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Arsenic and groundwater properties o...

Dhar, Ratan Kumar.

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Arsenic and groundwater properties of Araihazar, Bangladesh.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Arsenic and groundwater properties of Araihazar, Bangladesh./
Author:	Dhar, Ratan Kumar.
Description:	208 p.
Notes:	Adviser: Yan Zheng.
Contained By:	Dissertation Abstracts International67-08B.
Subject:	Chemistry, Analytical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3232012
ISBN:	9780542850905

Arsenic and groundwater properties of Araihazar, Bangladesh.
Dhar, Ratan Kumar.

Arsenic and groundwater properties of Araihazar, Bangladesh. - 208 p.

Adviser: Yan Zheng.

Thesis (Ph.D.)--City University of New York, 2006.

Arsenic is a highly toxic and ubiquitous metalloid dispersed throughout the earth's crust. It can be mobilized in the environment through a combination of natural processes. The mobilization of arsenic from aquifer materials usually occurs under reducing conditions and is microbially mediated. This was observed in aquifers of Araihazar, Bangladesh. There, elevated dissolved As concentrations in groundwater were found mostly in the form of inorganic arsenic as arsenite, using several analytical methods including one that uses a modified colorimetric method. However, time series data demonstrate that variations in groundwater As concentrations were considerably less in comparison to other redox-sensitive elements such as Fe, Mn and S, suggesting that there are significant decoupling between As mobilization and redox state of the aquifer. To resolve the uncertainty regarding whether mobilization of As from sediment requires reduction or not at crustal abundances, a series of laboratory microcosm experiments using a representative natural sediment sample collected from Araihazar, Bangladesh were conducted. The results show that mobilization of As does not require reduction. The mobilization and reduction of Fe and Mn are predominantly limited by availability of electron donors such as lactate. However, the mobilization and reduction of As appears to have more limiting factors such as the type of microbes present in the system. This study also reinforced the notion that although reducing conditions are key to the mobilization of As in Bangladesh shallow aquifer, As concentrations can be significantly decoupled from Fe and P. This difference, in part, is because Fe and P concentrations are regulated by several mineral precipitation reactions. In addition to potential differences in microbial communities, there is a remarkable difference in several nutrients between the Holocene shallow aquifer and the Pleistocene deep aquifer. Future studies of the implication of the nutrient and microbial contrast on As mobility in both aquifers and viability of deep aquifer as a drinking water source are much needed.

ISBN: 9780542850905Subjects--Topical Terms:

586156
Chemistry, Analytical.

Arsenic and groundwater properties of Araihazar, Bangladesh.
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005 20110915
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035 $a (UMI)AAI3232012
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100 1 $a Dhar, Ratan Kumar. $3 1291535
245 1 0 $a Arsenic and groundwater properties of Araihazar, Bangladesh.
300 $a 208 p.
500 $a Adviser: Yan Zheng.
500 $a Source: Dissertation Abstracts International, Volume: 67-08, Section: B, page: 4304.
502 $a Thesis (Ph.D.)--City University of New York, 2006.
520 $a Arsenic is a highly toxic and ubiquitous metalloid dispersed throughout the earth's crust. It can be mobilized in the environment through a combination of natural processes. The mobilization of arsenic from aquifer materials usually occurs under reducing conditions and is microbially mediated. This was observed in aquifers of Araihazar, Bangladesh. There, elevated dissolved As concentrations in groundwater were found mostly in the form of inorganic arsenic as arsenite, using several analytical methods including one that uses a modified colorimetric method. However, time series data demonstrate that variations in groundwater As concentrations were considerably less in comparison to other redox-sensitive elements such as Fe, Mn and S, suggesting that there are significant decoupling between As mobilization and redox state of the aquifer. To resolve the uncertainty regarding whether mobilization of As from sediment requires reduction or not at crustal abundances, a series of laboratory microcosm experiments using a representative natural sediment sample collected from Araihazar, Bangladesh were conducted. The results show that mobilization of As does not require reduction. The mobilization and reduction of Fe and Mn are predominantly limited by availability of electron donors such as lactate. However, the mobilization and reduction of As appears to have more limiting factors such as the type of microbes present in the system. This study also reinforced the notion that although reducing conditions are key to the mobilization of As in Bangladesh shallow aquifer, As concentrations can be significantly decoupled from Fe and P. This difference, in part, is because Fe and P concentrations are regulated by several mineral precipitation reactions. In addition to potential differences in microbial communities, there is a remarkable difference in several nutrients between the Holocene shallow aquifer and the Pleistocene deep aquifer. Future studies of the implication of the nutrient and microbial contrast on As mobility in both aquifers and viability of deep aquifer as a drinking water source are much needed.
590 $a School code: 0046.
650 4 $a Chemistry, Analytical. $3 586156
650 4 $a Geochemistry. $3 539092
650 4 $a Health Sciences, Public Health. $3 1017659
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