Mathematical model for hydraulically aided electrokinetic remediation of aquifer and removal of nonanionic copper

One of the most cost-effective in situ technologies for soil and groundwater (i.e., aquifer) remediation is electrokinetic remediation. In electrokinetic remediation, electromigration due to electric field is combined with hydromigration due to hydraulic flow by purge water to remove pollutants from aquifers through the pore water. This study aims at investigating theoretically the role of electromigration (as active movement) of pollutants and the role of hydromigration (as passive movement) of pollutants in electrokinetic remediation, and making it clear that the control variables for electrokinetic remediation are the applied voltage and the hydraulic flow rate. These aims are pursued by construction of a mathematical model based on physico-chemical considerations and by model simulations of the electrokinetic remediation applied to the virtual aquifer polluted by heavy metals of copper sulfate. According to numerical simulations with the model: (1) heavy metal (nonanionic copper) is removed from the upstream anode region and accumulated in the downstream cathode region; (2) to carry away the heavy metal outside the aquifer (global removal), hydromigration by purge water flow is essential; and (3) electromigration contributes mainly to the redistribution of heavy metals within the aquifer (local removal and local accumulation).     

Spatial and Temporal Variability in Estuary Habitat Use by American Alligators

Estuarine habitat occupied by Alligator mississippiensis, a primarily freshwater species, is spatially and temporally heterogeneous largely due to a salinity gradient that fluctuates. Using long-term night light survey data, we examined seasonal patterns in alligators’ habitat use by size classes in midstream and downstream estuary zones of Shark River, Everglades National Park, in southern Florida. We observed predominantly large-sized alligators (total length?≥?1.75 m); observations of alligators in the small size classes (0.5 m?≤?total length?<?1.25 m) were rare especially in the higher-salinity downstream zone. The density of alligators in the downstream zone was lower than that of the midstream zone during the dry season when salinity increases due to reduced precipitation. Conversely, the density of the large size alligators was higher in the downstream zone than in the midstream zone during the wet season, likely because of reduced salinity. We also found a significant declining trend over time in the number of alligators in the dry season, which coincides with the reported decline in alligator relative density in southern Florida freshwater wetlands. Our results indicated high adaptability of alligators to the fluctuating habitat conditions. Use of estuaries by alligators is likely driven in part by physiology and possibly by reproductive cycle, and our results supported their opportunistic use of estuary habitat and ontogenetic niche shifts.     

A heating process of Kuchi-erabu-jima volcano,Japan, as inferred from geomagnetic field variations and electrical structure

Since August 2000, we have recorded the total intensity of the geomagnetic field at the summit area of Kuchi-erabu-jima volcano, where phreatic eruptions have repeatedly occurred. A time series analysis has shown that the variations in the geomagnetic field since 2001 have a strong relationship to an increase in volcanic activity. These variations indicate thermal demagnetization of the subsurface around the presently active crater. The demagnetization source for the early variations, until summer 2002, was estimated at about 200 m below sea level. For the variations since 2003, the source was modeled on the basis of the expansion of a uniformly magnetized ellipsoid. The modeling result showed that the source is located at 300 m above sea level beneath the crater. We carried out an audio-frequency magnetotelluric survey with the aim of obtaining a relation between the demagnetization source and the shallow structure of the volcano. A two-dimensional inversion applied to the data detected two good conductors, a shallow thin one which is restricted to a region around the summit area, while the other extends over the edifice at depths between 200 and 800 m. These conductors are regarded as clay-rich layers with low permeability, which were assumed to be generated through hydrothermal alteration. The demagnetization source for the early variations was possibly located at the lower part of the deep conductor and the source after 2003 lies between the two conductors, where groundwater is considered to be abundant. Based on these results, as well as on seismological, geodetic, and geochemical information, we propose a heating process of the Kuchi-erabu-jima volcano. In the initial stage, high-temperature volcanic gases supplied from the deep-seated magma remained temporarily at the level around the lower part of the less permeable deep conductor since the ascent path had not yet been established. Then, when the pathway developed as a result of repeated earthquakes, it became possible for a massive flux of volcanic gases to ascend through the conductor. The high temperature gases reached the aquifer located above the conductor and the heat was efficiently transported to the surrounding rocks through the groundwater. As a consequence, an abrupt increase of the gas flux and diffusion of the heat through the aquifer occurred and the high-temperature zone expanded. Since the high-temperature zone is located beneath another conductor, which acts as caprock, we assume that the energy of the phreatic explosion is accumulated there.     

Phase-lagged warming and the disruption of climatic rhythms during the Matuyama–Brunhes magnetic polarity transition

The influence of the geomagnetic field on climate, a long hotly disputed issue, was examined for the Matuyama–Brunhes (MB) magnetic polarity transition using palynological and paleomagnetic data sets from a high accumulation rate (ca. 50 cm/kyr) sediment core from Osaka Bay. During the period from marine oxygen isotope stages (MIS) 20 to 18, climate change is well correlated with global ice volume variation in the precession cycle, with the exception of the early half of MIS 19. The postglacial warming after substage 20.2 was interrupted by cooling that began just before the sea-level highstand correlated with substage 19.3 and persisted until about a mid-point between 19.3 and 19.2, followed by a rapid warming. The thermal maximum clearly postdates the highest sea-level highstand by 6–7 kyr, and the connection between orbital forcing and climate was disrupted. The cooling event coincided with the center of the paleointensity low during the MB transition. This unusual climate cooling across a sea-level peak is very likely related to the field intensity decrease. The data from Osaka Bay may suggest an instance where the geomagnetic field has influenced climate in the past.     

Application of fuzzy multi-attribute decision-making to select and to rank the post-mining land-use

The selection of an optimal reclamation method is one of the most important portions of the surface mining design. There are many factors in this problem which seriously influence decision-making. The fuzzy set theory was applied due to the effect of uncertain parameters involved in the decision-making process. Therefore, the fuzzy multi-attribute decision-making method was proposed. The aim of this study is to use the fuzzy technique for order preference by similarity to ideal solution method for ranking the optimal post-mining land-use and the fuzzy analytic hierarchy process method in order to determine the weights of each criterion. This approach is applied to the surface coal mine by employing 28 criteria which influence the decision-making procedure. The TOPSIS and AHP methods have been the most used methods of mining decision-making and demonstrated their ability to make critical decisions. By evaluating the alternatives and considering effective criteria with proposed methods, agriculture is the optimal post-mining land-use.     

Pyroxenes from lherzolite inclusions of Itinome-gata,Japan

The lherzolites have recrystallized to plagioclase lherzolites consisting of olvine, pyroxenes, chromian spinel, plagioclase and pargasite at a depth of 20 to 25 km in the uppermost part of the mantle. It is believed that the garnet lherzolites and spinel lherzolites were originally derived from depths of 50–75 km and 30–50 km respectively. The clinopyroxenes contained about 10 mol. % of jadeite and Tschermak's molecules, respectively and the orthopyroxenes also included about 5–10% of Tschermak's component. Transported upward, the garnet was transformed through pyroxene-spinel symplectite to olivine, plagioclase and spinel aggregates, and most of the jadeite amd some Tschermak's components in the pyroxenes formed secondary pyroxenes and pargasite, and finally plagioclase under isochemical conditions.     

Wellbore‐Wall Compression Effects on Monitored Groundwater Levels and Qualities

The effects of wellbore‐wall compression from rough excavation on monitored groundwater levels and qualities under natural hydraulic gradient conditions were investigated in a shallow clayey Andisol aquifer. Nine wellbores reaching the underlying aquitard at about 2.6‐m depth were constructed by dynamic cone penetrometry to mimic rough wellbore construction. Five of these were constructed under wet aquifer soil conditions and the remaining four under dry conditions. A 15‐month period monitoring showed that the groundwater levels in the wellbores constructed under wet conditions responded significantly in retard of, and in narrower ranges than, those constructed under dry conditions. The wellbore‐wall hydraulic conductivities at the former wellbores were calculated to be more than one to two orders of magnitude lower than those at the latter ones. Furthermore, remarkable nitrate removal attributable to the occurrence of a heterotrophic denitrification was observed in one of the former wellbores. In contrast, the groundwater levels and qualities in the latter wellbores appeared to be generally similar to those monitored in the conventional soil coring and augering‐derived wellbores. Our results suggest that the wellbore‐wall compression induced by rough excavation under wet and soft aquifer soil conditions leads to a substantial decrease in the wellbore‐wall hydraulic conductivity, which in turn can lead to unreliable groundwater levels and qualities. This problem can occur in clayey Andisols whenever the aquifer soil is wet; however, the problem can be largely avoided by constructing the wellbore under dry and hard aquifer soil conditions.     

Photographic Observations of the 1996 Leonid Fireballs in Japan

Several Leonid fireballs were successfully photographed by the Japanese Fireball Network and by other observers in Japan on 16 November, 1996. A totals of seven of these were simultaneously observed from two or more stations, from which the orbital and physical data were deduced. The radiant of these fireballs were very small, only 0.1°, similar to that of the 1991 Perseids. The 1996 Leonids showed a lower magnitude distribution index similar to those obtained in the 1961 and 1965 Leonids. All of these showers occurred before perihelion passage of the parent comet. We conclude that we have already encountered the elongated front part of the dust trail of the Leonid parent comet, where the trail is probably composed of larger dust particles. This revised version was published online in July 2006 with corrections to the Cover Date.     

Radiant point,trajectory and velocity from single photographic or TV observation

The radiant point can be decided by using assumption that a meteor's velocity is constant by only one photograph with rotation shutter or one TV camera. Trajectory and initial velocity can be decided by using additional assumption beginning with the height of a meteor. In this method, the radiant point can be computed accurately when trajectory length is long enough which can be regarded constant velocity and measurement's error is small.