Postglacial anthropogenic fires related to cultural changes in central Japan,inferred from sedimentary charcoal records spanning glacial–interglacial cycles

We examined long-term charcoal records spanning the glacial–interglacial cycles that are evident in two cores collected from Lake Biwa in central Japan. We found that the records of the two cores have a similar long-term variation pattern of charcoal concentrations and abundant large charcoal fragments in postglacial sediments, which indicates that frequent fires occurred near the shores of Lake Biwa during the postglacial period. Analogous natural conditions in the early postglacial period and the early part of the last interglacial period strongly suggest that the frequent fires that occurred only during the postglacial period were anthropogenic. A comparison between the charcoal records of Lake Biwa sediments and the cultural changes and human populations in this district suggests that anthropogenic fires in this district were influenced by the lifestyle and culture of each era rather than by the populations. Humans tended to use more fire at the start of the settlement during the early Neolithic era in this region, in spite of the small population size.     

Assessing land-use and carbon stock in slash-and-burn ecosystems in tropical mountain of Laos based on time-series satellite images

In the tropical mountains of Southeast Asia, slash-and-burn (S/B) agriculture is a widely practiced and important food production system. The ecosystem carbon stock in this land-use is linked not only to the carbon exchange with the atmosphere but also with food and resource security. The objective of this study was to provide quantitative information on the land-use and ecosystem carbon stock in the region as well as to infer the impacts of alternative land-use and ecosystem management scenarios on the carbon sequestration potential at a regional scale. The study area was selected in a typical slash-and-burn region in the northern part of Laos. The chrono-sequential changes of land-use such as the relative areas of community age and cropping (C) + fallow (F) patterns were derived from the analysis of time-series satellite images. The chrono-sequential analysis showed that a consistent increase of S/B area during the past three decades and a rapid increase after 1990. Approximately 37% of the whole area was with the community age of 1–5 years, whereas 10% for 6–10 years in 2004. The ecosystem carbon stock at a regional scale was estimated by synthesizing the land-use patterns and semi-empirical carbon stock model derived from in situ measurements where the community age was used as a clue to the linkage. The ecosystem carbon stock in the region was strongly affected by the land-use patterns; the temporal average of carbon stock in 1C + 10F cycles, for example, was greater by 33 MgC ha⁻¹ compared to that in 1C + 2F land-use pattern. The amount of carbon lost from the regional ecosystems during 1990–2004 periods was estimated to be 42 MgC ha⁻¹. The study approach proved to be useful especially in such regions with low data-availability and accessibility. This study revealed the dynamic change of land-use and ecosystem carbon stock in the tropical mountain of Laos as affected by land-use. Results suggest the significant potential of carbon sequestration through changing land-use and ecosystem management scenarios. These quantitative estimates would be useful to better understand and manage the land-use and ecosystem carbon stock towards higher sustainability and food security in similar ecosystems.     

Integrated vegetation classification and mapping using remote sensing and GIS techniques

1INTRODUCTIONResearchonglobalenvironmentalchange,especiallyglobalvegetationchange,hasbeenmoreandmoreemphasizedbyscientistsandgovernments.HoWever,theinvestigationofvegetationcoveredinlargeareaneedagreatdealoffundandlaal.Asthesatelliteremotesensingdatahavebeenavailablesinceearly1980s,thesedataarebeingemployedtowardstOtheimprovementofvegetationclassification.NOAA--AVHRRdatahavebeenmoreandmoreusedbyscientistsbecauseOfitsshorttemPOralrefution,largescope,inexpensivecostandbreadwavebands.On…     

Seasonal variation of <Superscript>228</Superscript>Ra/<Superscript>226</Superscript>Ra ratio in surface water from the East China Sea and the Tsushima Strait

A total of 21 surface water samples were collected on the east side of the East China Sea (ECS) (3 sites) and at the Tsushima Strait (1 site), and ²²⁶Ra and ²²⁸Ra activities were measured using low-background γ-spectrometry. The ²²⁸Ra/²²⁶Ra ratios among the samples exhibited notable seasonal variation (²²⁸Ra/²²⁶Ra = 0.2–2.6) accompanying changes of salinity (31.7–34.7). Seasonal water circulation within the ECS is hypothesized to cause the change by altering the mixing ratio of ²²⁸Ra-rich continental shelf water and ²²⁸Ra-poor Kuroshio water.     

Effective location of active control devices for building vibrations caused by periodic excitation acting on intermediate storey

In order to investigate ways of reducing vibrations of building structures subjected to excitation acting on intermediate storey, active vibration controls are conducted with active control devices installed on different floors of the structure, and the effective location of control devices is also investigated. In this paper, we propose a new ‘Discrete‐Optimizing Control Method’ for vibration control. The control forces are determined analytically which makes the ‘discrete‐index function’ minimum. Through numerical simulation, the Discrete‐Optimizing Control Method is proved to be an effective control method. The response reduction effects are best when the control devices are concentrated on the adjacent three floors of the vibration source. Copyright © 2000 John Wiley & Sons, Ltd.     

Dynamic non-linear analysis of reinforced concrete shear wall by finite element method with explicit analytical procedure

A numerical procedure for a dynamic non-linear finite element analysis is proposed here to analyse three-dimensional reinforced concrete shear wall structures subjected to earthquake motions. A shear wall is modelled as a quasi-three dimensional structure which is composed of plane elements considering the in-plane stiffness of orthogonal flange panels. The proposed constitutive model is based on the non-linearity of reinforcement and concrete in which the tension stiffening in tension and the degradation of stiffness and strength in compression of concrete after cracking are considered. The acceleration-pulse method, which is a kind of explicit analytical procedure, is employed to solve the non-linear dynamic equations, where the dynamic equation can be solved without stiffness matrix and so the iterative procedure is not necessary for descending portion of stress–strain relationship caused by cracking and softening after compressive strength in concrete. The damping effect is considered by assuming equivalent viscous damping which can give good cyclic behaviours of inertia force vs. displacement relationships. This analytical method was applied to a test specimen of a reinforced concrete shear wall with a H-shaped section which was vibrated up to failure by using a large-scale shaking table with high -performance in Japan. The test was performed as one of the dynamic model tests for evaluation of seismic behaviour of nuclear reactor buildings. The calculations were performed sequentially from the elastic range to failure. The comparison with the test results shows that this approach has good accuracy. © 1997 by John Wiley & Sons Ltd     

A new type of submerged rock drill, “MD-300PT”

A new type of rock drill, which has compact size and a simple mechanism and which can be automatically operated in water, was developed. The drill can obtain 75 cm of rock core from a rocky bottom covered by thin sediments at a maximum depth of 300 m.The drill was operated under a current of 1.5 knots in Sagami Bay south of Tokyo and obtained a 40-cm core of volcanic conglomerate of Miocene age from the slope of a small bank at a depth of 130 m. During the operation the vessel was not anchored.     

Rhonite in molten inclusions from the olivine of allivalite nodules from Malyi Semyachik Volcano and basalts of Klyuchevskoi Volcano,Kamchatka

A microprobe study of olivine found in allivalite nodules from lavas discharged by Malyi Semyachik Volcano and of olivine phenocrysts from basalts discharged by Klyuchevskoi Volcano revealed the presence of rhonite as a daughter mineral, for the first time ever. Rhonite was found in small (10–50 μm) grains that are xenomorphic in intergrowths with other minerals and have regular crystallographic outlines in contact with glass. We also found high-alumina clinopyroxene, chromium-free spinel, and hornblende. Residual glass is distinguished by its higher concentrations of SiO₂, Al₂O₃, alkalies, and by lower concentrations of FeO, MgO, and CaO. The chemical composition of the rhonite we studied is characterized by limited variations of the major components and fits the formula (Si,Al)₆(Ti,Al,Fe⁺³,Fe⁺²,Mn,Mg)₆(Ca,Na)₂O₂₀ well. The data points in the composition of the rhonites we have studied lie in the overall field of much more variable compositions to be found in the field. Unlike the previous findings in alkaline and subalkaline rocks, the rhonite we describe in the present report was found in rocks of the tholeiitic and calc-alkaline series.     

Metal contents in Porites corals: Anthropogenic input of river run-off into a coral reef from an urbanized area, Okinawa

In order to monitor pollutants from urban areas to coral reefs, metal contents in Porites coral samples collected from the Hija River mouth and at nearby sites from the estuary were analyzed. The corals were cleaned by oxidative and reductive treatments to effectively eliminate detritus and organic materials. Metal-to-calcium (Me/Ca) ratios in the samples were determined by ICP-MS. Filtered samples of river water were also measured similarly for metal concentrations. The extent of anthropogenic contribution by riverine input was assessed by comparing the Me/Ca values in corals to those of Rukan-sho, an unpolluted coral reef. High riverine inputs of Mn, Cd, Zn and Ag were observed from Me/Ca values in the coral samples. Manganese in the coral samples showed strong dependence on salinity, varying inversely to the distance from terrestrial sources. Considering a lead background of 25.0 nmol/mol measured in the Rukan-sho corals, Pb/Ca in corals of the Hija River estuary that are two and three times higher may indicate lead enrichment in the river mouth. Because Pb is only moderately high in the Hija River water compared to its concentration in surface seawater, lead may have accumulated in the estuarine water and sediments, resulting in an elevated concentration of lead available for coral uptake.