YANO Yasunori



Center for International Relations


Assistant Professor

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  • P7. Countermeasure for Arsenic Contamination Groundwater at Uttar Pradesh in India

    Ito Kenichi, Yano Yasunori, Sezaki Mitsuhiro, Shiomori Koichiro, Yokota Hiroshi

    23   153 - 154   2011

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    Language:Japanese   Publishing type:Research paper (scientific journal)  

  • Arsenic contamination in groundwater of Samta, Bangladesh

    Yokota H., Tanabe K., Sezaki M., Yano Y., Hamabe K., Yabuuchi K., Tokunaga H.

    Water Science and Technology   46 ( 11-12 )   375 - 380   2002

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:Water Science and Technology  

    In March 1997, we analyzed the water of all tubewells used for drinking in Samta village in the Jessore district, Bangladesh. It has been confirmed from the survey that the arsenic contamination in Samta was one of the worst in the Ganges basin including West Bengal, India. 90% of the tubewells had arsenic concentrations above the Bangladesh standard of 0.05 mg/l. Tubewells with higher arsenic concentrations of over 0.50 mg/l were distributed in the southern area with a belt-like shape from east to west, and the distribution of arsenic concentration showed gradual decreasing toward northern area of the village. In order to examine the characteristics of the arsenic distribution in Samta, we have performed investigations such as: 1) the characteristics of groundwater flow, 2) the distribution of arsenic in the ground, 3) the concentration of arsenic and the other dissolved materials in groundwater, and 4) the distribution of arsenic concentration of trivalence and pentavalence. This paper examines the mechanism of arsenic release to groundwater and explains the above-mentioned characteristics of the arsenic contamination in Samta through the investigations of the survey results for these years.

    DOI: 10.2166/wst.2002.0765


  • Arsenic Pollution of Groundwater in Bangladesh : Characteristic of Arsenic Concentration and Mechanism of Arsenic Elution to Groundwater in Samta

    TANABE Kimiko, YANO Yasunori, HIROKI Minenari, HAMABE Kazuhiro, YABUUCHI Kazuhiro, YOKOTA Hiroshi, HIRONAKA Hiromi, TOKUNAGA Hiroshi, RAHMAN M. Hamidur, AHMED M. Feroze

    Journal of Japan Society on Water Environment   24 ( 6 )   367 - 375   2001.6

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:Japan Society on Water Environment  

    We have surveyed water quality in Samta village in Bangladesh since March 1997, and analyzed the arsenic concentrations of groundwater in the area surrounding Samta. This paper shows the results of the survey, concerning the characteristics of arsenic contamination of groundwater and the nechanism of arsemic elution.<br>1) The arsenic concentration of groundwater in Samta showed the tendency to increase with the passage of time.<br>2) The arsenic contamination is observed widely in the area surrounding Samta, although not so high as in Samta.<br>3) It is characteristic that concentration of HCO<sub>3</sub><sup>-</sup> and Fe<sup>2+</sup> in groundwater are high and their distribution is in accordance with that of arsenic contamination.<br>4) The pentavalent arsenic concentration in groundwater was higher than that of trivalent in the north of Samta, but in the south trivalent arsenic concentration was higher than that of pentavalent.<br>5) The distribution of HCO<sub>3</sub><sup>-</sup>, Fe<sup>2+</sup> and EC in groundwater explains that the mechanism of arsenic elution to groundwater is mainly caused via the reduced state of groundwater and partially via oxidation state.<br>6) There is some correlation between thickness of upper muddy layer and distribution of arsenic concentration of groundwater in Samta.

    DOI: 10.2965/jswe.24.367

  • Arsenic contamination in groundwater and hydrogeological background in Samta village, western Bangladesh(<Special issue>elucidating the mechanism of arsenic contamination of groundwater in Asia with special reference of research in Bangladesh)

    Research Group for Applied Geology Sub-group for Arsenic Contamination, Miyazaki University Research Group for Arsenic Contamination in Groundwater

    Earth Science (Chikyu Kagaku)   54 ( 2 )   105 - 126   2000

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:The Association for the Geological Collaboration in Japan  

    <p>The groundwater contamination by arsenic has become a serious problem for human health in Bangladesh and West Bengal State of India. Since 1996, the Asia Arsenic Network (AAN) and the Research Group for Applied Geology (RGAG) have started their activities to tackle the arsenic problem in Bangladesh. The AAN and RGAG selected Samta village in Jessore district, western Bangladesh as a pilot village for their activities. The RGAG has carried out hydrogeological investigations including core sample analysis and groundwater monitoring at constructed observation wells since 1998 to reveal the source and the mechanism of the arsenic contamination. The AAN and the research group of Miyazaki University measured concentration of arsenic and groundwater quality at the observation wells and selected private wells. It is known by the AAN that the concentration of As is higher than the Bangladesh drinking water standard (=0.05mg/l) in the southern part of the village, whereas the As concentration is lower than the standard in the northeastern part. Samta village is bounded on the east by the Betna river, that flows from north to south with bending toward west. The geomorphology of Samta village, which is situated on the Ganges delta and has elevation between about 5 to 7m, is subdivided into natural levee, gentle slope and back swamp. The continuous core drilling was performed up to a depth of 64m at the central part of the village to investigate subsurface hydrogeologic conditions. A total of 23 observation wells were drilled with collecting core samples in Samta village and Deuli village, which is located east of Samta village. Soil auger survey and interpretation of existing deep tube wells' data were also carried out. As a result, it is found that the sediments of Samta village within a depth of 200m consist of lower sandy layer (ls), lower muddy layer (lm), upper sandy layer (us), upper muddy layer (um), upper most sandy layer (ums), upper most muddy layer (umm), and embankment (b). The sediments are hydrogeologically classified into the unconfined aquifer (ums) having perched water, the first aquitard (um), the first confined aquifer (us), the second aquitard (lm), and the second confined aquifer (ls). The private tube wells extract groundwater from the first aquifer, which is contaminated by As. The deep tube wells constructed by the Department of Public Health Engineering (DPHE) use the groundwater from the second aquifer, which is not contaminated by As so far. Gradual rise in rainy season and sharp drop in dry season were characterized by the changes in piezometric head in the first aquifer. A typical recession curve was not found from the hydrograph, indicating that the changes are affected by vertical leakage caused by the pumpage from the deeper part of the first aquifer for irrigation use. The result of As content test shows that the As content is high in the first aquitard (um), ranging from 3.0 to 261.5mg/kg. Particularly, peaty samples in the layer have high As contents from 46.5 to 261.5mg/kg. On the other hand, the As content in (umm), (ums), and (us) was relatively low (0.7 to 23.0mg/kg). The distribution of As content in (um) shows that high As content is found in the central to southern Deuli and in the central to southern Samta. The As concentration in groundwater of the first aquifer was measured by the field kit using Hironaka method, AAS in Miyazaki University, and SDDC spectrophotometry in DPHE Rajshahi laboratory. The results show that the As concentration is high in the southern part of Samta and low in the northeastern part. The measurement at private wells shows that As concentration in October 1997 (rainy season) is higher than that in March 1997 and May 1998 (dry season). The As concentration measured at the observation wells having different well depths and screen depths at the same location shows that the groundwater in the upper part of (us) has</p><p>(View PDF for the rest of the abstract.)</p>

    DOI: 10.15080/agcjchikyukagaku.54.2_105