In this study, a rapid digital mapping system was developed using a tablet PC. Usually, digital maps are more compact and handy than hard-copy maps. GPS receivers are convenient devices for real-time positioning in outdoor fields. A digital pen provides the useful interface for a tablet PC. GIS application (ESRI ArcGIS) can enlink these devices and technologies. The distributions of snow-covered and forested areas were visually confirmed from a moving vehicle, and were input into digital maps through a tablet PC. In this system, the GPS receiver displays the current location on the digital maps. The digital maps are seamless, and can be scrolled automatically incorporating information from the GPS receiver. This mapping system, therefore, can obtain and record ground truth data quickly at a speed comparable to that of a moving vehicle, even if the operator does not have any experience of computer mapping. In comparison with mapping using hard-copy maps, 60% of the time necessary for in situ mapping is saved using this system. On the other hand, only 20% of the time necessary for editing the map is saved, due to the difficulty of making a clean copy of an in situ map. In conclusion, 30% of the total time for obtaining ground truth data is saved using this mapping system, which certainly contributes to field surveys in general.
The transportation and circulation of water in the Earth is global from the surface of the Earth to the lower mantle and the core. Water is trapped in hydrous minerals in subducting slabs, and is transported into the deep mantle. One of the most important water reservoirs is the mantle transition zone. Measurements of the diffusion of hydrogen in high-pressure minerals together with seismic and electrical conductivity measurements indicate that water is concentrated locally in the mantle transition zone beneath the subduction zone. The contrast in water solubility between upper mantle and transition zone minerals suggests that there is dehydration melting, and dense hydrous magma might exist in a stable state at the base of the upper mantle, which is consistent with seismic observations suggesting a low-velocity region at this depth.
The climate in the Quaternary is characterized by ice age cycles with periods in the range of tens of thousands to a hundred thousand years, triggered by long-term insolation variations due to the Earth's orbital and precessional motions. Although we can accurately calculate long-term insolation variations at the top of the Earth's atmosphere, we need to know the physical and dynamical processes occurring in the complicated climate system of the Earth in order to understand the true nature and origin of the ice age cycles. In this manuscript, first we briefly review how the gravitational interaction between planets causes insolation variations. Then, we summarize the recent status of large-scale numerical experiments as to how the ice age cycles take place in the climate system of the Earth, with a particular focus on dynamical modeling of ice sheets.
A five-year strategic project (S-1 project), which was organized to clarify the carbon dynamics of terrestrial ecosystems in East Asia was conducted from April 2002 to March 2007 with financial support from the Ministry of Environment, Japan. It had four themes. The first was a bottom-up approach using micrometeorological and ecological techniques to measure carbon dioxide fluxes at sixteen tower sites in Japan and East Asia. The second was a top-down approach using. an inverse model based on atmospheric CO2 concentration data finely measured at six western Siberian sites. The third was a modeling approach driven by data-based quality-controlled data from the first theme and artificial satellite data. The fourth and final theme synthesized the results of the three themes mentioned above following a systems approach, which led to a comprehensive conclusion. The main results obtained by the many principal investigators of the S-1 project are summarized below. 1. Characteristic seasonal changes of Net Ecosystem Production (NEP) were obtained from ten tower flux sites including forest and grassland sites. 2. Annual NEP values obtained by micrometeorological and ecological techniques showed almost satisfactory agreement at the six forest sites, although those obtained by the micrometeorological technique were usually higher than ones obtained by the ecological technique. 3. A satisfactory agreement was obtained for seasonal changes of biomass at a paddy field site between results obtained by micrometeorological and ecological harvesting techniques. 4. Seasonal changes of NEP in western Siberia estimated by an inverse model showed a similar pattern to those of an ecological process-based model, Sim-CYCLE, but there was a fairly large difference between the estimated annual values of the two models. 5. Gross Primary Production (GPP) and Net Primary Production (MPP) maps of a spacially high resolution drawn by Sim-CYCLE revealed a characteristic pattern reflecting the diverse vegetation types in East Asia. This region was estimated to be a net carbon sink, with 57 Tg carbon on an annual average during the six years from 2000 to 2005, although annual values fluctuated greatly due to weather conditions.
This article outlines the latest scientific knowledge on global warming/climate change, especially in the meteorological and climatological fields, presented in the fourth assessment report (AR4) from Intergovernmental Panel on Climate Change (IPCC) in 2007, and provides a comparison with the third assessment report (TAR). In the review of WG1 report, we summarize “Observed recent climate change” and “Future climate projection, ” referring to major events and climate variables. In the review of WG2, we summarize the results on the main potential impacts of global warming projected on the natural environment and ecosystems in the future. Finally, a review of downscaling studies is presented, which are very important as they provide a bridge between regional scale climate change information presented in WG1 and WG2. Since TAR, progress in understanding how climate is changing in space and in time has been gained through improvements and extensions of numerous datasets and data analyses, broader geographic coverage, better understanding of uncertainties, and a wider variety of measurements. Understanding of anthropogenic warming and cooling influences on climate has also improved. AR4 concludes with very high confidence (higher than TAR) that : i) climate warming is unequivocal and ii) the global average net effect of human activities since 1750 has been one of warming. In studies on the impacts of global warming, understanding of global warming risk is evaluated more quantitatively based on greatly increased studies of observed trends in the physical and biological environment and their relationships with regional climate change, as well as improved future climate projections on a regional scale.
A new field of dryland science is emerging as a synthetic and interdisciplinary approach that seeks to understand the fundamental characteristics and dynamics of nature and human activities in drylands and their interactions. The applied aspect of dryland science attempts to address environmental and socio-economic issues that occur in the dryland nature-human system by taking region-specific appropriate measures to maintain and enhance its sustainability. First, this review paper aims to outline the major results of the IPCC Fourth Assessment Report on observed and projected future climate change in the world's drylands and their impacts on the nature-human system. The second purpose is to summarize the conceptual framework and the methodology from dryland science to measure the sustainability or the vulnerability of the system against drought as a perturbation. Recommendations are given for developing a drought early warning system as an earth-scientific proactive countermeasure to mitigate the impact.
Recent advances in studies on long-term changes in precipitation amount and its characteristics in the world and its regional aspects are reviewed. According to the IPCC Fourth Assessment Report (IPCC, 2007), global annual land precipitation has increased about 1.08-1.10 mm per decade since 1901. Precipitation amount mainly increased in middle and high latitudes. Increases in winter precipitation are obvious in Eurasia, North America and northern Europe. On the other hand, decreasing tendency are observed in southern Europe, northern Africa, and South and Southeast Asia. There is no evident trend in Oceania and Central America. Although a long-term increasing trend is seen in the global land average precipitation, there are distinct decadal-scale temporal variations in precipitation time series. It is expected that precipitation characteristics, such as precipitation frequency, and intensity, will increase because of an increase in the water holding capacity of the atmosphere in a fu.ture warmer world. Changes in precipitation characteristics have been investigated in many re gions around the world. The frequency of heavy precipitation has tended to increase in several countries in the middle and high latitudes during recent decades. In Central America and the Caribbean region, interannual variations related to SST variations in the tropical Pacific and the tropical Atlantic were observed. The contribution of very wet days to annual total precipitation across the globe has sharply increased in recent decades. However, daily precipitation data used for investigating on the precipitation characteristics are very limited, particularly, in African and Southeast Asian regions. Thus, the long-term changes in precipitation characteristics presented in a number of recent global and regional reports are not very reliable for these regions. Data rescue activity, particularly, for the first half of the 20th century is urgently needed in such sparse data regions, as Africa and Southeast Asia.
Recent studies on climate change during the historical period are reviewed in this paper. Firstly, methods, limitations and materials for reconstructing past climates are summarized. Historic diaries and old documents are useful particularly for the period of the past 500 years. Some indices for expressing the climatic conditions found in the historic materials are introduced. Historic documents and materials found in China since 4, 000 BP were published in 2004. On the other hand, daily weather data at several stations for the 15 and 16 centuries in Japan were published in 2004 and 2006, respectively. Secondly, the “Little hypsithermal (warm) period” during the period from the 4th century to the 10th century is described. In the final part of the present paper, examples of an ancient central government in Japan, planning of Heijoukyou (an old center of government), settlements developed on the Boso Peninsula, Chiba, Japan, and parallel activities in Southeast Asia are discussed in relation to the changing climate during the “Little climatic optimum” from the 8th century to 9th century, which was the peak of the “Little hypsithermal (warm) period”. It is pointed out that the changes were roughly in parallel.
Recently, environmental problems caused by hazardous chemicals have become a great concern in terms of geo-pollution and soil contamination. Natural sources of heavy metals in soil and sediments are quite common in the subsurface environment in Japan, which has large metal deposits and geologic formations from marine strata. Background levels of As, Pb, Cd, and other toxic elements are relatively high in soil and sediments compared to other countries in Europe and Asia. This paper presents the features of heavy metals in soils, and the distribution and concentration of heavy metals in Japan in terms of soil and geo-pollution. We have developed a geo-informatics system with risk maps for heavy metals on a regional scale, based on the accumulated results of various geological and environmental surveys. The role of environmental geology is also discussed to propose remedial action for soil contamination, and to reveal the importance of risk management. The geo-environment risk assessment system, one of the outcomes of our research, can be used to reduce contamination due to heavy metals and toxic chemicals in soil using geo-environment information data. These research outcomes can also be applied to environmental problems such as ecological risk assessment, tunnel excavation in civil engineering, and land use policy in industrial location.
We have developed a GIS-based geosphere integration information system named Geosphere Environmental Informatics for evaluating heavy metal distribution on a national-scale. Geosphere Environmental Informatics includes various geosphere environmental information such as geological map, soil map, vegetation topography, locations of mineral deposits, alteration zone, anomalies of heavy metals, satellite images, groundwater information, and concentrations of heavy metals in rocks, soils and river-bed sediments. The system has some new geoprocessing tools. The Map integration tool integrates various geosphere maps. The River catchment tool creates individual stream networks with their features. The Intelligence search refinement tool extracts the objective characteristics of geosphere information from the GIS database. Heavy metal concentrations of several kinds of rock and river-bed sediments distributed in the model field (Kuroko deposits district in Akita Prefecture, Japan) were examined to evaluate heavy metal concentrations caused by mining and those in a natural state. Hydrothermal alteration zones related to are mineralization show the strong effects of heavy metal concentrations in river-bed sediments. It is difficult to distinguish artificial pollution from the natural abundance of heavy metals in altered rocks and river-bed sediments around a mine. A field survey over a wide area and detailed analyses of items including transport and precipitation mechanisms are required to evaluate artificial heavy metal pollution in a mining district. Chemical species of heavy metals in extracted solutions from rocks were examined by successive filtration. Heavy metals extracted from black slate existed in the solution as truly dissolved species. On the other hand, the amounts of truly dissolved species in solutions extracted from weathered slate decreased, and dominant chemical species of heavy metals were adsorbates on fine and coarse colloidal particles. In addition, colloidal particles show different REEs affinities. These results imply possible fractionation among REEs during chemical weathering and transport processes by colloidal particles.
The soil Contamination Countermeasures Law (referred to hereafter as the Law) was legislated to prevent damage to health from toxic substances (e.g. As, Cd, and Pb) in soils and sediments, caused by oral ingestion of these toxic substances through drinking ground water and eating foods containing fine-grained soil and sediment particles. To apply the Law, we must judge whether soils have high toxic metal concentrations or high leachabilities caused by anthropogenic or natural processes. If high toxic metal concentrations or high leachabilities are caused by natural processes, administration of the Law should not oblige landowners, managers, and occupiers of contaminated sites to remedy them. Therefore, it is essential to determine natural levels of As, Cd, and Pb concentrations and their leachabilities in soils and sediments. We also need to evaluate the potential risk of natural contamination and potential harm to human health. We obtained toxic metal concentrations of rocks, sediments, and soils in the Anesaki and Sendai areas, as well as their leachabilities, to publish “Geochemistry of rocks, sediments, and soils of these areas”. Arsenic, Cd, and Pb concentrations in these areas are lower than the regulated level (150 mg/kg) under the Law. However, the leachabilities of some marine sediments are higher than regulated levels (0.01 mg/L) under the Law. The arsenic leachabilities of some marine sediment samples become higher as the pH of the leaching test solution increases, because As occurs as an anion in the test solution, and is absorbed efficiently by allophane and iron oxyhidrite as pH increases. The arsenic concentration of the leaching test solution will be higher than regulated levels, when the sediment releases calcium ions and pH increases. Meanwhile, cadmium leachabilities of some marine sediment samples become higher as the pH of the test solution decreases, because Cd occurs as a cation in the solution and will be absorbed by these minerals efficiently as pH decreases. The cadmium concentration of the leaching test solution will be higher than regulated levels, when the sediment releases sulfate ions and pH decreases.<BRSome Tatsunokuchi sediments in the Sendai area are characterized by high Cd (>10 mg/ kg) and high Cd/Zn ratio (>0.2). These values are similar to those of seawater suggesting that seawater is the main source of Cd and Zn, and that they were concentrated in the sediment. Such a high Cd sediment must be treated carefully to prevent soil and river contamination.
There are many volcanoes and hot springs in Japan; therefore, many geological layers inherently contain substantial amounts of heavy metals originating from hydrothermal alternation processes. The toxicities of heavy metals contained in geological layers have long been recognized as health and/or environmental risks from the development of metal or non-metal resources in mining areas. Recently, the environmental impacts of naturally-originating heavy metals during construction work for civil engineering purposes, such as roads and tunnels, have been recognized to raise similar risks. The Soil Contamination Countermeasures Law enforced in 2003 defines responsible corporations in charge of preventing environmental contamination of the ground, and stipulates technical aspects regarding investigation surveys and countermeasure techniques. This law mainly covers soil contamination cases, especially in urban areas, to preserve human health. Therefore, it has not been able to deal fully with the environmental impacts of contamination by toxic heavy metals due to construction work not only in urban areas but also in suburban areas. The intent of this paper is to review and discuss chemical characteristics and environmental impacts of naturally-occurring heavy metals. Furthermore, some case studies on necessary assessment methodologies and countermeasures techniques are introduced.
Humic substances (HSs), which are ubiquitous in soil environments, are directly and/or indirectly related to the detoxification of organic pollutants. To enhance the catalytic activity of iron (III) -porphyrins (Fe (III) -Por) and phthalocyanines (Fe (III) -Pc), which mimick the active centers of oxidative enzymes from soil microorganisms, the effects of adding of HSs were examined. In this paper, the author reviews a series of works on the effects of humic substances on the oxidative degradation of organic pollutants by biomimetic catalytic systems. The degradation of pentachlorophenol by both Fe (III) -Por and Fe (III) -Pc was dramatically enhanced in the presence of some HSs with lower polarity. It was found that self-degradation of catalysts resulted in a reduction of catalytic activity. In addition, Fe (III) -Por was incorporated into HS via hydrophobic interactions, and kinetic constants for self-degradation decreased with an increase in the binding constant. Therefore, the formation of a supramolecular complex between Fe (III) -Por and HS can stabilize the catalyst, and this leads to enhanced catalytic activity.
Microorganisms have a variety of functions that relates to the remediation of subsurface contaminants. Therefore, they are important in subsurface environments. Studies on subsurface microbial ecology with the aim of remediating subsurface contamination have mainly focused on groundwater or aquifer materials because the aquitard (composed of clay or silt) has been considered as a place with little or no microbial activity. However, recent studies on microbiology in aquitard materials have revealed new aspects of this environment. The aquitard can be a source of nutrients, such as organic matter, to the adjacent aquifer, and stimulate microbial activity in the aquifer. Microbial activity is considered to be limited by the pore size distribution of the aquitard, and relatively higher microbial activity has been detected in a younger and shallower aquitard with larger pore size. In this article, I introduce these relationships between subsurface microorganisms and the aquitard.
The nitrate contamination level in groundwater depends on hydrogeological properties underground as well as the agricultural system aboveground. Excessive use of nitrogen fertilizers leads to nitrate contamination of groundwater under the crop area, and the nitrate concentration level will be severe if the ground is composed of coarse material and has high permeability. The impact of nitrate reaching groundwater is also influenced by the microbial activity of anaerobes in soil that contributes denitrification. In the present state of this issue in Japan, the main governmental action for this problem is to reduce the excessive use of fertilizer and manure. However, groundwater monitoring results by the Japan Environmental Protection Agency indicates that nitrate contamination is still spreading nationwide and the nitrate concentration in groundwater has exceeded the regulation level (10 mg/L) in 5% of the monitoring wells since 1995. Therefore, development of an effective cleanup measure has been required. In this paper, pilot-scale field application of a horizontal Permeable Reactive Barrier (PRB), which is a nitrate cleanup technology for the vadose zone, is introduced. The horizontal PRB installed in this study consists of an accelerative denitrifying layer with low permeability and an organic matter supplying layer embedded on it. The low permeable layer using field soil retains a lot of water in the vadose zone because of capillary force, and a reductive condition adopted for denitrification seems to be gradually formed in the barrier. In fact, the concentration of nitrate in soil water (unsaturated condition) declined from 6-8 mg/L to less than 0.1 mg/L in the accelerative denitrifying layer without an organic matter supplying layer, and an increase of inorganic carbon (IC) content from 35 mg/L to 50 mg/L was observed. An increase of IC indicates that the field soil originally contained a significant amount of water-soluble organic matter and biological mineralization of dissolved organic matter occurred in pore water. Therefore, a low permeable soil layer with a suitable organic content acts as a denitrification layer, and installation of such a layer under the ground could be an effective measure to preserve groundwater from nitrate impact.
The states of contaminated soil vary widely; therefore, the techniques applicable to the soil concerned and appropriate equipment should be selected and used with care. The authors developed a contamination diagnosis method involving an investigation into types of contamination and contaminated states of different grain-size fractions, as well as a highly efficient method of remediating heavy metal-contaminated soil using grain sorting, gravity separation, and grainsurface attrition according to the properties of the soil. We conducted soil remediation using contamination diagnosis and highly efficient remediation methods for both on-site and fixed-site (off-site) cleaning cases, and achieved cleaning efficiencies exceeding 80% in both cases (more than 80% of contaminated soil was cleaned). The cleaned soil obtained in the on-site case was reused as backfill at the site. The cleaned soil in the fixed-site case (off-site case) was effectively recycled as a raw material for fine aggregate.