and eyesore problems. These problems are becoming important factors in quarries near towns in Japan.     

Isotopic evolution and climate paleorecords: modeling boundary effects in groundwater-dominated lakes

We used an isotopic mass-balance model to examine how the hydrogeologic setting of lakes influences isotopic response of evaporating lake water to idealized hydroclimatic changes. The model uses a monthly water and isotope balance approach with simplified water-column structure and groundwater exchanges. The framework for comparative simulations is provided by lakes in a region of the Northern Rocky Mountains that display high interlake geochemical variability, thought to be controlled by groundwater hydraulics. Our analysis highlights several isotopic effects of flow between aquifers and lakes, leading to possible divergence of isotopic paleorecords formed under a common climate. Amplitude of isotopic variation resulting from simulated climate forcing was greatly damped when high groundwater fluxes and/or low lake volume resulted in low lake fluid residence time. Differing precipitation and evaporation scenarios that are equivalent in annual fluid balance (P−E) resulted in different isotopic signatures, interpreted as a result of evaporation kinetics. Concentrating low-δ groundwater inflow during spring months raised springtime lake δ values, a counterintuitive result of coincidence between times of high groundwater inflow and the evaporation season. Transient effects of reduced fluid balance caused excursions opposite in sign from eventual steady-state isotopic shifts resulting from enhanced groundwater inflow dominance. Lags in response between climate forcing and isotopic signals were shortened by high groundwater fluxes and resulting short lake residence times. Groundwater-lake exchange exerts control over patterns of lake isotopic response to evaporation through effects on lake residence time, inflow composition, and seasonal timing of inflow and outflow. Sediments from groundwater-linked lakes, often used for paleoenvironmental analysis, should be expected to reflect isotopic complexities of the type shown here. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Inter-manufacturer Difference and Temperature Dependency of the Fall-Rate of T-5 Expendable Bathythermograph

The fall-rate of the T-5 expendable bathythermograph (XBT) produced by Tsurumi Seiki (TSK) Co., Ltd and that by Sippican Inc., are intercompared by a series of contemporaneous and colocated measurements with conductivity-temperature-depth (CTD) profilers. It is confirmed that the fall-rates of the two manufacturers' T-5 differ by about 5 percent, despite the fact that they had been believed to be identical for many years. The cause of the difference is discussed on the basis of a detailed cross-examination of the two T-5 models. It is found for the first time that the two models are different in several respects. The manufacturer's fall-rate equation is only applicable to the Sippican T-5, for which Boyd and Linzell's (1993) equation seems to be slightly more accurate. Kizu et al.'s (2005) equation gives a clearly less biased depth than the manufacturers' equation for the TSK T-5. It is also found that the fall-rates of both T-5 models are dependent on water temperature, perhaps because of viscosity. The temperature-dependency of the fall-rate of the TSK T-5 is larger than that of the Sippican T-5.     

Iron-water reaction at high pressure and temperature, and hydrogen transport into the core

We observed a direct reaction of metallic iron with water to form iron hydride and iron oxide, 3Fe + H₂O–>2FeH_x + FeO, at pressures from 6 GPa to 84 GPa and temperatures above 1,000 K in diamond anvil cell (DAC). Iron hydride is dhcpFeH_x or -FeH_x, and iron oxide has the rhombohedral or B1 structure at pressures at least up to 37 GPa. The formation of an assembly composed of dhcpFeH_x and FeO with the B8 structure was observed at 84 GPa. In primordial Earth, water formed by dehydration of the low temperature primitive materials reacts with metallic iron in the high temperature component to form iron hydride FeH_x and iron oxide FeO. The former would be incorporated in the iron forming the core. Thus hydrogen could be an important element of the Earths core. This reaction would be essential for transport of hydrogen into the core in the accretion stage of the Earth.     

Intermittent Phase Transitions in a Slider-block Model as a Mechanism for Earthquakes

— The aperiodic behavior of a two-dimensional stick-slip slider-block model of earthquakes is the subject of this study. The phenomenon of temporal phase transitions between creep and stick-slip motions is thoroughly analyzed and attributed to type-I intermittency. Asymmetry in the elastic forces is shown to play a key role in the emergence of complex behavior in the model. The unpredictability of chaotic bursts in the intermittent regime indicates potential difficulties for earthquake forecasting.     

Sequence-stratigraphic signatures of hemipelagic siltstones in deep-water successions: the Lower Pleistocene Kiwada and Otadai Formations, Boso Peninsula, Japan

Sequence-stratigraphic signatures of hemipelagic siltstones were investigated using profiles of the magnetic susceptibility and selected chemical composition of the Early Pleistocene deep-water successions of the Kiwada and Otadai Formations on the Boso Peninsula, Japan. In the context of an independently developed sequence-stratigraphic framework for the submarine-fan deposits of the Otadai Formation, the magnetic susceptibility and chemical composition, such as the concentrations of TiO₂, MgO and Fe₂O₃, show that the lowstand systems tract deposits have higher values of these parameters than the transgressive and highstand systems tract deposits. In contrast, the CaO contents have inverse relationships with the magnetic susceptibility and are higher in the transgressive and highstand systems tract deposits. The positions of sequence boundaries largely coincide with the horizons from which the magnetic susceptibility and the contents of mafic component increase abruptly. The sequence-stratigraphic variations in the magnetic susceptibility and chemical composition of the submarine-fan hemipelagic siltstones are due to increases in the input of fine-grained, terrigenous clastic sediments from midwater flow suspension, in addition to the direct fluvial supply of relatively unmodified terrigenous clastic sediments during relative sea-level lowstands, although grain size of hemipelagic siltstones does not exhibit any distinct variation through depositional sequences. The Kiwada Formation is characterized by siltstone-dominated basin-plain deposits and its sequence-stratigraphic classification has been difficult when using just lithofacies features. Nevertheless, the profiles of the magnetic susceptibility and chemical composition of the basin-plain deposits are similar to those of the submarine-fan deposits with duration largely equivalent to the 41,000-years obliquity cycle of the Early Pleistocene oxygen isotope sea-level index. This finding indicates that the profiles of the magnetic susceptibility and chemical composition of hemipelagic siltstones reflect sequence-stratigraphic variation in the input of fine-grained terrigenous clastic sediments to the deep-water environments and are crucial for the recognition of cryptic sequence boundaries in hemipelagic successions.