Landfill development in the urban fringe of Metro Manila

In low-lying areas of urban and suburban regions in Asia, the use of landfill has allowed urban land use to encroach onto watery landforms, such as back marshes, which were formerly used as rice fields. To improve understanding of the associations between land-use patterns and landfill development, we carried out a case study in the urban fringe of Metro Manila in the Philippines. We examined landfill volume derived from land-use change using GIS, and field surveyed qualitative aspects of the landfill used. We calculated the rate of application of landfill in low-lying housing development areas to be 5.0 × 10³ m³ km^?2 year^?1, most of which consisted of offsite disposal of construction waste or crushed rock produced by urban development and renewal on the adjoining uplands. The flow of fill material from offsite sources to onsite landfill development areas was on the basis of individual agreements between suppliers and developers.     

Changes in microbial community composition in the leaf litter of successional communities after volcanic eruptions of Mount Usu,northern Japan

Changes in the fungal and bacterial biomass and community structure in litter after the volcanic eruptions of Mount Usu, northern Japan were investigated using a chronosequence approach, which is widely used for analyzing vegetation succession. The vegetation changed from bare ground(10 years after the eruptions) with little plant cover and poor soil to monotonic grassland dominated by Polygonum sachalinense with undeveloped soil(33 years) and then to deciduous broad-leaved forest dominated by Populus maximowiczii with diverse species composition and well-developed soil(100 years). At three chronosequential sites, we evaluated the compositions of phospholipid fatty acids(PLFAs), carbon(C) and nitrogen(N) contents and the isotope ratios of C(δ13C) and N(δ15N) in the litter of two dominant species, Polygonum sachalinense and Populus maximowiczii. The C/N ratio, δ13C and δ15N in the litter of these two species were higher in the forest than that in the bare ground and grassland. The PLFAs gradually increased from the bare ground to the forest, showing that microbial biomass increased with the development of the soil and/or vegetation. The fungi-to-bacteria ratio of PLFA was constant at 5.3 ± 1.4 in all three sites, suggesting that fungi were predominant. A canonical correspondence analysis suggested that the PLFA composition was related tothe successional ages and the developing soil properties(P 0.05, ANOSIM). The chronosequential analysis effectively detected the successional changes in both microbial and plant communities.     

Sound velocity and elastic properties of Fe–Ni and Fe–Ni–C liquids at high pressure

The sound velocity (V _P) of liquid Fe–10 wt% Ni and Fe–10 wt% Ni–4 wt% C up to 6.6 GPa was studied using the ultrasonic pulse-echo method combined with synchrotron X-ray techniques. The obtained V _P of liquid Fe–Ni is insensitive to temperature, whereas that of liquid Fe–Ni–C tends to decrease with increasing temperature. The V _P values of both liquid Fe–Ni and Fe–Ni–C increase with pressure. Alloying with 10 wt% of Ni slightly reduces the V _P of liquid Fe, whereas alloying with C is likely to increase the V _P. However, a difference in V _P between liquid Fe–Ni and Fe–Ni–C becomes to be smaller at higher temperature. By fitting the measured V _P data with the Murnaghan equation of state, the adiabatic bulk modulus (K _S0) and its pressure derivative (K _S ^′ ) were obtained to be K _S0 = 103 GPa and K _S ^′  = 5.7 for liquid Fe–Ni and K _S0 = 110 GPa and K _S ^′  = 7.6 for liquid Fe–Ni–C. The calculated density of liquid Fe–Ni–C using the obtained elastic parameters was consistent with the density values measured directly using the X-ray computed tomography technique. In the relation between the density (ρ) and sound velocity (V _P) at 5 GPa (the lunar core condition), it was found that the effect of alloying Fe with Ni was that ρ increased mildly and V _P decreased, whereas the effect of C dissolution was to decrease ρ but increase V _P. In contrast, alloying with S significantly reduces both ρ and V _P. Therefore, the effects of light elements (C and S) and Ni on the ρ and V _P of liquid Fe are quite different under the lunar core conditions, providing a clue to constrain the light element in the lunar core by comparing with lunar seismic data.     

Circulation and Material Transport in Suo-Nada during Spring and Summer

An attempt was made to reproduce the circulation pattern in Suo-Nada, Japan during spring and summer season in order to elucidate the water exchange mechanism in the basin. Two hydrographic surveys at the end of each season were conducted covering the entire Suo-Nada area. A three-dimensional hydrodynamic Princeton Ocean Model (POM) was used to compute the current resulting from the observed density and wind field. During spring, a very pronounced counter clockwise gyre is situated near the opening of the basin. This is replaced by a clockwise circulation which seemed to occupy the whole domain during summer. Within each season, however, the vertical distribution of current does not show any remarkable differences, indicating the dominance of horizontal current and a very weak estuarine flow. These observational and numerical results were used to estimate the remnant function and the corresponding average residence time of permanently dissolved matter (PDM) and transformable matter (TM). The results revealed a small difference in the average residence times of materials within each season but a large seasonal variability between spring and summer. Furthermore, calculations based on climatological density fields have indicated a similar trend of variation between the seasonal values of average residence times. This revised version was published online in July 2006 with corrections to the Cover Date.     

Caprella watch: a new approach for monitoring butyltin residues in the ocean

A comparative study on the butyltin levels in various organisms showed that marked bioaccumulation occurs in certain lower trophic levels; i.e. from seawater to phytoplankton and into caprellid amphipods, Caprella spp. Caprella spp., which inhabit algal communities and aquaculture beds in the subtidal zone, are small crustaceans with reduced movement and a life-span of less than 3 months. These characteristics indicate that Caprella spp. may be well-suited for monitoring butyltin residue changes over small spatial and temporal scales. Two groups of organisms, mussels and neogastropods, have been mainly used for monitoring butyltin in shallow water ecosystems. These invertebrates mainly inhabit the intertidal zone where the butyltin levels vary widely depending on the immersion period and exposure to the sea surface microlayer. Monitoring using neogastropods may also over estimate exposures after restrictions on tributyltin, since neogastropods show an irreversible response to residue changes owing to their long life-spans. Thus, we propose usage of Caprella spp. to monitor temporal and spatial changes in baseline concentrations of butyltins.     

Hydrothermal plumes in the eastern Manus Basin, Bismarck Sea: CH4, Mn, Al and pH anomalies

We present evidence for strong hydrothermal activity in the eastern Manus Basin (depth: 1700–2100 m), the existence of large scale triple-layered buoyant plumes at depths of 1100 m (“shallow plume”), 1700 m (“deep plume”), and 1400 m (“middle plume” with less extent than the other two plumes) that were revealed from water column anomalies of CH₄, Mn, Al and pH observed in November to December 1990. Judging from the horizontal distribution of these parameters, the deep plume seems to originate from two distinct hydrothermal sites (eastern and western sites) in the research area, the eastern site being visually ascertained with deep-tow observations at the same time. The CH₄/Mn ratio (mol mol⁻¹) of the deep plume (0.02–0.05) is the lowest yet observed in hydrothermal plumes. The order of magnitude difference of CH₄/Mn ratios between the shallow plume and the deep plume suggests that different kinds of fluid-rock interaction occurred to make the hydrothermal end members for the deep and shallow plumes. The shallow plume, which had an areal extent of more than 50 km, may be an episodic “megaplume”, because it was not recognized in the previous CH₄ profiles in 1986, and because it has a similar CH₄/Mn ratio as the megaplume observed in the North Fiji Basin. We found that the eastern deep plume is characterized by enormously high aluminium concentrations (0.6– 1.5 μmol kg⁻¹), pH anomalies (0.1) and high Al/Mn ratios (10–17). The endmember fluid for the eastern deep plume may have an unusually low pH value to dissolve this much aluminum during fluid-rock interaction, or this plume may originate from an eruption-influenced fluid.     

Current measurements with surface and subsurface drifters

An examination of behaviors of a subsurface drogue and a subsequent examination of current measurement with a drifter comprising the drogue as its important part are made in the channel between Oshima and Izu Peninsula. The drogue submerged to the anticipated depth of 300 m within 10 minutes after launching. Since then the drogue kept its depth and operated normally. From the comparison with the velocity measurement by the use of a currentmeter moored at a station in the vicinity of the drifter's track, it is verified that the drifter's motion well reflects the motion of a water parcel around the drogue.     

大气气溶胶的垂直非均一对向上亮度和卫星遥感地表反射率的效应

均一模式和两层模式是两个忽略气溶胶垂直非均一、并广泛用于卫星遥感的辐射模式。通过两个模式的数值模拟，分析了气溶胶的垂直非均一对向上天空亮度和卫星遥感地面反射率的效应。数值模拟选用了２４个有代表性的气溶胶模式。对于具有强分子散射的卫星短波通道，由于分子和气溶胶散射性的明显不同，应用均一和两层模式计算的向上亮度往往存在较大误差。对长波通道，如果气溶胶的光学特性随高度变化不大，该亮度误差较小，但如果存在不同散射相函数和一次散射反照率的气溶胶层，该误差仍可能较大。对于干净的大气，由均一和两层模式计算的亮度误差可分别高达３１．４％和３１．５％，而对于混浊的大气，该误差可分别高达６７．８％和５９．２％。该亮度误差可以引起地表反射率解存在大的不确定性，特别是对于短波通道和强吸收的气溶胶。对于包含强吸收气溶胶的混浊大气，均一和两层模式不适合于大气订正应用。     

Role of precursory less-viscous mixed magma in the eruption of phenocryst-rich magma: evidence from the Hokkaido-Komagatake 1929 eruption

During the 1929 activity of Hokkaido-Komagatake volcano, the Plinian eruption of a phenocryst-rich andesite was preceded by a small eruption of more mafic magma formed by magma mixing. A similar eruption sequence has been reported for some other eruptions (Pallister et al. 1996; Venezky and Rutherford 1997), suggesting that eruption of a mixed magma is a precursor of phenocryst-rich magmas. For the purpose of understanding the tapping processes of the phenocryst-rich magma chamber, we investigated the temporal variation in the erupted magma and estimated the viscosity and density of the end-member and mixed magmas with constraints drawn from petrography. For the precursory mixed magma we estimate 33dž vol.% phenocrysts, andesitic-dacitic melt composition, 3 wt.% H₂O content, and temperature of 1040°C. In comparison, for the climactic, silicic end-member magma we estimate 48Dž vol.% phenocryst, high-silica rhyolitic melt, 3 wt.% H₂O, and temperature of 950°C, respectively. The mafic end-member magma, which was not erupted, is thought to be an almost aphyric basaltic-andesitic magma, based on mass balance calculation of the phenocryst content. The proportion of the mafic end-member magma component in the mixed magma was calculated to be 20-40 wt.%. On the basis of these data, we estimate magma viscosities of 10^3.9, 10^6.9, and 10^2.0 Pa s for the mixed, silicic end-member, and mafic end-member magmas, respectively. The calculated density differences among these magmas are inconsequential when possible errors are considered. We calculate the minimum excess pressure required for dike propagation to be 31 MPa for the silicic end-member magma and 8 MPa for the mixed magma, using the estimated viscosity and dike propagation model of Rubin (1995). If we assume that excess pressure is limited by the wall rock strength of the magma chamber, excess pressure retainable in the magma chamber is less than ca. 20 MPa. This suggests that the mixed magma was able to ascend to the surface without freezing, whereas the viscous silicic end-member magma could not. The formation and precursory eruption of the mixed magma are, therefore, effective and necessary initiation processes for the phenocryst-rich, viscous magma eruption.     

Fatty acids and hydrocarbons in surficial sediments of Lake Huron

Fatty acid and hydrocarbon distributions in surficial sediments from ten locations in southern Lake Huron indicate both aquatic and terrigenous recent biological sources of these geolipid materials. Normal alkanoic acids appear to be derived primarily from aquatic sources whereas normal alkanes are from multiple origins. Geolipid distributions are determined by the nature of the biogenic source and are modified during transport and deposition. Sediments receiving urban runoff in Saginaw Bay contain large amounts of non-biogenic hydrocarbons of a petroleum or industrial nature.