Masayoshi Nakawo

The groundwater recharge mechanism in the hyper-arid Gobi Desert of Northwestern China was analyzed using water balance and tracer-based approaches. Investigations of evaporation, soil water content, and their relationships with individual rainfall events were conducted from April to August of 2004. Water sampling of rainwater, groundwater and surf...

We measured water quality, oxygen, and hydrogen stable isotopes and tritium concentrations in river water, irrigation water, and groundwater in irrigated areas of the middle basin of the Heihe River Basin, located in a semiarid region, in September 2008. Geochemical data clarified groundwater recharge and flow processes, including effects of human...

A multiple parameter dating technique was used to establish a depth/age scale for a 171.3 m (145.87 m w.e.) surface to bedrock ice core (Bl2003) recovered from the cold recrystallization accumulation zone of the Western Belukha Plateau (4115 m a.s.l.) in the Siberian Altai Mountains. The ice-core record presented visible layering of annual accumula...

A hydrological field survey using multi-tracers was performed to identify groundwater recharge sources and those contribution rates at the village scale in an irrigated area in a semi-arid region. Groundwater, river water and irrigation water samples were taken in Pingchuan village which is irrigated by river water and groundwater in Heihe River ba...

In order to reconstruct the past climate and environmental changes, we carried out sampling and chemical analyses of surface snow and ice, and precipitation on Qiyi Glacier, Qilian Mountains, western China, in August and September 2004. A mean pH value of surface snow and ice was 7.07. We found high correlation (r=0.98) between difference of total...

Spatial and temporal variations in the suspended sediment concentration (SSC) of supraglacial lakes in debris-covered areas were investigated on the Lirung Glacier in the Langtang region of central Nepal from May to Octorber 1996. Twenty-eight lakes of various sizes were observed on the glacier. SSC varied widely among the lakes from 0 to 364 mg l-...

Over the last two millennia, agricultural land in the Hei river basin, northwest China, has been subjected to a series of significant droughts and flood events. These documented hydrological events were compared to estimates of fluvial and fluvioglacial discharge from the mountains. Areal extents of glaciers are important for validation as water ma...

old environments, including glacier ice and snow, are known habitats for cold-adapted microorganisms. We investigated the potential for cold-adapted yeast to have propagated in the snow of the high-altitude Belukha glacier. We detected the presence of highly concentrated yeast (over 104 cells mL−1) in samples of both an ice core and firn snow. Incr...

During the period December 1979 to June 1980, five visits were made to observe and measure ice behaviour around the wharf at Nanisivik, on Baffin Island. The measurements included ice thickness, temperature, salinity, and density, as well as horizontal movements of the ice cover. In March 1980, additional measurements and observations were made of...

In this study, we used a 4.00-m pit on Belukha glacier in Russia's Altai region and attempted to establish the timing of chemical deposition events by analyzing pollen profiles. As the pollen deposition of each examined taxon on the glacier surfaces followed a distinct seasonal phenology, seasonal layers could be identified over a two-year period....

In a previous study, past summer temperatures were reconstructed from melt features in the Belukha ice core, Siberian Altai. We evaluated the climatic representativeness of net accumulation and melt features by comparing two Belukha ice cores retrieved at neighboring sites by different institutions and dated by different methods. Melt features in b...

The variations of stable isotopes including deuterium excess d over south-west China are displayed, and the relationships of the stable isotopes in precipitation with temperature and humidity at different altitudes are also researched. Under the prevailing monsoon system, distinct seasonality for δ18O and d in precipitation are shown and the revers...

Discharge was calculated from a mountainous area, including discharge from glaciers, in the Qilian Shan (Qilian Mountains) of northwest China. The studied Yingluoxia basin is 9983 km ² in area, with glaciers making up 0·3% of the basin. The calculation method was based on the heat balance, requiring only daily temperature and precipitation. Calcula...

A 51 m deep ice core was re-drilled on the Dunde Ice Cap of western China in 2002, 15 years after the previous ice core drilling in 1987. Dating by seasonal variations in δ18O and particle concentration showed that this 51 m deep ice core covered approximately the last 150 years. The stratigraphy and density showed that more than 90% of the ice cor...

A snow algal community on Rikha-Samba Glacier in the western Nepali Himalayas was investigated in October, 1998. Examination of surface snow and ice on the glacier revealed that this community consisted of mainly seven taxa including green algae and cyanobacteria. The algal community showed an altitudinal distribution on the glacier: its biomass de...

no abstract available

Since ancient times meltwater from glaciers in mountain zones has been an important water resource in the arid region of northwest China. Meteorological elements for heat balance calculations at the glacier surface were simplified with the aim of simulating discharge fluctuations from the July 1st Glacier over a span of decades. By estimating relat...

Stable isotope exchange processes between solid and liquid phases of a natural melting snowpack are investigated in detail by separating the liquid water from snow grains at different depths of the snowpack and collecting the bottom discharge using a lysimeter. In the melting–freezing mass exchange process between the two phases, the theoretical sl...

The isotopic composition of solid and liquid portions of natural melting snowpack is investigated in detail by the separating of liquid water from snow grains at different depths of the snowpack. The slope of the δD–δ18O line for the liquid phase is found to be lower than for the solid phase. This is proved to be due to the isotopic fractionation o...

In July 2003, a 171m long ice core was excavated from top of Belukha glacier (4,200m a. s. l.) in the Russian Altai Mountains. We examined vertical distributions of microorganisms (unicellular green algae, fungal spore, yeast) and pollens for potential use of ice core dating and reconstruction of past climate. Microorganisms have no seasonal variat...

This paper presents the stable isotope data of the snow pack and summer precipitation collected at the July 1 Glacier, Qilian Mountains in northwest China and analyses their relationships with meteorological factors. On an event scale, there is no temperature effect on the δ 18O values in the summer precipitation, whereas the amount effect is shown...

River discharge and groundwater level data were collected in the Heihe River basin, which is the second largest inland river in Northwestern China. The surfacewater-groundwater interaction, particularly in the lower desert reaches, was analyzed with the help of isotope data of water collected from the river. In the non-irrigation period, river wate...

The coherent variations of annual snow accumulation rate and dust deposition over 60 years are recorded in an ice core drilled at 6530 ma.s.l. on the Chongce ice cap, located in the west Kunlun Shan, south of the Taklimakan desert in China. These records were investigated in the context both of the dust transport pathways from the source region and...

The albedo reduction on glacier surfaces in past summers due to microbiological activities and mineral particles should be considered to reconstruct precise fluctuation of glacier mass balance. However, there is little knowledge on preservation of the microorganisms and the mineral particles in glacier ice. In particular, influence of superimposed...

Hydrological observation was carried out at the July +st Glacier in the Qilian mountains, northwest China, during the glacier melting season from ,**, to ,**.. Water discharge was measured using two methods, current meter and salt water. The results of these methods showed a good correspondence. A logger for water level was settled at the glacier t...

Ice-core and snow samples collected on Belukha glacier, Russian Altai mountains, were analyzed for n-alkanes by gas chromatography. On the basis of the total concentrations (T-HCs), carbon preference index (CPI) values and the plant wax contributions (WaxC n), it is suggested that mountain glaciers on the Asian continent received higher loading of...

The Aeolian Dust Experiment on Climate Impact (ADEC) was initiated in April 2000 as a joint five-year Japan–China project. The goal was to understand the impact of aeolian dust on climate via radiative forcing (RF). Field experiments and numerical simulations were conducted from the source regions in northwestern China to the downwind region in Jap...

A survey of July 1st glacier, Qilian Shan, China, was carried out in 2002. Previously, the glacier's boundary had been recorded in 1956, and further research had been carried out in the mid-1970s and 1980s. Our survey reveals that area shrinkage and surface lowering have accelerated in the past 15 years. Surface elevation changes can result from ch...

2003年度より全国共同利用センターとして水の安定同位体組成に関する共同研究を開始し，多様な水試料の水素及び酸素安定同位体組成を現在まで行っている．極域から熱帯域，また海洋から大陸内部まで広域に採取された海水，土壌水，河川水，降水，降雪，氷，水蒸気等の多様な水試料を長期間にわたって高い精度・確度を維持しながら分析を行うために，専従の運営委員会を設置し，測定前後の試料管理，質量分析計の管理，分析結果の質的管理を含めて総合的に管理運営するシステムを構築した．2003年以降約1年半にわたる標準水の測定結果によれば，水素及び酸素同位体組成についてそれぞれ0.5‰，0.03‰の再現性を保っていることがわかった.

Abstract: An accurate time scale is necessary for interpretation of an ice core reco rd. The e stablishment of chro no logy is especially difficult for sites where the conventional annual - layer counting using stable isotopes fails due to much less snow deposition. In this work , dating from the analysis of insoluble micro-particles ranging from...

Reliable chronologies in ice cores and snow pits from many alpine glaciers in latitudes between 60° N and 60° S are often difficult to establish owing to problems with annual-layer counting. Problems arise from melting, wind erosion and the negligible amount of precipitation in some seasons, all of which tend to obscure the seasonal variations in δ...

We carried out snow-pit observations at Nagaoka, Niigata prefecture, Japan, where the snow layers were at the melting point. It was observed that the water content in the snowpack was nearly constant at approximately 10%, and the coarsening rate of snow particles was about 0.4 × 10-3 mm3 h-1, which was in the range between the rate for dry snow and...

There is a diverse biological community on the snow and ice surface of glaciers. Recent change of glaciers reported in many parts in the world may affect the biological community on the glaciers. Temporal variation of biological activity on a Himalayan glacier was recovered from a 15 m deep ice core drilled in 1998. The dating showed that the core...

Glacier melt water has an important role for water cycle in the arid region, northwest China, since the amount of precipitation in the mountains is much larger than those in the lower desert area. Historically ground water in the desert has been irrigated by meltwater from glaciers and seasonal snow in the mountains. Isotope ratio of the discharge...

The stable isotopic ratio of water vapor (d18O and dD) was measured near July-1st (Qiyi) Glacier (39.25N, 97.75E, 4250 m) in Northwest China. From 11 to 17 August 2003, we collected and then analyzed atmospheric samples at July-1st Glacier and a base camp (BC), that was 4km from Qiyi. Then the temporal change of the isotopic composition was compare...

Ice core studies from middle and low latitude glaciers have a problem that a reliable dating method has proved difficult due to wind erosion and vanishingly small amount of seasonal precipitation. They obscure the annual signal from the seasonal variations in chemical concentrations and oxygen isotope ratios that are typically used to date for ice...

An extended deuterium excess (d or d-excess) record covering the last three glacial-interglacial cycles (ca. 340,000 years) was obtained from the Dome Fuji ice core, Antarctica. In order to interpret the Antarctic d record as a climatic history of vapor source regions, the record should be corrected for the Antarctic site temperature effect. We pro...

Spatial and temporal variations of oxygen and hydrogen stable isotopes in precipitation were observed on the Tibetan Plateau and in Nepal during the GAME/Tibet field campaign in 1998. Different spatial patterns in delta-18O were found between active and break phases of Indian monsoon activity. During a break phase, low delta-18O with relatively low...

The introduced mathematical model takes into account the role of the kinetic fractionation effect in a supersaturation environment at the ice surface as liquid and solid phases coexist in mixed cloud. Using the model, the temperature effect of stable isotopes in precipitation is simulated under different cooling conditions. The rate of change of δ...

Post-depositional change of isotope concentration was investigated in a temperate snow pack. Daily snow pit studies were carried out at Moshiri, Hokkaido, for about a week in April 1998. During this time the snow layers were at the melting point. Isotope analysis was conducted on snow particles and the liquid water in between the particles every 5...

There is no temperature effect in the southern Tibetan Plateau and South Asia to the south of the Tanggula Mountains. Amount effect has been observed at a few sampling stations accounting for about a half of the statistical stations. There is notable temperature effect in the middle and northern Tibetan Plateau and its adjacent Central Asia to the...

The ablation amount for entire ice cliffs reaches about 2017( of that at the whole debris-covered area, the ablation rate at the ice cliff mainly depends on shortwave radiation, which differs widely with the orientation of all ice cliff. Therefore, the distribution of ice cliffs ill relation to their orientation was observed oil a debris-covered gl...

The ablation amount for entire ice cliffs reaches about 20% of that at the whole debris-covered area; the ablation rate at the ice cliff mainly depends on shortwave radiation, which differs widely with the orientation of an ice cliff. Therefore, the distribution of ice cliffs in relation to their orientation was observed on a debris-covered glacier...

1998年2月から4月にかけて北海道母子里で積雪調査を実施し,そのうち融雪期の湿潤積雪層の同位体比の時間変化過程を調べた.調査では,湿潤積雪から層毎に,固相試料(雪粒子)と液相試料(間隙水)とを別々に採取した.観測期間中の降水と積雪下面からの流出水もあわせて採取した.それぞれの試料についての酸素,水素の同位体比を測定した.その結果,雪粒子の同位体比は間隙水よりも大きい値をとった.その差は表面から下層にいくほど増加する傾向が認められた.また,雪粒子,間隙水ともその同位体比は時間とともに大きくなる結果を得た.これらの結果を解析したところ,積雪表面で融解してできた間隙水の流下が,雪粒子の同位体比の変化に大きな影響をもたらす事が示唆された.

The correlations of the δ18Omax in the shallow ice core from the Guliya ice cap on the Tibetan Plateau with the global sea surface temperatures (SST) and height at the 500 hPa over the Northern Hemisphere were analyzed. The correlated regions on oceans that have a significant influence on the δ18Omax in the Guliya ice core are all located in ocean...

The variation of the δ18O in precipitation and the relationship with precipitation amount at Kyangjin Base House and Yala Glacier Camp in Langtang Valley, Nepal Himalayas were analyzed. The variations of the δ18O with precipitation had great scatter, and the correlations between the δ18O and precipitation changed with time on the synoptic scale. On...

This paper deals with the quantitative impact of air temperature on the measured water content value of wet snow by Akitaya calorimeter. Based on the pre-experiments, a set of operating standards was determined. Upon the standards, large amounts of snow(grains)-water separation and snow water content measurement were conducted in the field. By regr...

Intensive observation of the pressure head in subsurface water and sampling of subsurface water were performed to investigate the subsurface how process in the Tibetan plateau from July 24 to September 12-the monsoon season-1998. Pressure head of the subsurface water was monitored using tensiometers and subsurface water was sampled using suction ly...

The temporal and spatial variations of the δ18O in precipitation on the Tibetan Plateau are analyzed. There is no temperature effect in the southern Tibetan Plateau. Amount effect has been observed at Lhasa station. However, the seasonal variations of the δ18 in precipitation are different from that of precipitation intensity, showing that the prec...

Successive snow pits were dug intensively in a melting snowcover. Water was successfully separated from snow grains in the field for the first time. By measuring δ18O values of water and snow grain samples as well as comparing isotopic profiles, it is found that meltwater percolating down in snow develops quick and clear isotopic fractionation with...

Glaciers are important features in climate studies. The smaller alpine glaciers respond to climatic variation in ways visible during the human lifetime. Glacial processes modify the landscape leaving signatures of past climatic conditions. The large ice sheets have an important role in the global heat and water balance, which in turn play a major r...

Ablation of natural ice under a dust cover was investigated at Lirung Glacier, Nepal Himalayas. Total ablation of a relatively flat ice surface was increased to a maximum of about 4 to 5 fold when the initial dust concentration increased from 0 to 0.112 kg in 2. Ablation decreased from the maximum rate when the dust concentration exceeded 0.112 kg...

There are many supraglacial ponds on debris-covered glaciers in the Nepal Himalayas. The heat absorbed at the surface of a pond was estimated from heat budget observations on the Lirung Glacier in Langtang Valley, Nepal. The results indicated an average heat absorption of 170 W m-2 during the summer monsoon season. This rate is about 7 times the av...

A new model for coupled mass balance and flow of a debris-covered glacier was developed to account for the effects of supraglacial debris on glacier evolution. The model is reasonably consistent with observations of recent shrinkage of the ablation area of Khumbu Glacier, Nepal Himalayas from 1978 to 1999. The model predicts formation and succeedin...

Ablation and heat balance were measured in debris-covered and debris-free areas of the ablation zone of Khumbu Glacier from 22 May to 1 June 1999. On the debris-free ice, the ablation rates ranged from 1.4 to 4.7 cm day" 1 and were inversely correlated with the albedo. The contribution of turbulent heat flux to melting was very small, so net radiat...

中部山岳地帯の立山・室堂平 (標高2450m) に堆積した春季の積雪に含まれる化学成分濃度の深度分布を調べた.1996年4月に採取した室堂平の積雪に含まれるイオン成分は, 濃度の深度分布の類似性から海塩成分 (Na+, Cl-, Mg2+) や黄砂関連成分 (Ca2+, F-, C2O42-, PO43-), 人為的汚染関連成分 (NO3-, 非海塩性SO42-, NH4+, 非海塩性K+, H+) とに分けられた.海塩成分は特に厳冬期に, 黄砂関連成分には春季に数回の濃度ピークがあった. 人為的汚染関連成分の濃度分布は, 初冬季にも春季にも濃度が高くなっていたが, 黄砂関連成分濃度の変化とも深度分布が類似している場合もあった.非海塩性Srと非海塩性Ca2+濃度とは良い相関関係にあり, 平均...