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| 2. |
- Hossain, M., et al.
(författare)
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Potentiality of intermediate depth aquifer as a source of arsenic and manganese safe tubewells in Bangladesh
- 2012
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Ingår i: Understanding the Geological and Medical Interface of Arsenic, As 2012 - 4th International Congress: Arsenic in the Environment. - : Taylor & Francis Group. - 9780415637633 ; , s. 71-73
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Konferensbidrag (refereegranskat)abstract
- Shallow tubewells excepting those installed in red/off-white sediments are mostly contaminated with high arsenic. Social survey conducted in 96 villages of Matlab, a worse-affected area of Bangladesh, reveals that only 18% of tubewells provide As-safe water. In such a condition, high Manganese in many wells is found to be an additional problem. Based on monitoring in depth-specific piezometers, drinking water wells were installed in intermediate depth aquifer around 120 m. Ninety percent of the wells installed in light grey medium sand, had arsenic concentrations below the Bangladesh standard of 50 ÎŒg/L and manganese was within the previous WHO guideline (0.4 mg/L). Availability of similar sand over this depth range could be targeted by local drillers to tap safe water at a reasonable cost. Replication trials and periodical monitoring are emphasized for validation and sustainability.
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| 3. |
- Hossain, Mohammad, et al.
(författare)
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Strategic approach for up-scaling safe water access considering hydrogeological suitability and social mapping in Matlab, southeastern Bangladesh
- 2013
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Konferensbidrag (refereegranskat)abstract
- In recent years, there has been a significant progress in understanding the source and mobilization process, sediment-water interactions, and distributions of arsenic in groundwater environment in Bangladesh. However, the impacts of arsenic mitigation are still very limited. A social survey conducted during 2009-2011 in 96 villages in Matlab revealed that only 18% of total tubewells provide As-safe water. The safe water access also varied between 0 and 90 percent in the region due to lack of knowledge about the local geology and unplanned tubewell development. SASMIT, an initiative of KTH-International Groundwater Arsenic Research Group has developed a method for safe tubewell installation considering hydrogeological suitability, safe water access and other relevant social and demographic information into account.Piezometers installed at 15 locations over an area of 410 km2, using local boring techniques allowed to delineate the hydrostratigraphy, characterize the aquifers in terms of sediment characteristics, water chemistry and hydraulic head distribution, which ultimately led to the identification of the suitable aquifers for tapping safe water. The piezometer locations with safe drinking water quality were then targeted for safe well installation based on the determination of safe buffer distances in a cluster of a few villages (mouzas). Social mapping of all the villages within the mauzas were done using GIS to evaluate the availability of safe water options for a cluster of households (bari). For safe well installations, priority was given to regions with safe water access, greater number of beneficiaries especially in poor households, and easy access to the site from a cluster of households. Through this approach, it was thus possible to make 95% of the newly installed wells As-safe thus scaled up the safe water access upto 40% in some mauzas. Thus the as a strategy to improve safe water access, the SASMIT study recommends investigating the hydrogeological suitability through installation of few piezometers with a minimum effort and based on the results the implementation plan can be made using GIS based social mappings for relatively uniform distribution and to maximize the safe water access.
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| 4. |
- Jacks, B., et al.
(författare)
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The influence of fodder on vitamin A and ?-carotene in milk - Sahelian mali
- 1999
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Ingår i: Ecology of Food and Nutrition. - 0367-0244 .- 1543-5237. ; 38:2, s. 145-164
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Tidskriftsartikel (refereegranskat)abstract
- Vitamin A deficiency has been reported on repeatedly in recent years from the Sahel region in West Africa. Nomadism, pastoralism and agro-pastoralism are the common systems for food production in the area. Milk was a major food item prior to the repeated droughts of the past few decades. This investigation has looked at the retinol content in milk from various domestic animals at the end of the dry season, which is critical from vitamin A supply point of view. Milk from cows fed on hay from the previous year was devoid of retinol, while milk from goats contained good levels regardless of whether the source of fodder was browse or fresh grass after the onset of rains. Acacia tortilis, a common and preferred fodder tree, is rich in ?-carotene. Establishing small-scale cultivation of other ?-carotene rich, indigenous, woody, non-spiny fodder-species such as Maerua crassifolia, is therefore proposed to increase the vitamin A content, and therefore the value of cow's milk. This could be integrated into the ongoing tree-plantation programs for dune stabilisation.
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| 7. |
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| 8. |
- Bhattacharya, Prosun, et al.
(författare)
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Geogenic arsenic in groundwaters from Terai Alluvial Plain of Nepal
- 2003
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Ingår i: Journal de Physique IV. - : EDP Sciences. - 1155-4339 .- 1764-7177. ; 107, s. 173-176
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Tidskriftsartikel (refereegranskat)abstract
- The origin and mobility of arsenic (As) in the groundwater environment has received serious attention in recent years. Recent studies have reported naturally occurring As in groundwaters of the Terai Alluvial Plains (TAP) in southern Nepal, where groundwater exploitation has increased since the 1960s. The source of As in TAP is geogenic and leached primarily due to weathering of As bearing rocks and sediments in the Himalayas. In our present study, we have investigated the groundwater chemistry in the central part of the TAP in Nawalparasi district. TAP groundwaters are near-neutral to alkaline, with predominantly reducing character and high HCO3-, low SO4- and NO3- concentrations. Elevated HCO3 levels possibly result due to the oxidation of organic matter, low SO42- levels reflect sulfate reduction. Elevated NH4+ concentrations in these groundwaters suggest dissimilatory nitrate reduction in the aquifers. Total arsenic (As,.,) levels in groundwater varied from 1.7 mug/L to as high as 404 mug/L with dominance of As(III) species and elevated levels of dissolved Fe and Mn. Arsenic is mobilized in groundwaters as a result of desorption of As-oxyanions adsorbed onto Fe- and Mn-oxides as well as reductive dissolution of these surface reactive phases from the sediments along with release of As in anoxic groundwaters.
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| 9. |
- Bhattacharya, Prosun, et al.
(författare)
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Metal contamination at a wood preservation site : characterisation and experimental studies on remediation
- 2002
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 290:03-jan, s. 165-180
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this investigation was to determine the occurrence of As, Cu, Cr and Zn in the soil at an abandoned wood preservation unit and to examine some possible extractants for the contaminants in the soil. The mean As content of the contaminated surface soils (0-10 cm) was 186 mg kg(-1), where as the mean concentrations of Cu, Cr and Zn in soils from the contaminated area were 26, 29 and 91 mg kg(-1), respectively. The elevated As content in the mineral soils is related to adsorption of inorganic As phases in the fine grained fractions, which are characterised by large surface area and high positive surface charge under the current acidic conditions. Cu and Cr were found to be rather mobile, which is reflected in their lower abundance in soils and significant accumulation in sediments in the drainage leaving the area. The fine fraction of the soil (<0.125 mm) has an average metal content increased by nearly 34% as compared to the <2-mm fraction conventionally used for the analysis and assessment of soil contamination. The <2-mm fraction constitutes approximately 65% of the total weight while the fine fraction (< 0.125 mm) constitutes approximately 10%. These facts, taken together, are essential for the choice of remediation measures. Oxalate solutions have been tested as extractants for soil remediation. Dark acid oxalate extraction dissolves the amorphous Al- and Fe-oxides and hydroxides and mobilises the adsorbed inorganic As species. Oxalate also acts as a ligand for the cationic heavy metals, releasing them from exchangeable sites. With a three-step sequential leaching, up to 98-99% of the metals could be removed. At lower concentrations and higher pH, the leaching decreased to approximately 70%.
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| 10. |
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